Research Article
Sornali Saha
Abstract
The effect of selected environmental stressors (pH, temperature, Ultra Violet exposure, PAH and heavy metals) on important physiological activities of mangrove bacteria was assessed. Cellulose degradation and phosphate solubilisation are two such important physiological activities mainly regulated by mangrove bacteria. Cellulase is a crucial enzyme required for converting waste cellulosic materials into foods and cleans the lignocellulosic waste present in the environment. Along with cellulases, phosphatases are also physiologically necessary enzymes required for maintaining environmental balance. Phosphatases are essential enzymes required for degradation of toxic agricultural waste containing organophosphates, like parathion, paraoxon, diazinon, coumaphos, and Malathion etc. For analysing the effects of environmental stressors on phosphatase and cellulose activity, a previously isolated bacterial culture designated as NE3B02 from Bhitarkanika mangrove, Odisha, India (stored as glycerol stock at -80°C) was screened for phosphate solubilisation and cellulose degradation potential. The mangrove bacterium efficiently solubilizes phosphate and utilizes cellulose at normal environmental conditions [pH=7, temperature (25°C to 37°C)]. Any alterations in environmental conditions interfere with phosphatase and cellulase production ability. The phosphate solubilisation activity of isolate increased with decrease in pH (from pH 7.4 to 7.1). Similarly the cellulose utilization ability of isolate NE3B02 also increased with decrease in pH (pH 7.4–pH 7.1). With increased temperature and time of UV exposure (short UV rays) the phosphate solubilisation and cellulose utilization potential of the isolate decreases significantly. PAH pollutant significantly elevates phosphate solubilisation and cellulose utilization ability of NE3B02. Heavy metal cadmium declines the activities of phosphatase and cellulose, whereas the phosphatase and cellulose activities were completely inhibited in the presence of heavy metal lead. The conclusions were drawn on the basis of calculation of solubilisation index for phosphatase activity and diameter of cellulose clearance zone was considered for cellulose activity.