School of Biological Sciences and Institute for Global Food Security, Medical Biology Centre, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK.
ISME J. 2018 Apr;12(4):973-980. doi: 10.1038/s41396-017-0031-7. Epub 2018 Jan 16.
Many areas of the ocean are nutrient-poor yet support large microbial populations, leading to intense competition for and recycling of nutrients. Organic phosphonates are frequently found in marine waters, but require specialist enzymes for catabolism. Previous studies have shown that the genes that encode these enzymes in marine systems are under Pho regulon control and so are repressed by inorganic phosphate. This has led to the conclusion that phosphonates are recalcitrant in much of the ocean, where phosphorus is not limiting despite the degradative genes being common throughout the marine environment. Here we challenge this paradigm and show, for the first time, that bacteria isolated from marine samples have the ability to mineralise 2-aminoethylphosphonate, the most common biogenic marine aminophosphonate, via substrate-inducible gene regulation rather than via Pho-regulated metabolism. Substrate-inducible, Pho-independent 2-aminoethylphosphonate catabolism therefore represents a previously unrecognised component of the oceanic carbon, nitrogen and phosphorus cycles.
海洋的许多区域营养物质匮乏，但仍支持大量微生物种群，这导致了对营养物质的激烈竞争和循环利用。有机膦酸盐在海洋水中经常被发现，但需要专门的酶进行分解代谢。先前的研究表明，海洋系统中编码这些酶的基因受 Pho 调控子控制，因此受无机磷酸盐的抑制。这导致了这样的结论，即在磷不是限制因素的情况下，膦酸盐在海洋的大部分区域是难降解的，尽管降解基因在整个海洋环境中很常见。在这里，我们首次挑战了这一观点，并表明，从海洋样本中分离出来的细菌具有通过底物诱导基因调控而不是通过 Pho 调控代谢来矿化 2-氨基乙基膦酸盐（最常见的生物海洋氨基膦酸盐）的能力。因此，底物诱导、Pho 独立的 2-氨基乙基膦酸盐分解代谢代表了海洋碳、氮和磷循环中以前未被识别的组成部分。
