Browsing by Author "Shivanand, P."

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Halophilic bacteria and their compatible solutes -osmoregulation and potential applications
(2011) Shivanand, P.; Mugeraya, G.
Halophilic bacteria grow over an extended range of salt concentrations. Their metabolic patterns are distinct compared to their terrestrial counterparts and obligate halophiles. The possibility of rapid adjustment to changes in the external salt concentration makes them potential candidates for bioprocessing. Halophilic bacteria produce enzymes, metabolites, solutes, exopolysaccharides and pigments which have high commercial value. However, compared to the obligate halophilic archaea, they have been less studied with only a few reports available on designing the production processes. Compatible solutes are the highly soluble, low-molecular weight organic compounds that make halophilic bacteria versatile in their adaptation to salinity. Halophilic bacteria either take in the solutes from the medium or synthesize them de novo. Compatible solutes include amino acids, carbohydrates or their derivatives, sugars and polyols. In addition to their stabilizing effects, they offer a multitude of physiological and potential biotechnological applications ranging from stabilizers of biomolecules, stress-protective agents to therapeutic agents and cosmetic actives. Exploring the significant applications of compatible solutes could be an attractive proposition towards commercialization. Moreover, it would enlighten the bases of adaptations of moderately halophilic bacteria.
Utilization of renewable agricultural residues for the production of extracellular halostable cellulase from newly isolated halomonas sp. strain PS47
(2013) Shivanand, P.; Mugeraya, G.; Kumar, A.
A newly isolated biopolymer-degrading halophilic bacterium, Halomonas sp. strain PS47, yielded higher cellulase activity (0.0076 U/ml) in mineral salt medium (MM63). Activity increased to 0.029 U/ml when carboxymethyl cellulose (0.5 % w/v) was used as carbon source and further to 0.138 U/ml when a combination of yeast extract and peptone was used as nitrogen source. Enzyme secretion was maximal during late exponential and stationary phases (0.15 U/ml, 48 h). Among different agro-residues (1 % w/v), wheat bran gave the highest activity (0.12 U/ml) at pH 7.5, 30 �C and 6 % (w/v) NaCl. The cellulase exhibited higher activity at pH 7.1 and 50 �C. The enzyme exhibited activity over a wide range of NaCl concentrations (0-4 M). Optimum activity was at 0-1 M NaCl. At 4 M NaCl, activity was reduced to 65 % of the initial value. The present investigation thus contributes to the limited information available on halostable cellulases. � Springer-Verlag Berlin Heidelberg and the University of Milan 2012.
Utilization of renewable agricultural residues for the production of extracellular halostable cellulase from newly isolated halomonas sp. strain PS47
(2013) Shivanand, P.; Mugeraya, G.; Kumar, A.
A newly isolated biopolymer-degrading halophilic bacterium, Halomonas sp. strain PS47, yielded higher cellulase activity (0.0076 U/ml) in mineral salt medium (MM63). Activity increased to 0.029 U/ml when carboxymethyl cellulose (0.5 % w/v) was used as carbon source and further to 0.138 U/ml when a combination of yeast extract and peptone was used as nitrogen source. Enzyme secretion was maximal during late exponential and stationary phases (0.15 U/ml, 48 h). Among different agro-residues (1 % w/v), wheat bran gave the highest activity (0.12 U/ml) at pH 7.5, 30 °C and 6 % (w/v) NaCl. The cellulase exhibited higher activity at pH 7.1 and 50 °C. The enzyme exhibited activity over a wide range of NaCl concentrations (0-4 M). Optimum activity was at 0-1 M NaCl. At 4 M NaCl, activity was reduced to 65 % of the initial value. The present investigation thus contributes to the limited information available on halostable cellulases. © Springer-Verlag Berlin Heidelberg and the University of Milan 2012.