Microbial community composition and dynamics in high-temperature biogas reactors using industrial bioethanol waste as substrate

Abstract

Stillage, which is generated during bioethanol production, constitutes a promising substrate for biogas production within the scope of an integrated biorefinery concept. In this study, a microbial community was grown on thin stillage as mono-substrate in a continuous stirred tank reactor (CSTR) at a constant temperature of 55 °C, at an organic loading rate of 1.5 goTS/L*d and a retention time of 25 days. Using an amplicon-based dataset of 17,400 high-quality sequences of 16S rRNA gene fragments (V2-V3 regions), predominance of Bacteria assigned to the families Thermotogaceae and Elusimicrobiaceae was detected. Dominant members of methane-producing Euryarchaeota within the CSTR belonged to obligate acetoclastic Methanosaetaceae and hydrogenotrophic Methanobacteriaceae. In order to investigate population dynamics during reactor acidification, the organic loading rate was increased abruptly, which resulted in an elevated concentration of volatile fatty acids. Acidification led to a decrease in relative abundance of Bacteria accompanied with stable numbers of Archaea. Nevertheless, the abundance of Methanosaetaceae increased while that of Methanobacteriales decreased successively. These findings demonstrate that a profound intervention to the biogas process may result in persistent community changes and reveals uncommon bacterial families as process-relevant microorganisms.

Profile of bacterial communities in South African mine-water samples using Illumina next-generation sequencing platform

“…bacteria associated with Lucilia spp. (Singh et al 2014), tobacco waste extract (Liu et al 2014a, b14), styrene-degrading biofilters (Portune et al 2014), activated sludge (Zhao et al 2014), high-temperature biogas reactors (Röske et al 2014), phyllosphere of rice (Ren et al 2014), river receiving effluents from swine farm and farmhouse restaurant (Lu and Lu 2014), endophytes of sugar beet (Shi et al 2014), petroleum reservoir , intestinal environment of rats , mine tailings (Liu et al 2014a, b), heavy metals polluted soil (Gołębiewski et al 2014), soil horizons and drain sediments of coastal acid sulfate landscape (Stroud et al 2014). The first 16S rRNA gene-based microbial analysis of mine-water systems was done in the mid-1990s (Goebel and Stackebrandt 1994).…”

High temperature biogas reactors to treat stillage from an industrial bioethanol process: Metabolic and microbial characterization

“…. Interestingly, and based on DGGE analysis, the original digested sludge showed much higher microbial diversity than the consortium developed on thin stillage as mono‐substrate . The ammonia concentration decreased from 2.0 g/L to 0.4 g/L, while the pH value decreased from 8.0 to 7.4.…”

“…As previously described by Röske et al. , DGGE analyses were performed using total reactor DNA as templates. In brief, 16 S rRNA‐encoding gene fragments from Bacteria were amplified by using the specific oligonucleotides GM5for_GC (5′‐ CCTACGGGAGGCAGCAG‐3′) and 907rm (5′‐CCGTCAATTCMTTTGAGTTT‐3′) as published by Muyzer et al.…”

“…Amplicons from methanogenic Archaea were obtained by the application of primers 0376for_GC (5′‐CCAGGCCCTACGGGGYGC‐3′) and 0691rev (5′‐GGATTACARGATTTCAC‐3′) in PCR as described by Röske et al. and Watanabe et al. .…”

“…In the European Union, more than 8000 biogas plants are currently operating, but very few of them process primarily protein‐rich waste, although a huge amount is being generated continuously in pig, cattle, and bird farms . Therefore, knowledge about microbial and metabolite details in such an environment is rare . The aim of the present study was to investigate the biogas formation using thin stillage as a mono‐substrate at elevated temperatures.…”