Anaerobic Microbial Degradation Research Articles

New insights into the anaerobic microbial degradation of decabrominated diphenyl ether (BDE-209) in coastal marine sediments

Severe contamination of decabrominated diphenyl ether (BDE-209, an emerging persistent organic pollutant) in coastal marine sediments has posed a serious threat to the marine ecosystems. Anaerobic microbial degradation can affect the toxicity and environmental fate of BDE-209 in anoxic marine sediments. However, little is known about the anaerobic microbial degradation of BDE-209 in anoxic marine/coastal sediments. In this study, the anaerobic degradation of BDE-209 in microcosms containing coastal marine sediments from a contaminated bay located in Southern China was investigated. It was observed that over 70% of the BDE-209 (5 μmol) added to the anaerobic sediment microcosms disappeared after 90-day of incubation. Thirty-five debrominated products (tetra- to nonaBDEs) were identified by GC-MS. Remarkably, a majority of these products (i.e. 20 products, including BDE-52, -92, −101, −102, −103, −133, −144, −146, −150, −161, −171, −172, −175, −177, −178, −180, −182, −188, −193, −199) have not been previously reported in the literature on the anaerobic microbial degradation of BDE-209 in sediments. There was no preferential debromination among ortho-, meta-, and para-bromines on BDE-209 and higher-brominated diphenyl ethers were the predominant debromination products. High-throughput sequencing revealed that the relative abundances of 9 microbial genera in the sediment microcosms increased as the anaerobic degradation of BDE-209 progressed, indicating their involvements in the degradation process. Taken together, our findings provided new insights into the anaerobic microbial degradation of BDE-209 in anoxic marine sediments.

Enhanced anaerobic degradation of selected nitrogen heterocyclic compounds with the assistance of carboxymethyl cellulose

Carboxymethyl cellulose (CMC) is a modified cellulose compound that is dispersible in water. Microbial anaerobic degradation of nitrogen heterocyclic compounds (NHCs) in wastewater treatment may be enhanced by CMC addition, but this remains uncertain due to a lack of experimental evidence. In this study, It was demonstrated that CMC is a suitable co-metabolic matrix in an enhanced anaerobic degradation of quinoline and indole in coal gasification wastewater. When the dosage of CMC was 0.5 mg/L, a reactor exhibited a high degradation efficiency on quinoline and indole, with ratios of 95.23 ± 1.99% and 94.33 ± 3.45%. The addition of CMC increased the concentration of extracellular polymeric substances in anaerobic sludge and increased the particle size of the sludge, which improved the microbial stability and sedimentation of anaerobic granular sludge. Analysis of high-throughput sequencing indicated that the addition of CMC improved the richness and diversity of bacterial and archaea communities. Acetic acid metabolism was the primary mechanism to produce methane during anaerobic degradation of NHCs wastewater.

Microbial anaerobic digestion: process dynamics and implications from the renewable energy, environmental and agronomy perspectives

Microorganisms have been allied with serious deleterious environmental, human and public health hazards. Microbial interactions are vital in the biotransformation of wastes to valuable end products via the waste-to-energy technology. Microbial anaerobic degradation has been considered as a powerful tool to address the shortcomings faced by conventional energy sources (e.g. the conventional energy sources are non-renewable, can deplete over time and are very costly). It is the anaerobic breakdown of organic wastes within the precincts of an airtight biodigester, by the concerted activities of four metabolically linked microorganisms participating at specific phases of the process to ultimately yield methane and carbon dioxide. Microorganisms are present in these wastes from animal origin, feeds or during collection of the wastes for disposal. The threefold benefit of the process includes: firstly, sanitization of the organic wastes whereby the pathogens of environmental and public health significance can be reduced to threshold levels recommended for safe handling by humans. Also, it addresses the pollution problem caused by greenhouse gas emission. Secondly, the recovered digestate contains macro- and micronutrients that are valuable for plant growth. Soil amendment with digestate influences the microbial activity, the microbial biomass structure and the size which in turn improve on soil fertility and quality thus, improve on food security. Clearly, this minimizes the use of synthetic chemical fertilizers with adverse effects. Thirdly, anaerobic digestion of biomass generates biogas, a renewable energy from waste degradation which can be used for cooking, heating and or harnessed to produce electricity.

