bluuebunny/crossref_metadata_2025 huggingface dataset:
Some investigations concerning the entropy balances of microbial fermentations — primary and secondary metabolite production
Authors: Bormann E.‐J. , Grosse H. H. , Menz J.
Published: February 2007

In order to check the usefulness of the resulting equations of a model concerning entropy balances of microbial fermentation processes apropriate experiments were analyzed. To take into account both primary and secondary metabolism data of previously carried out fermentations of the amino acid L‐lysine and the antibiotic nourseothricin respectively were used.

The obtained results indicate the agreement of the calculated values with the supposed thermodynamic relations showing the expected decrease of entropy production to a minimum as well as the zero balance of the entropy variation.

The course of entropy production during the phase of product formation gave rise to discuss this phenomenon from a more general viewpoint with respect to the role of secondary metabolites as a possible way to avoid “overheating” of cells or membranes although energy substrates are available in excess.
Interconversion and glucose‐induced inactivation of glucose transport systems in Candida shehatae
Authors: Lucas Cǎndida , van Uden N.
Published: February 2007

During starvation (derepression) glucose‐grown cells of Candida shehatae IGC 3607 displayed total interconversion of facilitated diffusion of glucose into a glucose‐proton symport, dependent on de novo protein synthesis (proteosynthetic interconversion). The reverse process, inactivation of the proton symport induced by glucose or 2‐deoxyglucose, was not accompanied by reemergence of the facilitated diffusion function. The inactivation process had a rapid initial and a slow second phase. The rapid inactivation depended on the external sugar concentration and was reversible while the subsequent slow inactivation was irreversible and independent of the external concentration of the signalling sugar. Interaction of the latter with a surface receptor was indicated by the range of sugar concentrations that affected rapid inactivation.
Mutants of Rhizobium meliloti defective in nodulation
Authors: Małek Wanda
Published: February 2007

Using nitrosoguanidine (NTG) two nodulation defective (Nod−), auxotrophic mutants of the Rhizobium meliloti strain L5.30 have been isolated. In their Sym plasmid, pRmeL5.30b, a large deletion has been demonstrated. Both mutants were adsorbed into root hairs of lucerne, but were unable to induce root hair curlings. The nodulation of lucerne was restored to both hair‐curling (Hac−) mutants by the introduction of the Sym plasmid pJB5JI of R. leguminosarum and by plasmid pEK25, carrying a 3.6 kb AvaI/EcoRI fragment of “common” nod genes of R. meliloti 41. This led to the conclusion that in these Nod− deletion mutants nod mutations were concerned with “common” nod genes.
Reduction of testosterone, androstendione and their derivatives by Aphanocladium album
Authors: Dmochowska‐Gladysz Jadwiga , Kolek Teresa , Siewiński Antoni
Published: February 2007

A strain of Aphanocladium album reduces the C‐3 carbonyl group in testosterone or androstendione to to 3α‐allyl alcohol. In some derivatives of these steroids the same carbonyl group is reduced to allyl alcohol with stereospecificity, depending on whether chlorine at C‐4 or a 17α‐methyl group is present. On the other hand, the presence of C‐4 methyl group, a C‐19 hydroxy group, a C‐17 acetyl one, or a double bond conjugated with the 4‐en‐3‐ ketone system totally inhibits the formation of allyl alcohols at C‐3.

At the samé time, the C‐17 carbonyl group in androstendione or in its derivatives is reduced to a respective 17β‐alcohol.

In the derivatives with an additional 2‐exomethylene group the double bond at this group is reduced.
Adaptive growth at high temperatures of the lactose‐fermenting yeast Kluyveromyces marxianus var. marxianus
Authors: Sampaio J. P. , Spencer‐Martins I.
Published: February 2007

The temperature profile of growth and death rates of a strain of Kluyveromyces marxianus var. marxianus was found to be essentially dissociative, with an optimum temperature for growth at around 38 °C and sustained exponential growth up to 43–44 °C. At temperatures near the maximum temperature for growth a second growth period was observed. This did not correspond to the second branch in the ARRHENIUS plots characteristic of associative profiles, since growth was not balanced and after a while the growth rate increased to values similar to those of the first period. The biomass yield on lactose was not dependent on the growth temperature, a behaviour typical of yeast strains with dissociative temperature profiles.
Cytological effects of fungal metabolites produced by fungi isolated from Egyptian poultry feedstuffs
Authors: Abdou R. F. , Megalla S. E. , Moharram A. M. , Abdel‐Gawad K. M. , Sherif T. H. I. , Mahmood A. L. El‐Syed , Lottfy A. E.
Published: February 2007

The cytogenetic effects of fungal metabolites produced by 113 strains belonging to 36 fungal species and isolated from 5 substrates of commercial poultry feedstuffs were tested for their effect on the growing root meristems of Allium cepa.

The fungal metabolites of Paecilomyces canescens, Aspergillus fumigatus, Syncephalastrum racemosum, Aspergillus terreus and Mucor hiemalis strongly suppressed cell division. Metabolites from other strains had less effect on cell division but permitted the appearance of several abnormalities through different mitotic stages. In general, chromosomal aberrations were more obvious with metabolites of Aspergillus species, Mucor circinelloides and Cladosporium cladosporioides.

