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The review uses data obtained by the authors and available in the literature to discuss microbial collagenolytic enzymes, widely employed in scientific research, biotechnology, and medicine. Collagenases differing in their structure and the specificity of their action on collagen fibrils were isolated from bacteria (including marine isolates), actinomycetes, and fungi. Collagenases produced by Clostridium histolyticum and Achromobacter iophagus are the best studied enzymes; both are metalloenzymes that contain Zn2+ in their active site and retain collagenolytic activity in the presence of Ca2+. Serine-type collagenolytic proteases were also found in microorganisms. These enzymes differ from "true" collagenases by the structure of their active site. Both serine proteases and metalloproteases with high collagenolytic activities were isolated from the culture liquids of Streptomyces and Actinomyces strains. The biosynthesis of collagenases is induced by the addition of various collagen-containing substrates to the cultivation medium.

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An investigation of the effects of drying and drying-rewetting cycles under vacuum conditions of 10(-2) torr at -30 degrees C on conidia of the atmospheric strain Penicillium chrysogenum from 48-77 km heights, collected by meteorological rockets found that survival and restoration of the initial physiological properties were possible through some very efficient protective cellular mechanisms. Such adaptive possibilities explain the widespread diffusion of microbial cells throughout the biosphere of our planet.

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The ability of an Actinomyces strain--Streptomyces spp. to produce extracellular proteases has been studied under varied cultivation conditions during the growth cycle. The activity of enzyme preparations precipitated from the culture liquid was determined with various substrates--gelatin, casein, fibrinogen, fibrin and collagen. The isolated enzyme complex possessed caseinolytic, fibrinolytic, thrombolytic and collagenolytic activities.

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A strain of the genera Pseudomonas genera was found to possess hemolytic, fibrinolytic and thrombolytic activities. The fibrinolytic activity of the lyophilized unpurified preparation was 900 conventional units/mg. After incubation in the blood plasma, the activity completely remained. The preparation (1 microgram/ml, 750 micrograms of protein) obtained by precipitation with ammonium sulfate (80% saturation) completely lysed in vitro human blood thrombi for 50 min. The strain studied can find practical applications in medical industry.

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The literary and experimental data obtained by the authors concerning the ability of various microorganisms to synthesize exoproteases lysing the thrombi of human blood are presented in the article. Various methods of enhancing the thrombolytic activity of microorganisms cultures, the properties of some isolated and purified preparations, methods of enlarging the specificity of the enzymes to fibrin and of reduction of their toxicity are considered.

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The ability of marine bacteria A. piscicida to produce exoproteases that were able to lyse human blood clots has been studied. Optimal conditions for biosynthesis of these enzymes have been found. The enzyme has been partially purified. In concentration of 1 mg/ml it has activity corresponding to that of 500 micrograms/l plasmine and 100 micrograms/ml trypsine. The enzyme activity was completely inhibited after incubation in human blood plasma.

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The literary and own experimental data on the genetic apparatus changes in microorganisms after drying are reviewed. In the survived drying cells the total content of nucleic acids decreases, some amount of mainly high-molecule ribonucleic acid decomposes. The RNA isolation into the suspended medium is also observed in connection with the destructive processes in the cytoplasmic membrane and the decomposition of some intracellular structures. The dehydration of microbial cells violates the normal processes of DNA replication, and sometimes it leads to the conformational changes in molecule structure. In some cases the damage in the genetic apparatus causes the mutation changes of microorganisms. This should be taken into account in experiments where lyophilized cultures are used.

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The effect of dehydration on the morphology and fine structure of conidia was studied with the atmospheric and collection strains of Aspergillus niger and Penicillium chrysogenum. Dehydration did not cause changes in the structure of most conidia. However, destructive changes in the conidial wall and membrane were found in some conidia. The cytological changes of conidia were either reversible or irreversible, which determined their survival rate during dehydration.

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Aspergillus niger and Penicillium chrysogenum strains were isolated from the mesosphere and characterised. Their properties significant for migration in the atmosphere are discussed. The possibility of the anabiotic state of these fungi under the action of dehydration and low temperatures was studied as well as the degree of their resistance to the aforementioned extreme factors.

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The aim of this work was to study certain physiological-biochemical characteristics of Aspergillus niger, strain 26, isolated from the mesosphere as well as those of its mutant having light-brown conidia. The parent strain and its mutant were grown in a liquid Chapek medium to study accumulation of the biomass, changes in the pH of the medium, as well as assimilation of glucose, nitrogen (NO3-) and phosphorus (PO4-). The content of polysaccharides, protein, RNA and DNA was determined in the biomass. The parent culture and its mutant had the same growth dynamics and changes in the pH of the growth medium. They assimilated nitrogen, phosphorus and glucose at the same rate. No significant differences were found in the content of DNA, RNA, protein and polysaccharides. Lipids were an exception: their content was higher by ca. 26% in the mutant as compared with the parent strain. Apparently, the elevated sensitivity of the mutant to UV is due not only to a loss of certain pigments, but also to a damage of other protective mechanisms of the cell.

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The literature data on toxins of neuroparalytic action, produced by pyrrophytic algae and capable of being accumulated by edible mollusks, are presented. The LD50 for mice of saxitoxin, the best known and most strongly acting toxin, is 5-10 microgram/kg. some toxins of dinoflagellates have been isolated in purified form. Their physicochemical properties have been studied and the structural formula of crystalline derivatives of saxitoxin has been established. The major problem of environmental protection is associated with a study of toxic dinoflagellates.

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Literature material is presented on the ability of free-living nodule bacteria for asymbiotic nitrogen fixation, detected for the first time in 1975. Necessary components of the nutrient medium in the use of which the nitrogen-fixing ability of rhizobia in pure cultures is manifested, proved to be sugars and intermediates of the citric acid cycle, as well as small quantities of bound nitrogen. The experimental data available in the literature are evidence of the presence of a complete assortment of genes for the synthesis of the nitrogenase enzyme complex in free-living nodule bacteria.

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