Assessment of bacillus pumilus isolated from fresh water milieu for bioflocculant production

A bioflocculant produced by a Bacillus species was assessed with regards to its physiochemical properties and flocculating efficiency. Identification of the bacteria through 16S rDNA sequencing revealed it to have 99% similarity to Bacillus pumilus strain ZAP 028. The optimum culture conditions for bioflocculant production by the bacterial strain were inoculum size of 4% (v/v), maltose as a sole carbon source, multiple nitrogen source (yeast extract, urea and ammonium sulfate) and medium initial pH 7. The bioflocculant was thermostable with high flocculating rate for kaolin suspension at low dosage 0.1 mg/mL over a wide pH range (3-11). Fourier-transform infrared (FTIR) spectroscopy analysis result of the purified bioflocculant showed that hydroxyl, amino and carboxyl groups were the main functional moieties in its molecular structure. The bioflocculant was composed of sugar (75.4%), protein (5.3%) and uronic acid (15.4%). Scanning electron microscopy (SEM) showed a dendritic bioflocculant structure and the energy dispersive X-ray spectroscopy (EDX) analysis revealed that the purified bioflocculant had weight fractions of elements as follows: 22.71% of C, 11.56% of N, 41.60% of O, 0.51% of S and 7.98% of P. The bioflocculant produced had strong flocculating activity and high thermal stability, which affords its utilization in industrial processes.