Content of carbon, nitrogen, oxygen, sulfur and phosphorus in native aquatic and cultured bacteria

Abstract

The content of carbon, nitrogen, oxygen, phosphorus and sulfur was measured in individual cells from 6 native aquatic samples and 4 samples of cultured bacteria by X-ray microanalysis using a transmission electron microscope (TEM). The molar C N:P ratio for the pooled sample was 50:lO:l From length and width measurements of unfixed air-dried cells we estimated cell volumes over a total range of 0.0026 to 15.8 pm3. and mean C:volume ratios of 30 to 162 fg for the samples included. For the marine samples we found mean N:C ratios of 0.25 to 0.28, while cells from fresh or brackish waters had mean N:C ratios of 0.17 to 0.20, indicating differences in nutrient availability. The P:C ratios for the samples analyzed varied from 0.040 to 0.090, with a pooled mean of 0.052, which is approximately twice that of the Redfield ratio for P C . For 0:C ratios we estimated a pooled mean of 0.37 and a range of 0.22 to 0.77 for all samples. We may conclude that slow-growing or non-growing cells have low 0 -C ratios. The mean S:C ratio for all samples was 0.031, with a range of 0 016 to 0.084 for the sample means. A general conclus~on is that single-cell analyses of elemental composition give important information on the physiological conditions of cells and on possible nutrient limitations. The rationale for this is the assumption that changes in macromolecular composition are due to nutrient availability.

Torn apart and reunited: impact of a heterotroph on the transcriptome of Prochlorococcus

“…That response was attributed to phosphate stress (Tai et al, 2009), and similar dynamics could be at play here as well. The Pro99 medium used in this study was calculated to be replete for N, P and other essential inorganic compounds, given cyanobacterial and heterotroph cell abundances and expected cellular requirements (Fagerbakke et al, 1996;Bertilsson et al, 2003). While some nutrient stress could have occurred in our co-cultures, any competition between these two strains was not of a sufficient magnitude to impact Prochlorococcus growth rates or final stationary phase cell density (Figure 1a).…”

Contamination Control for Scientific Drilling Operations

“…It remains questionable 593 whether the distribution of E.coli cells provides a realistic estimate of the distribution of 594 contaminant cells in a drill core because they are about an order of magnitude larger 595 than subsurface microbes (Fagerbakke et al, 1996) and may therefore get trapped at 596 pore throats where smaller indigenous cells can easily fit through. Other attempts were 597 the addition of a phototrophic cyanobacterium followed by detection via cultivation and 598 quantification of chl-a (Colwell et al, 1994), or a cultured GFP-expressing Pseudomonas 599 strain and detection via a highly sensitive PCR (Juck et al, 2005).…”

Toward a mechanistic understanding of how natural bacterial communities respond to changes in temperature in aquatic ecosystems

“…Traditionally, bacteria have been thought of as a low carbon/phosphorus (C:P) component of the pelagic food web with a constrained biomass stoichiometry (Fagerbakke et al, 1996). However, emerging evidence suggests that bacterial C:P ratios can be significantly higher than traditionally thought and highly variable (Elser et al, 1995;Villar-Argaiz et al, 2002;Hall, 2006).…”