Biopolymer Synthesis and Detection by Soil Bacteria and Yeast

Abstract

Biopolymers have emerged as potential alternatives to synthetic plastics over the last decades because they share very similar characteristics, are biodegradable and thus can reduce the global pollution caused by synthetic plastics. The primary focus of this work was to explore PHB synthesizing ability of indigenous soil bacteria and yeast during a single-phase growth condition. Three bacterial (two soil isolates and Bacillus subtilis) and one yeast species were used for the study. PHB synthesis study was carried out under batch experimental setup at incubation temperatures of 25 and 37°C. Evidence of PHB synthesis were confirmed by Sudan Black B staining for bacterial and yeast cells isolates. The highest PHB granules recovered was estimated to be 87 mg/100ml at an optimal temperature of 37°C, with none of the test microbial species showing PHB production at 25°C. Generally, the test isolates showed distinct strategies of PHB accumulation at different incubation periods; some throughout the growth period and others only when growth is at the stationary stage. In the majority of the isolates, growth rate of the test isolates was however directly proportional to the quantity of PHB produced. The PHB synthesizing potential of the test microbial species could be optimized by growing mixed cultures of both exponential and stationary PHB synthesizing organisms in a single fermentation process step, where PHB production is guaranteed to occur throughout the incubation process. This optimization strategy along with its ideal process conditions can lend to the sustainability of this technology.