Effects of different sodium salts and nitrogen sources on the production of 3-hydroxybutyrate and polyhydroxybutyrate by Burkholderia cepacia

Identifying ligninolytic bacteria for lignin valorization to bioplastics

Biological valorization of lignin to bioplastics is a promising route to improve biorefinery efficiency and address environmental challenges. A two-stage screening procedure had been designed to successfully identify four ligninolytic bacteria from soil samples. The isolated bacteria displayed substrate preference of guaiacyl- and hydroxyphenyl-based aromatics, but they effectively synthesized polyhydroxyalkanoates (PHAs). B. cepacia B1-2 and P. putida KT3-1 accumulated 27.3% and 20.9% PHA in cells and achieved a titer of 280.9 and 204.1 mg/L, respectively, from p-hydroxybenzoic acid. The isolated bacteria exhibited good ligninolytic performance indicated by the degradation of β-O-4 linkage and small molecules. B. cepacia B1-2 grew well on actual lignin substrate and yielded a PHA titer of 87.2 mg/L. With the design of fed-batch mode, B. cepacia B1-2 produced the highest PHA titer of 1420 mg/L from lignin-derived aromatics. Overall, isolated ligninolytic bacteria show good PHA accumulation capacity, which are the promising host strains for lignin valorization.

A review on polyhydroxyalkanoate production from agricultural waste Biomass: Development, Advances, circular Approach, and challenges

Polyhydroxyalkanoates are biopolymers produced by microbial fermentation. They have excellent biodegradability and biocompatibility, which are regarded as promising substitutes for traditional plastics in various production and application fields. This review details the research progress in PHA production from lignocellulosic crop residues, lipid-type agricultural wastes, and other agro-industrial wastes such as molasses and whey. The effective use of agricultural waste can further reduce the cost of PHA production while avoiding competition between industrial production and food. The latest information on fermentation parameter optimization, fermentation strategies, kinetic studies, and circular approach has also been discussed. This review aims to analyze the crucial process of the PHA production from agricultural wastes to provide support and reference for further scale-up and industrial production.