bluuebunny/crossref_metadata_2025 huggingface dataset:
Production of propionic acid by microbiological way. Part 1. Influence of the initial sugars and product concentrations
Authors: Obaya M. C. , Ramos J. , Eng F. , Villa P. , Valdés E. , Martínez A. , González J. , Berovides E. , Williams I. , Chivas M. , Cuellar A.
Published: December 2004

The best yields and productivities of 0.38 g · g−1 and 0.35 g · l−1 h−1, respectively, for the propionic acid production in a batchsystem using sugar‐cane final molasses as carbon source were obtained when an initial TRS concentration of 50 g · l−1 was used.

It was obvious that this process is severely inhibited by the acids produced and the most drastic effect (μ = 0) was at a TVA concentration near to 250 mmol · l−1, independently of the initial TRS concentration employed.

A generalizated equation of noncompetitive inhibition was adjusted:

and kinetic inhibition constants for each initial TRS concentration studied were estimated.
Cellulolytic enzymes of the ligninolytic white‐rot fungus Phlebia radiata
Authors: Rogalski J. , Hatakka A. , Wojtaś‐Wasilewska M. , Leonowicz A.
Published: December 2004

The ligninolytic fungus Phlebia radiata growing in a low‐nitrogen medium with Avicel cellulose as the sole carbon source produced a full spectrum of celluloytic enzymes. Some properties of these enzymes were investigated during the growth of the fungal culture.
Control of the degree of hydrolysis of a protein modification with immobilized protease by the pH‐drop method
Authors: Ge S. J. , Zhang L. X.
Published: December 2004

A mathematical model, DH = 1/k(10−2ΔpH − 1), between the pH‐drop (ΔpH) and degree of hydrolysis (DH) of an enzymatic modification of casein was developed to assess the DH in a packed‐bed column reactor by directly monitoring the pH value of the modified protein system. It was demonstrated that the linear DH range and the k value of the equation were dependent on the reactor type and the specificity of the proteolytic enzymes immobilized on chitin used in the present study, but no effect of the substrate casein concentration on the linear DH range was observed. Since DH and ΔpH values of the modified casein correlated with the flow rate in a packed‐bed column reactor, it was suggested that the DH value, in a considerably wide range of casein modification with a certain immobilized protease in a column reactor, could be controlled by adjusting the flow rate of the substrate and monitored by a pH‐meter. This relationship might be used as a basis for scale‐up and long‐term operation of enzymatic modification of proteins by immobilized protease in a column reactor.
Enantioselective esterification of butanol‐2 in an enzyme membrane reactor
Authors: Ceynowa J. , Sionkowska I.
Published: December 2004

The enzymatic esterification of octanoic acid with racemic butanol‐2 was investigated. Esterifications of the acid were performed in a forced flow enzyme membrane reactor. The used membrane was prepared by a phase inversion process in polyamide‐6 solution followed by the chemical immobilization of a lipase‐catalyst.

Influences of water content and pH were estimated. Their optimum values are equal to 0.5% w/w and pH 8. The reaction rate (at 303 K) of 5.1 × 10−5 mol/h·cm2 of the membrane area, and at least 85% enantiomeric excess in the produced ester mixture were obtained.

The activity of immobilized lipase in the membrane process is about two times higher than that of the native lipase in the esterification performed in a tank reactor.
Optimization of the fermentation of whey by Lactobacillus casei
Authors: Rincón J. , Fuertes J. , Moya A. , Monteagudo J. M. , Rodríguez L.
Published: December 2004

Optimization studies have been carried out for the production of L‐lactic acid from the fermentation of whey by Lactobacillus casei. Two Statistical Designs, a full 24 Factorial Design and a full 32 Factorial Design, have been used to determine the most suitable values of the operational variables for obtaining the maximum lactic acid production rate. The variables selected for study were temperature, pH, lactose concentration, and inoculum concentration. Among them only temperature and pH were found to affect the response significantly. A second‐order polynomial empirical model relating both the response (lactic acid production rate) and the variables was formulated. The maximum acid production rate was found when the values of pH and temperature were 5.4 and 38°C, respectively. All conclusions are restricted to the experimental range studied.
Killer yeasts of Kluyveromyces and Hansenula genera with potential application in fermentation and therapy
Authors: Michalčáková S. , Sulo P. , Sláviková E.
Published: December 2004

The killing/immunity interactions among killer strains of the genera Kluyveromyces, Hansenula and Saccharomyces from the Czechoslovak Collection of Yeasts were studied with the aim to find the strains with broad specificity and killer activity targeted against a range of undesirable wild yeasts causing stuck fermentations. Among 49 tested Kluyveromyces strains, five strains were found, and among 55 Hansenula strains, ten yeast strains were found with activity against a sensitive strain of Saccharomyces. Hansenula mrakii CCY 38‐7‐1 and Hansenula saturnus var. subsufficiens CCY 38‐4‐2 showed exceptional activity against the wine contaminants, Zygosaccharomyces bailii, as well as against pathogenic Candida species within a broad range of pH 2.9–5.1. Their potential biotechnological application is discussed.
Expression of the 2,4‐D degrading plasmid pJP4 of Alcaligenes eutrophus in Rhizobium trifolii
Authors: Feng L. , Van Zwieten L. , Kennedy I. R. , Rolfe B. G. , Gartner E.
Published: December 2004

