CNR-IAMC, Institute for Coastal Marine Environment, Section of Messina, Messina, Italy.
Microb Ecol. 2012 Jul;64(1):54-66. doi: 10.1007/s00248-012-0011-4. Epub 2012 Feb 21.
The distribution of extracellular enzymatic activities (EEA) [leucine aminopeptidase (LAP), ß-glucosidase (GLU), alkaline phosphatase (AP)], as well as that of prokaryotic abundance (PA) and biomass (PB), dissolved organic carbon (DOC), particulate organic carbon and particulate total nitrogen (POC, PTN), was determined in the epi-, meso-, and bathypelagic waters of the Mediterranean Sea along a West-East transect and at one Atlantic station located outside the Strait of Gibraltar. This study represents a synoptical evaluation of the microbial metabolism during early summer. Decreasing trends with depth were observed for most of the parameters (PA, PB, AP, DOC, POC, PTN). Significant differences between the western and eastern basins of the Mediterranean Sea were found, displaying higher rates of LAP and GLU and lower C/N ratios more in the eastern than in the western areas. Conversely, in the epipelagic layer, PA and PB were found to be higher in the western than in the eastern basins. PB was significantly related to DOC concentration (all data, n = 145, r = 0.53, P < 0.01), while significant correlations of EEA with POC and PTN were found in the epipelagic layer, indicating an active response of microbial metabolism to organic substrates. Specific enzyme activities normalized to cell abundance pointed out high values of LAP and GLU in the bathypelagic layer, especially in the eastern basin, while cell-specific AP was high in the epi- and bathypelagic zone of the eastern basin indicating a rapid regeneration of inorganic P for both prokaryotes and phytoplankton needs. Low activity and abundance characterized the Atlantic station, while opposite trends of these parameters were observed along the Mediterranean transect, showing the uncoupling between abundance and activity data. In the east Mediterranean Sea, decomposition processes increased probably in response to mesoscale structures which lead to organic matter downwelling.
细胞外酶活性（EEA）[亮氨酸氨肽酶（LAP）、β-葡萄糖苷酶（GLU）、碱性磷酸酶（AP）]以及原核生物丰度（PA）和生物量（PB）、溶解有机碳（DOC）、颗粒有机碳和颗粒总氮（POC、PTN）的分布在沿西-东横剖面的地中海以及直布罗陀海峡外的一个大西洋站的中、深海水中进行了测定。这项研究代表了对初夏微生物代谢的综合评估。大多数参数（PA、PB、AP、DOC、POC、PTN）随深度呈下降趋势。地中海西部和东部盆地之间存在显著差异，东部地区的 LAP 和 GLU 速率较高，C/N 比值较低。相反，在表水层中，PA 和 PB 在西部盆地比东部盆地更高。PB 与 DOC 浓度显著相关（所有数据，n = 145，r = 0.53，P < 0.01），而在表水层中发现 EEA 与 POC 和 PTN 呈显著相关，表明微生物代谢对有机底物的活跃反应。细胞丰度归一化的特定酶活性指出了深海层中 LAP 和 GLU 的高值，特别是在东部盆地，而细胞特异性 AP 在东部盆地的表水层和深海层中较高，表明了无机 P 的快速再生为原核生物和浮游植物的需求。大西洋站的特征是低活性和丰度，而沿地中海横剖面观察到这些参数的相反趋势，表明丰度和活性数据之间的解耦。在地中海东部，分解过程可能会增加，以响应导致有机物向下沉降的中尺度结构。