The mutagenic effects produced by these fungal metabolites reflect the risk that might take place through the consumption of these contaminated feedstuffs.
Effect of protonophore on growth of Escherichia coli
Authors: Nakano S. , Onoda T.
Published: February 2007

When 20 μM of carbonyl cyanide‐m‐chlorophenyl hydrazone (CCCP) were added to a M medium containing glucose as an energy source at pH 7.6, the Escherichia coli K12 strain 3301 was able to grow, whereas on the medium containing NaCl above 200 mM, the growth was remarkably suppressed by the addition of 20 μM CCCP. Furthermore, when glucose was replaced by either glycerol or lactate as an energy source, no growth occurred in the presence of 20 μM of CCCP. When glycerol was used as a substrate, O2 consumption by whole cells was observed in the presence of 20 μM of CCCP, but not in the case of lactate. We found that 14C‐lactate uptake was completely inhibited by the addition of 20 μM of CCCP. The cells, which were incubated for 24 h on a M medium containing glucose in the presence of 20 μM of CCCP produced many more organic acids (mainly, acetate and lactate) than was the case in its absence. It appears that the influx process of external lactate when this was added as an energy source, was completely inhibited by addition of CCCP (20 μM), but the efflux process of lactate that was produced by glycolysis, was not influenced by this protonophore. On the other hand, it is suggested that on the hyposalts medium, a proton motive force (pmf) is not necessary for the growth of the strain 3301, whereas pmf is necessary for growth to occur.
Untersuchungen zum Methankreislauf in der Saale
Authors: Berger Ursula , Heyer Jürgen
Published: February 2007

The activities and interrelations of the processes of methanogenesis and methane oxidation were investigated in the water and sediment of the middle Saale River. The studies showed that in the impounded reaches of the river, which is heavily polluted by organic waste and inorganic compounds, sediments occur with high methane production rates (6.3–64.6 mmol/m2 · h). The methane oxidation in the surface sediment layer (20–240 μmol/1 · h) was shown to function as an effective barrier for the methane diffusion out of the sediment. The methane concentrations in the anaerobic sediment were very high (383–1696 μmol/1), but low in the water (0.33–9.3 μmol/1) in consequence of oxidation processes and water turbulence. The distribution of methane‐oxidizing bacteria was studied. High cell concentrations were found (water, 8.8 · 101 — 2.8 · 104 cells/ml; sediment, 1.3 · 106 — 1.3 · 107 cells/gram). The ecological importance of the processes of the methane cycle was evaluated by calculation of the oxygen demand (methane oxidation) and of the mineralization capacity in the river system. The anaerobic mineralization of organic matter with the methanogenesis as terminal step amounted to 59–87% of the total mineralization. The sediment and consequently the particular organic load was found to be a significant factor for estimation and control of the water quality in the river.
Enantioselectivity of the metabolism of some monoterpenic components of coniferous tree resin by Armillariella mellea (honey fungus)
Authors: Draczynska‐Lusiak Bozena , Siewinski Antoni
Published: February 2007

Transformation of (±)α‐pinene, (±)α‐terpineol, and (±)α‐limonene by Armillariella mellea proceeds enatio‐selectively. (±)α‐Pinene oxidizes (via α‐terpineol) (to (4S)‐trans‐sobrerol faster than to (4R)‐isomer. (4R)‐Trans‐sobrerol and (4S)‐1,2,8‐p‐menthantriol are formed in excess from (±)α‐terpineol, whilst transformation of (±)‐limonene yields an excess of (4R) 8‐p‐menthene‐1,2‐diol.
Combined effects of salinity and temperature on some morphological aspects of four zoosporic fungi
Authors: El‐Hissy Farida T. , Khalil A. M.
Published: February 2007

The quantitative and qualitative formation and deformations of vegetative mycelia, zoosporangia and their discharge, oogonia, antheridia, gemmae, resting sporangia and male and female gametangia varied according to variations in NaCl concentration, temperature and incubation period. Species‐dependent differences were observed.
Critical steps in degradation of chloroaromatics by rhodococci IV. Detailed kinetics of substrate removal and product formation by resting pre‐adapted cells
Authors: Janke D. , Ihn W. , Tresselt D.
Published: February 2007

In kinetic experiments it was demonstrated that turnover of various monochloroaromatic non‐growth substrates (i.e. 2‐chloroaniline, 3‐chloroaniline, 3‐chlorophenol, 4‐chlorophenol, 3‐chlorobenzoic acid) by resting pre‐adapted cells of Rhodococcus sp. An 117 or An 213 typically results in the accumulation of cis‐4‐carboxymethylene‐but‐2‐en‐4‐olide as the principle dead‐end product while cometabolic 2‐chloroaniline turnover by resting aniline‐grown cells of Rhodococcus rubropertinctus IMET 7481 yielded nearly stoichiometric amounts of 2‐chloro‐cis,cis‐muconic acid. Evidence is presented that the observed cometabolic effect of glucose on turnover of the respective monochloroaromatics is primarily associated with their initial oxygenative conversion into chlorocatechols. Based on the described experimental data, it was concluded that the failure of rhodococci to bring about total degradation of chloroaromatics through chlorocatechols is mainly due to the absence in these organisms of a modified ortho‐cleavage pathway (i.e. maleylacetatepathway).
Beladung von Polystyrol Festphasen mit mikrobiellen Erregern und deren Polysaccharid‐Antigenen zum Screening monoklonaler Antikörper
Authors: Mehl M. , Starke R. , Urban Anette , Hoffmann A. , Kiessig St. , Schmidt G.
Published: February 2007

Before screening monoclonal antibodies using enzyme immuno assays, it is necessary to prove that the coating of the solid phases occurs efficiently. The adhesion of whole cells of group B streptococci, Escherichia coli K1, Haemophilus influenzae type b and Candida albicans as well as B‐Streptococcus group antigen, H. influenzae type b capsular antigen, and C. albicans cell wall antigen to polystyrene solid phases was studied and detected by the following methods:.

