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1.
Upflow anaerobic sludge blanket (UASB) reactor is one of the most applied technologies for various high-strength wastewater treatments. The present study analysed the microbial community changes in UASB granules during the transition from mesophilic to thermophilic conditions. Dynamicity of microbial community in granules was analysed using high-throughput sequencing of 16S ribosomal RNA gene amplicons, and the results showed that the temperature strictly determines the diversity of the microbial consortium. It was demonstrated that most of the microbes which were present in the initial mesophilic community were not found in the granules after the transition to thermophilic conditions. More specifically, only members from family Anaerolinaceae managed to tolerate the temperature change and contributed in maintaining the physical integrity of granular structure. On the contrary, new hydrolytic and fermentative bacteria were quickly replacing the old members in the community. A direct result from this abrupt change in the microbial diversity was the accumulation of volatile fatty acids and the concomitant pH drop in the reactor inhibiting the overall anaerobic digestion process. Nevertheless, by maintaining deliberately the pH levels at values higher than 6.5, a methanogen belonging to Methanoculleus genus emerged in the community enhancing the methane production. 相似文献
2.
Knowledge of connections between operational conditions, process stability, and microbial community dynamics is essential to enhance anaerobic digestion (AD) process efficiency and management. In this study, the detailed temporal effects of a sudden glycerol-based organic overloading on the AD microbial community and process imbalance were investigated in two replicate anaerobic digesters by a time-intensive sampling scheme. The microbial community time response to the overloading event was shorter than the shifts of reactor performance parameters. An increase in bacterial community dynamics and in the abundances of several microbial taxa, mainly within the Firmicutes, Tenericutes, and Chloroflexi phyla and Methanoculleus genera, could be detected prior to any shift on the reactor operational parameters. Reactor acidification already started within the first 24 h of the shock and headed the AD process to total inhibition in 72 h alongside with the largest shifts on microbiome, mostly the increase of Anaerosinus sp. and hydrogenotrophic methanogenic Archaea. In sum, this work proved that AD microbial community reacts very quickly to an organic overloading and some shifts occur prior to alterations on the performance parameters. The latter is very interesting as it can be used to improve AD process management protocols. 相似文献
3.
A psychrotolerant microbial consortium from a low-temperature anaerobic EGSB bioreactor was grown separately on acetate, propionate,
butyrate, and H 2/CO 2 at 30 and 10°C in glass flasks. In the course of the experiments, the cultivation temperature was changed at different time
intervals. The initial rates of substrate utilization were higher at 30 than at 10°C. However, the microbial consortium was
found to be well adapted to low temperatures; when grown at 10°C for 1.5–5 months, the rates of butyrate, propionate, and
H 2/CO 2 utilization increased steadily. When grown at 30°C for 1.5–2.5 months, this consortium retained its ability to degrade VFA
and H 2/CO 2 at 10°C. However, after long-term (150 days) cultivation at 10°C, its ability to utilize the substrates at 30°C decreased.
In the consortium grown in the acetate-containing medium, a Methanosaeta-like methanogen was predominant; in media with propionate and butyrate, besides VFA-degrading bacteria, acetoclastic Methanosaeta-like and hydrogenotrophic Methanospirillum-like methanogenic archaea prevailed. A Methanospirillum-like strain predominated in the H 2/CO 2-containing medium. The Methanospirillum strain of this microbial community was presumably psychrotolerant. A method based on changes in the cultivation temperature
is of practical interest and can be used to start up new bioreactors. 相似文献
4.
In this study, dual-cylindrical anaerobic digesters were designed and built on the pilot plant scale for the improvement of anaerobic digestion efficiency. The removal efficiency of organics, biogas productivity, yield, and microbial communities was evaluated as performance parameters of the digester. During the stable operational period in the continuous mode, the removal efficiencies of chemical oxygen demand and total solids were 74.1 and 65.1%, respectively. Biogas productivities of 63.9 m 3/m 3-FWW and 1.3 m 3/kg-VS removed were measured. The hydrogenotrophic methanogen orders, Methanomicrobiales and Methanobacteriales, were predominant over the aceticlastic methanogen order, Methanosarcinaceae, probably due to the tolerance of the hydrogenotrophs to environmental perturbation in the field and their faster growth rate compared with that of the aceticlastics. 相似文献
5.