The 2,4‐dichlorophenoxy acetic acid (2,4‐D) degrading plasmid, pJP4, was transferred into Rhizobium trifolii ANU843 from its nature host Alcaligenes eutrophus JMP134 by conjugation. The ability to degrade 2,4‐D was expressed in the transconjugant ANU843p as shown by a total loss of UV‐absorbent compounds and by gas chromatographic analysis. However, the transconjugant was unable to grow on 2,4‐D alone. When the transconjugant strain ANU843p was inoculated onto white and subterranean clover plants in laboratory trials, the transconjugant retained the capacity of nodulation, but the nitrogen‐fixation activity was diminished, particularly in the case of subterranean clover. The plasmid in the transconjugant was stable in nodules for at least nine weeks after inoculation and could be of value in applications requiring the protection or removal of the 2,4‐D involving cometabolism with plant substrates.
The effects of some amino acids on growth and lipid production in Inonotus obliquus grown in vitro
Authors: Kahlos K.
Published: December 2004

The effect of the distribution of free and esterified fatty acids, including triterpenes and sterols, on the mycelial growth of the basidiomycete Inonotus obliquus (Pers. ex Fr.) Pilat in malt extract and solid supplemented mineral media was investigated. The amino acids DL‐alanine. DL‐aspartic acid, L‐glutamic acid, L‐leucine, L‐methionine, and L‐serine were added to the cultures at nitrogen concentrations of 0.1, 0.5 and 0.9 g/l, respectively. Differences in the average mycelial growth were distinct at concentrations of 0.5 g/l and 0.9 g/l. L‐Methionine had the highest inhibitory effect on growth. At all concentrations, the amino acids reduced the production of lanosterol. The other identified triterpenes were inotodiol, 3β,hydroxy‐lanosta‐8,24‐dien‐21‐al, 3β,21‐dihydroxy‐lanosta‐8,24‐diene, trametenolic acid, and ergosterol peroxide. The main fatty acids were either C 16:0 or C 18:2 both free or in glycerides.
Carbon requirements of Colletotrichum gloeosporioides PENZ
Authors: Madan M.
Published: December 2004

Monosporic isolates of Colletotrichum gloeosporioides were made from Punica grantum and one suitable isolate was selected for further work on carbon nutrition. Preliminary experiments showed that a pH value of 5, a temperature of 32°C and a period of 14 days were optimum conditions for the growth of this pathogen.

Out of 41 carbon compounds tested, the pathogen showed excellent growth on starch, maltose, melibiose, dextrose, sucrose, raffinose, and dulcitol; good on tartaric acid, mannose, galactose, fructose, mannitol, and castor oil; fair on inulin, isopropyl alcohol, coconut oil, and pectin; poor on sorbose, n‐butyl alcohol, arabionose, maleic acid, ethyl alcohol, succinic acid, citric acid, ribose, and malic acid, and no growth on the rest of the carbon compounds. In general, compounds which supported the best mycelial growth, yielded excellent or good sporulation of C. gloeosporioides and vice versa.
Modelling the aerobic degradation of toluene in a closed chemostat with and without a head space outlet
Authors: Löser C. , Ray P.
Published: December 2004

The microbial aerobic decontamination of waste waters contaminated with highly volatile pollutants was experimentally investigated in a closed chemostat in [1]. The experiments, using a previously isolated Pseudomonas strain, were carried out with synthetic waste water containing toluene and saturated with either nitrogen or oxygen. A model for the interpretation of the experimentally determined process behaviour has been derived in this study. A comparison of the process curves obtained by simulation (numerical solutions of the model equations) with the experimentally determined results confirmed the model concepts. The model analysis supplied equations describing the process in a steady state as a function of the technical process parameters. These equations were used to draw conclusions for the practical operation of waste‐water purification processes in closed chemostats.
The microbial conversion of different agricultural residues and its biological efficiency
Authors: Patrabansh S. , Madan M.
Published: December 2004

A number of agricultural residues such as Saccharum munja Roxb. (Sarkanda), Oryza sativa L. (Paddy straw, as the control), Vinna unguiculata (L.) Walp (Cowpeas), Abelmoschus esculentum (L.) Moench (Lady's finger), Zea mays L. (Maize) and Cyamopsis tetragonoloba (L.) Taub. (Guar) were used for the cultivation of Pleurotus sajor‐caju (Fr.) Singer. The biological efficiency of the fruit bodies of Pleurotus sajor‐caju from the above mentioned substrates were found to be 13.47, 11.20, 8.37, 8.31, 6.87, and 6.08 percent, respectively. S. munja and paddy straw were found to be the best substrates for the growth of P. sajor‐caju followed by Z. mays, V. unguiculata, A. esculentum, and C. tetragonoloba.
Yeast entrapment in Duckweeds: Immobilization performance and biomass localization within the support particles
Authors: Richter E. , Ehwald R. , Blinkrei K.
Published: December 2004

Cell structured support material (CSM) prepared from Wolffia arrhiza fronds were loaded with Saccharomyces cereevisiae by the propagation of yeast cells introduced in the aerenchyma. The loading process could be strongly accelerated by preventing the growth of freely suspended yeasts in the fermenter. The pathway of the inoculation through the stomata could be visualized by transparent light microscopy of amylase and protease treated CSM. Slices of the loaded CSM clearly showed that the framework of the inner chlorenchyma cells remains intact during the propagation of the included yeast cells. Most of the yeast cells were found to be localized as a dense suspension within unbroken cells. During long‐term treatment of the loaded CSM at high convection, about one third of the yeasts was released into water with a constant rate greater than 0.34 h−1. The residual amount of yeast cells remained in a stable compartment from which further loss did not occur for the period tested (20–48 h). It is assumed that the stable compartment is identical with the interior of chlorenchyma cells. The results are discussed in relationship to the possible use of the immobilized biomass in fermentation.
Determination of the Ks values during the growth of Alcaligenes eutrophus on phenol, 2,4‐dichlorophenoxyacetic acid and fructose
Authors: Müller R. H. , Babel W.
Published: December 2004

