title: Activity and growth of microbial populations in pressurized deep-sea sediment and animal gut samples.
abstract: Benthic animals and sediment samples were collected at deep-sea stations in the northwest (3,600-m depth) and southeast (4,300- and 5200-m depths) Atlantic Ocean. Utilization rates of [14C]glutamate (0.67 to 0.74 nmol) in sediment suspensions incubated at in situ temperatures and pressures (3 to 5 degrees C and 360, 430, or 520 atmospheres) were relatively slow, ranging from 0.09 to 0.39 nmol g-1 day-1, whereas rates for pressurized samples of gut suspensions varied widely, ranging from no detectable activity to a rapid rate of 986 nmol g-1 day-1. Gut flora from a holothurian specimen and a fish demonstrated rapid, barophilic substrate utilization, based on relative rates calculated for pressurized samples and samples held at 1 atm (101.325 kPa). Substrate utilization by microbial populations in several sediment samples was not inhibited by in situ pressure. Deep-sea pressures did not restrict growth, measured as doubling time, of culturable bacteria present in a northwest Atlantic sediment sample and in a gut suspension prepared from an abyssal scavenging amphipod. From the results of this study, it was concluded that microbial populations in benthic environments can demonstrate significant metabolic activity under deep-ocean conditions of temperature and pressure. Furthermore, rates of microbial activity in the guts of benthic macrofauna are potentially more rapid than in surrounding deep-sea sediments.
mesh_terms: D000085:Acetates / Q000378:metabolism; D000818:Animals; D001419:Bacteria / Q000254:growth & development*; D002250:Carbon Radioisotopes; D003445:Crustacea / Q000382:microbiology*; D004447:Echinodermata / Q000382:microbiology*; D005399:Fishes / Q000382:microbiology*; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D007422:Intestines / Q000382:microbiology*; D007700:Kinetics; D010101:Oxygen Consumption; D011312:Pressure; D012616:Sea Cucumbers / Q000382:microbiology*; D012623:Seawater; D014871:Water Microbiology
chemical_list: D000085:Acetates; D002250:Carbon Radioisotopes; D005971:Glutamates; D018698:Glutamic Acid