School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, NSW, 2052, Australia.
School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, 2308, Australia.
FEMS Microbiol Ecol. 2019 Apr 1;95(4). doi: 10.1093/femsec/fiz031.
The severity of environmental conditions at Earth's frigid zones present attractive opportunities for microbial biomining due to their heightened potential as reservoirs for novel secondary metabolites. Arid soil microbiomes within the Antarctic and Arctic circles are remarkably rich in Actinobacteria and Proteobacteria, bacterial phyla known to be prolific producers of natural products. Yet the diversity of secondary metabolite genes within these cold, extreme environments remain largely unknown. Here, we employed amplicon sequencing using PacBio RS II, a third generation long-read platform, to survey over 200 soils spanning twelve east Antarctic and high Arctic sites for natural product-encoding genes, specifically targeting non-ribosomal peptides (NRPS) and Type I polyketides (PKS). NRPS-encoding genes were more widespread across the Antarctic, whereas PKS genes were only recoverable from a handful of sites. Many recovered sequences were deemed novel due to their low amino acid sequence similarity to known protein sequences, particularly throughout the east Antarctic sites. Phylogenetic analysis revealed that a high proportion were most similar to antifungal and biosurfactant-type clusters. Multivariate analysis showed that soil fertility factors of carbon, nitrogen and moisture displayed significant negative relationships with natural product gene richness. Our combined results suggest that secondary metabolite production is likely to play an important physiological component of survival for microorganisms inhabiting arid, nutrient-starved soils.
由于其作为新型次生代谢产物储库的潜力较高，地球寒冷带的环境条件的严峻性为微生物生物采矿提供了有吸引力的机会。南极和北极圈内的干旱土壤微生物群系富含放线菌和变形菌，这两个细菌门已知是天然产物的丰富生产者。然而，这些寒冷、极端环境中次生代谢物基因的多样性在很大程度上仍然未知。在这里，我们使用第三代长读长平台 PacBio RS II 进行了扩增子测序，对跨越十二个东南极和高北极地点的 200 多个土壤进行了天然产物编码基因的调查，特别是针对非核糖体肽 (NRPS) 和 I 型聚酮化合物 (PKS)。NRPS 编码基因在南极更为广泛，而 PKS 基因仅可从少数几个地点中回收。由于它们与已知蛋白序列的氨基酸序列相似性较低，许多回收的序列被认为是新颖的，特别是在东南极站点中。系统发育分析表明，很大一部分与抗真菌和生物表面活性剂型簇最相似。多元分析表明，土壤肥力因素（碳、氮和水分）与天然产物基因丰富度呈显著负相关。我们的综合结果表明，次生代谢产物的产生可能是微生物在干旱、营养贫瘠的土壤中生存的重要生理组成部分。
