bluuebunny/crossref_metadata_2025 huggingface dataset:
Biochemical characterization of a shikimic acid‐resistant mutant of Nostoc linckia
Authors: Kumar Dhruv
Published: February 2007

The growth of Nostoc linckia was significantly inhibited by shikimic acid concentrations greater than 4.0 μg ml−1 and was completely inhibited at 10.0μg ml−1. Shikimic acid increased the duration of the lag phase and the doubling time and hastened the onset of the retardation phase of growth. A mutant (NLshi) capable of growing in presence of 50 μg ml−1 shikimic acid, was isolated by nitrosoguanidine mutagenesis from the wild type population at a frequency of about 1 × 10−5 to 1 × 10−6. The mutant grew slower than the wild type. Both the wild type and the mutant strain grew photoheterotrophically in light, with and without 3 (3–4 dichlorophenyl) 1,1‐dimethyl urea (DCMU) and in darkness when provided with glucose. Glucose supplementation promoted ammonium uptake from the medium, when wild type and mutant were grown in an ammonium‐supplemented medium. Glucose stimulated heterocyst production and nitrogenase activity in both the strains. As compared to wild type, this mutant showed higher heterocyst frequency and nitrate reductase activity but its ammonium uptake activity was lower. No significant difference in glutamine synthetase and nitrogenase activities of the mutant were observed. The mutant was stable and retained its resistance even after several subcultures through medium free of shikimic acid.
Production of thermozymocidin (myriocin) by the pyrenomycete Melanconis flavovirens
Authors: Šašek Václav , Sailer Miroslav , Vokoun Jindřich , Musílek Vladimír
Published: February 2007

Submerged culture of the pyrenomycete Melanconis flavovirens produces a strongly active antifungal antibiotic. The antibiotic was isolated from the culture mash. In purified compound the physico‐chemical characteristics, including 1H NMR spectrum, were estimated. The antibiotic was found to be identical with thermozymocidin (myriocin) as confirmed by comparison with synthetically prepared thermozymocidin.
Phaseolotoxin production by Pseudomonas syringae pv. phaseolicola: The influence of temperature
Authors: Nüske Jörg , Fritsche Wolfgang
Published: February 2007

Phaseolotoxin (N‐sulphodiaminophosphinyl‐ornithyl‐alanyl‐homoarginine) is a phytotoxic secondary metabolite produced by Pseudomonas syringae pv. phaseolicola. The production of the phytotoxin is strongly regulated by temperature. The optimal temperature for phaseolotoxin production is 18 °C. Temperatures in the range between 18 °C and 30 °C inhibit the production of phaseolotoxin in an increasing manner. By temperature shift experiments and the inhibition of protein synthesis by chloramphenicol it was demonstrated, that the synthesis of enzymes related to toxin synthesis and not the regulation of the activity of the responsible enzyme system is affected by higher temperatures.
Effect of organic soil amendments on the incidence of brown spot disease in maize caused by Physoderma maydis
Authors: Osunlaja S. O.
Published: February 2007

Six organic materials were added to the soil in a field recently showing a high incidence of brown spot disease in maize caused by Physoderma maydis. All the amendments lowered significantly the occurrence of the disease in comparison to the unamended control. However, the ability to suppress the disease differed substantially among the amendments. Rice bran and rice straw were most effective in this respect. The suppression of the disease appeared to be related to an increased microbial activity in the soil.
Invasion of wood by basidiomycetous fungi. V. The role of fungal elicitors of plant cell necrobiosis in the expression of pathovirulence and kratovirulence
Authors: Gramss G.
Published: February 2007

Within the intact tree the live cell is the exclusive carrier of phytopathological defence reactions against microbial attack. In a comprehensive search for fungal virulence factors capable of weakening the living tissues in timber, 48 species of wood‐destroying basidiomycetous fungi (WBF)1) with known degree of pathosism and the corresponding degree of saprophytism were grown on liquid still cultures. Droplets of the filtered culture fluids were then applied to pin‐prick wounds in the interveinal area of leaves from several tree and one herb species. Within 48 hours of development circular spots of brown necrotic tissue expanded around the pin pricks to indicate and approximately quantify the presence of fungal elicitors of necrobiosis. The resulting necrobiosis index was, with certain exceptions, not correlated with the antimicrobial potency (kratovirulence) of the fungus, its pathosism against standing timber, and the activity of exoenzymes in white‐rot fungi. The necrobiosis index was, in part, positively correlated with the activity of those brown‐rot fungi that dispose of an effective wood‐decay capacity. Characteristic of the fungal species as well as of the fungal strain the necrobiosis index ranked from 0 to 1,421.2 mm2 necrotic net area per 300 pin pricks but there was no fungus to be unable of eliciting browning in at least a few of the leaf species. The most severe necrosis was permanently observed on leaves of several generally oversusceptible tree species rather than on the notorious host species of the test fungus. It is therefore concluded that the elicitors of plant cell necrobiosis in WBF are predominantly host‐nonspecific stress factors that may sometimes increase fungal pathovirulence. Their purification should help characterize their action as phytotoxic, necrobiotic, enzymatic, or even antimicrobial.
Biochemical mechanism of keratin degradation by the actinomycete Streptomyces fradiae and the fungus Microsporum gypseum: A comparison
Authors: Kunert Jiří
Published: February 2007

