中国新疆火焰山土壤环境及细菌群落结构

Soil fertility status and bacterial community structure on Huoyan Mountain, China

为评价火焰山地区土壤环境现状,并了解环境因子对土壤微生物数量和细菌群落结构的影响,测定了土壤理化性质和4种典型土壤酶活性,结合传统分离培养计数所得微生物数量进行主成分分析(Principal Component Analysis,PCA)和相关性研究,运用变性梯度凝胶电泳(Denaturing Gradient Gel Electrophoresis,DGGE)技术结合冗余分析(Redundance Analysis,RDA)解析影响细菌群落结构的关键因子.结果表明:(1)火焰山地区土壤肥力状况较差,主要特点为含水率低、养分贫瘠和盐碱化严重,其中盐分含量是限制土壤肥力水平的关键因素,脱氢酶活性可作为快速评价火焰山土壤肥力的重要指标,多酚氧化酶活性最能代表火焰山土壤系统内的肥力变异状况;(2)火焰山土壤微生物数量处于较低水平,细菌为绝对优势菌群(占98.13%),土壤水分是决定微生物数量的关键因子,但盐分含量与微生物数量的相关性不明显;(3)环境因子与土壤细菌群落多样性和结构分布的相关性密切,全氮含量和土壤水分是影响细菌群落多样性的关键因子,各环境因子对不同细菌群落的影响迥异,其共同作用决定了火焰山地区细菌群落结构分布.

For a comprehensive understanding of the extreme soil habitats on the Huoyan Mountain,the main factors for microbial growth need to be investigated.This paper aimed to evaluate the soil fertility status and to find out how environmental conditions affect the soil bacterial community structure on Huoyan Mountain.Correlation analysis and principal component analysis（PCA） were used to explore how soil physicochemical properties correlate with soil enzyme（polyphenol oxidase,dehydrogenase,catalase,urease） activities and microbe quantity.Denaturing gradient gel electrophoresis（DGGE） and redundancy analysis（RDA） were used to study the relationship between soil bacterial community diversity and environmental variables.The soil on Huoyan Mountain was found to be relatively infertile.Both moisture and nutrient content were extremely low,and the soil was severely salinized.The PCA indicated that total salt content was the key factor limiting soil fertility,that dehydrogenase activity could be used as an important indicator of soil fertility,and that polyphenol oxidase could represent the variation of soil fertility.The total soil microbial count was relatively low.Bacteria accounted for approximately 98% of the soil microbes.According to the correlation analysis,the microbe quantity was most significantly related to moisture content,but not to salt content.The RDA suggested that environmental variables,especially total nitrogen and moisture contents,correlate significantly with soil bacterial community diversity and structure.This research identified the key environmental variables for soil fertility and bacterial community structure.These results will provide a scientific basis for both soil management and further studies on microbes in the extreme environment on the Huoyan Mountain.