A marine bacterium, Oceanobacillus sp. Pinky, isolated from Algoa Bay sediment produces a thermostable glycoprotein flocculant

Abstract

In this study, we report on the bioflocculant production potential of an Oceanobacillussp. isolated from the marine sediments of Algoa Bay. The bacteria produced an extracellular bioflocculant optimally in the presence of sodium carbonate as source of carbon with flocculating activity of about 95.5%. Other optimal culture conditions included: tryptone as nitrogen source (flocculating activity, 84.5%); presence of Ca2+; inoculum size of 2% (v/v) and alkaline pH (10). Composition analyses revealed the purified bioflocculant to be thermostable and composed of polysaccharide and protein. Optimum dose of the purified bioflocculant for the clarification of 4 g/L kaolin clay suspension at neutral pH was 0.2 mg/ml. Scanning electron microscopic (SEM) observations were indicative of a porous bioflocculant structure while Fourier transform infrared (FTIR) spectrum revealed the presence of carboxyl, hydroxyl and amine groups. We proposed that the bacteria hold promise as a potential source of new bioflocculant compound(s). Key words: Oceanobacillus sp., bioflocculant, glycoprotein, marine sediment, Algoa Bay.