Peroxidase competition procedure, scintillations measurement of 32phosphate‐labelled germs, and reactions with monoclonal antibodies.
Flavovirin — a new antifungal antibiotic produced by the pyrenomycete Melanconis flavovirens
Authors: Sailer Miloslav , Šašek Václav , Sejbal Jan , Buděšínky Miloš , Musílek Vladimír
Published: February 2007

The pyrenomycete Melanconis flavovirens was found to produce a mixture of two antifungal antibiotics. The first has been already described; the antibiotic is identical with thermozymocidin (myriocin). The second antibiotic is a new compound, whose isolation and identification is presented in this paper. The chemical structure of this substance (C21H37NO5) was determined to be 2‐amino‐2‐hydroxymethyl‐3,4‐trans‐epoxy‐14‐oxo‐eicos‐trans‐6‐enoic acid. After the producer it was named flavovirin and it possesses strong activity against yeasts and a moderate effectivity against filamentous fungi.
Quantitation of the relationship between tester cell number inoculated and SOS‐inducing potency of 4‐nitroquinoline‐1‐oxide (4‐NQO) in an automated version of the SOS chromotest
Authors: Janz Siegfried , Wolf Gerhard , Huttunen Tapani , Raabe Ferdinand , Storch Helmi
Published: February 2007

The SOS chromotest is a simple quantitative short‐term bacterial assay for the detection of genotoxic activity of pure compounds or complex samples. On the basis of consecutive experiments aimed at demonstrating the relationship between the inoculum size and the outcome of the test using 4‐nitroquinoline‐1‐oxide (4‐NQO) as model genotoxin. It is shown that within the suitable range of the cell number there is a negative correlation between the number of tester cells and test sensitivity. Moreover, it could be demonstrated that the peak of the dose response curve, i. e., the maximal induction factor, is systematically influenced by the actual value of the ratio of β‐galactosidase to alkaline phosphatase enzyme activities at a 4‐NQO concentration of zero. Last but not least, some simple statistical data describing the performance of the automated version of the SOS chromotest are also given.
On the control of riboxin biosynthesis by Bacillus subtilis
Authors: Malkov M. A. , Tojtman A. I. , Kilfin G. I.
Published: February 2007

The pattern of directed riboxin biosynthesis by Bacillus subtilis was studied in dependence on the cultivation conditions using the material‐energy balance method (MEB).

By means of comparative evaluation of experimental and theoretical values of physiological indices received from the MEB equations, we determined the key fermentation periods where it was necessary to change both aeration and mixing regimes. During the period of controled biosynthesis characteristics of self‐regulation of the process have been observed, as expressed by periodical increases and decreases of glucose consumption rate and respiration intensity. The latter was inversely correlated to the velocity of riboxin synthesis and corresponded directly to changes of growth rate.
Plant growth substances produced by microorganisms of the rhizosphere and the soil
Authors: Leinhos Volker , Birnstiel Heide
Published: February 2007

Microorganisms isolated from the soil and the rhizosphere of wheat plants produce growth regulating substances with effects similar to gibberellins when grown in submerse cultures. Bioassays and thin layer chromatography were used for characterization. Different plant growth regulating substances and variations in their quantity were observed among microorganisms. The amounts of gibberellin‐like substances found in culture filtrates varied, in a range from 0.01 to 1.0 mg GA3 equivalents per liter.
Expression of β‐glucosidase and endo‐β‐1,4‐glucanase during development of Chaetomium fusisporale and their characterization
Authors: Sandhu D. K. , Puri R.
Published: February 2007

In the present study, the production of β‐glucosidase and endoglucanase and the pattern of their corresponding polymorphic forms occurring in the extracellular and cytosolic filtrates of Chaetomium fusisporale (ATCC 64772) has been studied. When C. fusisporale was grown on carboxymethyl cellulose (CMC) as the sole carbon source, the extracellular fractions contained most of these enzymes. The distribution of the enzymes varied with the age of the culture. By the use of electrophoretic techniques the presence of two forms of β‐glucosidase, i.e. β‐GLU II and β‐GLU III was detected in extracellular and cytosolic filtrates at early stages of growth, while at later stages two more isozymes of β‐glucosidase, i.e. β‐GLU I and β‐GLU IV, only appeared in the cytosolic filtrates. Similary, endoglucases isozymes EG I and EG II were present in both fractions at early stages of growth but at later stages, with the production of perithecia, EG III appeared. Thus, EG III, β‐GLU I and β‐GLU IV may indicate that they are correlated with the development of the fungus. In order to differentiate further between the multiple molecular forms of these enzymes two of them have been characterized with respect to temperature, pH, ethylenediamine tetra‐acetic acid (EDTA) and metal ions.
Unidirectional internuclear transfer of linked genes in heterokaryons of Candida albicans
Authors: Sarachek Alvin , Lovchik Julie A.
Published: February 2007

Nutritionally balanced heterokaryons of the naturally diploid, asexual yeast, Candida albicans are produced by fusing protoplasts of complementing auxotrophic strains. Spontaneous unidirectional internuclear transfers of an intact gene linkage group in established heterokaryons is demonstrated. Evidence is presented that a transfer event (i) typically involves a single chromosome which is added to the resident homologues of a recipient nucleus, (ii) can occur equally well in either direction between complementing nuclei and (iii) may encourage gene conversion at transferred loci in the recipient nucleus. The bearing of these findings on application of protoplast fusion to parasexual genetic analysis of C. albicans is discussed.
Relationship between the fatty acid composition and the type of antibiotics produced by Streptomyces lasaliensis
Authors: Podojil M. , Steinerová N. , Cudlín J.
Published: February 2007

