Zeitschrift fur allgemeine Mikrobiologie最新文献

A method for the quantitative determination of free and esterified ergosterol in lipid fractions from biomasses grown on hydrocarbons as sole carbon source is described. Column chromatography was used for the fractionation of lipids. Esterified ergosterol was determined in the benzene fraction and free ergosterol in the methanol fraction by known methods.

The relation between product formation and growth kinetics could be characterized by two facts: the specific product formation rate depends on the ageing of the population and on the specific growth rate. These relation was formulated and quantified by a mathematical model, which was fitted to experimental data of a representative fermentation run und used to predict an optimal fermentation mode. In the result of this discussion cyclic fed batch fermentation was found to be optimal.

In strongly acidic medium (70% HClO4) streptothricins form a fluorophore (lambda ex = 312 nm; lambda em = 381 nm) with unknown structure. A fluorimetric determination of pure or crude products and cultures, respectively, was worked out based on this reaction. Concentrations for fluorescence measurements were in the range of 10(-8) - 2 X 10(-7) moles. Interferences of the assay are discussed, a statistical evaluation of results and a comparison between microbiological and fluorimetric findings are given.

A new and rapid working method is presented for electronmicroscopic preparation of capsules from gram negative bacteria, e.g. Bordetella bronchiseptica and Pasteurella multocida. The advantage of the new technique is the availability of the results within 30 min after starting the preparation. The staining of the capsule by alcian blue has to be done as a first step together with glutaraldehyde fixation, before staining the bacterial cell with phosphotungstic acid. The new staining technic also reveals structural details of the capsule. The described procedure was found to be useful in controlling the development of the bacterial capsule depending on culture media for propagation and maintenance of the above mentioned bacteria.

Many taxonomically different strains of actinomycetes as well as several other procaryotic and eucaryotic microorganisms were shown to produce inducers of cytodifferentiation and anthracycline biosynthesis being active towards blocked mutant ZIMET 43682 of Streptomyces griseus. 37 out of 40 strains of the species of S. griseus (92.5%) yielding different kinds of antibiotics were able to induce both the formation of aerial mycelium in the indicator strain ZIMET 43682 concomitant with the biosynthesis of anthracycline antibiotics. 80 (26.3%) out of 304 strains belonging to 94 different Streptomyces species were also producers of inducing agents. Among 77 strains of actinomycetes belonging to 28 different genera being apart from Streptomyces, 12 strains displayed inducing activity (15.6%). The results obtained so far support the conclusion that the formation of inducing agents was neither associated with a particular species of Streptomyces nor its capacity to produce a given antibiotic. The occurrence of inducers has been observed even with members of other genera. Few strains were capable of inducing only one of the differentiation-associated functions. Some strains of Streptomyces species produced at least two different kinds of inducers discernible by their Rf values on TLC.

Arsenate-resistant (AsR) clones were obtained with high frequency from colony populations of streptothricin-producing strains of Streptomyces noursei by the paper strip method. Whereas in the AsR-strains obtained from both wild type and mutant NG 13 the antibiotic production was reduced to approx. 60% of the parental level, the AsR clones isolated from colony populations of mutant UV 12 displayed increased productivity (less than or equal to 150%). However, their improved capacity to produce streptothricins was lost rapidly after repeated cell propagation in submerged cultures, suggesting that unstable genetic elements were involved in enabling S. noursei to grow in the presence of toxic concentrations of arsenate.

Stringent and relaxed strains of E. coli subjected to isoleucine starvation were examined by follow-wing the incorporation of 3H-thymidine into chromosomal DNA. After valine treatment to trigger an isoleucine deprivation (p)ppGpp is synthesized in the stringent strain only. Remarkable differences in the morphology of the amino acid starved cells of the stringent and relaxed strains can be observed. Upon isoleucine limitation 3H-thymidine incorporation into DNA is reduced in both strains, but this inhibition is remarkably delayed in the relaxed strain. Our result show that the reduction of chromosomal DNA synthesis during amino acid limitation occurs also without ppGpp, but in the presence of ppGpp this process is accelerated.

Penicillium oxalicum produced two isozymes of polygalacturonase (PG) and a pectate lyase (PL). The enzymes were separated and purified following ammonium sulphate precipitation, ion exchange chromatography, ultrogel column chromatography and isoelectric focusing. The first isozyme of polygalacturonase (PGI) was rather unstable hence its properties could not be much assayed. PGII macerated and killed yam tissue in 4 hours but PL was unable to do so. Enzyme assay for the end-products of degradation of sodium polypectate and yam tissue showed that PGI was an exo-enzyme while PGII and PL were endo-enzymes. Endo-polygalacturonase (PGII) appears to play the major role (as the macerating enzyme) in the pathogenesis of yam tissue infected by P. oxalicum.

Nystatin was used to develop a new method to select spores of the yeast Saccharomycopsis lipolytica. At low concentrations nystatin killed preferently growing cells of this yeast. At high concentrations nongrowing cells were affected as well. In contrast, spores were not sensitive to nystatin action. This differential response to the antibiotic suggested its use to select spores from sporulated yeast cultures.

Metalaxyl is used to control diseases caused by fungi of the order of the Perenosporales. We investigated the action of this fungicid eon nucleic acid and protein synthesis in liquid cultures of Phytophthora nicotianae. The uptake of 32P, 3H-uridine, 3H-thymidine and 14C-leucine as precursors of nuclei acid and protein synthesis by the mycelium was not inhibited by metalaxyl. RNA synthesis as indicated by 3H-uridine incorporation was strongly inhibited (about 80%) by 0.5 micrograms/ml of metalaxyl. The inhibition was visible already few minutes after addition of the toxicant. Since the inhibition of incorporation of 3H-thymidine into DNA and of 14C-leucine into protein became significant 2-3 hours later, we conclude that metalaxyl primarily interfers with RNA synthesis. Synthesis of ribosomal RNA is more affected (more than 90%) than that of tRNA (about 55%) and poly(A)-containing RNA. Since in the presence of actinomycin, in contrast to metalaxyl, protein synthesis is inhibited immediately as a consequence of complete inhibition of RNA synthesis and of the short life-time of mRNA, it is also evident that mRNA synthesis is less strongly inhibited, at least during the early period of metalaxyl action. The molecular mechanism of metalaxyl inhibition of the transcription process remains open. The fungicide did not inhibit the activity of a partially purified RNA polymerase isolated from the fungus. On the other hand, the RNA synthesis (14C-UTP-incorporation) by a cell homogenate and by isolated nuclear fractions was inhibited significantly. Possibilities of the molecular action of metalaxyl are discussed. The RNA synthesis of some plant systems (cell cultures of Lycopersicon peruvianum, isolated nuclei from the same cell cultures, purified RNA polymerase from Spinacia oleracea chloroplasts) was not inhibited by metalaxyl, not even at high concentrations.