Two keratinolytic organisms, the procaryote Streptomyces fradiae and the fungus Microsporum gypseum, were cultured on sterile sheep's wool in a mineral solution. The loss in substrate was recorded and the degradation products in the cultivation fluid were analyzed. In M. gypseum the key reaction was the cleaving of the substrate disulfide bridges by means of sulfite excreted into the medium. Keratin denatured by „sulfitolysis’︁ was further attacked by extracellular proteases. A typical finding was the accumulation of peptides containing S‐sulfocysteine, the product of sulfitolysis of cystine. The overall excess of sulfur was removed by oxidation to sulfite and to sulfate, which was the main and final product. In S. fradiae the degradation was faster. The results did not prove that sulfite formed and the concentration of sulfate in the medium remained negligible. Neither could cysteine desulfhydration and hydrogen sulfide excretion be demonstrated. The medium was found to contain relatively high concentrations of sulfhydryl compounds, evidently cysteine‐containing peptides. Therefore, in this microorganism, keratin was most likely denatured by the direct reduction of cystine bridges. The main product of the elimination of excess sulfur was inorganic thiosulfate, which accumulated in the medium.
Purification and properties of the β‐glucosidase from a nitrile hydratase‐producing Brevibacterium sp. strain R312
Authors: Legras J. L. , Kaakeh M. R. , Arnaud A. , Galzy P.
Published: February 2007

Besides its nitrile hydratase and wide spectrum amidase activities, the Brevibacterium sp. R312 strain also possesses a constitutive β‐glucosidase. Its optimum pH is 6. The enzyme was purified by fractionation precipitation with ammonium sulfate followed by chromatographic elutions on Q‐Sepharose Fast Flow, Sephadex G‐200 and Phenyl Superose. The resulting purification was 1960 folds for a 6% yield. The molecular weight of this enzyme was estimated at 180,000. It contains two identical sub‐units. The pI is 5.5. This enzyme has a strong affinity for aryl‐ß‐glycosides: pNPG, prunassine; it could also degrade linamarine. It is inhibited by p‐chloromercuribenzoate, δ‐gluconolactone and glucose.
Auxotrophic mutants of the yeast Trichosporon adeninovorans
Authors: Samsonova Ida A. , Böttcher Fritz , Werner Carsta , Bode Rüdiger
Published: February 2007

We have isolated and characterized auxotrophic mutants of Trichosporon adeninovorans, strain PAR‐4 to get genetic markers that cover the entire nuclear genome of this thermotolerant yeast of technological interest. The nitrosoguanidine mutagenesis yielded mutants at a high frequency. We detected a broad spectrum of auxotrophic phenotypes in the random mutant samples. Obviously, strain PAR‐4 is a haploid or hyper‐haploid yeast. In correspondence we determined a low DNA content per cell. In contrast to NG1, UV light was an inefficient mutagen. UV survival curves were without the typical shoulder indicating suppression of repair of UV‐induced lethal lesions. Thus, the response of PAR‐4 to UV was different from those of Saccharo‐myces cerevisiae and other yeasts.
Toxicity of sodium diethyl‐dithiocarbamate (NaDDC) on photoautotrophic growth of Anacystis nidulans IU 625
Authors: Singh D. P. , Gothalwal R. , Bisen P. S.
Published: February 2007

The effect of a graded concentration (0.05–0.6 mmol/1) of sodium diethyldithiocarbamate (NaDDC) on the growth rate of Anacystis nidulans was found to be concentration‐dependent. A 50% inhibition (I50) of the growth rate was observed at 0.28 mmol/1 of NaDDC. A sudden decrease in cellular absorbance at 435,625 and 675 nm on the third day, and followed by a gradual decrease up to the 6th day indicated an NaDDC‐induced bleaching of the chlorophyll α and phycocyanin pigments. Furthermore, an NaDDC‐induced increase in absorbency at 340 nm after 48 hrs of light incubation was indicative of the reduced state of the carriers. The result on the reduction of 1,6‐dichlorophenol indophenol (DCPIP), cytochrome c and NADP was an NaDDC‐induced stimulation of all the reductive processes, with saturating rates at approximately 0.4 mmol/1 of NaDDC. Furthermore, the rate of DCPIP reduction in the presence of NaDDC was inhibited by rotenone (100 μmol/l). SHAM (salicyl hydraxamic acid, 500 μmol/l) and DCMU (100 μmol/l). Similarly, the addition of 10 μmol/l of DCMU resulted in the inhibition of both cytochrome and NADP reductions. Therefore, the results suggested that NaDDC could bring about the over‐reduction of carriers by interacting with the electron transport chain on or before the DCMU sensitive site. An NaDDC‐dependent general increase in the fluorescence of chlorophyll a was further stimulated by the electron transport inhibitors. The result on oxygen evolution was a 50% inhibition (I50) of H2O2 and H2O2 supported O2 evolution at 0.12 and 0.19 mmol/1 of NaDDC, respectively. Taken together, these could suggest that the highly reduced state of carriers in the presence of NaDDC might be preventing the uphill electron flow from the light‐harvesting pigment complex, H2O and H2O2. Thus, the foregoing results inferred that the bleaching of pigments and over‐reduction of electron carriers ultimately accounted for the death of the organism.
Occurrence of the general control of amino acid biosynthesis in yeasts
Authors: Bode R. , Schüssler K. , Schmidt H. , Hammer T. , Birnbaum D.
Published: February 2007

The response of three amino acid biosynthetic enzymes, threonine dehydratase, tyrosine aminotransferase and saccharopine dehydrogenase, to conditions of histidine, tryptophan or lysine limitation was investigated in 15 yeast species. The activities of all these enzymes increased about two‐ to fourfold as a result of action of the general control of amino acid biosynthesis in Brettanomyces anomalus. Candida maltasa, Hansemala polymarpa, Rhodosporidium toruloides, Saccharomyces cerevisiae and Yarrowia lipolyilca. No evidence for the existence of the general control was found in Candida brumptii, Candida, utilis, Hansenula anomala, Hansemula henricii, Khuyveromyces marxianus, Pichia gulliermondii, Saccharomycopsn capsularis, Trichosporan adenino‐voranis and Trigonopsis variabilis.
Amplification of pBR322 plasmid DNA in Escherichia coli relA strains during batch and fed‐batch fermentation
Authors: Hofmann K. H. , Neubauer P. , Riethdorf Sabine , Hecker M.
Published: February 2007

