Identification of odorous compounds from nine fermentor-cultivated Streptomyces strains.

The chemical composition was determined of odors produced by nine strains of streptomycetes (Streptomyces aureofaciens, S. avermitilis, S. cinnamonensis, S. coelicolor, S. griseus, S. lividans, S. rimosus, S. spectabilis, S. virginiae) cultivated in a fermentor under similar cultivation conditions. GC-MS analysis identified more than twenty noteworthy volatile chemical individuals. The main components of the odor spectrum were geosmin and unique homologues of oxolones (dihydrofuranones), minor compounds included, e.g., pyrazine derivatives, acetoin and its homologues, aromatic esters, furan derivatives.

Relationship between volatile odorous substances and production of avermectins by Streptomyces avermitilis.

The time course of production of odorous compounds, i.e. geosmin and oxolones, and of avermectins was determined during the cultivation of S. avermitilis in flasks, 1- and 50-L fermentors. The amount of the antibiotics increased with increasing cultivation time up to more than 2 g/L while the concentration of geosmin rose to more than 4 mg/L. Cultivation without reflux condenser resulted in a lower product formation due to the higher stripping of geosmin. A relatively tight correlation was found between the production of geosmin and the production of avermectins. The production of oxolones peaked on cultivation days 3-5, the sum of oxolones being 60 microg/L. Subsequently, the production dropped below a measurable level. This can be explained as being due to the inhibition of oxolone production by geosmin.

Use of the industrial yeast Candida utilis for cadmium sorption.

The sorption ability of Candida utilis biomass for cadmium ions with accumulating competence of dried cells and cells in alginate was compared. After an optimization of process conditions (pH 5.5, biomass concentration 1 g/L and c0 50 mg/L), the cadmium sorption capacity of dried yeast biomass was perceptibly higher than that of the other tested adsorbents. Considering the sorption of the dried yeast biomass equal to 100 %, the cells in alginate reached 86 % while native cells showed only 42 %.

Removal of copper ions from dilute solutions by Streptomyces noursei mycelium. Comparison with yeast biomass.

Sorption properties of Streptomyces noursei mycelium for copper ions were compared with the accumulation competence of dried and native yeast (Candida utilis) biomass. The copper sorption capacity of S. noursei after optimization was found to be higher than that of the two other adsorbents (dried yeast biomass 82 %, native Candida cells 48 % of the sorption capacity of the S. noursei mycelium).

Sterol compositions of the filamentous nitrogen-fixing terrestrial cyanobacterium Scytonema sp.

Thirteen unsaturated sterols were identified by gas chromatography--mass spectrometry using serially-coupled capillary columns from the filamentous nitrogen-fixing terrestrial cyanobacterium Scytonema sp. isolated from the microbial community of cyanobacterial on 'Black Cover' biofilms limestone walls in Jerusalem. The dominant sterols were cholest-5-en-3 beta-ol (18.9%), 3 beta-methoxycholest-5-ene (16.2%) and 3 beta-acetoxycholest-5-ene (11.2%).

Biodegradable plastics from renewable sources.

Plastic waste disposal is a huge ecotechnological problem and one of the approaches to solving this problem is the development of biodegradable plastics. This review summarizes data on their use, biodegradability, commercial reliability and production from renewable resources. Some commercially successful biodegradable plastics are based on chemical synthesis (i.e. polyglycolic acid, polylactic acid, polycaprolactone, and polyvinyl alcohol). Others are products of microbial fermentations (i.e. polyesters and neutral polysaccharides) or are prepared from chemically modified natural products (e.g., starch, cellulose, chitin or soy protein).

Fatty acid composition of six freshwater wild cyanobacterial species.

Hydroxy, n-saturated, branched, dioic, and unsaturated fatty acids in six freshwater wild cyanobacteria (Chroococcus minutus, Lyngbya ceylanica, Merismopedia glauca, Nodularia sphaerocarpa, Nostoc linckia, and Synechococcus aeruginosus) collected from different lakes and springs of Israel have been identified by gas chromatography-mass spectrometry (GC-MS).

Kinetics of phenol oxidation by Candida tropicalis: effects of oxygen supply rate and nutrients on phenol inhibition.

The kinetics of phenol degradation was estimated in a fed-batch reactor system. Effects of oxygen and nutrient excess or limitation as well as the presence of several essential ions on the phenol- and oxygen-specific uptake rates achieved simultaneously in a bioreactor were shown. Candida tropicalis was grown on phenol as the only carbon and energy source. Applying the best fit of polynomial function, the maximum specific uptake rates of phenol and oxygen, the critical concentrations of phenol, the half-saturation constants and inhibition constants were determined. Linear relationship between specific phenol uptake rate and the exogenous respiration rate was found regardless of the kind and presence of essential nutrients. At oxygen limitation both the phenol uptake rate and the cell affinity to phenol decreased more strongly compared with those under nutrient limitation. Oxygen in excess resulted in a significant increase of cell tolerance toward phenol. The presence of essential nutrients increased the specific phenol degradation rate and led to complete phenol oxidation.

D-amino-acid oxidase--an improved production of the enzyme by the yeast Trigonopsis variabilis in a laboratory fermentor.

The cultivation of the yeast Trigonopsis variabilis producing D-amino-acid oxidase (an enzyme participating in the transformation of cephalosporin C into 7-aminocephalosporanic acid for the production of beta-lactam antibiotics) was controlled by changes of dissolved oxygen tension and extended fermentation times. The production technology was optimized on a laboratory scale and scale-up parameters were identified.