The determination of the KS values presented here is based on the estimation of the stationary substrate concentrations in continuous cultivation experiments. The separation of biomass from the suspension was performed by an ultrafiltration step which succeeded within one second. The decay of substrate concentration during sampling was calculated to amount to less than 6% of the stationary substrate concentration at relevant growth rates. The KS values derived from these reduced substrate concentrations deviated by only 10% from the theoretical values at a biomass concentration of about 1 g/1. Thus relevant kinetic parameters can be calculated from the data obtained by this procedure. Values of 11, 59 and 14 μM were obtained with 2,4‐dichlorophenoxyacetic acid (2,4‐D), phenol and fructose, respectively. Similar KS values were derived with 2,4‐D and fructose by using a respirationbased determination for reasons of comparison. With phenol this value was only 7 μM which is as cribed to a physiological background.
Xylitol formation by Candida guilliermondii grown in a cane bagasse hemicellulosic hydrolysate: Effect of aeration and inoculum adaptation
Authors: Felipe M. G. A. , Vitolo M. , Mancilha I. M.
Published: December 2004

The xylose conversion into by Candida guilliermondii was evaluated in sugar cane bagasse hemicellulosic hydrolysate. The effect of air flow rates of 0.4, 0.6 and 0.8 vvm cn xylitol formation was studied. In addition, inoculum previously adapted to the hydrolysate was also tested in the fermentation carried out at 0.6 vvm. The results showed that xylitol production depends markedly on the aeration rate and on the previous adaptation of the yeast to the hydrolysate. When the highest productivity of xylitol was 0.39 g/l × h. However, during the fermentation carried out at an air flow rate of 0.6 vvm with adapted inoculum, the productivity increased to 0.65 g/l × h. Furthermore, the adapted cells performed quite well in the presencel of acetic concentrations of about 4.5 g/l in the medium.
Production of extracellular polysaccharides by a Rhizobium species from the root nodules of Tephrosia purpurea Pers
Authors: De P. S. , Basu P. S.
Published: December 2004

The Rhizobium sp., isolated from the root nodules of the leguminous climbing herb, Tephrosia Purpurea Pers., produced high amounts of extracellular polysaccharides (EPS) in yeast extract mannitol medium. Growth and EPS production started simultaneously, but the production reached its maximum in the stationary growth phase of the bacteria. Attempts were made to optimize the cultural requirements for growth and maximum EPS production. The EPS production was increased by 72.5% over the control when the medium was supplemented with mannitol (2%), thiamine hydrochloride (5 μg/ml) and KNO3 (0.1%). The EPS contained glucose, galactose and mannose monomers. The possible role of the rhizobial EPS was discussed.
Culture conditions for the production of amylolytic enzymes by a thermophilic Clostridium sp.
Authors: Odibo F. J. C. , Ulbrich‐Hofmann R.
Published: December 2004

The growth of a thermophilic Clostridium sp. and the production of α‐glucosidase, α‐amylase and pullulanase were studied under anaerobic conditions using different carbon and nitrogen sources and varying pH values and temperatures. Growth and enzyme activities were highest with soybean meal as the nitrogen source. The optimum concentration was 2.5% [w/v] for the production of α‐amylase as well as pullulanase and 2% [w/v] for α‐glucosidase. The best carbon source proved to be soluble starch for α‐amylase, and pullulanase and maltose for α‐glucosidase. Growth and enzyme production reached their optimum at pH 6.5 to 7.0 and 70°C. Under these conditions, the enzyme activities followed exponential growth with maximum yields of α‐glucosidase, α‐amylase and pullulanase at 28, 36, and 44 h.
Degradation of waste waters from olive oil mills by Yarrowia lipolytica ATCC 20255 and Pseudomonas putida
Authors: De Felice B. , Pontecorvo G. , Carfagna M.
Published: December 2004

Waste waters from olive oil processing may cause severe pollution in the Mediterranean area, since they have a high level of chemical oxygen demand (COD) (100–200 g/l) and contain other organic and inorganic compounds. In all olive oil producing countries, the reduction of pollution in olive oil mill waste waters at reasonable costs and using techniques suitable for most industrial applications is an unsolved problem.

For this paper, the yeast Yarrowia lipolytica ATCC 20255 was grown on waste waters from an olive oil mill in a 3.5 1 fermenter under batch culture conditions.

The results showed that the yeast was capable of reducing the COD value by 80% in 24 h. In this way, a useful biomass of 22.45 g/l as single cell protein (SCP) and enzyme lipase were produced.

During this process, most of the organic and inorganic substances were consumed, only aromatic pollutants were still present in the fermentation effluents. Therefore, we used a phenol degrader, namely Pseudomonas putida, to reduce phenolic compounds in the fermentation effuents after removing Yarrowia lipolytica cells. P. putida was effective in reducing phenols in only 12 h.
The role of formate for the growth of Rhodococcus opacus UFZ B 408 on pyridine
Authors: Brinkmann U. , Babel W.
Published: December 2004

R. opacus UFZ B 408 is able to use pyridine, a potentially growth‐inhibiting substrate, as the sole source of carbon, energy and nitrogen. In a previous publication [1] we reported that with the simultaneous utilization of a second carbon and energy source in carbon‐substrate‐limited chemostat culture, stable steady states could be achieved at higher dilution rates than with growth on pyridine as the sole substrate. Owing to the higher growth yield during growth on such a substrate mixture, both the specific pyridine consumption rates and the residual pyridine concentrations were lower at similar dilution rates than with growth on pyridine alone. Therefore, the critical growth‐inhibitory pyridine concentration was only achieved at a higher dilution rate.

