Zeitschrift fur allgemeine Mikrobiologie最新文献

Fermentations for the overproduction of citrate and isocitrate with S. lipolytica in media containing both glucose and n-alkanes as mixed C-source have been performed. Biomass and product yields strongly depend on the C-source of the inoculation culture. If the inoculation culture had been taken from media containing glucose as sole C-source both glucose and n-alkanes were utilized for cell growth in the main culture whereas only glucose was utilized if the inoculation medium contained only n-alkanes. For idiophasic citrate and isocitrate production both glucose and n-alkanes were consumed independently of the C-source of the inoculum but that C-source was preferentially utilized which has been the C-source of the inoculation culture. These findings are reflected by the activities of the isocitrate lyase and the pyruvate carboxylase, respectively. In S. lipolytica both anaplerotic pathways are coexisting but the C-source of the inoculation culture determines the level of the specific activities even if the ratio of the cell-mass of the inoculum to the cell mass of the main culture at the end of the growth phase is about 1:35.

During the turimycin fermentation hydrolytic enzymes are excreted responsible for orthophosphate release from phosphate-containing dissolved and undissolved complex medium constituents. Following a phosphate-limited growth period the phosphate release leads to a second growth period (diauxic growth). Depending on the rate of phosphate release the length of the lag phase of diauxic growth changes in different fermentations. The resulting second growth period is correlated with a transient delay in the formation of turimycin, of phosphatases and of nucleases. The amylolytic activities are formed already within the first hours after the beginning of fermentations. Phosphatases, nucleases and protease are excreted parallel to turimycin formation after extracellular phosphate limitation in presence of ammonia and glucose. A special role of phosphate limitation initiating enzyme synthesis is proposed.

Protoplast type L-form cells of Streptomyces hygroscopicus and S. griseus contain different types of inclusion bodies. Cytoplasmic cores and paracrystalline structures are peculiar inclusions which could not be observed in normal parent bacteria. The cytoplasmic cores are 1-4 micron long and 0.05-0.25 micron broad straight and stiff non-tubular structures consisting of homogeneous mode-rate electron opaque material. Paracrystalline inclusions have side-lengths between 0.2 and 0.5 micron and show a characteristic pattern of 15-20 nm thick straight dark lines and electron lucent intervening spaces of 20-30 nm. Both cytoplasmic cores and paracrystalline inclusions are apparently proteins. Their occurrence in L-form cells indicates an altered synthesis of one or several proteins in these cell types.

Growth of Candida albicans on artificial D-glucose derivatives (amino-, methyl-, acylglycosides and N-acetyl-D-glucosamine derivatives) was examined with the aim to find new inducers of the mycelial growth form. For representatives of particular groups (alpha-D-glucopyranosylamine, D-glucose and N-acetyl-D-glucosamine) some physiological (growth, doubling time, specific growth rate, oxygen uptake and CO2 production, respiration quotients), biochemical (dry weight yield, protein content, ethanol production), and morphological parameters (length-width quotient, volume, percentage of budding cells) of cultures in different growth phases were determined with regard to the type and concentration of carbon source. The results obtained may be valuable for studies of the structure-utilization relationships of carbohydrate derivatives as well as for the elucidation of yeast-mycelial transition in Candida albicans induced by unphysiological hexoses degradable intracellularly.

In vitro rearrangement of plasmid pDB102 together with comparative studies of other streptococcal plasmids allowed the localization of replication and copy control functions on sequences which were present on pDB102 and its naturally occurring ancestor pSM19035 as duplicates in inverted orientation. Evidence is presented that neither the presence of duplicate replication regions nor their arrangement in inverted orientation was essential for plasmid survival. Among the in vitro reconstructed plasmids were several that stably carried two or three sets of replication and copy control functions either as inverted or direct repeats or both. A copy control mutation is described which led to a tenfold increase of copy number over that of the naturally occurring plasmid pSM19035.

Pythium, Saprolegnia and Achlya were the basic components of the river mycoflora. Occurrence and periodicity of the fungal genera and species exhibited three different patterns during the different months of this investigation.

Commonly the TCA cycle fulfils an anabolic and a catabolic function in case of aerobic chemoorganoheterotrophic nutrition. In methylotrophic growth the TCA cycle is dispensable as a bioenergetic pathway. This is reflected by properties of citrate synthase in facultative methylotrophic bacteria. Two citrate synthases, a "chemoorganoheterotrophic" one, which is inhibited by NADH (or ATP in Acetobacter MB 58), and a "methylotrophic" one, which is not or less affected by energy indicators, were found in Pseudomonas oleovorans, Pseudomonas MS, Pseudomonas MA, and Acetobacter MB 58. The concentration of these citrate synthases depends on the manner of nutrition. Bacteria with ICL-negative-variant of the serine pathway and with ribulosebisphosphate pathway seem to possess only a "chemoorganoheterotrophic" citrate synthase. Possibly the anabolic function of this citrate synthase can be realized by metabolites.

Decomposition of substrates by heterotrophic microorganisms is accomplished in natural biotopes such as in soil and in waters, on or in macroorganisms but also in laboratory and industrial biotopes. The interest of man in these processes is manifold. Starting with the division of substrates into three groups of simple substrates, complex and mixed substrates with or without solid particles their qualitative and quantitative occurrence in nature and their significance in biotechnology will be discussed. In the decomposition of these substrates their utilization by pure cultures or mixed populations is to be exactly distinguished. Simple growth curves, di- or polyauxy, sequences of decomposition of simple substrates of a mixed substrate, population changes and successions are only some of the phenomena occurring in this process. The pathways of catabolism are subjected to manifold regulations on the three levels of stoichiometric regulation, the regulation of enzyme activity and the regulation of enzyme synthesis. In natural biotopes there is hardly a constant substrate supply over a longer period. That's why certain mechanisms of regulation are permanently acting. Thus the "normal" physiological state for microorganisms is characterized by permanent transition situations--called "transients". These reactions are also applied to many biotechnological processes.

Procaryotes have regulatory systems allowing to vary the metabolism in response to nutritional variations, to reduce the growth, and to start development. Nucleoside polyphosphates are mediators of coordinated alterations of metabolism. In this review, after a brief recall of the characteristics of the stringent response, the occurrence, determinations, and the metabolism of the nucleoside polyphosphates are presented. The representation of the pleiotropic effects includes the regulation of the protein synthesis and of the protein synthesis apparatus, of the protein turnover, of the N- and carbohydrate metabolism, of the formation of cell membranes and cell walls as well as the possible function of the development.