Biodegradation of DEHP by a new native consortium An6 (Gordonia sp. and Pseudomonas sp.) adapted with phthalates, isolated from a natural strongly polluted wetland

Abstract

Considering the high concentration of phthalic acid esters (PAEs) in Anzali international wetland, up to 40 times higher than the environmental risk limit, the aim of this study was to obtain an effective consortium and native bacteria in the degradation of diethyl hexyl phthalate (DEHP) from sediments of this ecosystem. For this purpose, sediments of 9 stations of Anzali wetland were enriched with PAEs in waterlogged conditions at 30 °C. The results showed that the consortium An6 (containing two cultivable bacteria with phthalate degradation ability, Pseudomonas putida strain ShA (MN298858), and Gordonia alkanivorans strain Sh6 (MK460262.1)) could biodegrade 100, 100, 90.57, and 58.73% of a mixture of DMP, DEP, DBP, and DEHP at high concentration (2000 mg/L each), respectively. The separate DEHP biodegradation by the above consortium showed that it could degrade 97% of 500 mg/L of DEHP in less than 3 days. Additionally, phthalic acid (PA) and monoethyl hexyl phthalate (MEHP) as intermediate products of DEHP biodegradation were identified by UPLC-Q-TOF-MS. Phthalate consumption patterns of strains ShA and Sh6 indicate that there is a possible complementary effect among these bacteria in PAEs biodegradation. The ability of consortium An6 belonging to the most polluted area (20–43 mg/Kg DEHP) of this wetland to degrade DEHP could be caused by the exposure of the microbial community of this area to PAEs over time that gives rise to a possible adaptation. Based on the findings, consortium An6 (with novel composition) and isolated bacteria can be suggested for the efficient remediating of PAEs in the different ecosystems. • Anzali international wetland has biopotential to self-purification of high concentration of phthalates. • The microbial community of the most polluted area of the lagoon has become more compatible with PAEs and is more efficient in phthalates degradation. • The consortium An6 could degrade phthalates at 2000 mg/L in waterlogged conditions. • Gordonia alkanivorans and Pseudomonas putida together cover the biodegradation of a broader spectrum of different PAEs. • Consortium An6 efficiently degraded 500 mg/L of DEHP in less than 3 days.