With the investigations presented here in carbon‐substrate‐limited continuous culture, the simultaneous utilization of pyridine and formate by R. opacus UFZ B 408 was studied. The yield coefficient during growth on pyridine as the sole substrate amounted to about 0.55 g dry mass/g pyridine. Theoretically, however, the carbon‐metabolism‐determined yield coefficient should have been about 0.915 g dry mass/g pyridine. Because of the difference between these two values the conclusion was drawn that pyridine is energetically deficient. That means that during growth on pyridine a part of the substrate was dissimilated to supply the energy required for the incorporation of the pyridine carbon into biomass. Formate cannot be used as a carbon source for growth by R. opacus UFZ B 408. However, with growth on pyridine, formate was oxidized simultaneously. During growth on pyridine/formate mixtures, the yield coefficient could be enhanced up to 0.7 g dry mass/g pyridine. That means that biologically usable energy, generated in the course of the formate oxidation, was used for the assimilation of pyridine carbon. The increase in the yield coefficient was related to the utilization ratio of formate to pyridine in a linear manner. However, the carbon‐metabolism‐determined yield coefficient of 0.915 g dry mass/g pyridine could not be achieved. That can be put down to the fact that R. opacus UFZ B 408 possesses only a limited capacity to oxidize externally supplied formate. Because of the limited formate oxidation capacity the probability is low that, with simultaneous utilization of formate, stable steady states could be achieved at substantially higher dilution rates than with growth on pyridine alone.

Enzymatic studies revealed the induction of both NAD(P)+‐linked glutaric dialdehyde dehydrogenase and isocitrate lyase during growth on pyridine. Therefore, the conclusion was drawn that pyridine is metabolized by R. opacus UFZ B 408 via the same pathway described for the utilization of pyridine by Nocardia Z1 [2]. This conclusion implies that the ability to oxidize formate represents a metabolic performance which seems not to be directly related to the pyridine metabolism of R. opacus UFZ B 408.
Modelling L‐glutamic acid production with Corynebacterium glutamicum under biotin limitation
Authors: Bona R. , Moser A.
Published: December 2004

The production of L‐glutamic acid with Corynebacterium glutamicum under biotin limitation was studied. Assuming a formal type of cell maturation, an adequate formal kinetic model was developed. This model includes growth, dependent on biotin, and uses the same retention term for describing the lag phase and cell maturation. Special attention was paid to the graphical interpretation of the performance between the variables, which is relevant for kinetics. Comparison between experiments and the model resulted in different degrees of agreement. However, the main trend of the experimental patterns of the complex bioprocess can clearly be mirrored in this model.
Production of indole acetic acid in root nodules and culture by a Rhizobium species from root nodules of the fodder legume Melilotus alba DESR.
Authors: Datta C. , Basu P. S.
Published: December 2004

The root nodules of Melilotus alba DESR., a fodder legume, contained high amounts of IAA. A tryptophan pool present in the nodule might serve as a source of IAA production. Presence of IAA oxidase and peroxidase in the nodules indicated the metabolism of IAA, at least in part, in the nodules. The Rhizobium species isolated from the root nodules produced a high amount of IAA (190 μg/ml) from L‐tryptophan supplemented basal medium. IAA production and microbial growth were coincident. The production of IAA by the Rhizobium sp. was increased by 315% when the medium was supplemented with lactose (1%), NiCl2 (10 μg/ml), cetyl pyridinium chloride (0.5 μg/ml) and glutamic acid (0.4%), in addition to L‐tryptophan (3 mg/ml). The possible role of the rhizobial production of IAA on the rhizobia‐legume symbiosis is discussed.
Influence of oxygen on the degradation of diesel fuel in soil bioreactors
Authors: Hupe K. , Heerenklage J. , Woyczechowski H. , Bollow S. , Stegmann R.
Published: December 2004

In fixed‐bed bioreactors, the influence of the oxygen content in the inlet air on the biodegradation of diesel fuel in unsaturated soil/compost mixtures was analyzed at 30°C over a period of 7 weeks. Firstly, a wide range from 0 to 80 vol.% O2 was investigated. Subsequently, the range below 5 vol.% O2 was examined more closely. Over the whole test period of seven weeks, no significant influence of oxygen could be observed above 1 vol. % O2 in the inlet air ‐ either on the decrease of the total contaminants or on the total mineralization. Anaerobic conditions should be avoided for the degradation of diesel fuel. During the test period, the courses of CO2 production varied significantly depending on oxygen supply. Furthermore, a model was developed to estimate the total mineralization as a function of oxygen supply. More investigations are recommended in order to test this model for practical application.
Detection of chlorocatechol 1,2‐dioxygenase genes in proteobacteria by PCR and gene probes
Authors: Kleinsteuber S. , Hoffmann D. , Müller R. H. , Babel W.
Published: December 2004

