Advanced Journal of Microbiology Research

Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (1), pp. 001-009, January, 2019. © International Scholars Journals

Full Length Research Paper

Isolation and characterization of heavy metal removing bacterial bioflocculants

J. Lin* and C. Harichund

School of Biochemistry, Genetics, and Microbiology, University of KwaZulu-Natal (Westville) Private Bag X 54001, Durban, Republic of South Africa.

Accepted 10 January, 2019

Abstract

Thirteen metal-tolerant bacteria capable of producing metal- removing bioflocculants were isolated from an industrial effluent sample. Pseudomonas sp. was found to be the pre-dominant species among the isolates (8 out of 13), followed by Herbaspirillium spp. (4) and one Paenibacillus sp. The flocculating activity of bioflocculants produced by these microorganisms was assayed using the kaolin clay. The heavy-metal-removal efficiency was determined using atomic absorption spectrometer before and after mixing the bioflocculant with the heavy metal solutions. Bioflocculants exhibit different flocculating abilities of removing kaolin clay in the presence of different heavy metals. Bioflocculants produced by Pseudomonas sp. CH₉ possessed the highest flocculating activity (1.8) compared to the remaining bioflocculants. The flocculating activities of CH₁₁ and CH₁₃ increased to 0.95 and 0.87 in the presence of Pb²⁺ and to 0.89 and 0.98 in the presence of Hg²⁺ respectively from 0.015 in the presence of Ca²⁺ in the standard kaolin clay assay. Up to 90% of Pb²⁺ was removed by Pseudomonas sp. CH₈ bioflocculants. Seventy-eight percent of Hg²⁺ and 66% of Cd²⁺ was removed by Pseudomonas sp. CH6 and Herbaspirillium sp. CH₁₃ bioflocculants respectively. Most of the bioflocculants demonstrated a higher percentage of heavy-metal removal at low concentrations. This study demonstrates that microbial bioflocculants have potential to be used as an alternative bioremedial tool for industrial effluents and wastewater treatments which are co-contaminated with heavy metals.

Key words: Bioflocculant; heavy metals, Pseudomonas sp., Herbaspirillium sp., Paenibacillus sp., Industrial effluent.