Determination of bacterial number and biomass in the marine environment

Abstract

Three techniques for the measurement of bacterial numbers and biomass in the marine environment are described. Two are direct methods for counting bacteria. The first employs an epifluorescence microscope to view bacteria that have been concentrated on membrane filters and stained with acridine orange. The second uses a transmission electron microscope for observing replicas of bacteria that are concentrated on membrane filters. The other technique uses Limulus amebocyte lysate, an aqueous extract from the amebocytes of the horseshoe crab, Limulus polyphemus, to quantitate lipopolysaccharide (LPS) in seawater samples. The biomass of gram-negative (LPS containing) bacteria was shown to be related to the LPS content of the samples. A factor of 6.35 was determined for converting LPS to bacterial carbon.

Species‐ and Age‐Specific Differences in Bacterial Resource Utilization by Two Co‐Occurring Cladocerans

“…The average volume of planktonic bacterial cells is generally 0.05-0.10 p,m 3 (Ferguson and Rublee 1976, Bowden 1977, Hobbie et al 1977, Watson et al 1977, Zimmerman 1977. The biomass of free bacteria available to zooplankton for the different experiments can be calculated by assuming a cell density of 1.07 g/mL, a dryto wet-mass ratio of0.23, and a carbon to dry-mass ratio of0.5 (Bowden 1977, Watson et al 1977. Calculated bacterial C biomasses were 8.6-17.2, 30.2-60.3, and 92.3-184.6 p,g/ L for the winter, spring, and summer experiments, given the above conversion factors and the range of mean cell volumes generally found.…”

“…Analyses of lake and pond carbon budgets suggest that zooplankton obtain a substantial proportion of their carbon from detritus pathways via bacteria (Wetzel 1975:611-613). Recent advances in methodology have confirmed that bacteria are both numerically abundant (Hobbie et al 1977, Watson et al 1977, Hobbie 1979, Porter and Feig 1980 and significant producers of biomass in the plankton.…”

Microbial community structure at the U.S.‐Joint Global Ocean Flux Study Station ALOHA: Inverse methods for estimating biochemical indicator ratios

“…There is a large range of published values of the biovolume-to-cell-carbon ratio (volume conversion factor, or VCF) for bacteria (Table 4). Some of these factors are deduced from assumed values of the carbon-to-dry-weight (C/DW) and dry-weight-to-wet-weight (DW/WW) ratios, and the density of the cells (p) [Ferguson and Rublee, 1976;Williams and Carlucci, 1976;Hagstrom et al, 1979;Jordan and Likens, 1980;Pedros-Alio and Brock, 1982] Values of the CCQ for a range of VCF' s and cell sizes are given in Table 5. For cells larger than about 0.5/am (ESD), only the lower end of the VCF range is consistent with the community-level solutions presented in this paper.…”

Measurement of cell volume of phototrophic bacteria in pure cultures and natural samples: phase contrast, epifluorescence and particle sizing

“…In natural samples the technique most frequently used to measure volumes of bacteria has been epifluorescence [12][13][14]18,20]. There are two commonly used epifluorescence techniques: that of Zimmermann and Meyer-Reil [25] (EPI1) and that of Hobbie et al [26] (EPI2).…”

“…Techniques currently in use include optical and electronic methods. In the first category three types of microscopy have been used most often: phase contrast [11], epifluorescence [12][13][14] and scanning electron microscopy (SEM) [7,8,15,16]. Some studies have been done comparing SEM and epifluorescence [17,18].…”