[Studies on the occurrence of Listeria monocytogenes in fecal samples of domestic and companion animals]. / Untersuchungen zum Vorkommen von Listeria monocytogenes in Kotproben von Haus- und Heimtieren.

Listeria (L.) monocytogenes was isolated from 33.3% fecal samples of 138 cattle (29 strains serovar 1/2b, 10 strains serovar 1/2a, 7 strains serovar 4ab), from 8% fecal samples of 100 hens (5 strains serovar 1/2b, 1 strain serovar 1/2a, 4ab and 4b each), from 8% fecal samples of 100 sheep (6 strains serovar 1/2a, 1 strain serovar 1/2b and 4ab each), from 5.9% fecal samples of 34 pigs (2 strains serovar 4ab), from 4.8% fecal samples of 400 horses (7 strains serovar 1/2a, 6 strains serovar 1/2b and 4ab each), from 1.3% fecal samples of 300 dogs (3 strains serovar 1/2b, 1 strain serovar 4ab), from 0.9% fecal samples of 350 pigeons (1 strains serovar 1/2a, 1/2b and 4ab each), from 0.4% fecal samples of 275 cats (1 strain serovar 4b) and from 5 respectively 2 fecal samples of 35 tortoises (3 strains serovar 4ab, 2 strains serovar 4b) respectively 5 amphibia (1 strain serovar 4ab and 4e each). Further 36.9% fecal samples of cattle, 15% fecal samples of hens, 6% fecal samples of horses, 5.9% fecal samples of pigs, 5% fecal samples of sheep, 4% fecal samples of dogs, 2.3% fecal samples of pigeons, 3 fecal samples of 35 tortoises and 1 fecal sample of 260 rabbits contained L. innocua. In further 2% fecal samples of hens, in further 1.5% fecal samples of horses and in further 0.6% fecal samples of pigeons was detected L. seeligeri. 3 fecal samples of horses and 1 fecal sample of dogs, lizards and amphibia each contained L. welshimeri, while in 1 fecal sample of tortoises and in 3 fecal samples of 33 lizards L. ivanovii was detected.

[Occurrence of Listeria monocytogenes in snakes, tortoises, lizards and amphibians raised as pets]. / Vorkommen von Listeria monocytogenes bei Schlangen, Schildkröten, Echsen und Amphibien in der Heimtierhaltung.

Listeria (L.) spp. were isolated from fecal samples of 9 (30.0%) from 30 tortoises, of 4 (12.1%) from 33 lizards, of 3 (60.0%) from 5 amphibia and of 1 (1.3%) of 76 snakes. All animals were kept as pets. 8 isolates were identified as L. monocytogenes, whereas 4 strains were serovar 4ab (3 tortoises and 1 amphibia), 3 strains serovar 4b (2 tortoises and 1 snake) and 1 strain serovar 4e (1 amphibia). Further 4 isolates were identified as L. ivanovii serovar 5 (3 lizards and 1 tortoise), 3 strains as L. innocua serovar 6b (3 tortoises) and 2 strains as L. welshimeri serovar 6a (1 lizard) respectively serovar 6b (1 amphibia).

Effect of recA protein on the DNAse activities of the recBC enzyme.

In Escherichia coli, the recBC enzyme is required for several cellular functions including recombination proficiency, UV resistance, and DNA breakdown following radiation damage to the chromosome, all of which appear to be also under the control of the recA gene. We have studied the influence of purified recA protein on the various nucleolytic activities of the recBC enzyme. Conditions were chosen (with GTP as nucleoside triphosphate) under which recA protein binds to single-stranded DNA without catalyzing D-loop formation and which are favorable for the DNase activities of the recBC enzyme. We found that the degradation of linear duplex DNA was unaffected, but that the endonuclease and exonuclease activities for single-stranded DNA were inhibited by about 50% and 35%, respectively. In contrast, no protection of circular duplex DNA containing single-stranded regions was observed. The results suggest that the recA protein by itself may not act as a potent inhibitor of recBC enzyme-dependent DNA degradation in vivo.

Degradation of linear and circular DNA with gaps by the recBC enzyme of Escherichia coli. Effects of gap length and the presence of cell-free extracts.

It is shown that circular PM2 DNA with two gaps of 13 nucleotides per molecule is degraded by purified recBC enzyme from Escherichia coli to acid-soluble material at a rate which is less than one tenth of the rate of solubilization of linear duplex DNA. Increasing the gap length in the circular DNA to 40-650 nucleotides does not affect the breakdown of the molecules by the recBC enzyme, nor does it change the proportions of the products formed (acid-soluble material, acid-insoluble fragments and non-degraded molecules). On the other hand, terminal gaps in linear duplex DNA produced by limited digestion with either exonuclease III or lambda exonuclease significantly reduce the rate of the degradation by the recBC enzyme, particularly when the gaps exceed 100 nucleotides. The results suggest that the recBC enzyme does not cleave gaps in circular DNA at random positions, but possibly at the junction between single-stranded and duplex DNA or close to it. The degradation of gapped circular DNA by purified recBC enzyme was used to search for an inhibitor of the recBC enzyme in extracts from ultraviolet-irradiated cells. No such inhibitor has been observed but rather a weak stimulatory factor for the solubilization of gapped circular DNA by the recBC enzyme. Thus, the experimental system appears not to be suited as a test in vitro for an ultraviolet-induced inhibitor of the recBC enzyme which has been postulated to be produced in recA+ lexA+ cells of E. coli after ultraviolet irradiation.