ABSTRACT
Such extreme factors as UV radiation, high temperature and salinity, and also the small amount of accessible water have an influence on microorganisms of coastal ecosystems of the Dead Sea. Resistance to these factors of the microorganisms isolated from ecosystems of this region (vertical steep gorge around the Dead Sea, clay-salt plain and black highly mineralized muds) is studied. Aerobic, chemoorganotrophic, thermotolerant, moderately halophilic bacteria which, according to their morphological and physiological properties, are similar to species Gracilibacillus halotolerans, Salimicrobium album and genus Caryophanon have been isolated from these ecosystems. All strains grew at 0-10% of NaCl in the medium (one strain--at 15% of NaCl), in the range of 30-50 degrees C. Resistance to UV radiation has been revealed in all the investigated bacteria Lethal doses of UV (LD90 and LD99.99) for spore-forming strains of genus Gracilibacillus were 100-170 and 1100-1500 J/m2, respectively; for strain Salimicrobium 6t1 (does not form spores)--70 and 400 J/m2; for the strain lt4 (genus Caryophanon), forming filamentous (or trychomes)--150 and 1400 J/m2. Some strains of genus Gracilibacillus had strong antagonistic effect on conditionally pathogenic test cultures Staphylococcus aureus 209p and Candida albicans UCM Y-690. It is conceivable that resistance of microorganisms of coastal ecosystems of the Dead Sea to extreme factors was generated under the influence of abiotic (physical and chemical) factors typical of this region.
Subject(s)
Adaptation, Physiological , Bacteria/growth & development , Biota , Oceans and Seas , Seawater/microbiology , Water Microbiology , Adaptation, Physiological/drug effects , Adaptation, Physiological/radiation effects , Bacteria/drug effects , Bacteria/radiation effects , Hot Temperature , Israel , Microbial Interactions/drug effects , Microbial Interactions/radiation effects , Microbial Viability/drug effects , Microbial Viability/radiation effects , Microscopy, Phase-Contrast , Salinity , Seawater/chemistry , Ultraviolet RaysABSTRACT
The method of isolation and quantitative account of pure cultures of obligate anaerobic hydrogen-forming clostridia is improved. A strain of hydrogen-forming bacteria Clostridium sp. BY-11 has been isolated from the association of sporulating bacteria. Quantitative indices of hydrogen synthesis and starch fermentation have been determined when growing the strain in the liquid medium. Concentration of H2 in the gas phase was 49%, microorganisms synthesized 128 1 of H2 from 1 kg of starch, the mass of starch decreased 7 times for 6 days. The mentioned indices for hydrogen synthesis and starch fermentation and for other organic model substrates in the future are the basis for creating the industrial biotechnology for production of hydrogen as the energy carrier under disposal of ecologically dangerous solid food waste.
Subject(s)
Biotechnology/methods , Clostridium/isolation & purification , Hydrogen/metabolism , Starch/metabolism , Anaerobiosis , Biofuels , Clostridium/physiology , Culture Media , Fermentation , Hydrogen-Ion ConcentrationABSTRACT
Technologically promising microbe association, consisting of aerobic and anaerobic sporulating bacteria has been isolated. The association synthesizes molecular hydrogen during fermentation of potato and starch. The association was isolated from soil, pasteurized on the boiling water bath. The association destroys potato during 5-7 days with a decrease of mass up to 17.4 times and synthesizes gas consisting of 60% of H2.