In various bacterial strains belonging to the β‐subdivision of proteobacteria which are capable of degrading chlorinated monoaromatic compounds, chlorocatechol 1,2‐dioxygenase genes were detected by PCR and Southern hybridization. Using PCR primers derived from the conserved sequence motifs of chlorocatechol 1,2‐dioxygenase genes tfdC, clcA and tcbC, PCR products of the expected size were obtained with the test strains, but not with negative control strains. The specificity of the PCR products was verified by hybridization using an oligonucleotide probe for an internal sequence motif which is evolutionarily conserved among chlorocatechol 1,2‐dioxygenases and some other dioxygenases that catalyze the intradiol aromatic‐ring‐cleavage. Hybridization with the tfdC PCR product from the 2,4‐D degradative plasmid pJP4 under stringent conditions revealed different extents of homology of the chlorocatechol 1,2‐dioxygenase genes to the canonical tfdC sequence in the various strains. These findings were confirmed by the nucleotide sequence analysis of the tfdC‐specific PCR products. From our results, we conclude that the PCR primer set is more suitable than the hybridization with pJP4‐derived gene probes for the detection of diverse chlorocatechol 1,2‐dioxygenase genes in proteobacteria.
Microbial cleaning of waste gas containing volatile organic compounds in a bioreactor system with a closed gas circuit
Authors: Berthe‐Corti L. , Conradi B. , Hulsch R. , Sinn B. , Wiesehan K.
Published: December 2004

The cleaning of the exhaust gases of a bioreactor containing volatile hydrocarbons in a bioreactor system with a closed gas circuit is described. The bioreactor system consisted of three different reactor types: a stirred tank which was filled with hydrocarbon‐containing waste water to simulate the exhaust gases of a remediation process; a trickle‐bed reactor for aerobic treatment of the exhaust gas from the stirred tank; and a photoreactor containing an algae culture which assimilated CO2 from the trickle‐bed reactor and also produced O2. With this bioreactor system, it was possible to efficiently remove volatile organic compounds (VOC) from the waste gases. Depending on the type of waste water investigated, elimination rates of 41% to 93% of BTEX (benzene, ethylbenzene, toluene, xylene) and 29% to 53% of VCH (volatile chlorinated hydrocarbons) were obtained. Due to the photosynthesis of the algae in the system's photoreactor, oxygen concentrations between 12% and 18% [v/v], equivalent to about 57% to 83% DOT, were obtained. This concentration permitted the aerobic degradation to be carried out without having to add fresh air. The trickle‐bed reactor and the photoreactor worked continuously, whereas the waste water in the stirred bioreactor was replaced in different batches. The accumulation of toxic compounds in the nutrient solutions of the trickle‐bed (EC‐50 > 30 g/l) and of the photoreactor (EC‐50 > 35 g/l) was low. Carbon dioxide concentrations in the gas flow were higher than in fresh air (1% to 3% [vol/vol]), but no long‐term accumulation of CO2 occurred. This means that the algae in the photoreactor were active enough to assimilate the CO2 which had been produced. They were also able to produce sufficient oxygen for aerobic hydrocarbon degradation. The system described is a first step towards treating waste gases which results from the bioremediation of hydrocarbon‐contaminated media in a closed gas circuit without any emission (e.g. VOC, CO2, germs).
Selection of hydroxyproline‐resistant cell lines from Solanum Tuberosum L. Callus. II. Plant regeneration and frost tolerance of regenerated plants
Authors: Anjum M. A.
Published: December 2004

The calluses of two hydroxyproline‐resistant lines (D20‐1 and D30‐1) of Solanum tuberosum L. were transferred to a solidified MS medium containing 1.0 mg/I IAA, 2.0 mg/l zeatin, 40.0 mg/l adenine sulphate, 1 g/l casein hydrolysate, 20 g/l sucrose and 10 g/l agar for plant regeneration. The shoot regeneration was only achieved from the callus of line D20–1. Regenerated shoots exhibited morphological variability. The degrees of frost tolerance were higher in the leaves of the regenerated plants compared with the leaves of the non‐selected control plants, but lower than that of the callus from which they were regenerated.
Separation of two dichlorprop/α‐ketoglutarate dioxygenases with enantiospecific properties from Comamonas acidovorans MC1
Authors: Müller R. H. , Babel W.
Published: December 2004

Comamonas acidovorans MC1, which is capable of degrading the chiral phenoxypropionate herbicides 2‐(2,4‐dichlorophenoxy)propionate [dichlorprop, (RS)‐2,4‐DP] and 2‐(4‐chloro‐2‐methylphenoxy)propionate [mecoprop, (RS)‐MCPP] and of degrading the phenoxyacetate herbicides 2,4‐dichlorophenoxyacetate (2,4‐D) and 4‐chloro‐2‐methylphenoxyacetate (MCPA), was investigated with respect to the enzymatic basis of this broad substrate specificity. The initial steps of the degradation pathway of (RS)‐2,4‐DP and 2,4‐D were studied. By applying either ion exchange chromatography or hydrophobic interaction chromatography it was possible to separate two enzyme fractions with etherolytic activity, which exhibited pronounced substrate specificity. One enzyme fraction was highly specific for the degradation of the R‐enantiomer of 2,4‐DP and did not essentially attack the S‐configuration. The other enzyme fraction showed pronounced activity toward the cleavage of the S‐enantiomer and additionally utilized 2,4‐D with almost equal velocity; (R)‐2,4‐DP was even cleaved at a low rate by this enzyme. These results confirm the existence of phenoxyalkanoatedegrading enzymes with enantiospecific properties in strain MC1.
Sanitization of immobilized biocatalysts for the production of 6‐aminopenicillanic acid
Authors: Nováčková J. , Plháčková K. , Sikyta B.
Published: December 2004

