Abstract

The combination of microorganisms in consortia enhances high bioflocculant yields. The study aimed at producing and characterising bioflocculant from Bacillus pumilus JX860616 and Alcaligenes faecalis HCB2. Bioflocculant TPT^-1 was obtained through ethanol extraction after optimum conditions were established. The characteristics of the bioflocculant TPT^-1 were obtained by scanning electron microscope equipped with elemental detector, Zetasizer nano, ultraviolet-visible spectrophotometry. Fourier transform infrared (IR) spectrophotometry and the thermal decomposition was used to conduct the thermal gravimetric analysis. The flocculation mechanism of TPT^-1 on Kaolin suspension was obtained by Zetasizer Nano. Glucose and yeast extract were the best energy sources, yielding 3.0 g/L of TPT^-1 in optimum conditions (30°C, 165 rpm, initial pH 6 and 72h). TPT^-1 revealed to be an anionic, heat stable glycoprotein, with the total carbohydrate content of 83.1% (w/w) and the total proteins content of 9.7% (w/w). The elemental analysis demonstrated the presence of N (1.3), C (15.0), O (44.8), P (0.8), Ca (9.0), Cl (2.8), Mg (0.4), S (12.1), K (11.4) and Na (1.9) in mass proportion (% w/w), while the IR spectrum showed the presence of hydroxyl, carbonyl and amine groups. Ba²⁺ mediated bridge flocculation mechanism between the bioflocculant TPT^-1 and Kaolin particles. The high flocculating capability (90%) and characteristics of TPT^-1 suggested its potentiality in industrial applications.

Key words: Bioflocculant TPT^-1, flocculating activity, flocculation mechanism and bacterial consortium.