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中國科學院新疆生態與地理研究所環境汙染與生態修復實驗室副研究員宋文娟以乾旱區湖泊沉積物和湖泊水體為研究對象，研究汞還原酶基因（merA）和汞甲基化基因（hgcA）的豐度及微宇宙體系中微生物多樣性組成和組間的差異。相關成果發表於Environmental Pollution（IF=6.792）。
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Highligts
Bacteria were the main microorganism involved in the mercury cycle.
High content of mercury could reduce the abundance of both merA and hgcA.
Higher input of algae biomass (250 mg L1) led to an increase of merA abundance.
Specific mercury methylator (Syntrophomonadaceae) increased under saline.
Abstract
Lakes in arid regions are experiencing mercury pollution via air deposition and surface runoff, posing a threat to ecosystem safety and human health. Furthermore, salinity and organic matter input could influence the mercury cycle and composition of bacterial communities in the sediment. In this study, the effects of salinity and algae biomass as an important organic matter on the genes (merA and hgcA) involved in the mercury cycle under mercury contamination were investigated. Archaeal merA and hgcA were not detected in sediments of lake microcosms, indicating that bacteria rather than archaea played a crucial role in mercury reduction and methylation. The high content of mercury (300 ng g1) could reduce the abundance of both merA and hgcA. The effects of salinity and algae biomass on mercury cycling genes depended on the gene type and dose. A higher input of algae biomass (250 mg L1) led to an increase of merA abundance, but a decrease of hgcA abundance. All high inputs of mercury, salinity, and algae biomass decreased the richness and diversity of bacterial communities in sediment. Further analysis indicated that higher mercury (300 ng g1) led to an increased relative abundance of mercury methylators, such as Ruminococcaceae, Bacteroidaceae, and Veillonellaceae. Under saline conditions (10 and 30 g L1), the richness of specific bacteria associated with mercury reduction (Halomonadaceae) and methylation (Syntrophomonadaceae) increased compared to the control. The input of algae biomass led to an increase in the specific bacterial communities associated with the mercury cycle and the richness of bacteria involved in the decomposition of organic matter. These results provide insight into mercury cycle-related genes and bacterial communities in the sediments of lakes in arid regions.
汞是一種全球性汙染物，大氣中的汞可通過乾濕沉降進入地表水和土壤，環境因素的變化可導致汞的轉化。從無機汞轉化而來的甲基汞（MeHg）可通過食物鏈進行生物積累，對人類健康構成威脅。微生物活動在汞生物地球化學循環中發揮關鍵作用，例如，merA基因編碼的汞還原酶能夠將Hg2+還原為Hg0。湖泊中的汞汙染影響沉積物微生物群落結構和功能。已有研究表明，長期的汞汙染會影響細菌、真菌群落組成及多樣性。
乾旱區的湖泊具有其特殊性，鹽鹼化程度高、藻菌生物膜廣布。藻菌生物膜衰亡之後是沉積物中有機質的重要補充。研究汞汙染條件下，鹽度和藻類生物質對沉積物微生物多樣性和汞循環基因豐度的影響，對分析乾旱區湖泊沉積物汞的生物地球化學循環具有重要意義。
中國科學院新疆生態與地理研究所環境汙染與生態修復實驗室副研究員宋文娟以乾旱區湖泊沉積物和湖泊水體為研究對象，室內模擬構建微宇宙實驗。採用qPCR技術，研究汞還原酶基因（merA）和汞甲基化基因（hgcA）的豐度；採用高通量測序的方法，研究微宇宙體系中微生物多樣性組成和組間的差異。
研究發現，沉積物中對汞還原和甲基化中起關鍵作用的是細菌而非古細菌。高含量的汞會降低merA和hgcA的豐度，且導致汞甲基化微生物（Ruminococcaceae，Bacteroidaceaceae和Veillonellaceae）的相對豐度增加；鹽度和藻生物質對汞循環基因的影響取決於基因類型和濃度；較高藻生物質輸入能夠增加merA豐度，降低hgcA豐度，且導致與汞循環有關的特定細菌群落的增加，從而提高參與有機物分解的細菌的豐富性。
責任編輯：宋瀟
校對和審核：張陽 王農