Differential microbial uptake of dissolved amino acids and amino sugars in surface waters of the Atlantic Ocean
Differential microbial uptake of dissolved amino acids and amino sugars in surface waters of the Atlantic Ocean
复制标题
大西洋表层水中微生物对溶解氨基酸和氨基糖的差异吸收
DOI：
10.1093/plankt/fbm091
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发表时间：
2007
影响因子：
2.1
通讯作者：
B. Fuchs
中科院分区：
文献类型：
--
作者：
M. Zubkov;G. Tarran;I. Mary;B. Fuchs
氮的生物利用度被认为限制了地球上最大的生物群落-海洋寡营养环流的生产力。为了评估这些和其他沃茨中微生物对小有机氮分子的需求，使用放射性示踪剂稀释的生物测定技术比较了氨基酸（亮氨酸、甲硫氨酸和酪氨酸）和氨基糖（葡糖胺和N-乙酰基-葡糖胺）以及葡萄糖的微生物摄取速率。生物测定是在横跨纬度范围从60°N到42°S的四个大西洋中部纬向样带上进行的。脑回中生物可利用的N-乙酰葡糖胺和葡萄糖的平均浓度为1 nM，比平均亮氨酸浓度高4倍。尽管其浓度较低，亮氨酸在15小时的脑回的平均周转时间分别为90和9倍短于N-乙酰-葡萄糖胺和葡萄糖的周转时间。此外，在氨基酸中，亮氨酸在脑回中的吸收速度比甲硫氨酸快1.5倍，比酪氨酸快2.5倍。因此，海洋浮游细菌作为一个社会表现出明显的偏好氨基酸，特别是亮氨酸，相比氨基糖。氨基酸优先吸收糖挑战了开放海洋中微生物氮或碳限制的概念。
Nitrogen bioavailability is considered to limit the productivity of oceanic oligotrophic gyres, the largest biomes on Earth. In order to assess the microbial requirement for small organic nitrogen molecules in these and other waters, the microbial uptake rates of amino acids (leucine, methionine and tyrosine) and amino sugars (glucosamine and N-acetyl-glucosamine) as well as glucose were compared using a bioassay technique of radiotracer dilution. The bioassays were carried out on four mid-Atlantic meridional transects spanning a latitudinal range from 60°N to 42°S. The mean concentrations of both bioavailable N-acetyl-glucosamine and glucose in the gyres were 1 nM, four times higher than the mean leucine concentration. Despite its lower concentration, the mean turnover time of leucine in the gyres of 15 h was 90 and 9 times shorter than the turnover time of N-acetyl-glucosamine and glucose, respectively. In addition, among amino acids, leucine was taken up in the gyres at a rate of 1.5 times faster than methionine and 2.5 times faster than tyrosine. Hence, oceanic bacterioplankton as a community showed a clear preference for amino acids, particularly leucine, compared with amino sugars. The preferential uptake of amino acids to sugars challenges the concept of microbial nitrogen or carbon limitation in the open ocean.