Stenotrophomonas sp. RZS 7, a novel PHB degrader isolated from plastic contaminated soil in Shahada, Maharashtra, Western India

Abstract

This paper reports an isolation and identification of novel poly-β-hydroxybutyrate (PHB) degrading bacterium Stenotrophomonas sp. RZS 7 and studies on its extracellular PHB degrading depolymerase enzyme. The bacterium isolated from soil samples of plastic contaminated sites of municipal area in Shahada, Maharashtra, Western India. It was identified as Stenotrophomonas sp. RZS 7 based on polyphasic approach. The bacterium grew well in minimal salt medium (MSM) and produced a zone (4.2 mm) of PHB hydrolysis on MSM containing PHB as the only source of nutrient. An optimum yield of enzyme was obtained on the fifth day of incubation at 37 °C and at pH 6.0. Further increase in enzyme production was recorded with Ca²⁺ ions, while other metal ions like Fe²⁺ (1 mM) and chemical viz. mercaptoethanol severally affected the production of enzyme.

Keywords: Biodegradation; PHB depolymerase; Poly-β-hydroxybutyrate; Stenotrophomonas sp..

Fig. 1

Time course of poly-β-hydroxybutyrate degradation as indicated by diameters (mm) of the clear zones on agar containing PHB at 28 °C, 37 and 45 °C

Fig. 2

a Effect of temperature on poly-β-hydroxybutyrate depolymerase enzyme activity. b Effect of pH on poly-β-hydroxybutyrate depolymerase enzyme activity. c Effect of metal ions on poly-β-hydroxybutyrate depolymerase enzyme activity. d Effect of different chemicals on poly-β-hydroxybutyrate depolymerase enzyme activity