黄河三角洲盐沼湿地甲烷厌氧氧化潜力及微生物群落对铁锰输入的响应研究

Methane anaerobic oxidation potential and microbial community response to Fe and Mn input in a salt marsh wetland ofthe Yellow River Delta

铁、锰是滨海湿地环境中重要的变价金属元素,金属依赖型甲烷厌氧氧化(Anaerobic oxidation of methane,AOM)过程与碳循环相耦合,在生物地球化学循环过程中起到重要的驱动作用.研究铁、锰对湿地甲烷厌氧氧化潜力及微生物群落的作用对于减缓因甲烷释放而带来的全球气候变暖具有重要意义.以黄河三角洲滨海湿地为研究对象,通过室内厌氧培养及高通量测序方法,系统研究了碱蓬盐沼湿地下甲烷厌氧氧化潜力及微生物群落对Fe^(3+)、Mn^(4+)输入的响应.结果表明:向土壤输入不同浓度的Fe^(3+)和Mn^(4+)后,浅层土的AOM潜力皆被抑制,深层土的AOM潜力则受到促进作用,且作用显著(p<0.05),说明不同土层对铁、锰输入的响应不同,这可能取决于土壤中铁、锰含量的本底值;在微生物层面,铁、锰输入对土壤微生物的丰富度及均匀度产生影响,土壤中的微生物群落结构同时也发生了显著变化,在门水平下,细菌中的Proteobacteria(变形菌门)和古菌中的Euryarchaeota(广古菌门)丰度显著升高,科、属水平下富集了可以促进甲烷氧化的Methylomonaceae(甲基单胞菌)且使其成为优势种,表明该菌可能深度参与了甲烷消耗及金属元素循环过程.本研究对滨海湿地甲烷厌氧氧化的机理研究及黄河三角洲微生物的多样性保护具有重要意义,同时也可为滨海湿地CH_(4)减排提供科学依据.

The metal-dependent anaerobic oxidation of methane is connected with the carbon cycle and plays a significant driving role in the biogeochemical cycle,and iron and manganese are important variable-valence metal elements in coastal wetland habitats.The role of iron and manganese elements in marsh methane and microbial communities’anaerobic oxidation capability is critical for mitigating global warming caused by methane emissions.Using indoor anaerobic culture and high-throughput sequencing technologies in a coastal wetland in the Yellow River Delta,the anaerobic oxidation capability of methane and the reactivity of the microbial community to Feand Mninput in suaeda salsa marsh wetlands were investigated.The AOM potential of shallow soils was decreased after different concentrations of Feand Mnwere added to the soil,whereas the AOM potential of deep soils was promoted,and the promotion effect was significant(p<0.05),indicating that different soil layers responded differently to Fe and Mn input,which may depend on the background values of Fe^(3+) and Mn^(4+) content in the soil.At the microbial level,the addition of Feand Mnaffected the abundance and homogeneity of soil microorganisms,as well as the structure of soil microbial communities,with a significant increase in the abundance of Proteobacteria among bacteria and Euryarchaeota among archaea at the phylum level,and enrichment of Methylomonaceae(which can promote methane oxidation)at the family.The presence of Methylomonaceae,which can increase methane oxidation,and its dominance at the family and genus levels suggest that this bacteria is involved in methane consumption and metalloid cycling activities.This study will be important for the study of the mechanism of methane anaerobic oxidation in coastal wetlands and the conservation of microbial diversity in the Yellow River Delta,as well as provide a scientific basis for CH_(4)reduction in coastal wetlands.