Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Germany.
Algorithms in Bioinformatics, Center for Bioinformatics, University of Tuebingen, Germany.
Sci Rep. 2016 Jun 29;6:28958. doi: 10.1038/srep28958.
In soils halogens (fluorine, chlorine, bromine, iodine) are cycled through the transformation of inorganic halides into organohalogen compounds and vice versa. There is evidence that these reactions are microbially driven but the key enzymes and groups of microorganisms involved are largely unknown. Our aim was to uncover the diversity, abundance and distribution of genes encoding for halogenating and dehalogenating enzymes in a German forest soil by shotgun metagenomic sequencing. Metagenomic libraries of three soil horizons revealed the presence of genera known to be involved in halogenation and dehalogenation processes such as Bradyrhizobium or Pseudomonas. We detected a so far unknown diversity of genes encoding for (de)halogenating enzymes in the soil metagenome including specific and unspecific halogenases as well as metabolic and cometabolic dehalogenases. Genes for non-heme, no-metal chloroperoxidases and haloalkane dehalogenases were the most abundant halogenase and dehalogenase genes, respectively. The high diversity and abundance of (de)halogenating enzymes suggests a strong microbial contribution to natural halogen cycling. This was also confirmed in microcosm experiments in which we quantified the biotic formation of chloroform and bromoform. Knowledge on microorganisms and genes that catalyze (de)halogenation reactions is critical because they are highly relevant to industrial biotechnologies and bioremediation applications.
在土壤中，卤素（氟、氯、溴、碘）通过将无机卤化物转化为有机卤化物，以及相反的过程进行循环。有证据表明，这些反应是由微生物驱动的，但涉及的关键酶和微生物群体在很大程度上是未知的。我们的目的是通过鸟枪法宏基因组测序来揭示德国森林土壤中编码卤化和脱卤酶的基因的多样性、丰度和分布。三种土壤层次的宏基因组文库揭示了已知参与卤化和脱卤过程的属的存在，如Bradyrhizobium 或 Pseudomonas。我们在土壤宏基因组中检测到了迄今为止未知的编码（脱）卤化酶的基因多样性，包括特异性和非特异性卤化酶以及代谢和共代谢脱卤酶。非血红素、非金属过氯酸盐酶和卤代烷烃脱卤酶的基因分别是最丰富的卤化酶和脱卤酶基因。（脱）卤化酶的高多样性和丰度表明，微生物对自然卤素循环有很强的贡献。这在微宇宙实验中也得到了证实，我们在实验中定量了三氯甲烷和溴仿的生物形成。对催化（脱）卤化反应的微生物和基因的了解至关重要，因为它们与工业生物技术和生物修复应用密切相关。
