Istituto di Biofisica, CNR, Pisa, Italy.
Biophys Chem. 2013 Dec 1;182:79-85. doi: 10.1016/j.bpc.2013.06.016. Epub 2013 Jul 1.
This study reports the first information on extracellular enzymatic activity (EEA) combined with a study of DOM dynamics at the Arno River mouth. DOM dynamics was investigated from both a quantitative (dissolved organic carbon, DOC) and a qualitative (absorption and fluorescence of chromophoric DOM, CDOM) perspective. The data here reported highlight that the Arno River was an important source of both DOC and CDOM for this coastal area. CDOM optical properties suggested that terrestrial DOM did not undergo simple dilution at the river mouth but, other physical-chemical and biological processes were probably at work to change its molecular characteristics. This observation was further supported by the "potential" enzymatic activity of β-glucosidase (BG) and leucine aminopeptidase (LAP). Their Vmax values were markedly higher in the river water than in the seawater and their ratio suggested that most of the DOM used by microbes in the Arno River was polysaccharide-like, while in the seawater it was mainly protein-like.
本研究报告了河口区细胞外酶活性（EEA）的第一手资料，并对 DOM 动态进行了研究。从定量（溶解有机碳，DOC）和定性（发色 DOM 的吸收和荧光，CDOM）两个方面研究了 DOM 动态。这里报告的数据突出表明，对于这个沿海地区，阿尔诺河是 DOC 和 CDOM 的重要来源。CDOM 光学性质表明，在河口处，陆地 DOM 并没有简单地被稀释，而是可能发生了其他物理化学和生物过程来改变其分子特征。这种观察结果进一步得到了β-葡萄糖苷酶（BG）和亮氨酸氨肽酶（LAP）“潜在”酶活性的支持。它们在河水中的 Vmax 值明显高于海水中的值，其比值表明，在阿尔诺河中，微生物利用的大部分 DOM 类似于多糖，而在海水中则主要是蛋白质样的。