Fermenter studies under batch and fed‐batch conditions were carried out to test the possibility of plasmid pBR322 production in large amounts by using E. coli relA strains. High amplification rates of pBR322 plasmid DNA were observed in E. coli CP79 (relA) and E. coli CP143 (relA) in both batch and fed‐batch cultivation after exhaustion of the amino acid arginine. The concentrations of plasmid DNA per unit of biomass were nearly the same in batch and in fedbatch fermentations of E. coli CP79 and E. coli CP143. Therefore, the significantly higher biomass concentration of the two strains after fed‐batch fermentation gave a dramatic increase in the yield of plasmid DNA per litre of medium in comparison to the batch process.

The results support the suggestion that E. coli relA strains are suitable hosts for production of large amounts of ColE1‐derived plasmids for recombinant DNA research.
N‐Acetylmuramic acid inhibits spore germination and germination enzymes
Authors: Brown W. C. , Morrison D. , Sanford W. , Granada S.
Published: February 2007

This report describes the inhibition of spore germination by N‐acetylmuramic acid. At concentrations of 20 mM and higher, the rate of germination of the treated spores was ten‐fold lower than that of the control spores. The inhibitor also depressed the activity of two germination‐related enzymes; a coat‐associated hexosaminidase and a core enzyme. These findings suggests that N‐acetylmuramic acid affects spore germination by inhibition of the corticolytic enzymes. The results are discussed with respect to the possible role of these enzymes in germination.
Studies on the mycoflora of Aswan High Dam Lake, Egypt: Monthly variations
Authors: El‐Hissy F. T. , Moharram A. M. , El‐Zayat S. A.
Published: February 2007

Fifty‐one species and one variety appertaining to twenty one genera of mesophilic fungi were recovered from the monthly samples of marginal water (44 species, 1 variety and 18 genera) and submerged mud (78 species, 1 variety and 30 genera) of Aswan High Dam Lake during the period from July 1985 to December 1986. The most common species were Aspergillus fumigatus, A. flavus, A. terreus, A. niger and Penicillium funiculosum. The highest fungal populations were almost detected either in October, in December 1985 or in February 1986. Of the 12 thermophilic and thermotolerant fungal species, A. fumigatus and A. nidulans were the most common. Paecilomyces variotii, Rhizomucor pusillus, Thermomyces lanuginosus, Thermoascus thermophilus and Sporotrichum thermophilum were fairly common in one locality or more. The physico‐chemical characteristics of water and mud samples were also followed.
Inhibition of growth of some plant pathogenic fungi by some antagonistic microorganisms isolated from soil
Authors: Ikotun T. , Adekunle Funke
Published: February 2007

Actinomyces species I and II (tentatively identified awaiting confirmation) and Trichoderma harzianum were isolated from soils grown to cassava plants. The Actinomyces species inhibited the growth of five plant pathogenic fungi at a distance whereas T. harzianum was an active hyperparasite which attacked the mycelia of target organisms (plant pathogens) and prevented their continued growth. The three microorganisms compared favourably with two other established antagonists, Bacillus cereus and B. subtilis. But the species of Actinomyces were especially more active. Soil inoculation of the antagonists have prevented root and tuber rot of cassava plants in the field and are likely to be useful for preventing other soil‐borne diseases of plants.
Synthesis and metabolism of roquefortine in Penicillium species
Authors: Reshetilova Tatiana A. , Kozlovsky Anatoly G.
Published: February 2007

The uptake of exogeneous 14C‐roquefortine by Penicillium farinosum cells and its metabolism was followed. Growth and roquefortine biosynthesis of three Penicillium species during a cultivation period of 14 d were investigated. Furthermore, the effect of cultivation conditions viz. various culture media on roquefortine uptake and biosynthesis as well as biomass production were studied. Some general problems of physiology and metabolic regulation of alkaloid formation in Penicillium species were discussed.
Mechanisms of bacterial degradation and transformation of chlorinated monoaromatic compounds
Authors: Häggblom Max
Published: February 2007

Chloroaromatics are xenobiotic compounds of environmental concern. They can be removed from the environment by (bio)degradation or by (bio)transformation. Recognition of the mechanisms and requirements of their biodegradation is of cardinal importance for understanding the fate of these chemicals in the environment, and for developing methods for biological treatment of wastes containing compounds of this type.

Cleavage of the carbon‐halogen bond is the critical step in degradation of chloroaromatics. As exemplified with chlorophenols, chlorobenzoates and chlorobenzenes in this review, two distinct strategies are employed by bacteria for degradation of chlorinated aromatic compounds: the particular chlorine substituents are removed either directly from the aromatic ring (as an initial step in degradation) or after oxygenative ring cleavage (from chlorinated aliphatic intermediates). Direct elimination of chlorine substituents from the aromatic ring occurs by displacement with either hydroxyl groups (hydrolytically or oxygenolytically) or hydrogen atoms (reductive dechlorination). Dechlorinations of the latter type require reducing power and are significant in anaerobic environments, but have also been observed with strictly aerobic bacteria.

