Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, People's Republic of China.
PLoS One. 2012;7(8):e43480. doi: 10.1371/journal.pone.0043480. Epub 2012 Aug 17.
Xylan is one of the most abundant biopolymers on Earth. Its degradation is mediated primarily by microbial xylanase in nature. To explore the diversity and distribution patterns of xylanase genes in soils, samples of five soil types with different physicochemical characters were analyzed.
METHODOLOGY/PRINCIPAL FINDINGS: Partial xylanase genes of glycoside hydrolase (GH) family 10 were recovered following direct DNA extraction from soil, PCR amplification and cloning. Combined with our previous study, a total of 1084 gene fragments were obtained, representing 366 OTUs. More than half of the OTUs were novel (identities of <65% with known xylanases) and had no close relatives based on phylogenetic analyses. Xylanase genes from all the soil environments were mainly distributed in Bacteroidetes, Proteobacteria, Acidobacteria, Firmicutes, Actinobacteria, Dictyoglomi and some fungi. Although identical sequences were found in several sites, habitat-specific patterns appeared to be important, and geochemical factors such as pH and oxygen content significantly influenced the compositions of xylan-degrading microbial communities.
CONCLUSION/SIGNIFICANCE: These results provide insight into the GH 10 xylanases in various soil environments and reveal that xylan-degrading microbial communities are environment specific with diverse and abundant populations.
木聚糖是地球上最丰富的生物聚合物之一。它的降解主要由自然界中的微生物木聚糖酶介导。为了探索土壤中木聚糖酶基因的多样性和分布模式，分析了五种具有不同物理化学性质的土壤类型的样本。
方法/主要发现：采用直接从土壤中提取 DNA、PCR 扩增和克隆的方法，从土壤中回收糖苷水解酶（GH）家族 10 的部分木聚糖酶基因。结合我们以前的研究，共获得了 1084 个基因片段，代表 366 个 OTUs。超过一半的 OTUs 是新的（与已知木聚糖酶的同一性<65%），并且根据系统发育分析没有密切相关的亲缘关系。所有土壤环境中的木聚糖酶基因主要分布在拟杆菌门、变形菌门、酸杆菌门、厚壁菌门、放线菌门、Dictyoglomi 和一些真菌中。尽管在几个地点发现了相同的序列，但似乎栖息地特异性模式很重要，并且地球化学因素如 pH 值和含氧量显著影响了木聚糖降解微生物群落的组成。
结论/意义：这些结果深入了解了各种土壤环境中的 GH 10 木聚糖酶，并揭示了木聚糖降解微生物群落具有特定的环境特异性，具有多样且丰富的种群。
