Preliminary Characterization of a Cellulase Producing Bacterial Strain Isolated from a Romanian Hypersaline Lake

Abstract

Cellulases are a group of enzymes that are used in many biotechnological processes. Since most of the enzymes synthesised by mesophilic microorganisms are unstable in industrial environments, it is necessary to direct research towards extremophile cellulolytic microorganisms because the enzymes synthesised by them are stable and active even in harsh physicochemical conditions. In the present investigation, our aim was to isolate and identify some microbial cellulolytic strains from a hypersaline lake located in Romania and to determine their optimal growth conditions. Of a total of 25 microbial strains isolated, only one extreme halotolerant bacterial strain was able to produce an endoglucanase. Based on molecular identification, we identified this cellulolytic strain as a species of Bacillus genus, most closely related to Bacillus zhangzhouensis. Optimal growth conditions were found to be at 15˚C, pH 7.5 and 2 M NaCl. Endoglucanase activity of this bacterial strain is influenced by both salinity and temperature. The most significant endoglucanase activity was detected in the presence of 3 M NaCl, after 72 h of incubation at 15˚C. In this situation, the amount of glucose released from a volume of 0.5 mL of 2% (w/v) carboxymethyl cellulose substrate is equivalent to 2.05 mg. In conclusion, this study represents the first preliminary characterization of a B. zhangzhouensis strain that has the ability to degrade cellulose and that demonstrates tolerance to high salt concentrations.

Bioprospecting for Novel Halophilic and Halotolerant Sources of Hydrolytic Enzymes in Brackish, Saline and Hypersaline Lakes of Romania

“…Salt Lake [22,24], the predominant ions being chloride and sodium, followed by sulfate and considerably lower quantities of magnesium. The biota of these ecosystems has been characterized particularly in terms of phyto-and zooplankton composition [24,28,29], but little or no information about their bacterial, archaeal and fungal communities is currently available [30][31][32]. Hence, these environments remain largely unexplored reservoirs of microorganisms potentially capable of producing novel bioactive compounds and industrially valuable molecules.…”

Metabolic Potential of Some Functional Groups of Bacteria in Aquatic Urban Systems

“…Four enzymatically different types of culture media were selected for enzymatic screening containing specific substrates [18,19]. Thus, agarized media with 1% starch, 1% casein, 1% Tween80 and 0.5% carboxymethylcellulose, respectively, were used in order to select bacteria able to produce amylases, proteases, lipases and cellulases.…”