Various biotransformation reactions, with only minor alteration of the parent compound, are an alternative to biogradation. Two environmentally significant transformation reactions discussed here are O‐methylation and O‐demethylation. The capability to O‐methylate chlorinated hydroxybenzenes seems to be widespread in bacteria. O‐Methylation is an environmentally important transformation reaction, since methylation increases the lipophilicity of the compound and thus the potential for bioaccumulation. Bacterial O‐demethylation of chlorinated methoxylated compounds has been observed under both aerobic and anaerobic conditions.
Enzyme regulation in in vivo‐constructed Pseudomonas putida strains with two alternative routes for oxidative degradation of phenol
Authors: Janke D. , Kujau M. , Zippel M. , Schöpp W.
Published: February 2007

Based on plate matings using P. putida strain BL10 as the recipient and either P. putida strain PG405 or PG125 as the donor, the transconjugant strains TK1 and TK3 were obtained. These were shown to harbour a single plasmid of a molecular size comparable to that of PGH1 (in the donor strain PG405) and pPGH11 (in the donor strain PG125), respectively. Clear‐cut evidence was presented that at least the transconjugant strain TK3 has the genetic potential of degrading phenol via both the ortho‐pathway (encoded by chromosomal genes) and the meta‐pathway (encoded by plasmid‐localized genes) due to two complete alternative enzyme sequences. However, in both transconjugant strains TK1 and TK3 only the meta‐pathway enzymes were found to operate during cell growth on phenol as the sole carbon source. Several lines of investigation indicated the observed predominance of the meta‐pathway in TK1 and TK3 cells growing on phenol to be a specific phenomenon resulting from coordinate induction of the respective plasmid‐encoded enzymes by the primary substrate.
Studies on the mycoflora of Aswan High Dam Lake, Egypt: Vertical fluctuations
Authors: Moharram A. M. , El‐Hissy F. T. , El‐Zayat S. A.
Published: February 2007

The fungal population of Aswan High Dam Lake showed marked vertical variations during the period of study which extended from July 1985 to December 1986. High fungal counts were observed at the surface water which were mainly due to the high counts of Aspergillus fumigatus and A. tertureus. Going deeper the fungal population decreased till 30 meters, then gradually increased to reach its maximum at the 70 meter depth (near the bottom of the lake). Such increase was basically due to the high population of Penicillium funiculosum. At each sampling time, the water temperature and the values of dissolved oxygen were always higher at the surface than near the bottom of the lake. The temperature ranged from 15° to 26 °C and the dissolved oxygen from 1.31 to 8.98 mg 1−1.
Microbial DNA topoisomerases and their inhibition by antibiotics
Authors: Zimmer C. , Störl K. , Störl J.
Published: February 2007

Supercoiling of bacterial DNA is regulated by topoisomerases and influences most of the metabolic processes involving DNA. The present review is devoted to a brief outline of the supercoiled state of DNA in bacteria and to all microbial topoisomerases hitherto described. Recent studies on topoisomerases of archaebacteria led to the discovery of a so‐called reverse gyrase, the properties of which are also discussed.

Special emphasis is given to a selective treatment of the effects of those antibiotics which act as gyrase inhibitors.
Mapping of the glucoamylase gene of Trichosporon adeninovorans by mitotic haploidization using hybrids from protoplast fusions
Authors: Büttner R. , Bode R. , Samsonova I. A. , Birnbaum D.
Published: February 2007

In two strains of Trichosporon adeninovorans genes of unknown location were assigned to linkage groups. Diploid strains were produced by protoplast fusion and partially haploidized by growth on benomyl causing mitotic haploidization. We show that both strains synthesize an extracellular glucoamylase with different properties. These differences could be used to map the corresponding gene in the segregants. We could map the glucoamylase gene from one of these yeast strains on linkage group II, one of the three linkage groups identified so far.
Occurrence of zoosporic and terrestrial fungi in some ponds of Kharga Oases, Egypt
Authors: El‐Nagdy M. A. , Abdel‐Hafez S. I. I.
Published: February 2007

Thirty‐nine species belonging to 13 genera of zoosporic fungi were collected from 33 water samples on sesame and hemp seeds as baits at 22 °C. Five genera were isolated in high occurrence:Allomyces(2 species),Achlya(9 species),Dictyuchus(4 species),Pythium(5 species) andSaprolegnia(5 species).Aphanomyces(4 species) andIsoachlya(2 species) were of moderate frequencies. The remaining six genera were less frequent:Anisolpidium, Brevilegnia, Calyptralegnia, Leptolegnia, PythiopsisandThraustotheca.

Sixty‐six species and 2 varieties belonging to 34 genera were identified on glucose‐(24 genera and 52 species + 1 variety) and cellulose (31 genera and 48 species + 2 varieties) CZAPEK DOX agar at 28 °C. The most common species on the two media wereAcremonium strictum, Aspergillus flavus, A. fumigatus, A. niger, Fusarium moniliforme, F. oxysporum, F. solani, Mucor racemosus, Penicillium chrysogenum andP. corylophilum.Some fungi were common only on cellulose agar medium such asChaetomium globosum, C. spiraleandMemnoniella echinata.
DNA probes for studying streptothricin resistance evolution in enteric bacteria
Authors: Tietze Erhard , Tschäpe Helmut , Golubev Alexander V.
Published: February 2007