In a deep aquifer associated with an accretionary prism, significant methane (CH 4) is produced by a subterranean microbial community. Here, we developed bioreactors for producing CH 4 and hydrogen (H 2) using anaerobic groundwater collected from the deep aquifer. To generate CH 4, the anaerobic groundwater amended with organic substrates was incubated in the bioreactor. At first, H 2 was detected and accumulated in the gas phase of the bioreactor. After the H 2 decreased, rapid CH 4 production was observed. Phylogenetic analysis targeting 16S rRNA genes revealed that the H 2-producing fermentative bacterium and hydrogenotrophic methanogen were predominant in the reactor. The results suggested that syntrophic biodegradation of organic substrates by the H 2-producing fermentative bacterium and the hydrogenotrophic methanogen contributed to the CH 4 production. For H 2 production, the anaerobic groundwater, amended with organic substrates and an inhibitor of methanogens (2-bromoethanesulfonate), was incubated in a bioreactor. After incubation for 24 h, H 2 was detected from the gas phase of the bioreactor and accumulated. Bacterial 16S rRNA gene analysis suggested the dominance of the H 2-producing fermentative bacterium in the reactor. Our study demonstrated a simple and rapid CH 4 and H 2 production utilizing anaerobic groundwater containing an active subterranean microbial community. 相似文献
6.
The objective of this study is to investigate the responses of methanogen populations to poultry waste addition by comparing the archaeal microbial populations in continuous anaerobic digesters with or without the addition of poultry waste as a co-substrate. Poultry waste was characterized as an organic/nitrogen-rich substrate for anaerobic digestion. Supplementing dilute dairy waste with poultry waste for anaerobic co-digestion to increase organic loading rate by 50% resulted in improved biogas production. Elevated ammonia derived from poultry waste did not lead to process inhibition at the organic loadings tested, demonstrating the feasibility of the anaerobic co-digestion of dairy and poultry wastes for improved treatment efficiency. The stability of the anaerobic co-digestion process was linked to the robust archaeal microbial community, which remained mostly unchanged in community structure following increases in organic loading and ammonia levels. Surprisingly, Crenarchaeota archaeal populations, instead of the Euryarchaeota methanogens, dominated the archaeal communities in the anaerobic digesters. The ecological functions of these abundant non-methanogen archaeal populations in anaerobic digestion remain to be identified. 相似文献
7.
In this study, the microbial community succession in a thermophilic methanogenic bioreactor under deteriorative and stable conditions that were induced by acidification and neutralization, respectively, was investigated using PCR-mediated single-strand conformation polymorphism (SSCP) based on the 16S rRNA gene, quantitative PCR, and fluorescence in situ hybridization (FISH). The SSCP analysis indicated that the archaeal community structure was closely correlated with the volatile fatty acid (VFA) concentration, while the bacterial population was impacted by pH. The archaeal community consisted mainly of two species of hydrogenotrophic methanogen (i.e., a Methanoculleus sp. and a Methanothermobacter sp.) and one species of aceticlastic methanogen (i.e., a Methanosarcina sp.). The quantitative PCR of the 16S rRNA gene from each methanogen revealed that the Methanoculleus sp. predominated among the methanogens during operation under stable conditions in the absence of VFAs. Accumulation of VFAs induced a dynamic transition of hydrogenotrophic methanogens, and in particular, a drastic change (i.e., an approximately 10,000-fold increase) in the amount of the 16S rRNA gene from the Methanothermobacter sp. The predominance of the one species of hydrogenotrophic methanogen was replaced by that of the other in response to the VFA concentration, suggesting that the dissolved hydrogen concentration played a decisive role in the predominance. The hydrogenotrophic methanogens existed close to bacteria in aggregates, and a transition of the associated bacteria was also observed by FISH analyses. The degradation of acetate accumulated during operation under deteriorative conditions was concomitant with the selective proliferation of the Methanosarcina sp., indicating effective acetate degradation by the aceticlastic methanogen. The simple methanogenic population in the thermophilic anaerobic digester significantly responded to the environmental conditions, especially to the concentration of VFAs. 相似文献
8.
