Does the High Nucleic Acid Content of Individual Bacterial Cells Allow Us To Discriminate between Active Cells and Inactive Cells in Aquatic Systems?

Abstract

The nucleic acid contents of individual bacterial cells as determined with three different nucleic acid-specific fluorescent dyes (SYBR I, SYBR II, and SYTO 13) and flow cytometry were compared for different seawater samples. Similar fluorescence patterns were observed, and bacteria with high apparent nucleic acid contents (HNA) could be discriminated from bacteria with low nucleic acid contents (LNA). The best discrimination between HNA and LNA cells was found when cells were stained with SYBR II. Bacteria in different water samples collected from seven freshwater, brackish water, and seawater ecosystems were prelabeled with tritiated leucine and then stained with SYBR II. After labeling and staining, HNA, LNA, and total cells were sorted by flow cytometry, and the specific activity of each cellular category was determined from leucine incorporation rates. The HNA cells were responsible for most of the total bacterial production, and the specific activities of cells in the HNA population varied between samples by a factor of seven. We suggest that nucleic acid content alone can be a better indicator of the fraction of growing cells than total counts and that this approach should be combined with other fluorescent physiological probes to improve detection of the most active cells in aquatic systems.

Flow cytometric analysis of virus-like particles and heterotrophic bacteria within coral-associated reef water

“…It has previously been demonstrated that HDNA cells represent the active component of bacterioplankton communities, while LDNA cells are likely to consist of dormant or dead bacteria (Gasol et al, 1999;Lebaron et al, 2001Lebaron et al, , 2002.…”

“…Based on di¡erences in SYBR Green £uorescence (DNA content) and side scatter (an indicator of cell size), heterotrophic bacteria were divided into two distinct populations, high DNA (HDNA) and low DNA (LDNA) (Gasol et al, 1999;Lebaron et al, 2001Lebaron et al, , 2002 (Figure 1). It has previously been demonstrated that HDNA cells represent the active component of bacterioplankton communities, while LDNA cells are likely to consist of dormant or dead bacteria (Gasol et al, 1999;Lebaron et al, 2001Lebaron et al, , 2002.…”

Microbial Ecology of Lake Kivu

“…Bouvier et al 2007 ) . The general pattern that emerges from the literature is that HNA cells appear to be not only larger cells but also more active cells, with high speci fi c metabolism and growth, and that changes in total bacterial abundance are often linked to changes in this fraction (Lebaron et al 2001 , but see Jochem et al 2004 ;Bouvier et al 2007 for other possible scenarios on this topic).…”

Intact polar and core glycerol dibiphytanyl glycerol tetraether lipids in the Arabian Sea oxygen minimum zone. Part II: Selective preservation and degradation in sediments and consequences for the TEX86

“…active as well as dormant, cells which possess an intact membrane (cf. Stevenson, 1978;Lebaron et al, 2001;Luna et al, 2002). IPL-GDGTs found in sediments and reported up to now as indicative of living Archaea are glycolipids with monohexose-and dihexose-GDGTs and GDGTs with a loss of m/z 341 (Biddle et al, 2006;Lipp and Hinrichs, 2009;Schubotz et al, 2009).…”