ABSTRACT
Microbial life inhabits deeply buried marine sediments, but the extent of this vast ecosystem remains poorly constrained. Here we provide evidence for the existence of microbial communities in ~40° to 60°C sediment associated with lignite coal beds at ~1.5 to 2.5 km below the seafloor in the Pacific Ocean off Japan. Microbial methanogenesis was indicated by the isotopic compositions of methane and carbon dioxide, biomarkers, cultivation data, and gas compositions. Concentrations of indigenous microbial cells below 1.5 km ranged from <10 to ~10(4) cells cm(-3). Peak concentrations occurred in lignite layers, where communities differed markedly from shallower subseafloor communities and instead resembled organotrophic communities in forest soils. This suggests that terrigenous sediments retain indigenous community members tens of millions of years after burial in the seabed.
Subject(s)
Aquatic Organisms/classification , Archaea/classification , Bacteria/classification , Coal/microbiology , Geologic Sediments/microbiology , Microbial Consortia , Seawater/microbiology , Aquatic Organisms/genetics , Aquatic Organisms/metabolism , Archaea/genetics , Archaea/metabolism , Bacteria/genetics , Bacteria/metabolism , Biomarkers/metabolism , Carbon Dioxide/metabolism , Japan , Methane/metabolism , Methanococcus/classification , Methanococcus/genetics , Methanococcus/metabolism , Methanosarcina barkeri/classification , Methanosarcina barkeri/genetics , Methanosarcina barkeri/metabolism , Pacific OceanABSTRACT
A total of 1578 culture and antimicrobial susceptibility results on clinical specimens from various sites of infection were analyzed, by using the software installed in the MicroScan System of an automated microbiology analyzer, and by mathematical calculation. A list of antimicrobial drugs of choice by the site of infection is determined on the basis of the computer and mathematical analysis of the above data. The list suggested in this in vitro study may be useful to clinicians for selection of an initial antimicrobial agent in hospitals or communities when an infection is suspected in a site of infection before the results of cultures and antimicrobial susceptibility tests are reported. This list may also be helpful for initial therapy in critically ill patients before ordering culture and susceptibility testing, as well as for preoperative prophylaxis.