ObjectiveTo reveal the shifts of microbial communities along ammonium gradients, and the relationship between microbial community composition and the anaerobic digestion performance using a high throughput sequencing technique.ResultsMethane production declined with increasing ammonium concentration, and was inhibited above 4 g l?1. The volatile fatty acids, especially acetate, accumulated with elevated ammonium. Prokaryotic populations showed different responses to the ammonium concentration: Clostridium, Tepidimicrobium, Sporanaerobacter, Peptostreptococcus, Sarcina and Peptoniphilus showed good tolerance to ammonium ions. However, Syntrophomonas with poor tolerance to ammonium may be inhibited during anaerobic digestion. During methanogenesis, Methanosarcina was the dominant methanogen.ConclusionExcessive ammonium inhibited methane production probably by decoupling the linkage between acidification process and methanogenesis, and finally resulted in different performance in anaerobic digestion. 相似文献
9.
Multi-walled carbon nanotubes (MWCNTs) released into the sewage may cause negative and/or positive effects on the treatment system. The objective of this study was to explore over 110 days’ effect of MWCNTs on the performance of anaerobic granular sludge and microbial community structures in an upflow anaerobic sludge blanket (UASB) reactor. The results showed that MWCNTs had no significant effect on the removal of chemical oxidation demand (COD) and ammonia in UASB reactor, but the total phosphorus (TP) removal efficiency increased by 29.34%. The biogas production of the reactor did not change. The anaerobic granular sludge tended to excrete more EPS to resist the effects of MWCNTs during the long-term impact. Illumina MiSeq sequencing of 16S rRNA gene revealed that MWCNTs did not affect the microbial diversity, but altered the composition and structure of microbial community in the reactor. In this process, Saccharibacteria replaced Proteobacteria as the highest abundant bacterial phylum. MWCNTs promoted the differentiation of methanogen structure, resulting in increase of Methanomassiliicoccus, Methanoculleus, and the uncultured WCHA1–57. These results indicated that MWCNTs impacted the performance of UASB reactor and the structures of the microbial community in anaerobic granular sludge. 相似文献
10.
The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies. 相似文献
11.
Aims: The objective of this work was to provide functional evidence of key metabolic pathways important for anaerobic digestion processes through the identification of highly expressed proteins in a mixed anaerobic microbial consortium. Methods and Results: The microbial communities from an anaerobic industrial‐like wastewater treatment bioreactor were characterized using phylogenetic analyses and metaproteomics. Clone libraries indicated that the bacterial community in the bioreactor was diverse while the archaeal population was mainly composed of Methanocorpusculum‐like (76%) micro‐organisms. Three hundred and eighty‐eight reproducible protein spots were obtained on 2‐D gels, of which 70 were excised and 33 were identified. The putative functions of the proteins detected in the anaerobic bioreactor were related to cellular processes, including methanogenesis from CO 2 and acetate, glycolysis and the pentose phosphate pathway. Metaproteomics also indicated, by protein assignment, the presence of specific micro‐organisms in the bioreactor. However, only a limited overlap was observed between the phylogenetic and metaproteomic analyses. Conclusions: This study provides some direct evidence of the microbial activities taking place during anaerobic digestion. Significance and Impact of Study: This study demonstrates metaproteomics as a useful tool to uncover key biochemical pathways underpinning specific anaerobic bioprocesses. 相似文献
12.