Probes for the detection of streptothricin resistance genes have been derived from recombinant plasmids. These include the streptothricin resistance gene probe sat 1/2 derived from Tn 1825 and specific for both the sat‐1 determinant of Tn 1825 and the sat‐2 determinant of Tn 1826, and the probe sat D derived from and specific for the sat‐1 determinant of transposon Tn 1825. A third streptothricin resistance gene probe, sat 3, represents the streptothricin resistance determinant sat‐3 of the IncQ R plasmid pIE639. Hybridization studies did not reveal any sequence homology between sat‐3 and the transposon‐ localized sat‐1 and sat‐2 determinants. Moreover, non of the different sat‐determinants isolated from plasmids of gram negative bacteria hybridized with the analogous resistance determinant of Streptomyces noursei, which had been cloned and named nat by KRÜGEL et al. (Gene, 1988, 62, 209–214). The sat 1/2 probe in combination with the sat D probe proved to be suitable for the identification and the differentiation of sat‐1 and sat‐2 determinants in different genetic environments. Streptothricin resistance genes related to those present on transposons Tn 1825 and Tn 1826 have been detected by hybridization with the probe sat 1/2 on plasmids isolated a long time ago before the application of streptothricins. The sat‐3 determinant appears to be exclusively associated with the IncQ plasmid pIE639.
Mutagenesis of Acetobacter methanolicus MB58 with the transposon Tn5
Authors: Dobrowolski P. , Gründig M. W.
Published: February 2007

Transposon mutagenesis was applied to the isolation of mutants of the facultatively methylotrophic Acetobacter methanolicus MB58. The transposon Tn5 (pSU2011) was transferred from Escherichia coli SM 10 by means of conjugation to Acetobacter methanolicus MB 58. Four out of 1850 stable Km‐resistant transconjugants were identified that were formaldehyde sensitive and failed to grow on methanol.
DNA sequences from Saccharomycopsis fibuligera capable of autonomous replication in Saccharomyces cerevisiae
Authors: Jurský František , Hostinová Eva
Published: February 2007

A Sau 3AI digest of total DNA from Saccharomycopsis fibuligera was cloned with the yeast‐integrating plasmid YEp24ΔEcoRI and the capacity for autonomous replication (ARS) was assayed in yeast. From eighty clones, five mitoticaly unstable yeast transformants were picked up, recombinant plasmids from these clones were recovered with Escherichia coli, mapped, hybridized with total DNA of S. fibuligera and tested to mitotical stability in Saccharomyces cerevisiae. Experiments suggested the existence of DNA sequences from dimorphic Saccharomycopsis fibuligera with ARS activity in Saccharomyces cerevisiae.
Spontaneous mutations in the galactose operons of Streptomyces coelicolor A3 (2) and Streptomyces lividans 66
Authors: Ali‐Dunkrah Umaru , Kendall Kevin , Cullum John
Published: February 2007

17 spontaneous Gal− mutants of S. coelicolor were studied using Southern blottings, but no insertion or deletion mutations were found. 10 mutants of S. lividans included three deletion mutations. The reasons for the lack of insertion mutants are discussed.
Acremonium chrysogenum differentiation and biosynthesis of cephalosporin
Authors: Bartoshevich Yu. E. , Zaslavskaya P. L. , Novak M. J. , Yudina O. D.
Published: February 2007

On the basis of structure‐functional analysis of the development of Acremonium chrysogenum, e.g. under conditions either stimulating antibiotic synthesis or not conductive to production, a scheme was proposed representing the various ways in which morphological differentiation occurs in the culture in dependence on the directions of its metabolism.

Three types of culture differentiation were determined. Type 1 differentiation is characterized by the transition of the vegetative stage into the reproductive one with the formation of conidia. Type 2 differentiation is characterized by the formation of typical arthrospores also being the reproductive form. Type 3 differentiation is characterized by the multistage transformation of the mycelium organization into the yeast‐like one which is metabolically more active and is a producer of antibiotics and enzymes.

In addition to the defined regularities in the development and differentiation of Acremonium chrysogenum structural peculiarities were observed which could be helpful to the search for regulators or specific enzymes taking part in the culture development.
Autolytic reduction of the nucleic acid content in Candida utilis
Authors: Kossaczká Zuzana , Vojtková‐Lepšiková Anna , Machová Eva
Published: February 2007

The nucleic acid content in Candida utilis was autolytically reduced only after previous lyophilization of yeast cells or pretreatment of the cells with ethyl acetate. These pretreatments provided a sufficient permeability of the cell membrane system and thus enabled a reduction of the nucleic acid content. While deep freezing of the cells (−35 °C) had no positive effect on the degradation of nucleic acids, lyophilization of yeast cells led to a 75% decrease of the nucleic acid content. Furthermore, a 55% reduction of the nucleic acid content was proceeded without a concomitant loss of proteins. Similar results were obtained by using ethyl acetate.
Studies on the early stages of infection of Alternaria alternata on groundnut (Arachis hypogaea L.)
Authors: Prasad P. , Devi P. Suvarnalatha , Reddy M. N.
Published: February 2007

Studies were conducted on the early stages of infection of groundnut leaves by Alternaria alternata. Inoculated leaves were periodically sampled, checked for germination of spores, growth of germ tubes, appressorium formation and method of sporulation. Evidence was observed for the entry of the germ tubes through the stomates (with or without the formation of appressorium‐like structures) or through the host surface by the formation of appressoria.
Substratinduzierte cAMP‐Signale in Wildstämmen und Mutanten von Saccharomyces cerevisiae
Authors: Sachse Ottomar
Published: February 2007

Addition of glucose or other substrates to starved Saccharomyces cerevisiae cells triggers a cyclic AMP signal which induces the protein phosphorylating cascade. Before the addition of various substrates the wild‐type and mutant yeast strains were arrested at the G1 phase of the cell division cycle by transferring the cells, grown at 26 °C to 36 °C in a synthetic medium without any substrate. After the temperature shift back to 26 °C different substrates were added and the cAMP levels were measured. The highest cAMP levels were observed immediately after the addition of the substrates. A relationship between the maximum growth rate of the individual strains or mutants at a given substrate and the intracellular cAMP level is discussed.
Fungal flora associated with combine harvester wheat and sorghum dusts from Egypt
Authors: Abdel‐Hafez S. I. I. , Moubasher A. H. , Shoreit A. A. M. , Ismail M. A.
Published: February 2007

