Poly(3-Hydroxybutyrate) Degradation by Bacillus infantis sp. Isolated from Soil and Identification of pha Z and bdh A Expressing PHB Depolymerase.

Poly(3-hydroxybutyrate) (PHB) is a biodegradable and biocompatible bioplastic. Effective PHB degradation in nutrient-poor environments is required for industrial and practical applications of PHB. To screen for PHB-degrading strains, PHB double-layer plates were prepared and three new species with PHB-degrading ability were isolated from the soil. In addition, Z and bdhA of all isolated were confirmed using a sp. universal primer set and established polymerase chain reaction (PCR) conditions. To evaluate the effective PHB degradation ability under nutrient-deficient conditions, PHB film degradation was performed in mineral medium (MM), resulting in a PHB degradation rate of 98.71% for PD3, which was confirmed in 5 d. Physical changes in the degraded PHB films were analyzed. The decrease in molecular weight due to biodegradation was confirmed using gel permeation chromatography (GPC) and surface erosion of the PHB film was observed using scanning electron microscopy (SEM). To the best of our knowledge, this is the first study on showing its excellent PHB degradation ability and is expected to contribute to PHB commercialization and industrial composting.