The GC‐MS method was used to analyze fatty acids in a parent strain of Streptomyces lasaliensis and its two mutants producing only lasalocid or quinomycin. The biosynthesis of these substances bears relation to differences in the relative proportion of fatty acids. Biosynthetic relationships were revealed between the starter fatty acid units, their precursors, i.e. valine, leucine and isoleucine, and the type of the antibiotic produced.
Sequence‐directed DNA bending upstream of the streptokinase promoter
Authors: Müller Jörg , Malke Horst
Published: February 2007

A 450‐base pair (bp) HinfI restriction fragment from the chromosome of Streptococcus equisimilis H46A contains the early coding region of the streptokinase gene (skc), the skc promoter, and a stretch of DNA 5′ to the – 35 region of the skc promoter. Two‐dimensional polyacrylamide (PA) gel electrophoresis at two different temperatures showed that this fragment migrates anomalously slowly on PA gels, suggesting the existence of a bent DNA conformation. Inspection of the nucleotide sequence confirmed this suggestion by revealing numerous oligomeric dA.dT tracts, some of which are in phase with the helix screw. Computer analysis of the sequence predicted the existence of two bending loci, one of which is located upstream of the skc promoter. In addition to showing DNA bending, the 450‐bp HinfI fragment contains multiple 13‐bp sequences homologous to the Escherichia coli integration host factor DNA‐binding consensus sequence. Insertion of IS1 into a site immediately upstream of the – 35 region decreased the expression level of skc in E. coli, suggesting that DNA conformation upstream of the promoter has a role in skc expression.
Some environmental and nutritional factors affecting growth of associated microorganisms of agadagidi
Authors: Sanni A. I.
Published: February 2007

A determination of the effect of temperature on growth of the test organisms revealed an optimum range of 30°–37°. From the pH– growth studies, tolerance to low pH levels was observed for all the microorganisms but the optimal range was 5.1–7.2. Various carbohydrates as sources of carbon were utilized.
Microbial synthesis of metabolites with antihypertensive activity: Aspects of fermentation derived inhibitors of angiotensin‐converting enzyme (ACE)
Authors: Manthey Anna , Reuter Gerhard
Published: February 2007

In this review the microbial angiotensin‐converting enzyme inhibitors are described. Especially from the microbiological point of view the characteristics of these metabolites are given, e.g. occurence, fermentation physiology and specificity. Besides these data, the structure, assays and some isolation problems are summarised. Apart from ACE inhibition the different biological activities of these secondary metabolites are discussed.
Streptomyces nucleotide 3′‐pyrophosphokinase are insensitive to stringent control
Authors: Mukai Jun‐Ichiro , Muta Shigeru , Ozumi Yukiko
Published: February 2007

The synthesis of GTP‐ and ATP‐3'‐pyrophosphate by Streptomyces morookaensis nucleotide 3′‐pyrophosphokinase was little affected by the presence of a ribosome‐deacylated tRNA‐poly A,G,U mixture in vitro. The Streptomyces pyrophosphokinases thus do not appear, unlike bacterial stringent factors, to play a significant role in the cellular stringent control.
Amino acids in the mycelium of four isolates of Macrophomina phaseolina pathogenic to groundnut (Arachis hypogaea L.)
Authors: Reddy M. N. , Devi P. Suvarnalatha , Reddy M. Basi
Published: February 2007

Single hyphal tip cultures of Macrophomina phaseolina, isolated from the lesions on pegs, pods, roots and stems of naturally infected groundnut plant, were analyzed for amino acid composition of the mycelium. The isolates varied, both qualitatively and also quantitatively in the composition of amino acids, both free and bound forms.
Degradation of different aromatic compounds by methanogenic consortia from Saale river sediment acclimated to either o‐, m‐ or p‐cresol
Authors: Kaminski Ute , Kuschk P. , Janke D.
Published: February 2007

Comparative experiments were conducted to examine undefined methanogenic consortia from Saale river sediment acclimated to either o‐, m‐ or p‐cresol for their potential to degrade different aromatic compounds. Each of the consortia under study proved specifically acclimated with respect to the particular cresol isomer used as the substrate during the enrichment procedure and failed to deal with any of the dimethylphenols tested. These findings clearly indicate that the enzyme systems initiating anaerobic (methanogenic) degradation of the different cresol (monomethylphenol) isomers are characterized by a narrow substrate specificity.

Degradation of the particular cresol isomers was accompanied by production of methane in amounts which correspond to 89–97% of the theoretically possible yield. In addition, several exogenously added structural analogues (e.g. benzoate, 2‐, 3‐ and 4‐hydroxybenzoic acid, guaiacol, catechol) were degraded with high rates after short acclimation periods or even without any initial delay, depending on the particular type of consortium used.

