The cyanate utilization capacity of marine unicellular Cyanobacteria
The cyanate utilization capacity of marine unicellular Cyanobacteria
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DOI：
10.4319/lo.2008.53.6.2485
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发表时间：
2008-11-01
影响因子：
4.5
通讯作者：
Post, Anton F.
中科院分区：
文献类型：
--
作者：
Kamennaya, Nina A.;Chernihovsky, Mark;Post, Anton F.
氰酸盐是尿素分解的副产品，是海洋环境中潜在的氮（N）源，但迄今为止，它很少受到关注。蓝细菌可能通过底物特异性 ABC 型转运蛋白 (cynABD) 获得这种化合物，并通过氰酶 (cynS) 活性将其转化为铵和二氧化碳。先前已暗示氰酸盐利用基因参与蓝藻氮胁迫反应，但其生态背景尚未研究。我们采用聚合酶链反应方案进行 cynA 扩增，以检查红海北部亚喀巴湾的氰酸盐补充潜力。我们还监测了具有不同 cynABDS 补体的蓝藻菌株在含氰酸盐培养基上的生长。我们表明，具有完整基因补充的菌株将氰酸盐用作唯一的氮源，并且在缺乏任何这些基因的菌株中观察到通过氰酸盐自然分解为铵的残余生长。寡营养的亚喀巴湾自然丰富的 cynA 产品表明，氰酸盐是原绿球藻的重要氮源，但不是聚球藻种群的重要氮源。非蓝细菌 cynA 序列表明多种其他光养微生物对氰酸盐的利用。我们假设在分层水体中，氰酸盐的利用仅限于缺氮的上层透光区，在那里它在“再生”初级生产中发挥作用。
Cyanate, a by-product of urea decomposition, is a potential nitrogen (N) source in marine environments, but to date it has received scant attention. Cyanobacteria presumably acquire this compound via a substrate-specific ABC-type transporter (cynABD), and they convert it to ammonium and carbon dioxide by cyanase (cynS) activity. Participation of cyanate utilization genes in N-stress responses in cyanobacteria has been implied previously, but its ecological context has not been studied. We employed polymerase chain reaction protocols for cynA amplification to examine the potential for cyanate recruitment in the Gulf of Aqaba, northern Red Sea. We also monitored growth of cyanobacterial strains with different cynABDS complements on cyanate-containing media. We showed that cyanate is utilized as the sole N source by strains with the full gene complement, and residual growth, fed by natural decay of cyanate to ammonium, was observed in strains lacking any of these genes. Natural abundance of cynA products in the oligotrophic Gulf of Aqaba indicates that cyanate constitutes an essential N source for Prochlorococcus, but not for Synechococcus populations. Noncyanobacterial cynA sequences indicate cyanate utilization by a variety of other phototrophic microorganisms. We hypothesize that in stratified water bodies, cyanate utilization is confined to the N-deplete upper photic zone, where it plays a role in "regenerated'' primary production.