Trophic interactions of proteolytic bacteria Proteinivorax tanatarense in an alkaliphilic microbial community

Lytic action of an anaerobic proteolytic bacterium Proteinivorax tanatarense on organisms with different cell wall types was studied. In the absence of photosynthetic oxygen release, this proteolytic was able to grow on intact biomass of cyanobacteria belonging to various systematic groups. It is probably their usual saprotrophic satellite responsible for the regulation of abundance of primary producers during the dark phase. Growth also occurred on the biomass of a nonphototrophic gram-negative microorganism Halomonas campisalis , a common component of alkaliphilic microbial communities. Comparative analysis of the interaction of the proteolytic with H. campisalis cells at different physiological states revealed the lytic action to be restricted to dead and/or weakened cells, rather than to the actively dividing ones. Strict specificity of the action of the proteolytic bacterium on gram-negative microorganisms with no effect on gram-positive ones was shown.