Isolation of Microorganisms Associated with Biodegradation of Household Domestic Wastes for Biogas Production in Niger State, Nigeria

This study focused on the isolation of microorganisms associated with biodegradation of domestic wastes in three rural communities (Gbadagbadzu (A), Ndawangwa (B), and Kuchiworo (C)) in Lavun Local Government Area of Niger State, Nigeria, for biogas production. The biogas was produced by anaerobic microbial degradation of different biodegradable household domestic waste aided by fresh rumen of cow. The anaerobic microbial degradation was carried out in a temperature range of 250C to 320C for a detention time of 39 days for rural biogas production. The results showed the presence of the following bacteria: Bacillus cereus, Sphingobacterium yamdrokense, Clostridium perfringens, Salmonella typhi, Alkaligenes faecalis, Pseudomonas aeruginosa, Staphylococcus epidermidis, Klebsiella pneumoniae and Bacillus licheniformis while fungi isolated were Muccor pusillus and Aspergillus flavus. The research therefore shows that household domestic wastes have the potential to produce biogas with or without the addition of inoculum.

Wet Corn Stover Storage: Correlating Fiber Reactivity With Storage Acids Over a Wide Moisture Range

Wet storage is synonymous with ensilage, a simple biotechnology that has been used to preserve forage for livestock feed for millennia. In this natural process, organic acids are produced by anaerobic microbial degradation of a small fraction of the biomass, and these acids reduce the pH to levels that minimize further microbial activity and can preserve the biomass for years as long as anaerobic conditions are maintained. These organic acids also result in mild pretreatment with potential to enhance downstream conversion processes, making this an effective storage strategy. However, the degree and significance of this natural pretreatment capability of ensiled storage on downstream processes has not previously been quantified across a range of storage conditions. In this study, the degree of pretreatment was investigated by measuring the reactivity of corn stover fiber to cellulolytic enzymes. Although the results indicated significant improvement in hydrolytic outcomes after wet storage, by a factor of up to 2.4, saccharification of cellulose to sugar monomers was still limited. The results also show that dominance of lactic acid in the ensilage process is key to wet storage [pretreatment] effectiveness as in the livestock feed industry. Lactic acid pKa value is lower than the pKa of other silage acids and lower than typical silage pH. This gives lactic acid the advantage of being in the more dissociated form, with more protons available to facilitate pretreatment hydrolysis. However, unlike the livestock feed industry, where quality feedstock is attainable within very narrow storage moisture range, for biofuel purposes, a wider range of 35 ―65% is appropriate in achieving a similar quality outcome. This is true both for the immediate fiber response to enzymes and with subsequent pretreatment. This wider moisture range implies more flexibility in harvest schedule without sacrificing feedstock quality, thus alleviating concerns over feedstock quality that biomass suppliers or biorefineries may have.

Diagenesis of Organic Matter in the Top Layer of the Sediments of the Peter the Great Bay in Hypoxia Locations

During Cruise 62nd of the R/V “Professor Gagarinsky” in September, 2014, the carbonate system of sediments and contents of nutrients and organic carbon in pore water were studied in two geochemical stations located in hypoxia areas in the Peter the Great Bay. It was established that the concentrations of silica, phosphorus, and ammonium increase by 5, 10, and 20 times, respectively, with sediment depth to 70–80 cm. The alkalinity, dissolved inorganic carbon, and the partial pressure of carbon dioxide significantly increase with depth, while рН value and organic matter (ОM) decrease. Changes in the chemical composition of pore water with sediment depth (0–80 cm) are caused by anaerobic microbial degradation of OM, concentration of which in the top sediment layer is 2–3%. The degradation products of OM in the bottom waters of bay and pore waters of bottom sediments indicate that its main sources are diatoms. During hypoxia, the oxygen demand rate by sediment surface near Furugelm Island is estimated to be 5 mmol/(m2 day). A combination of such factors as downwelling circulation, the absence of photosynthetically active radiation, and the high oxygen demand rate at the water/sediment interface provides hypoxia formation in the depressions of the Peter the Great Bay bottom topography.

Trace Element Behavior in Methane-Rich and Methane-Free Groundwater in North and East Texas.

There is concern about adverse impacts of natural gas (primarily methane) production on groundwater quality; however, data on trace element concentrations are limited. The objective of this study was to compare the distribution of trace elements in groundwater samples with and without dissolved methane in aquifers overlying the Barnett Shale (Hood and Parker counties, 207 samples) and the Haynesville Shale (Panola County, 42 samples). Both shales have been subjected to intensive hydraulic fracturing for gas production. Well clusters with high dissolved methane were previously found in these counties and are thought to be of natural origin. Overall, groundwater in these counties is of excellent quality with typically low elemental concentrations. Several statistical analyses strongly suggest that most trace element concentrations, generally at low background levels, are no higher and even reduced when dissolved methane is present. In addition, trace element concentrations are not correlated with distance to gas wells. The reduction in trace element concentrations is attributed to anaerobic microbial degradation of methane, is associated with a higher pH (>8.5), and, likely, with precipitation of carbonates and pyrite and formation of clays. Trace and other elements are likely incorporated within the precipitating mineral crystalline network or sorbed. High pH values are found throughout these high-methane clusters (e.g., Parker-Hood cluster), even in subregions where methane is not present, which is consistent with a pervasive natural origin of dissolved methane rather than a limited gas well source.