The composting process is carried out under aerobic conditions involving bacteria, archaea, and fungi. Little is known about
the diversity of archaeal community in compost, although they may play an important role in methane production and ammonia
oxidation. In the present study, archaeal community dynamics during cattle manure composting were analyzed using a clone library
of the archaeal 16S rRNA gene. The results indicated that methane-producing archaea (methanogen) and ammonia-oxidizing archaea
(AOA) may be the dominant microbes throughout the composting. The community consisted primarily of Methanocorpusculum-like and Methanosarcina-like sequences until day 2, while the number of Candidatus Nitrososphaera-like sequences increased from day 6 to day 30. Methanosarcina thermophila-like sequences were dominant from day 2, suggesting that M. thermophila-like species can adapt to increasing temperature or nutrient loss. A denaturant gradient gel electrophoresis analysis of
the archaeal amoA genes revealed that the dominant amoA gene sequence with 99% homology to that of Candidatus Nitrososphaera gargensis was identical to those obtained from a different composting facility. These data suggested that
AOA may play a role in ammonia oxidation in several composting practices. Our results provide fundamental information regarding
archaeal community dynamics that will help in understanding the collective microbial community in compost. 相似文献
13.
Although cold environments are major contributors to global biogeochemical cycles, comparatively little is known about their microbial community function, structure, and limits of activity. In this study a microcosm based approach was used to investigate the effects of temperature, and methanogenic substrate amendment, (acetate, methanol and H 2/CO 2) on methanogen activity and methanogen community structure in high Arctic wetlands (Solvatnet and Stuphallet, Svalbard). Methane production was not detected in Stuphallet sediment microcosms (over a 150 day period) and occurred within Solvatnet sediments microcosms (within 24 hours) at temperatures from 5 to 40°C, the maximum temperature being at far higher than in situ maximum temperatures (which range from air temperatures of -1.4 to 14.1°C during summer months). Distinct responses were observed in the Solvatnet methanogen community under different short term incubation conditions. Specifically, different communities were selected at higher and lower temperatures. At lower temperatures (5°C) addition of exogenous substrates (acetate, methanol or H 2/CO 2) had no stimulatory effect on the rate of methanogenesis or on methanogen community structure. The community in these incubations was dominated by members of the Methanoregulaceae/WCHA2-08 family-level group, which were most similar to the psychrotolerant hydrogenotrophic methanogen Methanosphaerula palustris strain E1-9c. In contrast, at higher temperatures, substrate amendment enhanced methane production in H 2/CO 2 amended microcosms, and played a clear role in structuring methanogen communities. Specifically, at 30°C members of the Methanoregulaceae/WCHA2-08 predominated following incubation with H 2/CO 2, and Methanosarcinaceaeand Methanosaetaceae were enriched in response to acetate addition. These results may indicate that in transiently cold environments, methanogen communities can rapidly respond to moderate short term increases in temperature, but not necessarily to the seasonal release of previously frozen organic carbon from thawing permafrost soils. However, as temperatures increase such inputs of carbon will likely have a greater influence on methane production and methanogen community structure. Understanding the action and limitations of anaerobic microorganisms within cold environments may provide information which can be used in defining region-specific differences in the microbial processes; which ultimately control methane flux to the atmosphere. 相似文献
14.
Thermophilic dry anaerobic digestion of sludge for cellulose methanization was acclimated at 53 °C for nearly 5 years using
a waste paper-based medium. The stability of the microbial community structure and the microbial community responsible for
the cellulose methanization were studied by 16S rRNA gene-based clone library analysis. The microbial community structure
remained stable during the long-term acclimation period. Hydrogenotrophic methanogens dominated in methanogens and Methanothermobacter, Methanobacterium, Methanoculleus, and Methanosarcina were responsible for the methane production. Bacteria showed relatively high diversity and distributed mainly in the phyla
Firmicutes, Bacteroidetes, and Synergistetes. Ninety percent of operational taxonomic units (OTUs) were affiliated with the phylum Firmicutes, indicating the crucial roles of this phylum in the digestion. Relatives of Clostridium stercorarium, Clostridium thermocellum, and Halocella cellulosilytica were dominant cellulose degraders. The acclimated stable sludge was used to treat garbage stillage discharged from a fuel
ethanol production process, and the shift of microbial communities with the change of feed was analyzed. Both archaeal and
bacterial communities had obviously changed: Methanoculleus spp. and Methanothermobacter spp. and the protein- and fatty acid-degrading bacteria became dominant. Accumulation of ammonia as well as volatile fatty
acids led to the inhibition of microbial activity and finally resulted in the deterioration of methane fermentation of the
garbage stillage. 相似文献
15.
