Enhanced Production of Microbial Exocellular Biopolymers for Removal of Phosphate from Water

Abstract

Phosphorus is an essential element required by all life forms for their survival and growth. Recent decades have witnessed expansion of agriculture, human population and industry resulting in increased use, and consequent elevations in discharge of phosphorus. In view of the untoward outcomes of excessive phosphorus discharge in water bodies, regulatory bodies have posed limits on phosphorus concentration in waste water. Permissible limits of phosphorus discharge are achieved through physical/chemical and biological methods of phosphate (the only bioavailable form of phosphorus) removal. However, installation and operational costs, availability of resources, phosphorus removal efficiency, recovery and reusability of phosphorus following treatment, waste management and occupational hazards are the major impediments in wide application of these methods. Sorbents derived from biological sources have gained immense interest in recent years as sustainable, non-toxic and cost effective alternatives for removal of pollutants. Despite their increasing popularity in remediation of other pollutants, biosorbents for phosphorus removal from waste water have not been extensively investigated. In fact, biosorbent-mediated phosphorus remediation has been restricted to sorbents prepared from agricultural wastes while microbial polymers have remained unexplored. The present study exploited the potential of bacterial exobiopolymer (EBP) as a biosorbent for phosphorus removal. An isolate producing phosphate-binding EBP was isolated from sludge and designated Acinetobacter haemolyticus TK15. In an attempt to potentiate EBP production, mutants were generated using Tn5 transposon mutagenesis and screened for EBP yield and phosphate removal. An insertional mutant which showed enhanced EBP production and high phosphate binding affinity was selected and designated A. haemolyticus MG606.