Zeitschrift fur allgemeine Mikrobiologie最新文献

Ultrathin sections of early germinating endospores of Thermoactinomyces vulgaris were studied by electron microscope. Only spores aerated with an air-CO2 mixture (5% CO2) grow out, while spores aerated with air (0.03% CO2) lyse by the 25th min of inoculation. The lysis is due to progressive, unlimited degradation of the spore integuments and a lack of cell wall formation around the spore protoplast. The requirement of CO2 for outgrowth could not be replaced by oxaloacetate. CO2 seems to be needed to energize the dormant cytoplasmic membrane of the spore to render it capable of initiating active transport processes and of synthesizing the germ cell wall.

Addition of oxygen-containing C1-compounds to chemostat cultures of GB 25 increases both the yield of biomass and the specific growth rate. At optimum concentrations the catalytic activity of these compounds increases with increasing growth rates. Their influence on maintenance coefficients and maximum yield coefficients decreases in the order CH3OH greater than CO2 greater than HCOOH greater than HCHO. This result together with spectrophotometric NADH determinations suggests that the NADH pool determines the balance between the assimilatory and oxidative utilization of formaldehyde.

The presence of 5-bromouracil (BU) as well as 5-bromo-2-deoxyuridine (BUdR) in the cultivation media of bacteria results in the distinct increase of UV sensitivity. With the nucleic acid base analogue 8-azaadenine (8-AA) a similar effect was confirmed, however, not so pronounced. In the experiments reported here the combined action of BU or BUdR and 8-AA on Escherichia coli, Proteus mirabilis, Bacillus subtilis and Bacillus cereus was investigated. The sensitization effect of BUdR does not increase if 8-AA is present additionally during cultivation. On the contrary, a decrease of sensibilization occurs. This result may be caused by the protective effect of the adenine derivative against UV irradiation, if it is present in the cell, but not incorporated into the DNA.

Comparative studies on the activities of isocitrate lyase (ICL) and malate synthase (MS) were carried out with Saccharomycopsis lipolytica incubating the yeast on media with different carbon sources. When cells were incubated in minimal medium with glucose, the activities of both enzymes were very low. In contrast, in minimal medium with acetate enhanced enzyme activities could be demonstrated. It is probably that the synthesis of ICL is repressed in presence of glucose. Furthermore the activity of ICL was inhibited by tricarboxylic acid cycle intermediates like succinic acid and oxalacetic acid. It was concluded that the syntheses of enzymes are derepressed. When cells of Sm. lipolytica were incubated in minimal medium with acetate, a high enzyme activity is evident. Synthesis of ICL on acetate was inhibited by cycloheximide and actinomycin D. The results were discussed comparing them with data obtained from other organisms.

The gene-enzyme relationships of the arom multienzyme complex of Schizosaccharomyces pombe that catalyzes steps two through six in the prechorismate polyaromatic amino acid biosynthetic pathway have been studied. The various mutants were subjected to biochemical analysis by direct enzymic assays. These studies have established that aro-3A, aro-3B, aro-3C, aro-3D, and aro-3E mutants lack, respectively, the enzymic activities 5-dehydroquinate synthase, 5-dehydroquinase, shekimate kinase, 3-enolpyruvylshikimate 5-phosphate synthase, and shikimate: NADP oxidoreductase. In S. pombe lack enzymic activities for the inducible quinate catabolic pathway. The functional significance of the arom aggregate is discussed.

A rapid and convenient method for producing protoplasts from 3 d old mycelium of the ascomycete Hypomyces ochraceus is described. The procedure involves a Helix pomatia enzyme preparation and sucrose (20%) for stabilization. Pretreatment with disulfide bond reducing agents reduced the amount of viable protoplasts. Formation of protoplasts and different stages of regeneration were observed by phase contrast microscopy. There was only one type of true regeneration from protoplasts to hyphae in 15-30% gelatine medium by direct forming a germ tube from the original protoplast. Cytological events and physiological conditions are discussed.

The present survey covers the regulatory role of microbial secondary metabolites and related compounds as endogenous signals of cell differentiation of the producing organisms. Several antibiotics have been shown to exert autoregulatory effects on differentiation-associated functions. The mechanisms of self-protection of the producing cells against the autotoxicity of secondary metabolites are discussed in terms of an integral part of the modulation of signal strength. As a further topic, the review deals with the hormone-like interference of particular metabolites with differentiating cells. Conclusive discussion concerns the potential use of microbial signal molecules either as tools for directed manipulations of product syntheses or as pharmaceutics.

Alternaria alternata (Fr.) Keissler produces a phytotoxic substance tentoxin. The influence of inorganic phosphate on the formation of this secondary metabolite was analyzed. Distinct phases of growth and metabolite formation can be defined. The first phase shows exponential growth, high QO2, protein and nucleic acid values and a rapid uptake of inorganic phosphate from the medium. The second phase shows linear growth and active tentoxin formation takes place. The highest yields of tentoxin are obtained, when inorganic phosphate in the medium was limited. The phosphate level also influences the ATP-pool of the mycelium. The role of ATP as an effector in phosphate mediated control of tentoxin synthesis was discussed.

Several yeast strains can grow with good yield (0.16 to 0.19 mg protein/mg carbohydrate) on nitrogen supplemented Jerusalem artichoke extract. The most promising strain is Lipomyces starkeyi. Including by-products (pulps, proteins of extract), protein production can reach 2 metric tons/ha.

A synthetic medium containing ammonium nitrate, urea, D-glucose, glycerol, and sodium glutamate was developed for growth of Xanthomonas oryzae and preparation of its phytotoxin. Culture filtrates and partially purified toxin preparations caused blight symptoms when inoculated in leaves of 30 days old rice plant cv. T(N)1. Toxin elicited quicker response than living cells. This activity was due to a non-dialysable, partial acid and heat labile glycopeptide. There was a sharp decrease in activity when culture filtrates and crude toxin preparations were heated at 100 degrees C for 30 min. Maximum activity was observed in pH range of 6.0-7.0 and a gradual loss at lower pH (5.0-3.0) and higher pH values (8.0-10.0). Unlike living cells which caused continuous lesion enlargement, toxin inoculation caused maximum attainment of lesion length within 4-6 weeks. Toxin preparation in concentration of 45 micrograms glucose/ml failed to evoke response. The study demonstrates that the purified toxin being easy in storage and causing quicker response than living cells when inoculated in rice leaves, may be used to screen rice varieties for bacterial blight resistance.