Identification of a novel acetate-utilizing bacterium belonging to Synergistes group 4 in anaerobic digester sludge.

Department of Civil and Environmental Engineering, Graduate School of Engineering, Gunma University, Kiryu, Japan.
The ISME Journal (Impact Factor: 8.95). 05/2011; 5(12):1844-56. DOI: 10.1038/ismej.2011.59
Source: PubMed

ABSTRACT Major acetate-utilizing bacterial and archaeal populations in methanogenic anaerobic digester sludge were identified and quantified by radioisotope- and stable-isotope-based functional analyses, microautoradiography-fluorescence in situ hybridization (MAR-FISH) and stable-isotope probing of 16S rRNA (RNA-SIP) that can directly link 16S rRNA phylogeny with in situ metabolic function. First, MAR-FISH with (14)C-acetate indicated the significant utilization of acetate by only two major groups, unidentified bacterial cells and Methanosaeta-like filamentous archaeal cells, in the digester sludge. To identify the acetate-utilizing unidentified bacteria, RNA-SIP was conducted with (13)C(6)-glucose and (13)C(3)-propionate as sole carbon source, which were followed by phylogenetic analysis of 16S rRNA. We found that bacteria belonging to Synergistes group 4 were commonly detected in both 16S rRNA clone libraries derived from the sludge incubated with (13)C-glucose and (13)C-propionate. To confirm that this bacterial group can utilize acetate, specific FISH probe targeting for Synergistes group 4 was newly designed and applied to the sludge incubated with (14)C-acetate for MAR-FISH. The MAR-FISH result showed that bacteria belonging to Synergistes group 4 significantly took up acetate and their active population size was comparable to that of Methanosaeta in this sludge. In addition, as bacteria belonging to Synergistes group 4 had high K(m) for acetate and maximum utilization rate, they are more competitive for acetate over Methanosaeta at high acetate concentrations (2.5-10  mM). To our knowledge, it is the first time to report the acetate-utilizing activity of uncultured bacteria belonging to Synergistes group 4 and its competitive significance to acetoclastic methanogen, Methanosaeta.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Conventional anaerobic digesters (ADs) treating dairy manure are fed with raw or fermented manure rich in volatile fatty acids (VFAs). In contrast, pre-fermented AD (PF-AD) is fed with the more recalcitrant, fiber-rich fraction of manure that has been pre-fermented and depleted of VFAs. Thus, the substrate of PF-AD may be likened to a lean diet rich in fibers while the pre-fermentation stage fermenter is fed a relatively rich diet containing labile organic substances. Previous results have shown that conventional and pre-fermented ADs fed with raw or pre-fermented manure, respectively, produced comparable methane yields. The primary objective of this study was to characterize, using next-generation DNA sequencing, the bacterial communities in various bioreactors (pre-fermentation stage fermenter; various operational arrangements PF-AD; conventional single-stage AD; and a full scale AD) and compare the Firmicutes to Bacteroidetes (F/B) ratios in these different systems. Firmicutes and Bacteroidetes constituted the two most abundant phyla in all AD samples analyzed, as well as most of the samples analyzed in the fermenters and manure samples. Higher relative abundance of Bacteroidetes, ranging from 26% to 51% of bacteria, tended to be associated with PF-AD samples, while the highest relative abundance of Firmicutes occurred in the fermenter (maximum of 76% of bacteria) and manure (maximum of 66% of bacteria) samples. On average, primary stage fermenters exhibited microbiological traits linked to obesity: higher F/B ratios and a 'diet' that is less fibrous and more labile compared to that fed to PF-AD. On the other hand, microbial characteristics associated with leanness (lower F/B ratios combined with fibrous substrate) were associated with PF-AD. We propose that bacterial communities in AD shift depending on the quality of substrate, which ultimately results in maintaining VFA yields in PF-AD, similar to the role of bacterial communities and a high fiber diet in lean mice.
    PLoS ONE 01/2014; 9(5):e97252. · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A mesophilic, obligately anaerobic, lactate-, alcohol-, carbohydrate- and amino-acid- degrading bacterium, designated strain 7WAY-8-7T, was isolated from an upflow anaerobic sludge blanket reactor treating high-strength organic wastewater from isomerized sugar production processes. Cells of strain 7WAY-8-7T were motile, curved rods (0.7-1.0 x 5.0-8.0 μm). Spore formation was not observed. The strain grew optimally at 37 °C (range for growth was 25-40 °C) and pH 7.0 (pH 6.0-7.5), and could grow fermentatively on yeast extract, glucose, ribose, xylose, malate, tryptone, pyruvate, fumarate, Casamino acids, serine, and cysteine. The main end products of glucose fermentation were acetate and hydrogen. In co-culture with hydrogenotrophic methanogen Methanospirillum hungatei, strain 7WAY-8-7T could utilize lactate, glycerol, ethanol, 1-propanol, 1-butanol, L-glutamate, alanine, leucine, isoleucine, valine, histidine, asparagine, glutamine, arginine, lysine, threonine, 2-oxoglutarate, aspartate, and methionine. A Stickland reaction was not observed with some pairs of amino acids. Yeast extract was required for growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite, and Fe (III) were not used as terminal electron acceptors. The G+C content of the genomic DNA was 61.4 mol%. 16S rRNA gene sequence analysis revealed that the isolate belongs to the uncultured environmental clone clade (called as 'PD-UASB-13' in the greengene database) in the bacterial phylum Synergistetes, showing less than 90 % sequence similarities with those of closely related described species such as Aminivibrio pyruvatiphilus and Aminobacterium colombiense (89.7 % and 88.7 %, respectively). The major cellular fatty acids were iso-C13 : 0, iso-C15 : 0, aiC15 : 0, C18 : 1, C19 : 1, C20 : 1 and C21 : 1. A novel genus of a species, Lactivibrio alcoholicus gen. nov., sp. nov. is proposed for strain 7WAY-8-7T (=JCM 17151T =DSM 24196T =CGMCC 1.5159T).
    International Journal of Systematic and Evolutionary Microbiology 03/2014; · 2.79 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Single-stage anaerobic digestion (AD) was operated to treat high-strength food wastewater (FWW) derived from food waste recycling facilities at two different organic loading rates (OLRs) of 3.5 (Phase I) and 7 (Phase II) kgCOD/m(3)d. Changes in composition of microbial communities were investigated using quantitative real-time PCR (qPCR) and barcoded-pyrosequencing. At the high FWW loading rate, AD showed efficient performance (i.e., organic matter removal and methane production). Bacterial communities were represented by the phyla Bacteroidetes, Firmicutes, Synergistetes and Actinobacteria. During the entire digestion process, the relative abundance phylum Chloroflexi decreased significantly. The qPCR analysis demonstrated that the methanogenic communities shifted from aceticlastic (Methanosarcinales) to hydrogenotrophic methanogens (Methanobacteriales and Methanomicrobiales) with high increase in the proportion of syntrophic bacterial communities. Canonical correspondence analysis revealed a strong relationship between reactor performance and microbial community shifts.
    Bioresource Technology 02/2014; · 5.04 Impact Factor

Full-text (2 Sources)

Available from
Jul 15, 2014