Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XXIV
Written by Irinel Gabriel PROCA, Camelia Filofteia DIGUȚĂ, Ştefana JURCOANE, Florentina MATEI
Hydrolytic enzymes produced by halotolerant/halophilic microorganisms display polyextremophilic properties, which determines particular industrial interest. The goal of this work was to detect at least one halotolerant bacterial strain for the ability to produce multiple enzymatic activities (amylases, proteases, lipases, cellulases) with biotechnological importance. Eighteen halotolerant bacterial strains, isolated from hypersaline water located in Lopătari, Romania, have been used in this study. Hydrolytic enzymes production was assayed by plate screening on basal media supplemented with following sources: 1% soluble starch (for amylase activity); 1% carboxymethylcellulose (for cellulase activity); skimmed milk (for protease activity); 1% Tween 80 and CaCl2 (for lipase activity). Positive reactions have been shown by the presence of a clear halo or precipitates around the bacterial isolates. All strains had at least one enzymatic activity. The lipases and amylases activities were the predominant hydrolytic activities detected. Our results revealed the ability of different halotolerant bacterial strains to present a combination of two or three hydrolytic enzymes: 10 isolates have produced amylases and proteases enzymes; 2 isolates - lipases and proteases enzymes; 1 isolate - amylases, proteases and cellulases enzymes and 3 isolates - proteases, lipases and cellulases enzymes, respectively. Potential enzymes production by isolate 11.5 also was evaluated in submerged cultivation on different substrates. Among the substrates tested, the production of hydrolytic enzymes by isolate 11.5 was enhanced when grounded cereals mixture 1% was used as sole substrate as carbon and nitrogen source: 312 U/ml (amylases), 0.22 U/ml (cellulases) and 0.09 U/ml (proteases).
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