Cultivation of Rubrivivax gelatinosus in fish industry effluent for depollution and biomass production

Abstract

One application of biotechnology that contributes to sustainable development is the utilization of industrial byproducts as substrates for the production of substances of interest by microorganism. In this work, liquid effluent from tilapia fish processing was used as a substrate for the growth of Rubrivivax gelatinosus with the aim of studying the bacterial photo heterotrophic metabolism. Cultivation conditions included 32 +/- A 2A degrees C, 1,400 +/- A 200 lux and 7 days. In the initial days, the best cell mass production (0.273 g l(-1) with 72 h), specific growth rate (0.188 h(-1) with 48 h) and chemical oxygen demand (COD) decrease (43% with 72 h) were reached. Typical bacterial oxycarotenoids were identified after 3 days of cultivation, averaging 3.03 mg g(-1) biomass. Bacterial growth in the effluent during the period of study resulted in pH increase to 7.9, total nitrogen, oils and greases and COD decreases of 22.46, 47.71 and 52%, respectively, and dry cell mass production of 0.18 g l(-1). The bacterial growth in the wastewater provided biomass and oxycarotenoids and the removal of pollutant load.