Shifts in the microbial community structure in different temperatures during sample storage from IODP Hole 325-M0058A

The objective of this study was to determine shifts in the microbial community structure and potential function based on standard Integrated Ocean Drilling Program (IODP) storage procedures for sediment cores. Standard long-term storage protocols maintain sediment temperature at 4°C for mineralogy, geochemical, and/or geotechnical analysis whereas standard microbiological sampling immediately preserves sediments at -80°C. Storage at 4°C does not take into account populations may remain active over geologic time scales at temperatures similar to storage conditions. Identification of active populations within the stored core would suggest geochemical and geophysical conditions within the core change over time. To test this potential, the metabolically active fraction of the total microbial community was characterized from IODP Expedition 325 Great Barrier Reef sediment cores prior to and following a 3-month storage period. Total RNA was extracted from complementary 2, 20, and 40 m below sea floor sediment samples, reverse transcribed to complementary DNA and then sequenced using 454 FLX sequencing technology, yielding over 14,800 sequences from the six samples. Interestingly, 97.3% of the sequences detected were associated with lineages that changed in detection frequency during the storage period including key biogeochemically relevant lineages associated with nitrogen, iron, and sulfur cycling. These lineages have the potential to permanently alter the physical and chemical characteristics of the sediment promoting misleading conclusions about the in situ biogeochemical environment. In addition, the detection of new lineages after storage increases the potential for a wider range of viable lineages within the subsurface that […]

本研究旨在探讨基于标准综合海洋钻探计划（Integrated Ocean Drilling Program，简称 IODP）的沉积物岩心存储程序，微生物群落结构和潜在功能的转变。标准的长期存储协议保持沉积物温度在 4°C，以供矿物学、地球化学和/或地质技术分析，而标准的微生物采样则立即将沉积物保存于 -80°C。在 4°C 的存储条件下，并未考虑到微生物群体可能在地质时间尺度上保持活跃的事实。在存储岩心中识别出活跃的微生物群体，将表明岩心内部的地球化学和地球物理条件随时间发生变化。为了验证这一可能性，研究人员从 IODP 325 航次大堡礁沉积物岩心中，在存储前和存储后 3 个月期间，对总微生物群落中代谢活跃的部分进行了表征。从海底 2 米、20 米和 40 米的互补沉积物样品中提取了总 RNA，并将其逆转录为互补 DNA，随后使用 454 FLX 测序技术进行测序，从六个样品中获得了超过 14,800 个序列。有趣的是，检测到的 97.3% 序列与在存储期间检测频率发生变化的谱系相关，包括与氮、铁和硫循环相关的关键生物地球化学相关谱系。这些谱系有可能永久改变沉积物的物理和化学特性，从而误导关于现场生物地球化学环境的结论。此外，存储后新谱系的检测增加了地下可能存在的更广泛的存活谱系的潜力。