Microbes are well-known for their great diversity and abundance in modern natural environments.They also are believed to pro-vide critical links among higher organisms and their associated environments.However,the low diversity of morphological fea-tures and structures of ancient microbes preserved in sediments and rocks make them difficult to identify and classify.This diffi-culty greatly hinders the investigation of geomicrobes throughout Earth history.Thus,most previous paleontological studies have focused on faunal and floral fossils.Here,geomicrobial functional groups(GFGs),or a collection of microbes featured in specific ecological,physiological or biogeochemical functions,are suggested to provide a way to overcome the difficulties of ancient mi-crobe investigations.GFGs are known for their great diversity in ecological,physiological and biogeochemical functions.In addi-tion,GFGs may be preserved as the biogeochemical,mineralogical and sedimentological records in sediments and rocks.We reviewed the functions,origins and identification diagnostics of some important GFGs involved in the elemental cycles of carbon,sulfur,nitrogen and iron.GFGs were further discussed with respect to their significant impacts on paleoclimate,sulfur chemistry of ancient seawater,nutritional status of geological environments,and the deposition of Precambrian banded iron formations.
To investigate the microbial utilization of organic carbon in peatland ecosystem, water samples were collected from the Dajiuhu Peatland and nearby lakes, central China across the year of 2014. The acridine orange （AO） staining and Biolog Eco microplates were used to numerate microbial counts and determine the carbon utilization of microbial communities. Meanwhile, physicochemical characteristics were measured for subsequent analysis of the correlation between microbial carbon utilization and environmental factors. Results indicated that total microbial counts were between 106107 cells/L. Microbial diversities and carbon utilization rates showed a similar pattern, highest in September and lowest in November. Microbial communities in the peat pore waters preferred to utilize N-bearing carbon sources such as amines and amino acids compared with microbial communities in lakes. The network analysis of microbial utilization of 31 carbon substrates clearly distinguished microbial communities from peat pore waters and those from lakes. Redundancy analysis （RDA） showed the total organic nitrogen content （P=-0.03, F=2.5） and daily average temperature （P=0.034, F=2.4） significantly controlled microbial carbon utilization throughout the sampling period. Our report is the first one to address the temporal and spatial variations of carbon uti- lization of microbial communities which are closely related to the decomposition of organic matter in the Dajiuhu Peatland in context of climate warming.
Rui-Cheng WangHong-Mei WangXing XiangYu GaoQing-Wei SongLin-Feng Gong
