Flocculating Properties of a Bioflocculant Produced by Bacillus sp. Isolated from a Marine Environment in South Africa

Flocculation is a process whereby chemicals (flocculants) stimulate aggregation of colloids and other suspended particles in a suspension to form floc. This is different from precipitation, because prior to flocculation, colloids are suspended in a liquid and not completely dissolved in a solution.1 Flocculation finds usefulness in many fields such as wastewater treatment, downstream processing, food and fermentation processes.2–4 Flocculating agents could be inorganic, synthetic or natural. Typical examples of natural flocculating agents are bioflocculants produced by microorganisms. Bioflocculants are the metabolite product of microorganisms produced during their growth. They are usually high molecular weight biopolymers, and are synthesised and released outside the cell.2 Compared with the conventional flocculants, bioflocculants are safe for use because of their relative inert nature.5 Thus, screening new microorganisms for bioflocculant with excellent flocculating activity has become a subject of intensive investigations globally. Bacillus species are positive to Gram-staining and are rod-like, their morphological arrangement are either in pairs or chains with round or square ends having single endospore. The genus currently comprises in excess of 60 species6 and have been reported to produce bioflocculant2,7–13 but isolates from marine environment are scanty in literature. Marine bacteria are amongst the most economically and biotechnologically valuable prokaryotes. They are responsible for the production of about 50 % of all discovered bioactive secondary metabolites.14 The rate of discovery of new compounds from terrestrial bacteria has decreased, whereas the rate of re-isolation of known compounds has increased, suggesting the need for exploring underexploited habitats such as the marine environment as sources of novel bioactive compounds including bioflocculants. In this report, we assessed the potential of Bacillus specie isolated from marine sediment in South Africa for the production of bioflocculant.