This study characterized the microbial community and population dynamics in an anaerobic hybrid reactor (AHR) treating cassava
starch wastewater. Methanogens and nonmethanogens were followed during the start-up and operation of the reactor, and linked
to operational and performance data. Biomass samples taken from the sludge bed and packed bed zones of the AHR at intervals
throughout the operational period were examined by 16S rRNA fluorescence in situ hybridization (FISH). The start-up seed and the reactor biomass were sampled during the feeding of the wastewater with a
chemical oxygen demand (COD) value of 8 g L −1 and a hydraulic retention time (HRT) of 8 days. These samples were characterized by the predominance of cells with long-rod
morphology similar to Methanosaeta spp. Following a sharp operational change, accomplished by increasing the COD concentration of the organic influent from
8 to 10 g L −1 and reducing the HRT from 8 to 5 days, there was a doubling of the organic loading rate, a reduction of the COD removal efficiency,
as well as decreased methane content in the biogas and an accumulation of total volatile acids in the reactor. Moreover, this
operational change resulted in a significant population shift from long-rod Methanosaeta-like cells to tetrad-forming Methanosarcina-like cells. The distributions of microbial populations involved in different zones of the AHR were determined. The results
showed that nonmethanogens became the predominant population in both sludge and the packed bed zone. However, the percentage
of methanogens in the packed bed zone was higher than that in the sludge bed zone. This higher percentage of methanogens was
likely caused by the fact that the packed bed zone provided a suitable environmental condition with an appropriate nutrient
availability for methanogen growth. 相似文献
16.
Aims: The aim of the study was to investigate the feasibility of a continuous reactor for psychrophilic anaerobic wastewater treatment by using the sludge from cold natural environment. Methods and Results: Six sludge samples (S1–S6) were collected from different cold natural locations to select sludge with high anaerobic microbial activity under low temperatures. After a 225‐day incubation, the maximum specific methane production rate of a waterfowl lake sediment (S1) at 15°C (70·5 mLCH 4 gVSS ?1 day ?1) was much higher than all other samples. S1 was thus chosen as the seed sludge for the reactor treating synthetic brewery wastewater at 15°C, by immobilizing the micro‐organisms on polyurethane foam carriers. The chemical oxygen demand (COD) removal efficiency reached over 80% after 240‐day operation at an organic loading rate of 5·3 kg m ?3 day ?1, and significant enrichment of biomass was observed. Clone libraries of the microbial communities in the inoculum had high diversities for both archaea and bacteria. Along with a decrease in microbial community diversities, the dominant bacteria (79·5%) at the end of the operation represented the phylum Firmicutes, while the dominant archaeon (41·5%) showed a similarity of 98% with the psychrotolerant methanogen Methanosarcina lacustris. Conclusions: The possibility of using anaerobic micro‐organisms from cold environments in anaerobic wastewater treatment under psychrophilic conditions is supported by these findings. Significance and Impact of the Study: This study enriches the theory on microbial community and the application on anaerobic treatment of sludge from cold natural environments. 相似文献
17.
The lipid composition of the microbial community inhabiting activated sludge in a pilot reactor for the anaerobic oxidation of ammonium (anammox) at the Kur’yanovo Treatment Plant (Moscow) has been studied. The fatty acid composition is mostly based on common fatty acids C 14–C 18 (95%) with both normal and isomeric structures. The biomass of activated sludge was found to contain lipids with the so-called ladderane substances (ladder alcohols and fatty acids) that are common for anammox bacteria: C 20-[3]-lad-derane and C 20-[5]-ladderane alcohols and C 18- and C 20-[3]-ladderane and C 18- and C 20-[5]-ladderane acids. In addition, the native extract contained both simple and compound ethers of the above-mentioned substances with residues of phosphocholine, phosphoethanolamine, and phosphoglycerine. The spectra of the electron impact and tandem mass spectrometry of certain substances have been obtained and published for the first time. 相似文献
18.
