TITLE:
Preliminary Characterization of a Cellulase Producing Bacterial Strain Isolated from a Romanian Hypersaline Lake
AUTHORS:
Robert Marian Ruginescu, Roxana Cojoc, Mădălin Enache, Veronica Lazăr
KEYWORDS:
Cellulases, Cellulose Residues Bioconversion, Cellulolytic Bacterial Strain, Hypersaline Lakes, Salt-Tolerant Enzymes
JOURNAL NAME:
Journal of Environmental Protection,
Vol.9 No.10,
September
7,
2018
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.