Distinct patterns of degradative activity towards the different aromatic test substrates were observed for the cresol‐acclimated bacterial consortia under study. The results obtained are insufficient to speculate about the precise degradation routes involved. They provide clear‐cut evidence, however, that use of mixtures of methanogenic consortia like those from Saale river sediment acclimated to o‐, m‐ and p‐cresol, respectively, would allow relatively fast biodegradation of a wide range of aromatic compounds under anaerobic (methanogenic) conditions.
Isolation and characterization of four methylotrophic bacterial strains
Authors: El‐Nawawy Amin S. , Banat Ibrahim M. , Elrayes Emad G. , Hamdan Ibrahim Y.
Published: February 2007

Four pure methylotrophic bacterial strains isolated from Kuwaiti soil were designated KISRI‐5, KISRI‐6.1, KISRI‐512 and KISRI‐5112, and deposited in NCIMB under NCIB numbers 12135, 12136, 12137 and 12138, respectively. Characterization tests showed that they grew well on methanol and slowly on glucose, at temperatures up to 44 °C and pH 7.0. However, they could not grow on numerous other organic carbon sources. The four strains were very close taxonomically, with minor differences in colony characteristics, lipids pattern, mole G + C% and resistance to certain antibiotics. All strains utilized monomethylamine, but not methane or trimethylamine; all contained ubiquinones with eight isoprene units (Q8), and had C16 as their major fatty acid component. Their characteristics indicate that they are different strains of restricted type M facultative methylotrophs, and could be considered new members of the genus Methylophilus.
Excision of transposon Tn917 in Bacillus subtilis
Authors: Adler Barbara , Hofemeister Jürgen
Published: February 2007

Excision of Tn917 from chromosomal sites in B. subtilis is characterized by reversion studies. We propose different modes of excision depending on the site of transposon insertion. Excision takes place as precise excision in one step which results in reversion of the mutant phenotype, or by a two‐step process where nearly precise excision of the transposon moiety is followed by precise excision of the nearly precise excision remnants. For this type of transposons a minor pathway or nonreplicative transposition is proposed to be connected with precise exsision.
Phycomyces blakesleeanus BURGEFF and several wood‐decay fungi in a bioassay for growth factor resources in fresh and microbially precolonized timber
Authors: Grams G.
Published: February 2007

The presence of the essential growth factor thiamine in timber was ascertained with the determination of the mycelial growth figures of several indicator fungi on the respective timber substrates. The behaviour of the absolutely thiamine‐dependent phycomycete, Phycomyces blakesleeanus BURGEFF (Pb), as well as of 6 strains of basidiomycetous wood‐decay fungi (WBF) that did or did not depend on exogenous vitamin supply proved in accordance that (i) both sapwood and heartwood material of 14 native timber species examined were able to furhish fungi with any degree of vitamin dependence with the essential growth factor(s); (ii) both fresh timber and timber pre‐colonized by bacteria, ascomycetous discolouration fungi, and WBF contained thiamine resources above the saturation level of 50 μg per kg; (iii) neither a thiamine supply of 2 to 20 mg per kg total weight nor the residues of microbial pre‐colonizers added to the vitamin pool of timber in that the growth of the test fungi could be further stimulated; (iv) the depressive growth of WBF on vitamin‐free liquid media was not observed on vitamin‐free solid media such as fertilized builder's sand. A vitamin supply did not improve the vigour of WBF of any degree of vitamin dependence, but it was a prerequisite for the growth of Pb on these substrates.

It is concluded that vitamins in timber have, on their permanent excessive presence, no ecological significance. They do not add to host wood specificity, to the election of the fungus' host range, to the specialization for gymnosperm wood, to the preference for sapwood or heartwood within the stem, to the establishment of pathogenesis on standing timber, and to the preference for fresh or pre‐colonized wood material.
Characterization of enteroinvasive Escherichia coli serotype 0164 by means of plasmid analysis and virulence assay
Authors: Todorova K. , Bratoeva M. , Daneva M.
Published: February 2007

Escherichia coli 0164 is the most prevalent serotype among the enteroinvasive E. coli in Bulgaria and is annually isolated in sporadic, as well in epidemic cases. We studied 243 strains of this serotype, isolated in different regions of the country over the period 1954–1988. The plasmid analysis performed revealed that the presence of large plasmid DNA with molecular size of 140 MDa was related to the virulence of the strains, assessed by the test of SERENY. The absence of this plasmid or its deletion led to the loss of virulence. In 92 % of the strains two small plasmids were demonstrated with molecular size of 6.0 MDa and 4.8 MDa, which appeared to be serotype‐specific. On the basis of the plasmid content of the strains, 7 plasmid profiles were differentiated. The stability of the plasmid profile within a given epidemic focus was confirmed.
Kinetics of secondary metabolite formation by wild type and mutant strains of Streptomyces griseus
Authors: Jacob H.‐E. , Katenkamp U. , Wagner Christina , Fleck W. F.
Published: February 2007

In a particle containing medium, the kinetics of formation of secondary metabolites of a Streptomyces wild type and a mutant strain were determined by spectrophotometric measurements of the anthracyclinone pigments and by the analysis of antibiotic activity of the substances produced. The results were related to the physiological state of the culture derived from the oxygen supply.

The total cultivation time was about 400 hours. The production of secondary metabolites started at the end of the logarithmic growth phase (after about 30 hours). During the following cultivation remarkable differences between the two strains regarding the formation of pigments and antibiotics occurred. In the wild type strain producing daunomycinone glycosides and related compounds with antibiotic activity, these antibiotics are active as inhibitors (negative feedback). Therefore, at a certain concentration of antibiotics, the de‐novo formation of anthracycline molecules was impaired. In the mutant strain, as the result of a genetic change, the secondary metabolite production was shifted to nonglycosylated compounds. The production of these substances is not influenced by feedback inhibition as in the case of the wild type strain. From that reason the amount of pigment increased slightly throughout the course of the experiment.

