title: Method for enumeration of 5-cyano-2,3-ditoyl tetrazolium chloride (CTC)-active cells and cell-specific CTC activity of benthic bacteria in riverine, estuarine and coastal sediments.
abstract: Bacteria are the most abundant and active organisms in marine sediments and are critical for nutrient cycling and as a food source to many benthic and pelagic organisms. Bacteria are found both as free-living cells and as particle-associated cells, which can make investigations of these communities difficult. We found that common procedures for extracting bacteria from sediments leave the bacteria clay particle-associated and the clay particles clump, which reduce the reproducibility of direct counts. We optimized a sonication/surfactant method that produces a homogeneous suspension of bacterial cells against a uniform background of clay particles, which results in reproducible samples for epifluorescence microscopy. We developed a method to estimate CTC-positive cells and cell-specific CTC content in intact cores of surficial sediment communities from riverine, estuarine and coastal sites. Benthic bacterial abundances averaged 4.9x10(8) cells/g dry wt sediments in Apalachicola River, Florida sediments, 4.9-13.8x10(9) cells/g dry wt sediments in a variety of Apalachicola Bay sediments and 3.6x10(8) cells/g dry weight in shallow, anoxic Gulf of Mexico sediments. Percent CTC-positive cells ranged from low values of 9-10% CTC-positive cells in Apalachicola River and Apalachicola Bay sediments to high values of 25% CTC-positive cells in anoxic Gulf of Mexico sediments. After correction for abiotic CTC reduction and chlorophyll interference, estimates of cell-specific CTC reduction ranged from 0.15 to 0.55 fmol CTC(red)/active cell in the Apalachicola Bay sediments to 1.6 to 3.8 fmol CTC(red)/active cell in anoxic Gulf of Mexico sediments.
authors: Department of Oceanography, Florida State University, Tallahassee, FL 32306-4320, USA. proctor@ocean.fsu.edu
authors: L M
authors: LM
authors: Proctor
authors: A C
authors: AC
authors: Souza
mesh_terms: D001419:Bacteria / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism*; D001431:Bacteriological Techniques; D015169:Colony Count, Microbial; D019015:Geologic Sediments / Q000382:microbiology*; D008856:Microscopy, Fluorescence; D010101:Oxygen Consumption; D013778:Tetrazolium Salts / Q000378:metabolism*; D014871:Water Microbiology
chemical_list: D013778:Tetrazolium Salts; C075453:5-cyano-2,3-ditolyltetrazolium