Metagenomic analysis of microbial communities continuously exposed to Bisphenol A in mangrove rhizosphere and non-rhizosphere soils

Bisphenol A (BPA) is widely distributed in littoral zones and may cause adverse impacts on mangrove ecosystem. Biodegradation and phytoremediation are two primary processes for BPA dissipation in mangrove soils. How -ever, the rhizosphere effects of different mangrove species on BPA elimination are still unresolved. In this study, three typical mangrove seedlings, namelyAvicennia marina, Bruguiera gymnorrhiza (L.) and Aegiceras corniculatum, were cultivated in soil microcosms for four months and then subjected to 28-day continuous BPA amendment. Un-planted soil microcosms (as control) were also set up. The BPA residual rates and root ex-udates were monitored, and the metabolic pathways as well as functional microbial communities were also in-vestigated to decipher the rhizosphere effects based on metagenomic analysis. The BPA residual rates in all planted soils were significantly lower than that in un-planted soil on day 7. Both plantation and BPA dosage had significant effects on bacterial abundance. A distinct separation of microbial structure was found between planted and un-planted soil microcosms. Genera Pseudomonas and Lutibacter got enriched with BPA addition and may play important roles in BPA biodegradation. The shifts in bacterial community structure upon BPA ad-dition were different among the microcosms with different mangrove species. Genus Novosphingobium increased in Avicennia marina and Bruguiera gymnorrhiza (L.) rhizosphere soils but decreased in Aegiceras corniculatum rhi-zosphere soil. Based on KEGG annotation and binning analysis, the proposal of BPA degradation pathways and the quantification of relevant functional genes were achieved. The roles of Pseudomonas and Novosphingobium may differ in lower BPA degradation pathways. The quantity variation patterns of functional genes during the 28 -day BPA amendment were different among soil microcosms and bacterial genera. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the rhizosphere effects of different mangrove species on BPA elimination in mangrove soils. The results showed that the microbial structure in the rhizosphere differed among microcosms with different mangrove species, leading to variations in BPA degradation pathways. Pseudomonas and Novosphingobium may play important roles in the biodegradation of BPA.