Under our experimental conditions the measurement of oxygen supply was a suitable indicator of the physiological state of culture.
The proton extrusion of growing yeast cultures as an on‐line parameter in fermentation processes: Quantitative determination of growth from milligram amounts of substrate in a minimized fed‐batch fermentation apparatus
Authors: Huth Joachim , Werner Sabine , müller Hans‐Georg
Published: February 2007

The proton extrusion of growing yeast cultures was demonstrated to be a very exact and reliable on‐line parameter for the description of the growth of yeasts and substrate consumption in batch fermentation processes. Using this parameter we were able to build up a minimized fermentation apparatus (working volume about 90 ml) which permits the description of growth from substrate amounts of 5 to 50 mg quantitatively in fed‐batch fermentation processes.

Using various yeast strains it was demonstrated for nitrogen‐free carbon sources such as hydrocarbons and carbohydrates that

1. the course of the proton extrusion indicates qualitatively whether any given carbon source can be utilized as a growth substrate or not, and that

2. the amount of proton extrusion is a reliable and reproducible quantitative parameter for growth on the tested substrate.

This minimized fermentation apparatus offers advantages and possibilities to detect growth of microorganisms from very small substrate amounts in submerged cultures.
Detection of a 2 μ derivative yeast plasmid with altered properties
Authors: Mink Mátyás , Stülke Jörg , Büttner Knut
Published: February 2007

The Saccharomyces cerevisiae (Sacch. cerevisiae) strain RXII, like many others, harbours plasmid DNAs. and one category of them is homologous to the 2 μ plasmid of yeast. DNA‐DNA hybridization experiments indicated altered structures of this species as regards the number and distribution of the restriction sites. The efforts made to clone either the whole plasmid in pBR328 or its fragments in pBR322 vectors remained unsuccessful, since deleted plasmids were isolated without insert DNA, and even the loss of vector sequences was observed. The data suggest, that the 2 μ derivative plasmid in strain RXII represent an unique category of this extrachromosomal genetic element.
Protein extracts for nutritional purposes from fragile strains of Saccharomyces cerevisiae: Construction of strains and conditions for lysis
Authors: Stateva Lubomira , Venkov Pencho , Lyutskanov Nikola , Koleva Lidia , Hadjiolov Asen
Published: February 2007

A superfragile strain, Saccharomyces cerevisiae 211, carrying three nonallelic nuclear determinants of cell lysis by osmotic shock was isolated from the haploid progeny of a cross between two laboratory fragile strains VY 1160 and SY 15. The strain Sacch. cerevisiae 211 is prototrophic, grows well in both laboratory and industrial media, only when supplemented with osmotic stabilizers. The average protein content of its biomass after growth in a molasses‐based nutritional medium is 48.7%. In laboratory conditions this strain releases about 60% of its cellular proteins by spontaneous lysis in water. However, on a pilot scale the protein yield decreases to about 25%. After a single disintegration step at 650 atm, practically all of the cellular protein – 91.5%, is extracted without any additional chemical treatment. This result cannot be reached in any of the wild type strains tested even after triple treatment at 650 atm.
A cytoplasmic factor involved in the expression of resistance to C8‐ATC in Saccharomyces cerevisiae
Authors: Misiewicz M. H. , Kotylak Z.
Published: February 2007

A dozen mutants of Saccharomyces cerevisiae, resistant to C8‐ATC have been characterized. C8‐ATC was previously established as a biologically toxic compound. Frequency of mutants (10‐7) was typical for spontaneous mutations. One very stable mutant was characterized extensively. The genetical analysis revealed that resistance in this mutant was determined by single‐gene mutation. The rhoo cells, obtained by ethidium bromide (EB) mutagenesis of the resistant strain, were completely devoid of resistance. A large percentage of rho‐ cells, obtained by a moderate EB treatment of resistant cells were still able to express resistance to C8‐ATC. Therefore we hypothesized that, in our particular strain, a cytoplasmic factor is involved in nuclear determination of resistance.
Intracellular expression of hIFNα genes in Escherichia coli and Bacillus subtilis directed by staphylokinase signals
Authors: Breitling Reinhard , Gase Klaus , Behnke Detlev
Published: February 2007

Portable expression units for intracellular formation of heterologous proteins in Escherichia coli and Bacillus subtilis were constructed by inserting the transcription and translation initiation signals of the staphylokinase sak42D gene into the polylinker of plasmid pUC18. Fusions with ATG‐gene cassettes coding for mature human interferons (hIFN) α1 and α2 resulted in intracellular expression of both proteins in E. coli. The 20 fold lower yield of hIFNα2 was not due to unfavorable mRNA secondary structure formation as ruled out by constructing a hybrid hIFNα1/α2 gene. Intracellular expression of IFNα1 in B. subtilis reached 6 x 104 IU/ml. Nuclease SI mapping of transcriptional start sites revealed differential promoter usage in E. coli and B. subtilis. In E. coli transcription from the sak42D promoter was drastically reduced by by transcription initiating from upstream lac and tet promoters. In contrast, in B. subtilis transcription proceeded exclusively from the sak42D promoter.
Cloning of the resistant EcoRII recognition site of phage T7 into an EcoRII‐sensitive plasmid makes the site susceptible to the restriction enzyme
Authors: Krüger Detlev H. , Prösch Susanna , Reuter Monika , Goebel Werner
Published: February 2007

The recognition sequence 5'‐CC(A/T)GG for EcoRII in the bacteriophage T7 genome is refractory to this restriction endonuclease, despite not bearing the specific (protective) methylation. Following the integration of this site as part of a 219 bp fragment (in which the recognition sequence is flanked by about 100 bp of T7 origin) into the EcoRII‐sensitive vector pUC18, the T7 site becomes susceptible to cleavage, too. The same is true of recombinant pBR322 plasmids containing the T7‐derived recognition site. The results show that the flanking sequences are not immediately responsible for the refractory behaviour of EcoRII sites and are in agreement with data according to which EcoRII requires the coordinated presence of at least two recognition sites in its DNA substrate.
Purification and properties of α‐amylase from Micrococcus varians
Authors: Adeleye Adeyemi I.
Published: February 2007

