Degradation of poly(3-hydroxybutyrate- co-3-hydroxyvalerate) by a newly isolated Actinomadura sp. AF-555, from soil

Abstract

The purpose of this study was to isolate the poly (3-hydroxybutyrate- co-3-hydroxyvalerate) (PHBV) degrading microorganisms from soil, and the analysis of degradation by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. After soil burial for 120 days at 37 °C, a new actinobacterial strain, Actinomadura sp. AF-555, was isolated from the surface of PHBV film, through an enrichment technique. The increase in biomass on the surface of PHBV film pieces and in the medium after culturing in basal salt medium indicated that it utilizes PHBV as a source of carbon and energy. Scanning electron microscopy of PHBV film at the end of incubation showed many changes in surface morphology, such as erosion and extensive roughening of the surface with pit formation, as compared to the untreated plastic pieces. The FTIR spectra of PHBV film showed a decrease in the peak from 1725 cm −1 (untreated plastic film) to 1721 cm −1, and disappearance of a peak present in controls, at 2745 cm −1, indicating the breakdown of ester (>C O) or O–R groups and –C–H bonds, respectively. The intensity of the band at 1185 cm −1, the amorphous state-sensitive band, increased, indicating an increase in 3HV content. It can be concluded that soil contains microorganisms that can potentially be used for biodegradation of plastic wastes.