Five different chemical reagents and γ‐rays were tested for the sanitization of immobilized biocatalysts with high penicillin G acylase (PGA) activity. The most effective chemical reagents were N‐cetyl‐N,N,N‐trimethylammonium bromide (CTAB) and 2‐isopropyl‐5‐methylphenol (thymol). The optimum concentration of CTAB for the treatment of the immobilized enzyme was 0.25% [w/v] and 1 h, for immobilized cells 0. [w/v] and 3 h. The optimum concentration of thymol for the immobilized enzyme was found to be 0.1% [w/v] and 1 h, for immobilized cells 0.27% [w/v] and 2 h. The optimum dose of γ‐rays for the sanitization of the immobilized enzyme was established as 3.2 kGy, for immobilized cells as 4.5 kGy.
Application of zeolites in the downstream processing of the character impact compound 2,5‐dimethyl‐4‐hydroxy‐furan‐3‐one (furaneol)
Authors: Pundsack E. , Scheper Th.
Published: December 2004

The purpose and scope of this article is to introduce capable zeolites into downstream processing of natural compounds, especially flavour compounds like 2,5‐dimethyl‐4‐hydroxy‐3(2H)‐furan‐3‐one (Furaneol®

Furaeol is a registered trademark of FIRMENICH, Ch

). The synthesis and the recovery of Furaneol from L‐rhamnose are presented. Therefore adsorption isotherms of the zeolites ZSM5 and DAY with varying modules have been determined and adsorption experiments using model and reaction mixtures of Furaneol synthesis were performed and will be discussed.
Functionalized conducting polymers: Enhancement of the redox reversibility of polypyrrole by substituting polyether chains at the 3‐positions
Authors: Delabouglise Didier , Garnier Francis
Published: December 2004

The performance of solid state batteries which employ conducting polymers as electrodes can be enhanced by the substitution of polyether chains onto the polymer backbone. The synthesis of pyrrole substituted in this manner (see Figure) is reported and the redox characteristics of the polymer based on this starting block described.

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Molecular Materials I. Molecular materials mimic inorganic network solids
Authors: Miller Joel S.
Published: December 2004

Functional organic materials have been developed over the last twenty‐five years which compete for applications in optical, electrical and magnetic technologies with the more traditional inorganic network solids. In the first article of a regular series Joel Miller of DuPont describes some applications of these molecular materials, warns of some of the pitfalls involved and sets the scene for his future articles.
Ferroelectric liquid crystal with extreme polarization: X‐Ray structure analysis of the crystalline phase
Authors: Colquhoun Howard M. , Dudman Christopher C. , Robinson Gareth C. , O'Mahoney Caroline A. , Williams David J.
Published: December 2004

Ciral liquid crystalline compounds which adopt the S phase are of interest as they can possess a spontaneous, permanent and macroscopic dipole moment (ferroelectric polarization) even in the absence of external fields. The compound reported here (see figure) has the highest known spontaneous polarization (520 nC cm−2) and therefore could improve the switching speeds of electro‐optic devices substantially.

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Dielectric spectroscopy: Fashionable again
Authors: Kremer Friedrich , Vallerien Sven U. , Zentel Rudolf
Published: December 2004

The molecular dynamics of polymers and liquid crystals (see figure) affect the properties of these materials. The different modes of, for example, relaxation can be studied to great effect using a modern version of an old spectroscopic method—dielectric spectroscopy—which makes use of molecular dipoles to gain an insight into these processes.

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Energetic Materials
Authors: Iyer Sury , Slagg Norman
Published: December 2004

Metastable molecues possessing high reactivity can be employed as explosives, propellants, and pyrotechnics. The properties, sensitivities and kinetics of energetic materials used as nitroaromatics and nitramines, which are in both military and civilian use, are discussed and the theory of detonation described.
Biomaterials highlights V. Percutaneous amputation stump extensions
Authors: Heimke Günther
Published: December 2004

Biomaterials highlights V. The joining of the stump of an amputated limb to the man‐made extension presents a number of medical, mechanical and materials problems not least of which is how the extension should penetrate the skin without causing infection.
Organic Semiconductors for new electronic devices
Authors: Horowitz Gilles
Published: December 2004

Field effect transistors, schottky diodes, and solar cells are among the applications of organic semiconductors now being developed. Questions concerning charge generation and transport as well as doping mechanisms in these materials, which include polyacetylenes, polythiophenes and metallophthalocyanines are reviewed, and future directions in both experimental and theoretical work discussed.
Inorganic materials IV. Transparent ceramics and glass‐ceramics
Authors: Partridge Graham
Published: December 2004

Ceramic hotplates in the kitchen through which the heating rings canonlybe seen when they are hot, and covers for tungsten‐halogen lamps are two applications of ceramic‐based materials which transmit light in the visible and near infrared regions of the spectrum.
Diamond thin film technology II Part A. Diamond and diamond‐like carbon
Authors: Bachmann Peter K. , Linz Ute
Published: December 2004

Recent developments reported at an Advanced Study Institute (ASI) meeting held on Italy, including the production of 12C‐enriched diamond single crystals using the recrystallization technique shown in the Figure are described.