Impact of sorption processes on PCE concentrations in organohalide-respiring aquifer sediment samples

The evaluation of groundwater contaminant e.g. tetrachloroethene (PCE) degradation processes requires complete quantification of and pathway analysis of the groundwater contaminant under investigation. For example the reduction of PCE concentrations in the groundwater by unknown dissolution and/or sorption processes will impede interpretation of the fate and behaviour of such contaminants. In the present study PCE dissolution and sorption processes during anaerobic microbial degradation of chlorinated ethenes were investigated. For this purpose, microcosms were prepared using sediment samples from a PCE-contaminated aquifer, which in previous studies had demonstrated anaerobic organohalide respiration of PCE. Solid/water distribution coefficients (kd) of PCE were determined and validated by loss-on-ignition (LOI) and PCE sorption experiments. The determined kd magnitudes indicated methodological congruency, yielding values for sediment samples within a range of 1.15±0.02 to 5.93±0.34L·kg−1. The microcosm experiment showed lower PCE concentrations than expected, based on spiked PCE and observed anaerobic microbial degradation processes. Nevertheless the amount of PCE spike added was completely recovered albeit in the form of lower chlorinated metabolites. A delay due to dissolution processes was not responsible for this phenomenon. Sorption to sediments could only partially explain the reduction of PCE in the water phase. Accordingly, the results point to reversible sorption processes of PCE, possibly onto bacterial cell compartments and/or exopolymeric substances.

Self-sustaining advanced wastewater purification and simultaneous in situ nutrient recovery in a novel bioelectrochemical system

Wastewater containing abundant organics and nutrient resources requires large energy input in conventional treatment technologies to reach the discharge standard and/or to recover nutrient resources. This study presents a self-sustaining advanced wastewater purification and in situ nutrient recovery process accomplished by a newly designed 10-liter-scale bioelectrochemical system containing membrane stack configuration, which was called an advanced microbial nutrient recovery cell (AMNRC). After subsequent treatments in the AMNRC’s anode, cathode and stacked desalination chambers, all the removals of organics and nutrient in the domestic wastewater were achieved higher than 95%, which represented <24.9mg/L of chemical oxygen demand, <14.2mg/L of total nitrogen (TN), <6.5mg/L of ammonium nitrogen (NH4+-N), and <0.49mg/L of total phosphorus (TP) were left in the final effluent. Three sequential treatment processes including anaerobic microbial degradation, aerobic microbial treatment, and electrical ion migration comprehensively facilitated the above removals. Meanwhile TN, NH4+-N and TP were concentrated in the recovery solution by 260%, 150%, and 490%, respectively. Ammonium and phosphate were then recovered as struvite during crystallization. The AMNRC was proved as an energy neutral approach to efficiently purify wastewater and simultaneously recover nutrient, the treatment processes were driven by the energy extracted from wastewater itself.

Microbial Community Response to Simulated Petroleum Seepage in Caspian Sea Sediments.

Anaerobic microbial hydrocarbon degradation is a major biogeochemical process at marine seeps. Here we studied the response of the microbial community to petroleum seepage simulated for 190 days in a sediment core from the Caspian Sea using a sediment-oil-flow-through (SOFT) system. Untreated (without simulated petroleum seepage) and SOFT sediment microbial communities shared 43% bacterial genus-level 16S rRNA-based operational taxonomic units (OTU0.945) but shared only 23% archaeal OTU0.945. The community differed significantly between sediment layers. The detection of fourfold higher deltaproteobacterial cell numbers in SOFT than in untreated sediment at depths characterized by highest sulfate reduction rates and strongest decrease of gaseous and mid-chain alkane concentrations indicated a specific response of hydrocarbon-degrading Deltaproteobacteria. Based on an increase in specific CARD-FISH cell numbers, we suggest the following groups of sulfate-reducing bacteria to be likely responsible for the observed decrease in aliphatic and aromatic hydrocarbon concentration in SOFT sediments: clade SCA1 for propane and butane degradation, clade LCA2 for mid- to long-chain alkane degradation, clade Cyhx for cycloalkanes, pentane and hexane degradation, and relatives of Desulfobacula for toluene degradation. Highest numbers of archaea of the genus Methanosarcina were found in the methanogenic zone of the SOFT core where we detected preferential degradation of long-chain hydrocarbons. Sequencing of masD, a marker gene for alkane degradation encoding (1-methylalkyl)succinate synthase, revealed a low diversity in SOFT sediment with two abundant species-level MasD OTU0.96.

