Ray Angelique E, Zhang Eden, Terauds Aleks, Ji Mukan, Kong Weidong, Ferrari Belinda C
School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia.
Australian Antarctic Division, Department of Environment, Antarctic Conservation and Management, Kingston, TAS, Australia.
Front Microbiol. 2020 Aug 12;11:1936. doi: 10.3389/fmicb.2020.01936. eCollection 2020.
Soil microbiomes within oligotrophic cold deserts are extraordinarily diverse. Increasingly, oligotrophic sites with low levels of phototrophic primary producers are reported, leading researchers to question their carbon and energy sources. A novel microbial carbon fixation process termed atmospheric chemosynthesis recently filled this gap as it was shown to be supporting primary production at two Eastern Antarctic deserts. Atmospheric chemosynthesis uses energy liberated from the oxidation of atmospheric hydrogen to drive the Calvin-Benson-Bassham (CBB) cycle through a new chemotrophic form of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), designated IE. Here, we propose that the genetic determinants of this process; RuBisCO type IE () and high affinity group 1h-[NiFe]-hydrogenase () are widespread across cold desert soils and that this process is linked to dry and nutrient-poor environments. We used quantitative PCR (qPCR) to quantify these genes in 122 soil microbiomes across the three poles; spanning the Tibetan Plateau, 10 Antarctic and three high Arctic sites. Both genes were ubiquitous, being present at variable abundances in all 122 soils examined (, 6.25 × 10-1.66 × 10 copies/g soil; , 6.84 × 10-5.07 × 10 copies/g soil). For the Antarctic and Arctic sites, random forest and correlation analysis against 26 measured soil physicochemical parameters revealed that and genes were associated with lower soil moisture, carbon and nitrogen content. While further studies are required to quantify the rates of trace gas carbon fixation and the organisms involved, we highlight the global potential of desert soil microbiomes to be supported by this new minimalistic mode of carbon fixation, particularly throughout dry oligotrophic environments, which encompass more than 35% of the Earth's surface.
贫营养型寒冷沙漠中的土壤微生物群落极为多样。越来越多的报道称,存在光养初级生产者水平较低的贫营养型地点,这使得研究人员对其碳源和能源产生了疑问。最近,一种名为大气化学合成的新型微生物碳固定过程填补了这一空白,因为它被证明在两个东南极沙漠中支持初级生产。大气化学合成利用大气中氢气氧化释放的能量,通过一种新的化学营养型核酮糖-1,5-二磷酸羧化酶/加氧酶(RuBisCO),即IE型,来驱动卡尔文-本森-巴斯姆(CBB)循环。在此,我们提出,这一过程的遗传决定因素,即IE型RuBisCO()和高亲和力1h型-[NiFe]-氢化酶()在寒冷沙漠土壤中广泛存在,并且这一过程与干燥且营养贫瘠的环境有关。我们使用定量PCR(qPCR)对跨越三大极地的122个土壤微生物群落中的这些基因进行了定量分析;这些地点包括青藏高原、10个南极地点和3个高北极地点。这两种基因普遍存在,在所检测的所有122种土壤中均有不同丰度(,6.25×10 - 1.66×10拷贝/克土壤;,6.84×10 - 5.07×10拷贝/克土壤)。对于南极和北极地点,针对26种测量的土壤理化参数进行的随机森林和相关性分析表明,和基因与较低的土壤湿度、碳和氮含量相关。虽然需要进一步研究来量化微量气体碳固定的速率以及相关生物,但我们强调,这种新的简约碳固定模式对沙漠土壤微生物群落具有全球潜在支持作用,特别是在整个干燥贫营养环境中,这些环境覆盖了地球表面超过35%的区域。