107 species and 8 species varieties belonging to 44 genera were collected from combine harvester wheat and sorghum dusts (35 genera and 91 species + 4 varieties) and from the atmosphere of their hay sites (26 genera and 69 species + 4 varieties) on glucose‐ and cellulose‐CZAPEK's Dox agar at 28 °C and 45 °C. The mycoflora of wheat and sorghum dusts were basically similar on the two types of media and the most common fungi were:Alternaria alternata, Aspergillus flavus, A. fumigatus, A. niger, A. ochraceus. A. svdowii, A. terreus, Cochliobolus spicifer, Emericella nidulans, Fusarium moniliforme, Penicillium chrysogenum, P. duclauxii, P.funiculosumandP. oxalicum.Truly thermophilic species were frequently encountered from the two substrates:Chaetomium thermophilum, Humicola griseavar. thermoidae, H. insolens, Malbranchea pulchella var.sulphurea, Rhizomucor pusillus, Sporotrichum thermophilum, Talaromyces thermophilus, Thermoascus thermophilusandThermomyces lanuginosus.

The airborne fungi in the two atmospheres were basically similar and the most prevalent species were members ofAlternaria(1 species),Aspergillus(18 species + 2 varieties),Chaetomium(2 species),Cochliobolus(3 species),Emericella(3 species + 2 varieties),Fusarium(3 species),Mucor(1 species),Penicillium(14 species) andStachybotrys(1 species).
The proton extrusion of growing yeast cultures as an on‐line parameter in fermentation processes: Determination of biomass production and substrate consumption in batch experiments with Candida maltosa EH 15 D
Authors: Huth Joachim , Blasig Rosel , Werner Sabine , Müller Hans‐Georg
Published: February 2007

Using the proton extrusion of growing yeast cultures (calculated from the alkali consumption required to maintain a constant pH‐value) it is possible to describe the growth of yeasts and the growth‐related substrate consumption on‐line and to do so more exactly than by determining these values with usual off‐line methods. In batch experiments with Candida maltosa in a mineral salt medium clear linear relationships could be demonstrated between the proton extrusion nH+ and the increase of biomass concentration (determined as dry weight, optical density and protein according to a modified LOWRY‐method) as well as substrate consumption (n‐hexadecane and NH+4 as the C‐ and N‐sources respectively). The biochemical basis of the proton extrusion seems to be connected with the NH+4‐metabolism. The simple on‐line registration of the proton extrusion offers various possibilities to use this value for control of fermentation processes.
Formation of a potent respiratory inhibitor at nitrite reduction by nitrite reductase isolated from the bacterium Paracoccus denitrificans
Authors: Kučera Igor , Skládal Petr
Published: February 2007

A new method of dissimilatory nitrite reductase (cytochrome cd1) isolation from the periplasmic fraction of anaerobically grown cells of the bacterium Paracoccus denitrificans was developed, using ionex and gel permeation chromatography with FPLC system (PHARMACIA, Sweden). In experiments with isolated enzyme it was shown that through a nitrite reduction, catalysed by this enzyme, a substance (presumably nitric oxide) was formed which at submicromolar concentrations inhibited terminal cytochrome oxidase of the respiratory chain of the same bacterium. These results help to explain formerly observed sensitivity of bacterial oxidase activity to NO‐2 and the mechanism of switching the electron flow from O2 to nitrogen terminal acceptors.
Protein extracts for nutritional purposes from fragile strains of Saccharomyces cerevisiae: Reduction of the nucleic acid content and applicability of the protein extracts
Authors: Lyutskanov Nikola , Koleva Lidia , Stateva Lubomira , Venkov Pencho , Hadjiolov Asen
Published: February 2007

92% of the cellular proteins from the osmotically fragile strain Sacch. cerevisiae 211 (MATa srbl srb2 tsl) were extracted by one passage in a high pressure disintegrator at 650 atm. After isoelectric precipitation, 60.1% of the proteins were isolated. The protein extract was rich in proteins (60–70%) but also contained 12–13% nucleic acids and 13–14 % carbohydrates. Mild conditions were created for simultaneous reduction of nucleic acids and carbohydrates in the lysate prior to precipitation of proteins. Under these conditions the amount of nucleic acids in the protein extract was reduced to 2 %, and that of the carbohydrates to 5.7 %. As a result of the whole procedure on a pilot scale, 1 1 culture of Sacch. cerevisiae 211 grown in molasses based nutritional medium yielded 1 g protein extract. The applicability of this protein extract for nutritional purposes was demonstrated by determination of its amino acid composition, acute toxicity tests with Tetrahymena pyriformis and short‐term animal nutrition tests. The results showed that the protein extract is a suitable source of SCP for nutritional purposes.
Flavonoids in seed coats of two Colutea species: Ecophysiological aspects
Authors: Aguinagalde Itziar , Perez‐Garcia Felix , Gonzalez Aldo E.
Published: February 2007

Colutea is a genus of great rusticity and is valuable as forage. Its domestication is limited by the low germination rates and high susceptibility of the seeds to fungal attack. Abundant kaempferol, quercetin and myricelin glycosides have been identified from seed coats of Colutea arborescens and C. atlantica. Their ecophysiological role is studied by bioassays: inhibition test of germination of Lactuca sativa; inhibition test of growth of Cladosporium cladosporoides and Sterigmatomyces polyborus isolated from the seed coats.
The proton extrusion of growing yeast cultures as an on‐line parameter in fermentation processes: Ammonia assimilation and proton extrusion are correlated by an 1:1 stoichiometry in nitrogen‐limited fed‐batch fermentations
Authors: Huth Joachim , Werner Sabine , Müller Hans‐georg
Published: February 2007

In preceding papers (HUTH et al. 1990a, b) the proton extrusion nH+ of growing yeast cultures was shown to be an exact and reliable on‐line parameter for the description of biomass production and consumption of the nitrogen (NH4+) and carbon sources quantitatively in batch and fed‐batch fermentation processes.

