Studies on bioflocculant production by Methylobacterium sp. Obi isolated from a freshwater environment in South Africa

Abstract

A bioflocculant-producing bacterium isolated from river water was identified as Methylobacterium sp.
Obi by 16S ribosomal ribonucleic acid (rRNA) gene sequencing. The nucleotide sequence was
deposited in the Genbank with accession number HQ537130. The bioflocculant secreted by the isolate
showed a peak flocculating activity of 72% in 1 g/L kaolin suspension supplemented with CaCl2. The
bioflocculant yield was maximal when glucose and peptone were used as carbon and nitrogen sources
respectively, at an optimum pH of 7. Calcium was the most effective cation in stimulating
bioflocculating activity. Chemical analyses of the purified bioflocculant revealed it to be a
polysaccharide