Anaerobic digestion (AD) is the most popular path of organic waste disposal. It is often used in wastewater treatment plants for excessive sludge removal. Methanogenic fermentation had usually been performed under mesophilic conditions, but in the past few years the thermophilic processes have become more popular due to economics and sludge sanitation. Methanogens, the group of microorganisms responsible for methane production, are thought to be sensitive to temperature change and it has already been proven that the communities performing methanogenesis under mesophilic and thermophilic conditions differ. But in most cases the research performed on methanogen diversity and changeability was undertaken in two separate anaerobic chambers for meso- and thermophilic conditions. It is also known that there is a group of microorganisms performing AD which are insensitive to temperature. Also the linkage between digester performance and its microbial content and community changeability is still not fully understood. That is why in this experiment we analyzed the bacterial community performing methanogenesis in a pilot scale anaerobic chamber during the shift from mesophilic to thermophilic conditions to point at the group of temperature tolerant microorganisms and their performance. The research was performed with PCR– DGGE (polymerase chain reaction–denaturing gradient gel electrophoresis). It occurred that the community biodiversity decreased together with a temperature increase. The changes were coherent for both the total bacteria community and methanogens. These bacterial shifts were also convergent with biogas production—it decreased in the beginning of the thermophilic phase with the bacterial biodiversity decrease and increased when the community seemed to be restored. DGGE results suggest that among a wide variety of microorganisms involved in AD there is a GC-rich group relatively insensitive towards temperature change, able to adapt quickly to shifts in temperature and perform AD effectively. The studies of this microbial group could be a step forward in developing more efficient anaerobic digestion technology. 相似文献
19.
The microbial population structure and function of natural anaerobic communities maintained in lab-scale continuously stirred
tank reactors at different lactate to sulfate ratios and in the absence of sulfate were analyzed using an integrated approach
of molecular techniques and chemical analysis. The population structure, determined by denaturing gradient gel electrophoresis
and by the use of oligonucleotide probes, was linked to the functional changes in the reactors. At the influent lactate to
sulfate molar ratio of 0.35 mol mol −1, i.e., electron donor limitation, lactate oxidation was mainly carried out by incompletely oxidizing sulfate-reducing bacteria,
which formed 80–85% of the total bacterial population. Desulfomicrobium- and Desulfovibrio-like species were the most abundant sulfate-reducing bacteria. Acetogens and methanogenic Archaea were mostly outcompeted,
although less than 2% of an acetogenic population could still be observed at this limiting concentration of lactate. In the
near absence of sulfate (i.e., at very high lactate/sulfate ratio), acetogens and methanogenic Archaea were the dominant microbial
communities. Acetogenic bacteria represented by Dendrosporobacter quercicolus-like species formed more than 70% of the population, while methanogenic bacteria related to uncultured Archaea comprising
about 10–15% of the microbial community. At an influent lactate to sulfate molar ratio of 2 mol mol −1, i.e., under sulfate-limiting conditions, a different metabolic route was followed by the mixed anaerobic community. Apparently,
lactate was fermented to acetate and propionate, while the majority of sulfidogenesis and methanogenesis were dependent on
these fermentation products. This was consistent with the presence of significant levels (40–45% of total bacteria) of D. quercicolus-like heteroacetogens and a corresponding increase of propionate-oxidizing Desulfobulbus-like sulfate-reducing bacteria (20% of the total bacteria). Methanogenic Archaea accounted for 10% of the total microbial
community. 相似文献
20.
In this study a microbial community suitable for anaerobic digestion of carrot pomace was developed from inocula obtained from natural environmental sources. The changes along the process were monitored using pyrosequencing of the 16S rRNA gene. As the community adapted from a diverse natural community to a community with a definite function, diversity decreased drastically. Major bacterial groups remaining after enrichment were Bacilli (31-45.3%), Porphyromonadaceae (12.1-24.8%) and Spirochaetes (12.5-18.5%). The archaeal population was even less diverse and mainly represented by a single OTU that was 99.7% similar to Methanosarcina mazei. One enrichment which failed to produce large amounts of methane had shifts in the bacterial populations and loss of methanogenic archaea. 相似文献
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