In the present paper we demonstrate that the biochemical basis of this proton extrusion must be connected with the nitrogen metabolism of growing yeasts: A strong acidification was found only during growth on NH4+ as the source of nitrogen, while the pH‐course was different for other substrates. Using NH4+limited fed‐batch conditions we detected an NH4+/H+ exchange ratio of exactly 1.0.

The usefulness of the proton extrusion as an on‐line parameter in fermentation control and its range of application are discussed.
Ultrastructural features of microbial colony organization
Authors: Tetz Victor V. , Rybalchenko Oksana V. , Savkova Galina A.
Published: February 2007

The ultrastructure of microbial colonies was studied. Inside the colonies three types of intercellular contacts were demonstrated. In the colonies of Gram‐negative bacteria, the cells were found to be connected by tight adhesions of outer membranes of the cell walls and membrane bridges. In the colonies of Gram‐positive bacteria, the intercellular contacts were formed by fusion of peptidoglucan layers of the cell walls. Bacterial cells were differentiated by the presence of a capsule‐like envelope. The obtained data indicate the existence of elements of cellular cooperation and specialization in microbial colonies.
Citrate metabolism in starved cells of Streptococcus lactis subsp. diacetylactis
Authors: Vilchez F. , Petit C. , Marczak R.
Published: February 2007

The effect of starvation on citrate metabolism by fully grown cells of Streptococcus lactis subsp. diacetylactis was studied by three different procedures.

An 8‐hour starvation period in fermented medium decreased citrate uptake rate but diacetyl and acetoin levels remained constant over a fermentation without starvation period: about 19 mg l‐1 diacetyl and 130 mg l‐1 acetoin were produced after utilization of 8.8 mM citrate. When fermentation products were discarded from the medium before starvation, diacetyl and acetoin levels reached 30 mg l‐1 and 240 mg l‐1, respectively.

When the cells were allowed to rest on an isotonic diluent, citrate uptake rate slowed down, but the diacetyl plus acetoin yield remained higher since the cells accumulated as much acetoin (120 mg l‐1) and more diacetyl (50 mg l‐1). Peak production of diacetyl still coincided with citrate exhaustion whereas a delay in acetoin production was observed.
Activity of mutagens in the fungus Gibberella fujikuroi
Authors: R.  , Brückner B. , Blechschmidt D. , Fischer W.
Published: February 2007

The efficacy of a number of mutagens was examined for Gibberella fujikuroi. Nitrosoguanidine (MNNG) was the most effective mutagen inducing mainly morphological and pigment mutants. X‐ray produced small mutagenic effect. After UV‐irradiation pigment mutants developed for the most part and a combination of UV‐ and x‐ray‐irradiation mainly influenced the growth rate. A combination of UV‐irradiation with MNNG elicited the highest number of mutants with increased GA3 production.
The Streptomyces aureofaciens plasmid pIMB R8 and its use for shuttle vector construction
Authors: Godány Andrej , Lacová Bibiana , Zelinka Jan
Published: February 2007

The cryptic low copy plasmid designated as pIMB R8 was isolated from an industrial strain of the chlortetracycline producer Streptomyces aureofaciens R8/26. Using restriction endonucleases the pIMB R8 plasmid was characterized to have 15 kb. Subcloning of the Bam HI fragments of pIMB R8 into replication probe vector resulted in the identification of the replication part. The 0.7 kb Bc/I – Bg/I fragment is sufficient for normal replication, but produces about fourty times high plasmid copy numbers than the original pIMB R8. Using the replication part of pIMB R8 we constructed several shuttle cloning vectors for the E. coli‐streptomycete system.
Leghämoglobin aus Wurzelknöllchenextrakten von Luzerne bei genotypischer Variation der Symbiose
Authors: Hoffmann Karl‐Heinz , Kaemmer Dieter , Miksch Gerhard , Lange Ingrid , Kleinert Thomas
Published: February 2007

The host plant genotype significantly influenced the nodule Lb content in all of the combinations examined between 5 alfalfa (Medicago sativa) cultivars and 5 Rhizobium meliloti strains inoculated, on the contrary not the bacterial genotype. The inoculation with the strains exhibiting an increased activity of uptake hydrogenase caused an elevation of the nodule Lb content. By IEF 4 major Lb components were found. Their proportions were changed throughout the nodule development.
Some factors affecting bioconversion of whole bagasse into fungal biomass
Authors: Nigam Poonam , Prabhu K. A.
Published: February 2007

Two isolated basidiomycetes mould cultures Polyporus BH1 and Polyporus BW1 and two standard white rot fungal cultures Pleurotus ostreatus and Polyporus versicolor were cultivated under submerged conditions on whole (untreated) bagasse for protein production. Some factors promoting better bioconversion were studied and selected. NORKRAN's medium at pH 5.0 with 1.0% bagasse of 80 mesh particle size using an appropriate quantity of inoculum, supplementing medium with an amino acid, without addition of any vitamin, etc. gave best results.
Distribution of three lysine‐catabolizing enzymes in various yeast species
Authors: Hammer Thomas , Bode Rüdiger , Schmidt Heike , Birnbaum Dieter
Published: February 2007