An extracellular α‐amylase from Micrococcus varians was partially purified (63 fold) by ammonium sulphate precipitation followed by dialysis and separated by molecular exclusion into three components with molecular weights ranging from approximately 14,000 to 56,000. The amylase had a pH optimum of 7.0 and apparent Km of approximately 0.5 mg ml‐1 for starch. The enzyme activity was stimulated by Ca2+ and Mg2+ ions. Optimum temperature was 45 °C while there was a complete absence of activity at 70 °C in 20 min. Ethylene diaminetetra acetic acid (EDTA) and iodoacetic acid (IA) inhibited the activity of the enzyme.
Amylase production by three Bacillus strains active at alkaline pH
Authors: Bezbaruah R. L. , Gogoi B. K. , Pillai K. R. , Nigam J. N.
Published: February 2007

Thermostable α‐amylases produced by three different strains of Bacillus species are reported. The organisms are isolated from soil. They are designated as Bacillus stearothermophilus A004, B. stearothermophilus AN002 and B. coagulans R3. The heat stable amylases produced by these organisms were partially purified and characterized. The temperature optimum for B. stearothermophilus A004 and B. stearothermophilus AN002 amylase is 80 °C, whereas the optimum temperature for amylase activity is 85 °C for B. coagulans R3. The amylases from all three strains show extremely broad pH ranges of activity (6.0–12.0). Furthermore, the α‐amylases from B. coagulans R3 retains 35% activity even at 0.1 n alkali solution. Action of these enzymes on starch produces glucose, maltose, maltotriose, maltotetrose and other higher oligosaccharides, indicating the α‐amylase nature of the three enzymes.
Some properties of the leucine‐biosynthesizing enzymes from Candida maltosa
Authors: Bode Rüdiger , Birnbaum Dieter
Published: February 2007

The enzymes of the leucine pathway of Candida maltosa were investigated and the regulatory pattern was established. l‐leucine inhibited the α‐isopropylmalate (IPM) synthase, the first enzyme of the pathway. The inhibition was competitive with respect to α‐ketoisovalerate (Ki = 0.81 mm) and non‐competitive with respect to acetyl‐CoA. The Km values of the enzyme were estimated to be 0.57 mm for α‐ketoisovalerate and 0.064 mm for acetyl‐CoA. The Km values of the second enzyme, IPM dehydratase, were estimated to be 4.57, 0.57 and 1.79 for α‐IPM, β‐IPM and citraconate, respectively. The Km values of the β‐IPM dehydrogenase were calculated to be 0.42 mm for β‐IPM and 0.34 mm for NAD+. For this enzyme a novel regulatory pattern, its inhibition by l‐valine, was found. The inhibition was competitive with respect to β‐IPM (Ki = 1.7 mm) and non‐competitive with respect to NAD+.
Characterization of sectored colonies of a high‐yielding Claviceps purpurea strain
Authors: Didek‐Brumec Matjana , Gaberc‐Porekar Vladimira , Alačević Marija , Druškovič Blanka , Sočič Helena
Published: February 2007

When sectored colonies of a high‐yielding Claviceps purpurea strain, producing ergotoxine alkaloids in submerged cultures, were investigated significant differences in surface morphology, mycelial differentiation, number of nuclei and in alkaloid production were established among sectors obtained after segregation. Biosynthetically most active sectors showed sclerotia‐like structure and a polynuclear state in cells, while low‐yielding sectors were composed mainly of undifferentiated hyphae with only few nuclei per cell. In cells of high productive sectors the content of DNA was about four times higher than in sectors of lower activity.
Assay of cellulolytic activity of cellulose‐decomposing fungi isolated from Egyptian soils
Authors: Moubasher A. H. , Mazen M. B.
Published: February 2007

Ninety two fungal species recovered on cellulose — Czapek's agar plates from Egyptian soils were assayed for their cellulolytic activities either at 28 °C (mesophilic) or at 45 °C (thermophilic or thermotolerant). The percentage increase of protein‐nitrogen over those of control was taken as a measure of this ability. At 28°C, the top species in cellulolytic activity were Penicillium oxalicum, Nectria haematococca, Gliocladium catenulatum, Myrothecium verrucaria and Aspergillus niger. The other species showed low, weak or non cellulalytic activity. At 45°C, the highest activity was manifested by Chactomium olivaceum, Sporotrichum thermophilum, Sepedonium chrysospermum, Aspergillus fumigatus, Humicola minima, Rhizomucor pusillus and Thermomyces lanugibnosus. All Penicillium species tested as well as some other fungal species were not capable of utilizing cellulsoe at 45°C.
Highly transformable mutants of Streptomyces aureofaciens containing restriction‐modification systems
Authors: Muchová Jana , Lacová Bibiána , Godány Andrej , Ševčíková Beatrica
Published: February 2007

Streptomyces aureofaciens 13 is a mutant defective in chlortetracycline production. It was chosen as a potentially useful host for gene cloning in investigations of the organization of the biosynthetic genes for the tetracycline antibiotic pathway.

