Significance of Lipoquinones as Quantitative Biomarkers of Bacterial Populations in the Environment

Abstract

The direct total count of bacteria and the concentration of isoprenoid quinones were measured in 82 samples from different aquatic and soil environments. The geometric mean of the total count (TC)/total quinine (TQ) ratios obtained with different environments ranged from 1.1 to 2.2´10 3 cells fmol -1 . When the concentration of the total respiratory quinone (TRQ), i.e., ubiquinones and menaquinones, were taken into account, the geometric mean of the TC/TRQ ratios fell into a range of 2.2 to 4.1´10 3 cells fmol -1 . A high positive correlation was noted between TC and TQ (r 2 =0.9864) or TRQ (r 2 =0.9990). Based on the relationship between TC and TRQ, 1 nmol of the total quinone was estimated to be equivalent to 2.5´10 9 cells of bacteria on average. These results indicate that the concentration of the respiratory quinones can be used as a good measure of bacterial counts and biomass in the environment.

Water Availability Is a Critical Determinant of a Population Shift from Proteobacteria to Actinobacteria during Start-Up Operation of Mesophilic Fed-Batch Composting

“…Quinone components of each fraction were quantified and identified by reverse-phase HPLC and photodiode array detection with external standards. Detailed information on these analytical procedures has been given previously 10,11,16) . Ubiquinones, menaquinones, and plastoquinones with n isoprene units in their side chain were abbreviated as Q-n, MK-n, and PQ-n, respectively.…”

Activity and Community Composition of Denitrifying Bacteria in Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-Using Solid-phase Denitrification Processes

“…Aliquots (10-50 µl) of these diluted samples were taken and used for direct cell counting. Total bacterial counts were measured by epifluorescence microscopy with ethidium bromide (EtBr) or SYBR Green II (Molecular Probes, Inc., Eugene, USA) staining as described previously 15,43) . Detection of viable cells using a LIVE/DEAD BacLight Bacterial Viability kit (Molecular Probes) was performed according to the manufacturer's instructions and as described previously 43) .…”

“…Quinone components were separated and identified by reverse-phase HPLC and photodiode array and mass spectrometric detection with external ubiquinone (Q-n) and menaquinone (MK-n) standards. Detailed information on the analytical procedures has been given previously 14,15) .…”

Increase in Alphaproteobacteria in association with a polychaete, Capitella sp. I, in the organically enriched sediment

“…In the bioremediation experiments, the introduced Capitella colonies increased explosively on the organically enriched sediment during the late autumn and winter, and the amount of sedimentary organic matter decreased significantly following the rapid population growth (Tsutsumi et al, 2005a;Kinoshita et al, 2008). Kunihiro et al (2008) found a significant positive correlation between Capitella biomass and the quinone content of the sediment as an indicator of the biomass of microorganisms (Saitou et al, 1999;Hiraishi et al, 2003), and a marked increase of ubiquinone-10 (UQ-10) among the quinones when dense patches of the worms were established in the organically enriched sediment. Since UQ-10 is one of the co-enzymes used for aerobic respiration in the respiratory chain by the members of the class Alphaproteobacteria (Collins and Jones, 1981), it is very likely that the efficient decomposition of organic matter of the organically enriched sediment was not realized in the bioremediation experiments by the single effect of the feeding activity of Capitella, but was caused by the associated activities of Capitella with the microorganisms in the sediment (Chareonpanich et al, 1993;Tsutsumi et al, 2002;Kunihiro et al, 2008;Wada et al, 2008).…”