Production and characterization of bioflocculant produced by Bacillus clausii NB2

Abstract

Molecular and bioflocculant properties characterization of a bacterium strain isolated from brewery wastewater was investigated. Effect of biotechnological parameters (pH, temperature, carbon source, incubation time, stationary and with agitation cultivation and agitation speed) was studied and obtained bioflocculant was characterized. Compositional analysis of the purified bioflocculant was determined. The new isolate strain was identified by 16S rRNA gene nucleotide sequence to have 91% similarity to Bacillus clausii. Cultivation at pH 5.0 and 30oC were the best conditions for bioflocculant production by Bacillus clausii NB2 strain with flocculating activity ranged from 28.83 – 81.05% and 42.68 – 79.68%. Glucose as carbon source was the best for bioflocculant production by Bacillus clausii NB2 strain with flocculating activity ranged from 4.76 – 84.23%, followed in order by abattoir effluent (flocculating activity 78.84%), palm oil effluent (flocculating activity 77.70%), sewage (flocculating activity 73.44%) and brewery effluent (flocculating activity 63.14%) respectively. Incubation time, agitation condition and agitation speed had a significant effect (P≥0.05) on bioflocculant production by this strain. The highest yield of bioflocculant production was obtained by submerged cultivation, in aerobe conditions for 72h at 160 rpm agitation speed. Functional group analyses using Fourier Transform Infrared (FT-IR) spectrophotometer shows the presence of -OH, -NH2, -CONH2 CO and -COO as functional groups and chemical analyses of the purified bioflocculant revealed it to be a glycoprotein with 88.71% of carbohydrate and 11.29% of protein.