Screening and the effects of production conditions on bioflocculants’ production by microorganisms isolated from wastewater

Abstract

Bioflocculants are biopolymers produced by microorganisms and used for removal of colloidal particles from solution.
Screening, production and the effect of physicochemical conditions on bioflocculants production by microorganisms
isolated from wastewater samples were investigated. Fifty-five (55) bacterial strains isolated from four different wastewater
samples were screened for bioflocculants production. The flocculating activity ranged from 3.29-74.15% in which
Streptomyces sp. HDW7 gave the highest. The best four bioflocculant producers, namely: Streptomyces sp. HDW7
(74.15%), Nocardia sp. OX5 (69.02%), Bacillus licheniformis PO7 (61.00%) and Micrococcus sp. PO3 (57.04%) were
selected for further studies.30oC, pH 7.0, and 72 hours supported the highest bioflocculants production. Bioflocculants
production under different carbon and nitrogen sources ranged from 79.00-88.00% and 61.00-87.00% in which maltose and
peptone supported the highest by 75% of the isolates (3 of the 4). Glucose and peptone supported the highest bioflocculant
production (87.00%) by Streptomyces sp. HDW7. Bioflocculants production under static and agitation condition ranged
from 36.66-58.33% and 60.66-87.33% with Streptomyces sp. HDW7 having the highest bioflocculant activity. Bioflocculants
production using single and the consortium strains ranged from 72.33 – 81.67% in which single strain, Streptomyces sp.
HDW7 had the highest followed by consortium of Streptomyces sp. HDW7 and Nocardia sp. OX5. In conclusion, some
microorganisms isolated from the wastewater had a high potential for bioflocculants production. 30oC, pH 7.0, 72 hours,
glucose and peptone supported the highest bioflocculants production by the selected bioflocculant producing isolates.