Polyhydroxyalkanoate synthesis and characterization: A proteogenomic and process optimization study for biovalorization of industrial lignin

PHA production from lignin and its further degradation to show its biodegradability. [Display omitted] •Burkholderia strain ISTR5 was established for PHA production from industrial lignins.•Optimization resulted in the production of 32.2% PHA mass fraction in biomass.•PHA co-polymer was characterized and its degradation was studied.•Genomic and proteomic analysis established R5 for lignin degradation and PHA production.•Pathways for lignin degradation and PHA degradation was also deciphered. The strain Burkholderia sp. ISTR5 (R5) was studied for polyhydroxyalkanoate (PHA) production on Kraft lignin (KL) and lignosulfonate (LS) as substrates. During the initial screening, the maximum PHA mass fraction in biomass produced on KL and LS was 23% and 18%, respectively, at 96 h. PHA production on KL was further optimized using the Box-Behnken Design (BBD) model of Response Surface Methodology (RSM). After optimization, a 42.5% increase in PHA production and a 32.2% increase in the total cell biomass was observed. PHA was characterized by GC–MS, TEM, FTIR, NMR, and fluorescence microscopy. It was found to be a small chain length PHA with a copolymer of poly (hydroxybutyrate-co-hydroxyvalerate) (PHBV). The degradation of PHBV was also studied using this strain; it was observed that R5 completely degraded PHBV in 120 h. Genomic and proteomic analysis of R5 revealed numerous enzymes for the metabolism of lignin degradation and PHA production.