Biological sulfur cycling in polar, low-temperature ecosystems is an understudied phenomenon in part due to difficulty of access and the dynamic nature of glacial environments. One such environment where sulfur cycling is known to play an important role in microbial metabolisms is located at Borup Fiord Pass (BFP) in the Canadian High Arctic. Here, transient springs emerge from ice near the terminus of a glacier, creating a large area of proglacial aufeis (spring-derived ice) that is often covered in bright yellow/white sulfur, sulfate, and carbonate mineral precipitates accompanied by a strong odor of hydrogen sulfide. Metagenomic sequencing of samples from multiple sites and of various sample types across the BFP glacial system produced 31 metagenome-assembled genomes (MAGs) that were queried for sulfur, nitrogen, and carbon cycling/metabolism genes. An abundance of sulfur cycling genes was widespread across the isolated MAGs and sample metagenomes taxonomically associated with the bacterial classes Alphaproteobacteria and Gammaproteobacteria and Campylobacteria (formerly the Epsilonproteobacteria). This corroborates previous research from BFP implicating Campylobacteria as the primary class responsible for sulfur oxidation; however, data reported here suggested putative sulfur oxidation by organisms in both the alphaproteobacterial and gammaproteobacterial classes that was not predicted by previous work. These findings indicate that in low-temperature, sulfur-based environments, functional redundancy may be a key mechanism that microorganisms use to enable coexistence whenever energy is limited and/or focused by redox chemistry.

中文翻译：

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微生物代谢冗余是富含硫的冰川生态系统的关键机制。

极地低温生态系统中的生物硫循环是一种未被充分研究的现象，部分原因是由于难以接近和冰川环境的动态性质。已知硫循环在微生物代谢中起重要作用的一种这样的环境位于加拿大高北极地区的Borup Fiord Pass（BFP）。在这里，从冰川终点附近的冰中涌现出短暂的泉水，形成了大片的冰原aufeis（泉水冰），通常覆盖着明亮的黄色/白色硫磺，硫酸盐和碳酸盐矿物沉淀，并带有强烈的臭味。硫化氢。来自BFP冰河系统多个地点和不同样本类型的样本的超基因组测序产生了31个由超基因组组装的基因组（MAGs），可对其进行硫，氮，以及碳循环/代谢基因。大量的硫循环基因广泛分布在分离的MAG和与细菌类别相关的分类基因组样本中Alphaproteobacteria和Gammaproteobacteria和弯曲杆菌（以前是Epsilonproteobacteria）。这证实了BFP先前涉及弯曲杆菌是负责硫氧化的主要类别的研究。但是，这里报道的数据表明，先前的工作未曾预测到α-蛋白细菌和γ-蛋白细菌类别中的生物被假定的硫氧化。这些发现表明，在低温，基于硫的环境中，每当能量受到氧化还原化学的限制和/或聚焦时，功能冗余可能是微生物用来实现共存的关键机制。