ISOLATION AND GROWTH OF THE PHOTOTROPHIC BACTERIUM RHODOPSEUDOMONAS-PALUSTRIS STRAIN B1 IN SAGO-STARCH-PROCESSING WASTE-WATER

An indigenous strain of the purple non-sulphur phototrophic bacterium, Rhodopseudomonas palustris strain B1, was selected for the utilizatio n and treatment of wastewater from a sago-starch-processing decanter. Growth of Strain BI under anaerobic-light conditions in the carbohydra te-rich effluent was optimized by using 50% (v/v) effluent diluted in a basal minimal mineral medium with the addition to 0.1% (w/v) yeast e xtract. The optimum level of nitrogen source supplement, ammonium sulp hate, was 1.0 g/l. Highest cell mass concentration was achieved by usi ng tungsten lamps as the light source with a light intensity of 4 klux . Under these optimal conditions, a maximum biomass of about 2.5 g dry cell/l with a pigment content of about 1.1 mg carotenoid/g dry weight cell was achieved after 96 h of anaerobic cultivation. There was a 77 % reduction in the chemical oxygen demand (COD) of the effluent. A cel l yield of about 0.59 g dry weight cell/g COD was obtained.