Key Laboratory of Integrated Regulation and Resource Department on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, China; Department of Biology and Chemistry, State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Science, Nanjing, China.
J Hazard Mater. 2018 Jan 5;341:177-186. doi: 10.1016/j.jhazmat.2017.07.063. Epub 2017 Jul 28.
A common congener of polybrominated diphenyl ethers, 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), is a prevalent, persistent and toxic pollutant. It could be removed by reduction debromination by microorganisms but the rate is often slow. The study hypothesized that spent mushroom substrate derived biochar amendment could accelerate the microbial reductive debromination of BDE-47 in anaerobic mangrove sediment slurries and evaluated the mechanisms behind. At the end of 20-week experiment, percentages of residual BDE-47 in slurries amended with biochar were significantly lower but debromination products were higher than those without biochar. Such stimulatory effect on debromination was dosage-dependent, and debromination was coupled with iron (Fe) reduction. Biochar amendment significantly enhanced the Fe(II):Fe(III) ratio, Fe(III) reduction rate and the abundance of iron-reducing bacteria in genus Geobacter, thus promoting bacterial iron-reducing process. The abundances of dehalogenating bacteria in genera Dehalobacter, Dehalococcoides, Dehalogenimonas and Desulfitobacterium were also stimulated by biochar. Biochar as an electron shuttle might increase electron transfer from iron-reducing and dehalogenating bacteria to PBDEs for their reductive debromination. More, biochar shifted microbial community composition in sediment, particularly the enrichment of potential PBDE-degrading bacteria including organohalide-respiring and sulfate-reducing bacteria, which in turn facilitated the reductive debromination of BDE-47 in anaerobic mangrove sediment slurries.
多溴二苯醚（PBDEs）的一种常见同系物，2,2',4,4'-四溴二苯醚（BDE-47），是一种普遍存在、持久且有毒的污染物。它可以通过微生物的还原脱溴作用去除，但速度通常较慢。本研究假设，用过的蘑菇基质衍生生物炭的添加可以加速 BDE-47 在厌氧红树林沉积物悬浮液中的微生物还原脱溴作用，并评估其背后的机制。在 20 周的实验结束时，添加生物炭的悬浮液中剩余 BDE-47 的百分比明显较低，但脱溴产物高于未添加生物炭的悬浮液。这种对脱溴的促进作用是剂量依赖的，脱溴与铁（Fe）还原偶联。生物炭的添加显著提高了 Fe(II):Fe(III) 比值、Fe(III)还原率和属 Geobacter 的铁还原菌的丰度，从而促进了细菌的铁还原过程。属 Dehalobacter、Dehalococcoides、Dehalogenimonas 和 Desulfitobacterium 的脱卤菌的丰度也受到生物炭的刺激。生物炭作为电子穿梭体，可能会增加铁还原菌和脱卤菌向 PBDEs 的电子转移，从而促进其还原脱溴。此外，生物炭改变了沉积物中的微生物群落组成，特别是包括有机卤化物呼吸和硫酸盐还原菌在内的潜在 PBDE 降解菌的富集，这反过来又促进了 BDE-47 在厌氧红树林沉积物悬浮液中的还原脱溴。