From the Streptomyces aureofaciens 13 strain, three suitable clones were used for our work. The conditions for optimal formation and efficient transformation of protoplasts with plasmid DNAs have been determined. Transformation frequencies of about 104 to 105 per microgram of plasmid DNA were obtained when plasmids were isolated from Streptomyces strains. From the patterns of restriction enzyme digestion of plasmid DNA isolated from Streptomyces aureofaciens transformants, it was observed that the clones express modification systems which render plasmid DNAs resistant to cleavage by HindIII and EcoRI. Additionally, one of the clones produces the restriction endonuclease Sau13I (isoschizomer of SauI).

The presence of the restriction‐modification system of Sau13I does not reduce the efficiency of plasmid transformation.
Growth and conidia production in race NG‐5/IA‐65 of Pyricularia oryzae Cav. in vitro
Authors: Awoderu V. A. , Esuruoso O. F. , Adeosun O. O.
Published: February 2007

The ability of Pyricularia oryzae to grow and sporulate under various artificial environmental conditions was investigated. The pathogen grew best on Potato Dextrose Agar and sporulated best on one percent Soluble Starch Yeast Extract Agar. Ammonium chloride medium as nitrogen source favoured its growth and conidia production. The pathogen utilized xylose, arabinose, starch, glucose and inulin for growth and conidia production. The minimum, optimum and maximum temperatures for growth and conidia production were 10°, 25° and 37°C. The humidity treatment increased conidia production from 8.0 × 103 to 18.4 × 103 conidia/ml. The optimal pH range for growth was 5.5–10.5 and 5.5–7.0 for conidia production. Exposing cultures to continuous artificial illumination enhanced conidia production.
Genetic studies of the ends of a lacked‐in Kappa prophage in Serratia marcescens by transductional and vegetative crosses
Authors: Steiger H.
Published: February 2007

In temperate phage x of Serratia marcescens several special features of different phages are combined. The unessential genes lI, iny, cII and, at least to some extent, even the integrase gene int are not subject to negative control by the repressor, the product of gene cIII. A genetic map of the prophage was established using defective, heat‐induced lysates of int− lysogens both in vegetative crosses with sus mutants of essential genes and in transduction of the four unessential genes to lysogenic recipients. Results from reciprocal four factor‐crosses concerning the order of the four genes had to be included. The four genes are located near the right end of the prophage, whereas cIII lies near its left end. In vegetative phage all five genes lie in an interval between the essential genes T and U, comprising 10% of x's genetic map. The right prophage end appears to face at least two trp cistrons, among them the gene encoding anthralinate synthetase.

lI encodes a product that masks the phage receptors in the cell wall. The gene product of iny interferes with the growth of infecting phage y. The natural function of cII is still unknown, but some of its mutants display a cold‐sensitive phenotype, their plaques being clear at 30°C and turbid at 37°C. Bacteria with such prophages stop producing viable progeny when the cultures are shifted from 37°C to 30°C. These cold‐sensitive mutants are partly dominant and partly recessive.

Analysing a virulent mutant, a gene ant encoding an antirepressor was discovered, but so far there is no evidence that it is regulated by an extra repressor. The gene is located relatively near the left prophage end.

Evidence is presented that the exogenotes in transduction with the defective lysates continue to exist for some time after a first recombinational event.
Correlation between branching and elongation in germ tubes of Streptomyces granaticolor
Authors: Kretschmer S.
Published: February 2007

With four individual germ tubes (GTs), the distinct time of birth of branches was correlated to the kinetics of GT‐elongation. During the first three hours, corresponding to five doubling times, branching was suppressed. The time of birth of the first branch (tb1) coincided with the 5th step of the typical stepwise increase of the GT elongation rate (α). During this time, the quasi‐exponential kinetics of α changed to linear kinetics, which was attained either at the 5th of 6th α‐step. At the 5th step, the quotient of successive α‐values had been reduced from 2 at the beginning of outgrowth to 1.2.

Once the first branch had been formed, further branches appeared as clusters (additional 2, 4, and 8 branches) at D‐intervals representing the doubling time of the hyphal length.

The first branch appeard always in the vicinity of the spore. The average distance to the spore of 6.6 μm corresponded to four unit cells. At tb1, the unbranched region located between the first branch and the tip of the GTs was 42 μm long. The data concernning timing and location of the first branching in GTs suggest that initiation of branching was dependent on the accumulation of envelope precursors.
The ability of Armillariella mellea to transform cyclic monoterpenic alcohols and their acetates
Authors: Draczyńska‐Łusiak B. , Siewiński A.
Published: February 2007

An Armillariella mellea culture was found to transform trans‐ sobrerol to a very small extent, whereas menthol resisted its action altogether. Acetylation of both alcohols, on the other hand, reappointed their reactivity in the same A. mellea culture. Thus, trans‐sobrerol monoacetate and menthyl acetate underwent a two‐step transformation involving hydroxylation (preserving the acetate link) to 3‐acetoxy‐6,8‐p‐methen‐diol and 8‐hydroxymenthyl acetate, respectively, which were converted by hydrolysis to 3,6,8‐p‐menthen‐triol and 8‐hydroxymenthol, respectively.

The transformation of racemic menthyl acetate was enantiospecific; (−) 8‐hydroxymenthol that was formed after 21 days contained 98% of enantiomer 1R, 3R, 4S.
Isolation of a double‐stranded RNA and a virus‐like particle from Geotrichum candidum
Authors: Matte O. , Chabalier C. , Ratomahenina R. , Bossy J. P. , Galzy P.
Published: February 2007

A virus‐like particle (VLP) of 42 nm diameter was isolated from the lipolytic microorganism Geotrichum candidum. The VLP contains a linear double‐stranded RNA molecule of 1.70 μm in length. Proteins of VLP were studied by polyacryl amide gel electrophoresis.