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Diamond and diamond‐like carbon
Authors: Bachmann Peter K. , Linz Ute
Published: December 2004

Research News/Diamond Thin Film Technology IIb: The second part of this article continues the description of work presented at a two‐week Advanced Study Institute held in the mountains of Tuscany. Topics under discussion were deposition methods, deposition parameters, and applications, including cutting tool inserts, armored IR optics, and X‐ray detector windows.
Tunneling microscopy in Baltimore
Authors: Rabe Jürgen P.
Published: December 2004

Conference Report: Jürgen Rabe reprots on his recent visit to a meeting on scanning tunneling microscopy in the USA.
The Materials Forum of the RWTH Aachen
Authors: Kopp Reiner
Published: December 2004

Essay: Interdisciplinary cooperation within a university can lead to imrpoved problem‐solving capability, and through this, enhanced interaction with industry. Another major advantage is the broadening of the education which can be offered to students. Progress in this direction at one of the stongest universities for materials science in Germany is described.
European research conferences
Authors: Hendeković Josip
Published: December 2004

Essay: Cooperative action in the organization of European ‘Gordon’‐like research conferences is coordinated by the European Science Foundation (ESF) which is based in Strasbourg. France. The aims and profile of the conference program, which includes meetings in physics, chemistry and materials science of relevance to work on advanced materials, and the ESF which started it are described.
Two‐step generation of aluminum microstructures on laser‐generated pd pre‐nucleation patterns using thermal cvd from (trimethylamine)trihydridoaluminum
Authors: Gottsleben Oliver , Stuke Michael , Roesky Herbert W.
Published: December 2004

Communication: Aluminium microstructures, important in electronics packaging applications, can be efficiently produced using a new two‐step method which involves thermal CVD from (trimethylamine)trihydridoaluminum onto lasergenerated spatially selective prenucleation patterns of a palladium catalyst. Interestingly, the aluminum continues to grow to heights of more than a few nanometers even after it has completely covered the palladium catalyst.
Synthesis of ceramic nanoparticles by the ultrasonic injection of an organosilazane precursor
Authors: Gonsalves Kenneth E. , Strutt Peter R. , Xiao Tongsan D.
Published: December 2004

Communication: Ceramic and metallic materials with nanometer‐scale morphology possess novel properties important in nanoprecision manufacturing, where isotropic material properties are required in miniaturized components, and in the development of new composite materials with strengths approaching the theoretical limtis Unlike currently used methods for the synthesis of nanoparticles which can only produce small quantities, the new method reported here (see figure) which involves laser‐induced cross‐linking of a liquid silazane precursor to give Si3N4/SiC ceramics can yield up to 100 g/h.

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Talking point. The scanning tunneling probe as a feynman ‘sewing’ machine?
Authors: Alberts Albert H.
Published: December 2004

Research News/Talking Point: The prospect of using the scanning tunneling microscope (STM) to ‘stitch’ together molecules of, for example, thiophene or pyrrole one by one to form macromolecular chains, or in the production of organic superconductors from Langmuir‐Blodgett arrays containing metal ions is discussed.
Thin‐film calorimetry and molecular electronics
Authors: Wright John D.
Published: December 2004

Research News: Understanding the effect of the doping process on organic semiconductors is a crucial step in the design of, for example, organic‐based gas sensors. A method is presented her which allows the thermal changes which accompany the various steps in the doping process to be accurately monitored. The technique combines the high sensitivity of interferometric detection with the low thermal mass of a single‐mode optical fiber.
Composites in Moscow
Authors: Kostikov V. I. , Zolkin P. I.
Published: December 2004

Conference Report: V. I. Kostikov and P. I. Zolkin of the State Research Institute of Graphite in Moscow report on a recent international conference on composite materials held in the USSR.
Technical and scientific societies on the upswing
Authors: Schepp Peter Paul.
Published: December 2004

Essay: The role of technical and scientific societies in information transfer, education, and the coordination of research and development efforts is examined with special emphasis on the Deutsche Gesellschaft für Materialkunde (DGM), the German Materials Society. The DGM, which was instrumental in the foundation of the European organization f. e. m. s., the Federation of European Materials Societies, is outlined and its relationship with other European materials societies, for example the European Materials Research Society (E‐MRS) is discussed.
Surface resistance of thick film YBa2Cu3OX
Authors: Alford Neil McN. , Button Tim W.
Published: December 2004

Research News: Radio‐frequency and microwave applications of high‐Tc superconductors (HTSC), for example delay lines (see figure) require films exhibiting a low surface resistance. A method has recently been developed for processing thick films of HTSC which results in a higher critical current density and lower surface resistance than previously achieved.

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Properties of amphiphilic terminally substituted conjugated nonaene‐ and 2‐docosylnonaene carboxylic acids in monolayers at the air–water interface
Authors: Effenberger Franz , Meller Paul , Ringsdorf Helmut , Schlosser Hubert
Published: December 2004

Communication: Amphiphilic, conjugated polyenes, (see figure) substituted with, for example, redox‐active groups such as ferrocene or other groups which allow for specific and selective excitation (energy intake), have been synthesized and their spectroscopic properties examined at the air‐water interface. The materials have potential applications in the storage and transfer of information on a molecular level.

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Talking point. Are free radicals involved in biodegradation of implanted polymers?
Authors: Williams David F. , Zhong Sheng P.
Published: December 2004

Research News/Talking Point: The role of cells and cellular products in polymer degradation is an important factor in examining the biocompatibility and performance of polymer‐based implants in surgery. Cells release many enzymes and biologically active species into their environment, a fact which makes it difficult to distinguish which released factor is dominant in any cell‐mediated degradation of implanted materials. The various possibilities are discussed and a mechanism involving free radicals proposed.
Intrazeolite Topotaxy
Authors: Ozin Geoffrey A. , Özkar Saim
Published: December 2004

The self‐assembly of semiconductor quantum dots or wires within the cavity of a zeolite or molecular‐sieve host to form qunatum supralattices has great potential in the development and study of organized systems with value in, for example, quantum electronics, nonlinear optics, optical data storage, and chemoselective sening. The organization of inorganic, organometallic, and metal‐carbonyl moieties on the internal surfaces of the hosts (e.g. see figure) is thebasis of the work and the chemsitry and its applications are reviewed.