28 yeast strains comprising a number of genera and species have been studied with respect to their ability to use l‐lysine as carbon or nitrogen source. Based on the utilization of this amino acid we could separate the yeasts into 3 groups. Enzymatic investigations demonstrate that yeasts can degrade l‐lysine by two distinct pathways. The first step of both ways was investigated and it was demonstrated that 3 enzymes, acetyl‐CoA: l‐lysine N‐acetyltransferase, l‐lysine α‐aminotransferase, l‐lysine α‐dehydrogenase, are able to catalyze the initial reaction. In 9 yeast strains the acetyltransferase was found. In 21 strains the aminotransferase and in 2 species the dehydrogenase could be detected. The enzyme formation could be enhanced in cells grown in the presence of l‐lysine as sole carbon and/or as sole nitrogen source.
Biosynthesis of tentoxin and dihydrotentoxin via protein turnover by Alternaria alternata
Authors: Liebermann B. , Schuffenhauer S. , Ihn W.
Published: February 2007

By shift experiments after labelling mycelium with d‐glucose‐U‐14C, l‐leucine‐U‐14C or Na15NO3, it was possible to demonstrate that in the biosynthesis of cyclic tetrapeptides during the idiophase, Alternaria alternata uses mycelium compounds produced and stored up in the trophophase. The participation of this protein turnover in the biosynthesis of tentoxin and dihydrotentoxin is very high, and differences are demonstrable concerning the single amino acids. If exogenous amino acids are available the fungus is also able to use them for the formation of the secondary products, in the early idiophase the highest incorporation rate was obtained.
Nachweis einer Fructokinase und ihre Bedeutung für den Stoffwechsel von Pseudomonas syringae pv. phaseolicola
Authors: Sauerstein J. , Schade R. , Emde J. , Reuter G.
Published: February 2007

The plant pathogenic Pseudomonas syringae pv. phaseolicola possesses a fructokinase which is epigenetically regulated. The kM values for fructose and ATP are 0.56 and 0.53 mM, respectively. About 23% of the activity observed with ATP was obtained with equimolar amounts of ITP. CTP, GTP, UTP, PEP and acetl‐P were ineffective, Fructokinase is responsible for the conversion of fructose to fructose‐6‐phosphate. In this way,. fructose, which is formed intracellulary during the growth in a sucrose or mannose containing medium, can be metabvolized via fructose‐6‐phosphate.
Host‐controlled modification and restriction as a criterion of evaluating the therapeutical potential of Pseudomonas phage
Authors: Gachechiladze K. K. , Balardshishvili N. S. , Adamia R. S. , Chanishvili T. G. , Krüger D. H.
Published: February 2007

The recently isolated phages ØST3 and ØST1 were compared as to their lysis behaviour in about 100 different P. aeruginosa strains. The growth of ØST3 varies greatly in different host strains. We demonstrated one case of “non‐classical”, host‐dependent modification and restriction. Here the capability to adsorb, and consequently to reproduce in a given host strain differs, depending on which modification the phage aquired in its former host. — The DNA‐containing phage ØST1 displays stable lysis properties in the majority of the host strains. This makes ØST1 a candidate for therapeutic phage preparations. One of the reasons for stable lysis properties is the apparent selection against recognition sites of restriction enzymes in its genome.
Steric course of the N‐methylation in the biosynthesis of ergot alkaloids by Claviceps purpurea
Authors: Gröger Detlef , Gröger Lisa , D'Amico Derin , He Min‐Xia , Floss Heinz G.
Published: February 2007

Using the chiral methyl group methodology, the methylation step in the biosynthesis of ergot alkaloids catalyzed by the enzyme AdoMet:dimethylallyltryptophan N‐methyltransferase was found to proceed with net inversion of methyl group configuration. The enzyme thus conforms to the majority of methyltransferases studied which mediate a direct SN2 transfer of the methyl group from AdoMet2) to the acceptor nucleophile in a ternary enzyme substrate complex.
Genetic recombination in Streptomyces michiganensis DSM 40 015 revealed three genes responsible for the formation of melanin
Authors: Held Thomas , Kutzner Hans J.
Published: February 2007

By UV and NTG mutagenesis numerous auxotrophic, antibiotic‐resistant and melanin‐negative mutants were isolated from Streptomyces michiganensis DSM 40 015 which proved to possess a efficient photoreactivation system. Using a mel− test strain with three auxotrophic markers and a antibiotic resistance for crosses with numerous prototrophic mel− strains three classes of mutants (melA, melB and melC) could be found. This classification was further supported by a series of crosses. The melC locus seemed to correspond to the melC locus of S. glaucescens which contains the tyrosinase structural gene.
Mechanistic studies of two amino acid racemases of broad substrate specificity from Pseudomonas striata and Aeromonas caviae
Authors: Reynolds Kevin , Martin Jennifer , Shen Shu‐Jane , Esaki Nobuyoshi , Soda Kenji , Floss Heinz G.
Published: February 2007

The conversion of l‐[α‐2H]alanine in H2O and unlabeled l‐alanine in 2H2O into d‐alanine, under nearly irreversible conditions, with the amino acid racemase from Pseudomonas striata showed significant internal transfer of the α‐hydrogen. This result has been interpreted as being indicative of a single base mechanism for the racemization.

The relative rates of deuterium incorporation into unlabeled d‐ and l‐methionine by the two amino acid racemases of broad substrate specificity from P. striata and Aeromonas caviae, were measured in 2H2O. The results showed a markedly different pattern, dependent upon the configuration of the initial substrate; with d‐methionine as substrate deuterium is incorporated into both enantiomers at approximately the same rate, but with l‐methionine as substrate deuterium is incorporated considerably faster into the d than the l enantiomer. These results argue against a single base mechanism of racemization for these enzymes and are best rationalized in terms of a double base model where only one of the bases undergoes proton (deuterium) exchange with the solvent while the amino acid is enzyme‐bound. The interpretation of the earlier experiment needs to be considered in light of these results.