Heterotrophic bacterial activity in selected aquaculture systems near cochin

The principal interest of the present investigation was to determine seasonal and vertical variation of chemoorganotrophic utilisation of glucose and sodium—acetate by the natural bacterial population in the aquaculture pond of Narakkal, Cochin using techniques which allow maintenance of the in situ gaseous concentrations during incubation. In addition salinity, dissolved oxygen, temperature, hydrogen—ion—.concentration, primary production, plant pigments and total bacterial concentration were determined seasonally and vertically because of their possible relationship to chemoorganotrophy.

Studies on Production of Bacterial Xylanases

Xylanases with hydrolytic activity on xylan, one of the hemicellulosic materials present in plant cell walls, have been identified long back and the applicability of this enzyme is constantly growing. All these applications especially the pulp and paper industries require novel enzymes. There has been lot of documentation on microbial xylanases, however, none meeting all the required characteristics. The characters being sought are: higher production, higher pH and temperature optima, good stabilities under these conditions and finally the low associated cellulase and protease production. The present study analyses various facets of xylanase biotechnology giving emphasis on bacterial xylanases. Fungal xylanases are having problems like low pH values for both enzyme activity and growth. Moreover, the associated production of cellulases at significant levels make fungal xylanases less suitable for application in paper and pulp industries.Bacillus SSP-34 selected from 200 isolates was clearly having xylan catabolizing nature distinct from earlier reports. The stabilities at higher temperatures and pH values along with the optimum conditions for pH and temperature is rendering Bacillus SSP-34 xylanase more suitable than many of the previous reports for application in pulp and paper industries.Bacillus SSP-34 is an alkalophilic thertmotolerant bacteria which under optimal cultural conditions as mentioned earlier, can produce 2.5 times more xylanase than the basal medium.The 0.5% xylan concentration in the medium was found to the best carbon source resulting in 366 IU/ml of xylanase activity. This induction was subjected to catabolite repression by glucose. Xylose was a good inducer for xylanase production. The combination of yeast extract and peptone selected from several nitrogen sources resulted in the highest enzyme production (379+-0.2 IU/ml) at the optimum final concentration of 0.5%. All the cultural and nutritional parameters were compiled and comparative study showed that the modified medium resulted in xylanase activity of 506 IU/ml, 5 folds higher than the basal medium.The novel combination of purification techniques like ultrafiltraton, ammonium sulphate fractionation, DEAE Sepharose anion exchange chromatography, CM Sephadex cation exchange chromatography and Gel permeation chromatography resulted in the purified xylanase having a specific activity of 1723 U/mg protein with 33.3% yield. The enzyme was having a molecular weight of 20-22 kDa. The Km of the purified xylanase was 6.5 mg of oat spelts xylan per ml and Vmax 1233 µ mol/min/mg protein.Bacillus SSP-34 xylanase resulted in the ISO brightness increase from 41.1% to 48.5%. The hydrolytic nature of the xylanase was in the endo-form.Thus the organism Bacillus SSP-34 was having interesting biotechnological and physiological aspects. The SSP-34 xylanase having desired characters seems to be suited for application in paper and pulp industries.

‘Studies on Bacterial Indicators and Pathogen Vibrio parahaemolyticus in Cochin Backwater

Microbiological studies on the incidence, behaviour, activity and ecological implications of marine micro~organisms, particularly microbial pathogens in coastal waters and estuaries exhibit the increasing concern and awareness of environmental impacts on health and wealth. Marine microbiologists have been active in investigating on the distribution, kinds of organisms and their activity in the environment. However, informations on the effect of environment on the ecology or on the distribution (spatial/temporal) of microbial comunity and competition among groups inhabiting the ecosystem are sparE§L Estuarine environment are complex with respect to diversity of habitats, variation in physicochemical parameters and contamination by terrestrial bacterial species. Being the organisms of‘public health significance, ecological studies on total coliforms, faecal coliforms, faecal streptococci, §. ggli and X. parahaemolyticus have great relevance as studies of these types would provide a wealth of information to environmentalists and to fishery industry. In order to evalé%e the status, role and significance of potentially hazardous bacterial species in natural environment it is necessary to monitor the ecology of such organisms systematically in relation to physico-chemical parameters