Zaccone Renata, Caruso Gabriella
Institute of Polar Sciences, ISP-CNR, Spianata S. Raineri 86-98122 Messina, Italy.
AIMS Microbiol. 2019 Sep 12;5(3):251-271. doi: 10.3934/microbiol.2019.3.251. eCollection 2019.
In most of the aquatic ecosystems, microorganisms are major players in the biogeochemical and nutrients cycles (Carbon Nitrogen, Phosphorus), through their enzymatic activities (leucine aminopeptidase, alkaline phosphatase and beta-glucosidase) on organic polymers such as polypeptides, organophosphate esters and polysaccharides, respectively. The small monomers released by decomposition are metabolised by microbes, supporting their growth. Most of the extracellular enzymes are adaptative and their synthesis and activity is strongly affected by environmental factors, consequently the relative importance of leucine aminopeptidase, alkaline phosphatase and beta-glucosidase reflects differences in the composition of organic matter and assume a different meaning. Since more than two decades, at the CNR the influence of climate changes, seasonal variability, depth and coastal input on the patterns of enzymatic activities in the Mediterranean Sea have been studied. Its particular characteristics of a semi-closed basin, high summer evaporation and the occurrence of important water dynamics, make this ecosystem particularly suitable as a model site for climate changes-related observations. The present paper reviews the current information of environmental changes on extracellular enzymatic activity obtained in the Mediterranean areas with the aim of evaluating the effects of environmental changes on the microbial activities. The obtained results revealed significant variations in the rates of hydrolytic activities in relation to space and time, with the highest levels generally found in the epipelagic layer (0-100m) and in coastal zones during warm periods. In the Central Mediterranean Sea their relationship with temperature changes was demonstrated. Spatial variations in the relative enzyme activities also suggested a modulation in the metabolic profiles of the prokaryotic communities, with biogeochemical implications in nutrient regeneration. Long term studies on microbial activity and abundances in relation with rising temperatures can have a predictive value to describe the evolutionary scenario of microbial processes and the response of microbial metabolism to climate changes in the Mediterranean Sea.
在大多数水生生态系统中，微生物通过其对有机聚合物（如多肽、有机磷酸酯和多糖）的酶促活性（亮氨酸氨肽酶、碱性磷酸酶和β-葡萄糖苷酶），在生物地球化学和养分循环（碳、氮、磷）中发挥着主要作用。分解产生的小单体被微生物代谢，以支持它们的生长。大多数细胞外酶具有适应性，其合成和活性受到环境因素的强烈影响，因此亮氨酸氨肽酶、碱性磷酸酶和β-葡萄糖苷酶的相对重要性反映了有机物组成的差异，并具有不同的意义。二十多年来，在意大利国家研究委员会（CNR），已经研究了气候变化、季节变化、深度和沿海输入对地中海酶促活性模式的影响。其半封闭盆地的特殊特征、夏季高蒸发率以及重要水动力的出现，使这个生态系统特别适合作为与气候变化相关观测的模型地点。本文综述了地中海地区关于环境变化对细胞外酶活性影响的现有信息，旨在评估环境变化对微生物活动的影响。所得结果表明，水解活性速率在空间和时间上存在显著变化，最高水平通常出现在温暖时期的上层水体（0 - 100米）和沿海区域。在地中海中部，证明了它们与温度变化的关系。相对酶活性的空间变化也表明原核生物群落代谢谱的调节，对养分再生具有生物地球化学意义。关于微生物活动和丰度与温度上升关系的长期研究，对于描述地中海微生物过程的演变情景以及微生物代谢对气候变化的响应具有预测价值。
