Luo Ling, Zhou Zhi-Chao, Gu Ji-Dong
Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, People's Republic of China.
Ecotoxicology. 2015 Oct;24(7-8):1508-16. doi: 10.1007/s10646-015-1452-6. Epub 2015 Mar 31.
This study investigated the diversity and abundance of bacterial lacasse-like genes in different particle size fractions, namely sand, silt, and clay of sediments in a subtropical mangrove ecosystem. Moreover, the effects of nutrient conditions on bacterial laccase-like communities as well as the correlation between nutrients and, both the abundance and diversity indices of laccase-like bacteria in particle size fractions were also studied. Compared to bulk sediments, Bacteroidetes, Caldithrix, Cyanobacteria and Chloroflexi were dominated in all 3 particle-size fractions of intertidal sediment (IZ), but Actinobacteria and Firmicutes were lost after the fractionation procedures used. The diversity index of IZ fractions decreased in the order of bulk > clay > silt > sand. In fractions of mangrove forest sediment (MG), Verrucomicrobia was found in silt, and both Actinobacteria and Bacteroidetes appeared in clay, but no new species were found in sand. The declining order of diversity index in MG fractions was clay > silt > sand > bulk. Furthermore, the abundance of lacasse-like bacteria varied with different particle-size fractions significantly (p < 0.05), and decreased in the order of sand > clay > silt in both IZ and MG fractions. Additionally, nutrient availability was found to significantly affect the diversity and community structure of laccase-like bacteria (p < 0.05), while the total organic carbon contents were positively related to the abundance of bacterial laccase-like genes in particle size fractions (p < 0.05). Therefore, this study further provides evidence that bacterial laccase plays a vital role in turnover of sediment organic matter and cycling of nutrients.
本研究调查了亚热带红树林生态系统沉积物中不同粒径组分（即砂、粉砂和黏土）中细菌漆酶样基因的多样性和丰度。此外，还研究了营养条件对细菌漆酶样群落的影响，以及营养物质与粒径组分中漆酶样细菌的丰度和多样性指数之间的相关性。与整体沉积物相比，拟杆菌门、嗜热栖热菌属、蓝细菌和绿弯菌门在潮间带沉积物（IZ）的所有3个粒径组分中占主导地位，但在所用的分级程序后放线菌门和厚壁菌门消失了。IZ组分的多样性指数按整体>黏土>粉砂>砂的顺序降低。在红树林沉积物（MG）的组分中，疣微菌门存在于粉砂中，放线菌门和拟杆菌门都出现在黏土中，但在砂中未发现新物种。MG组分中多样性指数的递减顺序为黏土>粉砂>砂>整体。此外，漆酶样细菌的丰度在不同粒径组分之间有显著差异（p<0.05），在IZ和MG组分中均按砂>黏土>粉砂的顺序降低。此外，发现养分有效性显著影响漆酶样细菌的多样性和群落结构（p<0.05），而总有机碳含量与粒径组分中细菌漆酶样基因的丰度呈正相关（p<0.05）。因此，本研究进一步提供了证据，证明细菌漆酶在沉积物有机质周转和养分循环中起着至关重要的作用。
