de Menezes Alexandre B, Prendergast-Miller Miranda T, Poonpatana Pabhon, Farrell Mark, Bissett Andrew, Macdonald Lynne M, Toscas Peter, Richardson Alan E, Thrall Peter H
CSIRO Agriculture Flagship, Crace, Canberra, ACT, Australia
CSIRO Agriculture Flagship, Waite Campus, Glen Osmond, SA, Australia.
Appl Environ Microbiol. 2015 May 1;81(9):3016-28. doi: 10.1128/AEM.00067-15. Epub 2015 Feb 20.
Cellulose accounts for approximately half of photosynthesis-fixed carbon; however, the ecology of its degradation in soil is still relatively poorly understood. The role of actinobacteria in cellulose degradation has not been extensively investigated despite their abundance in soil and known cellulose degradation capability. Here, the diversity and abundance of the actinobacterial glycoside hydrolase family 48 (cellobiohydrolase) gene in soils from three paired pasture-woodland sites were determined by using terminal restriction fragment length polymorphism (T-RFLP) analysis and clone libraries with gene-specific primers. For comparison, the diversity and abundance of general bacteria and fungi were also assessed. Phylogenetic analysis of the nucleotide sequences of 80 clones revealed significant new diversity of actinobacterial GH48 genes, and analysis of translated protein sequences showed that these enzymes are likely to represent functional cellobiohydrolases. The soil C/N ratio was the primary environmental driver of GH48 community compositions across sites and land uses, demonstrating the importance of substrate quality in their ecology. Furthermore, mid-infrared (MIR) spectrometry-predicted humic organic carbon was distinctly more important to GH48 diversity than to total bacterial and fungal diversity. This suggests a link between the actinobacterial GH48 community and soil organic carbon dynamics and highlights the potential importance of actinobacteria in the terrestrial carbon cycle.
纤维素约占光合作用固定碳的一半；然而，其在土壤中降解的生态学仍相对不太为人所知。尽管放线菌在土壤中数量众多且具有已知的纤维素降解能力，但其在纤维素降解中的作用尚未得到广泛研究。在此，通过使用末端限制性片段长度多态性（T-RFLP）分析和带有基因特异性引物的克隆文库，测定了来自三个配对牧场-林地地点土壤中放线菌糖苷水解酶家族48（纤维二糖水解酶）基因的多样性和丰度。为作比较，还评估了普通细菌和真菌的多样性与丰度。对80个克隆的核苷酸序列进行系统发育分析，揭示了放线菌GH48基因显著的新多样性，对翻译后的蛋白质序列分析表明，这些酶可能代表功能性纤维二糖水解酶。土壤碳氮比是跨地点和土地利用方式的GH48群落组成的主要环境驱动因素，表明底物质量在其生态学中的重要性。此外，中红外（MIR）光谱预测的腐殖有机碳对GH48多样性的重要性明显高于对细菌和真菌总多样性的重要性。这表明放线菌GH48群落与土壤有机碳动态之间存在联系，并突出了放线菌在陆地碳循环中的潜在重要性。
