Assessing Primary and Bacterial Production Rates in Biofilms on Pebbles in Ishite Stream, Japan

Abstract

Various measurements of microbial productivity in streambed pebble biofilms were analyzed almost monthly for 1 year to quantify the importance of primary production as an autochthonous source of organic matter utilized to support heterotrophic bacterial production in the dynamic food web within this natural microbial habitat. Bacterial density varied from 0.3x10(8) to 1.4x10(8) cells cm-2, and chlorophyll a concentration ranged from 0.7 to 25.9 microg cm-2, with no coupled oscillation between seasonal changes in these two parameters. In bottle incubation experiments, the instantaneous bacterial growth rate of bacteria was significantly correlated with their production rate [measured by frequency of dividing cells (FDC)] as follows: ln mu=0.138FDC-3.003 (n=15, r2=0.445, p<0.001). FDC values in the pebble biofilms increased with fluctuations during the study period, ranging from 3.6% to 9.2%. Bacterial production rates largely fluctuated between 0.15 to 0.92 microg C cm-2 h-1, and its seasonal pattern was similar to that of bacterial density. Net primary production measured between May 2002 to November 2002 attained minimum level (0.5 microg C cm-2 h-1) in June and maximum level (1.9 microg C cm-2 h-1) in August. Percentages of bacterial production to net primary production ranged between 21% and 120%. Because this ratio extends both below and above 100% for these parameters, it is likely that both autochthonous and allochthonous supplies of organic matter are important for production of bacteria in the pebble biofilms that develop in rapidly flowing fresh water streams.

Diel variations in frequency of dividing cells and abundance of aerobic anoxygenic phototrophic bacteria in a coral reef system of the South China Sea

“…In the present study, we observed for the first time the dividing cells of AAP bacteria using epifluorescence microscopy, which is a convenient and direct method for assessing bacterial growth rates (Hagstrom et al 1979, Newell & Christian 1981, Fukuda et al 2006. Observations of dividing cells have been conducted for many organisms, such as heterotrophic microprotozoa (Sherr & Sherr 1983), autotrophic picoplankton (Affronti & Marshall 1994), and heterotrophic bacteria (Hagstrom et al 1979, Newell & Christian 1981, Fukuda et al 2006), but no application to AAP bacteria has been reported to date.…”

“…FDC in total bacterial cells was counted according to Hagstrom et al (1979) and Fukuda et al (2006). A cell was counted as dividing if a clear invagination of the cell wall could be seen, but not a clear separatory space between daughter cells.…”

“…Observations of dividing cells have been conducted for many organisms, such as heterotrophic microprotozoa (Sherr & Sherr 1983), autotrophic picoplankton (Affronti & Marshall 1994), and heterotrophic bacteria (Hagstrom et al 1979, Newell & Christian 1981, Fukuda et al 2006), but no application to AAP bacteria has been reported to date.…”

Photosynthetic activity of epilithic algal communities in sections of the Torna stream (Hungary) with natural and modified riparian shading

“…Differences can be observed between the natural and the experimentally measured primary production (Fellows et al, 2006) because of (1) the presence of grazing macroinvertebrates (Murphy, 1984;Lamberti et al, 1987;Steinman, 1996;Wellnitz & Ward, 2000;Hillebrand & Kahlert, 2001), (2) changes of the flow velocity (McIntire, 1966;Horner et al, 1990;Cardinale et al, 2002;Villeneuve et al, 2010), (3) activity of bacteria (Fukuda et al, 2006) and (4) the photosynthetic parameters were determined after 3 weeks of in situ incubation, but the natural mature epilithon might be much older. Despite the shortcomings of the estimation of the primary production, the role of the epilithon communities in the nutrient and energy flux is undisputed.…”

Use of CMEIAS Image Analysis Software to Accurately Compute Attributes of Cell Size, Morphology, Spatial Aggregation and Color Segmentation that Signify in Situ Ecophysiological Adaptations in Microbial Biofilm Communities

“…Spatial pattern analyses that reject the null hypothesis of complete spatial randomness are typically followed by other tests that determine whether the pattern is uniform or aggregated, its local vs. regional spatial scale, and its spatial intensity [4,51]. We have found that this trend of nonrandom patterns was dominated by cooperative clustering plus some competitive uniform distributions in microbial biofilms in natural and managed habitats, including on root and leaf surfaces [53][54][55][56][57][58], freshwater streambed pebbles [59], and in river/lake ecosystems [4,22,52,60]. Thus, spatial analyses of microbial biofilms can reveal many insights on the ecological conditions that trigger the colonization behaviors creating them [4].…”