Leewis Mary-Cathrine, Uhlik Ondrej, Leigh Mary Beth
Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA.
Department of Biochemistry and Microbiology, Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Prague, Czech Republic.
Sci Rep. 2016 Feb 26;6:22145. doi: 10.1038/srep22145.
Aerobic mineralization of PCBs, which are toxic and persistent organic pollutants, involves the upper (biphenyl, BP) and lower (benzoate, BZ) degradation pathways. The activity of different members of the soil microbial community in performing one or both pathways, and their synergistic interactions during PCB biodegradation, are not well understood. This study investigates BP and BZ biodegradation and subsequent carbon flow through the microbial community in PCB-contaminated soil. DNA stable isotope probing (SIP) was used to identify the bacterial guilds involved in utilizing (13)C-biphenyl (unchlorinated analogue of PCBs) and/or (13)C-benzoate (product/intermediate of BP degradation and analogue of chlorobenzoates). By performing SIP with two substrates in parallel, we reveal microbes performing the upper (BP) and/or lower (BZ) degradation pathways, and heterotrophic bacteria involved indirectly in processing carbon derived from these substrates (i.e. through crossfeeding). Substrate mineralization rates and shifts in relative abundance of labeled taxa suggest that BP and BZ biotransformations were performed by microorganisms with different growth strategies: BZ-associated bacteria were fast growing, potentially copiotrophic organisms, while microbes that transform BP were oligotrophic, slower growing, organisms. Our findings provide novel insight into the functional interactions of soil bacteria active in processing biphenyl and related aromatic compounds in soil, revealing how carbon flows through a bacterial community.
多氯联苯是有毒的持久性有机污染物，其好氧矿化涉及上（联苯，BP）、下（苯甲酸盐，BZ）降解途径。土壤微生物群落中不同成员执行一种或两种途径的活性，以及它们在多氯联苯生物降解过程中的协同相互作用，目前还不太清楚。本研究调查了多氯联苯污染土壤中BP和BZ的生物降解以及随后通过微生物群落的碳流。DNA稳定同位素探测（SIP）用于识别参与利用（13）C-联苯（多氯联苯的未氯化类似物）和/或（13）C-苯甲酸盐（BP降解产物/中间体和氯苯甲酸盐类似物）的细菌类群。通过同时对两种底物进行SIP，我们揭示了执行上（BP）和/或下（BZ）降解途径的微生物，以及间接参与处理源自这些底物的碳（即通过交叉喂养）的异养细菌。底物矿化率和标记类群相对丰度的变化表明，BP和BZ的生物转化是由具有不同生长策略的微生物进行的：与BZ相关的细菌生长迅速，可能是富营养型生物，而转化BP的微生物是贫营养型、生长较慢的生物。我们的研究结果为土壤中活跃的细菌在处理联苯和相关芳香化合物时的功能相互作用提供了新的见解，揭示了碳如何在细菌群落中流动。
