Precision of bacterioplankton biomass determination: a comparison of two fluorescent dyes, and of allometric and linear volume-to-carbon conversion factors

By T. Posch, M. Loferer-Krössbacher, Guang Gao, A. Alfreider, Jakob Pernthaler, R. Psenner. 2001

120 citations recorded by the source corpus.

We studied the influence of methodology on the variability of bacterial direct counts and biomass estimates. Two frequently used fluorochromes, 4,6-diamidino-2-phenylindole (DAPI) and 3, 6-bis(dimethylamino)acridine (acridine orange (AO)), were applied to determine bacterial abun- dances and sizes along a vertical profile in a oligo-mesotrophic freshwater lake (Piburger See, Aus- tria). Only 90 ± 11% of AO stained bacteria were detected with the fluorochrome DAPI. On average, DAPI stained cells were half as large (48 ± 11% of mean cell volume) as cells stained with AO. The observed discrepancies in abundance and cell volumes were significantly related to community DNA synthesis rates, as suggested by lower differences at higher uptake rates of ( 3 H)thymidine. In addi- tion, a decrease in the relative DNA content cell -1 with increasing cell size was found in the bacteri- oplankton assemblage. Considering the staining properties of the 2 dyes, this may partially account for the observed differences in mean cell sizes. We summarized and evaluated most linear and allo- metric volume-to-carbon conversion factors published during the past 2 decades. Total bacterial bio- mass was estimated by applying several of these conversion factors to data sets determined from DAPI and AO stained preparations. Depending on the dye and conversion factor, bacterial biomass, averaged over the total water column, ranged between 5 µg C l -1 and 165 µg C l -1 . As a result of this comparison we recommend the use of allometric conversion formulae specifically elaborated for a particular dye, i.e., CC = 218 × V 0.86 (Loferer-Krosbacher et al. 1998) for DAPI stained bacteria and CC = 120 × V 0.72 (Simon & Azam 1989, recalculated by Norland 1993) for AO stained cells (where CC is cellular carbon content (fg C), and V is bacterial volume (µm 3 )). In addition, these 2 formulae pro- duced biomass estimates closest to the median values of estimates by all the investigated conversion factors.

Subfields: Ecology, Oceanography, Pollution

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In Ecology

1. J. Payet
2. S. Brigden
3. J. Clasen
4. C. Suttle
5. M. Middelboe
6. K. Young
7. M. Weinbauer
8. C. Brussaard

In Oceanography

1. C. Suttle
2. M. Weinbauer

Citations in the corpus

• Bacterial metabolism and growth efficiency in lakes: The importance of phosphorus availability (2004, unknown): “86 (Posch et al. 2001).”
• Evidence that viral abundance across oceans and lakes is driven by different biological factors (2008, result): “Posch et al. (2001) reported that estimates of bacterial abundance made with DAPI were about 10% lower than those made with AO, while Suzuki, Sherr & Sherr (1993) reported that DAPI counts in coastal seawater averaged only about 70% of those made with AO.”