Sea surface temperature fronts in the Northeastern Arabian Sea (NEAS) facilitate nutrient enhancement in the surface layers, resulting in high primary production. Such high production areas contribute to the accumulation of fresh organic matter rich in carbohydrates, thereby supporting higher heterotrophic metabolism. Transparent exopolysaccharides (TEP) are one of the carbohydrate polymers released as exudates during primary production or decaying process and their breakdown is mediated by a set of ectoenzymes that includes glucosidases and chitinases. Observations were carried out in different aged NEAS fronts to elucidate the influence of frontal age on the abundance of TEP, bacterial nucleic acid content (high nucleic acid content, HNA and low nucleic acid content, LNA), and ectoenzymatic activities. The fronts were classified as younger and older, depending on their first appearance and sampling day. A clear transition from HNA to LNA bacteria, variations in TEP and related ectoenzymatic activities in the fronts was influenced by the frontal age. The younger fronts were dominated by HNA bacteria, α-glucosidase, and chitinase activity. In contrast, an acceleration in β-glucosidase activity, bacterial production, which was related to TEP concentration, was evident in the older fronts. Further, a significant increase in protist numbers in older fronts was related to effective grazing on HNA bacteria and TEP. The active turnover of TEP by bacteria and protists facilitates strong microbial loop in NEAS frontal regions. Elucidating contribution of such changes in the frontal areas will provide a basis for a better understanding of microbial carbon cycling.

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额叶年龄如何影响细菌的生理状态：来自阿拉伯海东北部的案例研究

东北阿拉伯海 (NEAS) 的海面温度前沿促进了表层营养物质的增加，从而导致初级生产力的提高。这样的高产区有助于富含碳水化合物的新鲜有机物的积累，从而支持更高的异养代谢。透明胞外多糖 (TEP) 是在初级生产或腐烂过程中作为渗出物释放的碳水化合物聚合物之一，它们的分解由一组胞外酶介导，包括葡萄糖苷酶和几丁质酶。在不同年龄的NEAS锋面进行观测，阐明锋面年龄对TEP丰度、细菌核酸含量（高核酸含量，HNA和低核酸含量，LNA）和胞外酶活性的影响。根据它们的首次出现和采样日期，锋面被分为年轻和年长。从 HNA 到 LNA 细菌的明显转变、前沿中 TEP 的变化和相关的胞外酶活性受到前沿年龄的影响。年轻的前沿以海航细菌、α-葡萄糖苷酶和几丁质酶活性为主。相比之下，与 TEP 浓度相关的 β-葡萄糖苷酶活性加速，细菌产生在较旧的前沿中很明显。此外，旧阵线原生生物数量的显着增加与对海航细菌和 TEP 的有效放牧有关。细菌和原生生物对 TEP 的主动转换促进了 NEAS 额叶区域的强大微生物环。