Franco Diego C, Signori Camila N, Duarte Rubens T D, Nakayama Cristina R, Campos Lúcia S, Pellizari Vivian H
Departamento de Oceanografia Biológica, Instituto Oceanográfico, Universidade de São Paulo São Paulo, Brazil.
Centro de Ciências Biológicas, Universidade Federal de Santa Catarina Florianópolis, Brazil.
Front Microbiol. 2017 Feb 2;8:153. doi: 10.3389/fmicb.2017.00153. eCollection 2017.
Microorganisms dominate most Antarctic marine ecosystems, in terms of biomass and taxonomic diversity, and play crucial role in ecosystem functioning due to their high metabolic plasticity. Admiralty Bay is the largest bay on King George Island (South Shetland Islands, Antarctic Peninsula) and a combination of hydro-oceanographic characteristics (bathymetry, sea ice and glacier melting, seasonal entrance of water masses, turbidity, vertical fluxes) create conditions favoring organic carbon deposition on the seafloor and microbial activities. We sampled surface sediments from 15 sites across Admiralty Bay (100-502 m total depth) and the adjacent North Bransfield Basin (693-1147 m), and used the amplicon 454-sequencing of 16S rRNA gene tags to compare the bacterial composition, diversity, and microbial community structure across environmental parameters (sediment grain size, pigments and organic nutrients) between the two areas. Marine sediments had a high abundance of heterotrophic Gammaproteobacteria (92.4% and 83.8% inside and outside the bay, respectively), followed by Alphaproteobacteria (2.5 and 5.5%), Firmicutes (1.5 and 1.6%), Bacteroidetes (1.1 and 1.7%), Deltaproteobacteria (0.8 and 2.5%) and Actinobacteria (0.7 and 1.3%). Differences in alpha-diversity and bacterial community structure were found between the two areas, reflecting the physical and chemical differences in the sediments, and the organic matter input.
就生物量和分类多样性而言，微生物在大多数南极海洋生态系统中占主导地位，并且由于其高代谢可塑性而在生态系统功能中发挥着关键作用。金钟湾是乔治王岛（南极半岛南设得兰群岛）上最大的海湾，水文海洋学特征（水深测量、海冰和冰川融化、水体季节性进入、浊度、垂直通量）的综合作用创造了有利于有机碳在海底沉积和微生物活动的条件。我们从金钟湾（总深度100 - 502米）和相邻的北布兰斯菲尔德盆地（693 - 1147米）的15个地点采集了表层沉积物，并使用16S rRNA基因标签的扩增子454测序来比较这两个区域环境参数（沉积物粒度、色素和有机养分）之间的细菌组成、多样性和微生物群落结构。海洋沉积物中异养γ-变形菌的丰度很高（湾内和湾外分别为92.4%和83.8%），其次是α-变形菌（2.5%和5.5%）、厚壁菌门（1.5%和1.6%）、拟杆菌门（1.1%和1.7%）、δ-变形菌（0.8%和2.5%）和放线菌门（0.7%和1.3%）。在这两个区域发现了α-多样性和细菌群落结构的差异，反映了沉积物中的物理和化学差异以及有机质输入情况。
