Optimization for growth of Rhodocyclus gelatinosus in seafood processing effluents.

Tuna condensate was a better substrate than shrimp-blanching water or effluent from a frozen-seafood plant for growing Rhodocyclus gelatinosus under anaerobic conditions in the light. One strain out of four examined, R7, gave the highest biomass (4.0 g/l), cell yield (0.32 g cell/g COD), and COD removal (78%) in 1:10 (v/v) diluted tuna condensate. Shrimp-blanching water added to the tuna condensate further increased growth rate, biomass and COD removal. Optimal growth was at pH 7.0 and 3000 Lux light intensity. Acetate, pyruvate, glucose, glutamate, propionate or malate added to the tuna condensate did not increase cell yield, carotenoid or bacteriochlorophyll content or biomass protein. A maximum cell mass of 5.6 g/l (containing 50% protein) and 86% COD removal were obtained after 5 days' incubation under optimal conditions.