Chitosan Resistance of Bacteria and Micromycetes Differing in Ability to Produce Extracellular Chitinases and Chitosanases

Resumo

Effect of chitosan on growth and development of bacterial and fungal strains differing in their ability to synthesize chitinases and chitosanases was explored. Bacterial cultures simultaneously producing chitinases and chitosanases were found to be more resistant to soluble chitosan than both the strains synthesizing only chitinases and inactive bacteria. Paenibacillus ehimensis strain IB-739, which was characterized by inducible synthesis of chitinases and chitosanases, exhibited the highest resistance (minimal bactericidal chitosan concentration 14−15 mg/mL). No direct correlation was revealed between the level of chitosanase production by bacteria and their resistance to chitosan. Sublethal concentrations of chitosan promoted the growth of several bacterial strains; the most intensive growth of chitosan-degrading bacteria correlated with the maximal values of their chitosanase production. Within the concentration range studied (≤16 mg/mL), no inhibitory action of chitosan against exo-1,4-β-glucosaminindase-producing strain Penicillium sp. IB-37-2A was observed. Compared to inactive fungal cultures, the growth of this fungus was significantly activated in presence of chitosan; the maximal concentration of this polysaccharide resulted in a sixfold increase of Penicillium sp. IB-37-2A biomass yield.