Department of Civil and Environmental Engineering Division of Biological Engineering Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
Environ Microbiol. 2012 Jun;14(6):1363-77. doi: 10.1111/j.1462-2920.2011.02612.x. Epub 2011 Oct 18.
Primary productivity in the ocean's oligotrophic regions is often limited by phosphorus (P) availability. In low phosphate environments, the prevalence of many genes involved in P acquisition is elevated, suggesting that the ability to effectively access diverse P sources is advantageous for organisms inhabiting these regions. Prochlorococcus, the numerically dominant primary producer in the oligotrophic ocean, encodes high-affinity P transporters, P regulatory proteins and enzymes for organic phosphate utilization, but its ability to use reduced P compounds has not been previously demonstrated. Because Prochlorococcus strain MIT9301 encodes genes similar to phnY and phnZ, which constitute a novel marine bacterial 2-aminoethylphosphonate (2-AEPn) utilization pathway, it has been suggested that this organism might use 2-AEPn as an alternative P source. We show here that although MIT9301 was unable to use 2-AEPn as a sole P source under standard culture conditions, it was able to use phosphite. Phosphite utilization by MIT9301 appears to be mediated by an NAD-dependent phosphite dehydrogenase encoded by ptxD. We show that phosphite utilization genes are present in diverse marine microbes and that their abundance is higher in low-P waters. These results strongly suggest that phosphite represents a previously unrecognized component of the marine P cycle.
海洋贫营养区的初级生产力通常受到磷 (P) 可利用性的限制。在低磷酸盐环境中，许多参与 P 获得的基因的普遍性增加，这表明有效利用各种 P 源的能力对栖息在这些地区的生物是有利的。聚球藻是贫营养海洋中数量上占优势的初级生产者，它编码高亲和力 P 转运蛋白、P 调节蛋白和有机磷利用酶，但它利用还原 P 化合物的能力以前尚未得到证明。由于 MIT9301 菌株编码类似于 phnY 和 phnZ 的基因，这些基因构成了一种新的海洋细菌 2-氨基乙基膦酸盐（2-AEPn）利用途径，因此有人认为这种生物可能将 2-AEPn 用作替代 P 源。我们在这里表明，尽管 MIT9301 不能在标准培养条件下将 2-AEPn 用作唯一的 P 源，但它能够利用亚磷酸盐。MIT9301 利用亚磷酸盐似乎是由 ptxD 编码的 NAD 依赖性亚磷酸盐脱氢酶介导的。我们表明，亚磷酸盐利用基因存在于各种海洋微生物中，并且在低磷水中的丰度更高。这些结果强烈表明，亚磷酸盐代表了海洋 P 循环中以前未被识别的组成部分。