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Electrosynthesized thin films of group II–VI compound semiconductors, alloys and superstructures
Authors: Rajeshwar Krishnan
Published: December 2004

II‐IV compound semiconductors such as CdTe and Hg1–x CdxTe are important in a wide range of optoelectronics applications ranging from solar cells and infrared detectors to „smart”︁ goggles. An alternative to the cost‐intensive vacuum‐based production techniques is electrodeposition which allows large‐area deposition, close control of the deposition conditions, and obviates the need for toxic, organometallic precursors. The advantages and disadvantages of the method are discussed.
The first example of a tridentate azamacrocyclic metallomesogen
Authors: Lattermann Günter , Schmidt Steven , Kleppinger Ralf , Wendorff Joachim Heinz
Published: December 2004

The introduction of a metal into a mesogenic molecule can result in a complex with interesting electrical and magnetic properties. By reacting the non‐mesogenic cyclic amine shown in the figure with Ni(NO3)2 · 6H2O in absolute THF the first member of a new class of columnar liquid‐crystalline metal complexes with three nitrogen atoms as donor groups has been prepared.

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The mesomorphism of some diamides of alkyl‐substituted‐1,3‐Diaminobenzene
Authors: Malehete Jacques , Levelut Anne‐Marie , Liebert Lionel
Published: December 2004

The mesophases of several oddly shaped mesogenic diamides of 1,3‐diaminobenzene, substituted with three methyl groups in positions 2,4,6 or by a methyl and a tert‐butyl group in positions 2,5 have been studied by X‐ray diffraction. Limello‐columnar and uncommon nematic mesomorphic ordering have been observed and the role of hydrogen bonding in the phase behavior investigated.
The stability of Poled Nonlinear Optical Polymers
Authors: Man Hong‐Tai , Yoon Hyun N.
Published: December 2004

The long‐term thermal stability of poled polymers is of cruciial importance because the poled structure is inherently in a non‐equiilibrium state and relaxation in the poled polymers results from thermal reorientation effects. A quantitative understanding of the relaxation behavior is therefore of great use in optimizing the design of new polymer systems. The major factors involved are explained, and various theoretical models are applied to some nonlinear optical polymers developed at Hoechst.
Heat‐Reflecting Systems for automotive glazing
Authors: Grolig Gerhard , Kochem Karl‐Heinz
Published: December 2004

Special layer systems which reflect infrared radiation but have high transmission in the visible part of the spectrum are being incorporated into automobile windows in order to improve passenger comfort through reducing the amount of solar radiation reaching (and heating) the interior of the vehicle. The materials used, the structure of the multilayer systems, and the techniques used to produce them are discussed and a look is taken at the possibillity for future markets and developments.
Molecular relaxations in highly oriented polymer structures
Authors: Eichenauer Dieter , Jung Holger
Published: December 2004

The properties of high‐modulus fibers based on aromatic monomer units linked by ester or amide groups depends on the relative monomer concentrations. The morphologies of various copolymers are examined and the relationship between the thermo‐mechanical properties of the polymers and the dynamics of the individual polymer chains, as studied using dielectric spectroscopy, discussed.
Polymer‐derived silicon nitride and silicon carbonitride fibers
Authors: Vaahs Tilo , Brück Martin , Böcker Wolfgang D. G.
Published: December 2004

The pyrolysis of organoelemental polymerss provides a powerful route to high‐ppurity, high‐performance ceramics. The various factors influencing the production of low‐oxygen‐content ceramic fibers from polymeric silazanes are examined and the possibility of controlling the composition of the fibers by varying the pyrolysis atmosphere resulting in stable, amorphous phases is described. The fibers have great potential in the reinforcement of metal and ceramic matrix composites.
High‐density polyethylene pipe resins
Authors: Bohm Ludwig L. , Enderle Hans F. , Fleifßner Manfred
Published: December 2004

Efficient catalyst systems and an appropriate polymerization technology are required for the production of pipe resins which must exhibit both high stiffness and excellent service lifetimes (i.e. resistance to environmental stress cracking). The problem is that these requirements are contradictory but recently a polymer alloy has been developed with an elastic modulus over 1000 MPa and a failure time two orders of magnitude higher than that of standard materials.
Challenges and responses
Authors: Mabe Michael
Published: December 2004

Commercial publishers sometimes have a different view to those publishers associated with societies when it comes to fixing prices or to founding new journals. Last Fall, Kurt Paulus of Institute of Physics Publishing provided some insight from the point of view of the societies, this year Michael Mabe of Pergamon underlines the common goal of scientific publishers—serving the scientific community—while tracing the explosive development of the number of papers offered for publication in primary journals and teh difficulties associated with dealing with them.
Preparation of spinel ultrafiltration membranes
Authors: Pflanz Karl B. , Riedel Ralf , Chmiel Horst
Published: December 2004

New markets for membranes have resulted from recent developments in biotechnology and growing interest in environmental science. These applications make increased demands on the membranes, which in many cases cannot be met by polymer membrances. The preparation and characterization of a new ultrafiltration membrane composed of MgAl2O4 is described, which exhibits improved chemical and thermal stability with respect to phase transition, pore size, and particle growth compared to other inorganic ultrafiltration membrances.