Production, characterisation and flocculation mechanism of bioflocculant TMT^-1 from marine <i>Bacillus pumilus</i> JX860616

Abstract

Bioflocculant from marine Bacillus pumilus JX860616 was characterised and its flocculation mechanism determined. The bacterium was identified by 16S rRNA and the bioflocculant was obtained through solvent extraction after optimum medium composition and culture conditions were established. The physicochemical analysis of the bioflocculant were obtained by scanning electron microscopic (SEM) equipped with elemental detector, Fourier transform infrared (IR) spectrophotometry. The highest flocculating activity (93.3%) was obtained with optimum medium composition of the energy sources of glucose and (NH₄)₂SO₄ and culture conditions of; initial pH 6; and Ba²⁺ after 72 h, at the inoculum size of 2% (v/v). The bioflocculant (2.4 g/L) revealed to have a crystal-like porous structure and had the total carbohydrate of 83.1% w/w and proteins content of 6% w/w. The elemental analysis showed the presence of C (17.0), O (46.0), Na (4.3), Mg (6.8), P (4.1), S (7.0), Cl (5.9), K (7.4) and Ca (0.7) (% w/w). IR observations were indicative of hydroxyl, vinyl, amide and aliphatic amine groups. The bridging mechanism mediated by Ba²⁺ on colloidal Kaolin particles was proposed. The high flocculating activity of TMT^-1 implied that it has a promise in industrial applications.

Keywords: Bacillus pumilus JX860616, bioflocculant TMT^-1, flocculating activity and flocculation mechanism