Valorization of aromatic hydrocarbons into polyhydroxyalkanoates: advances towards sustainable waste gas treatment

Abstract

Benzene, toluene, ethylbenzene, xylene and styrene (BTEXS) are priority gaseous pollutants due to their wide- spread release and health risks. This study demonstrates an efficient BTEXS bioconversion process into poly- hydroxyalkanoates (PHA) using a specialized mixed microbial culture dominated by Pseudonocardia and Rhodococcus. The consortium achieved simultaneous degradation rates of 15.1 ± 3.9 g m 3h 1 for toluene and 17.6 ± 5.7 g m 3h 1 for ethylbenzene, with removal efficiencies over 90 %. The operating strategy promoted PHA accumulation up to 21.4 % gPHA gDCW 1 . A two-step process was successfully implemented consisting of an initial reactor for biomass growth followed by a second reactor under nitrogen deprivation. PHA analysis revealed the synthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer with a dynamic increase in 3- hydroxyvalerate content under prolonged nitrogen starvation. Metagenomics provided insights into the micro- bial networks and metabolic pathways involved in the process. This research offers a sustainable solution for mitigating BTEXS pollution while producing valuable bioplastics.