Enrichment of sulfidogenic bacteria from the human intestinal tract

Hydrogen sulfide is formed in the human intestinal tract as the end product of the anaerobic microbial degradation of sulfur compounds present in mucus, bile or proteins. Since human gut microbial sulfur metabolism has been poorly characterized, we aimed to identify and isolate the microorganisms involved in sulfide formation. Fresh fecal samples from one healthy donor and one diagnosed with irritable bowel syndrome were used as inocula for enrichments that were supplemented with sulfate or sulfite as electron acceptors in combination with different electron donors. After two transfers, cultures with high sulfide production were selected and the phylogenetic composition of the enriched microbial communities was determined. Sulfite respiration and cysteine degradation were the dominant sulfidogenic processes, and the most abundant bacteria enriched belonged to Bilophila and Clostridium cluster XIVa. Different isolates were obtained and remarkably included a novel sulfite reducer, designated strain 2C. Strain 2C belongs to the Veillonellaceae family of Firmicutes phylum and showed limited (91%) 16S rRNA gene sequence similarity with that of known Sporomusa species and hence may represent a novel genus. This study indicates that bacteria that utilize sulfite and organic sulfur compounds rather than merely sulfate are relevant for human intestinal sulfur metabolism.

Aerobic versus Anaerobic Microbial Degradation of Clothianidin under Simulated California Rice Field Conditions.

Microbial degradation of clothianidin was characterized under aerobic and anaerobic California rice field conditions. Rate constants (k) and half-lives (DT50) were determined for aerobic and anaerobic microcosms, and an enrichment experiment was performed at various nutrient conditions and pesticide concentrations. Temperature effects on anaerobic degradation rates were determined at 22 ± 2 and 35 ± 2 °C. Microbial growth was assessed in the presence of various pesticide concentrations, and distinct colonies were isolated and identified. Slow aerobic degradation was observed, but anaerobic degradation occurred rapidly at both 25 and 35 °C. Transformation rates and DT50 values in flooded soil at 35 ± 2 °C (k = -7.16 × 10(-2) ± 3.08 × 10(-3) day(-1), DT50 = 9.7 days) were significantly faster than in 25 ± 2 °C microcosms (k= -2.45 × 10(-2) ± 1.59 × 10(-3) day(-1), DT50 = 28.3 days). At the field scale, biodegradation of clothianidin will vary with extent of oxygenation.

Optical properties of chromophoric dissolved organic matter (CDOM) in surface and pore waters adjacent to an oil well in a southern California salt marsh

Chromophoric dissolved organic matter (CDOM) optical properties were measured in surface and pore waters as a function of depth and distance from an oil well in a southern California salt marsh. Higher fluorescence and absorbances in pore vs. surface waters suggest soil pore water is a reservoir of CDOM in the marsh. Protein-like fluorophores in pore waters at distinct depths corresponded to variations in sulfate depletion and Fe(II) concentrations from anaerobic microbial activity. These variations were supported by fluorescence indexes and are consistent with differences in optical molecular weight and aromaticity indicators. Fluorescence indices were consistent with autochthonous material of aquatic origin in surface waters, with more terrestrial, humified allochthonous material in deeper pore waters. CDOM optical properties were consistent with significantly enhanced microbial activity in regions closest to the oil well, along with a three-dimensional excitation/emission matrix fluorescence spectrum peak attributable to oil, suggesting anaerobic microbial degradation of oil.

Fate of Bisphenol A in Terrestrial and Aquatic Environments.

Bisphenol A (2,2-bis[4-hydroxyphenyl]propane, BPA), the monomer used to produce polycarbonate plastic and epoxy resins, is weakly estrogenic and therefore of environmental and human health interest. Due to the high production volumes and disposal of products made from BPA, polycarbonate plastic and epoxy resins, BPA has entered terrestrial and aquatic environments. In the presence of oxygen, diverse taxa of bacteria, fungi, algae and even higher plants metabolize BPA, but anaerobic microbial degradation has not been documented. Recent reports demonstrated that abiotic processes mediate BPA transformation and mineralization in the absence of oxygen, indicating that BPA is susceptible to degradation under anoxic conditions. This review summarizes biological and nonbiological processes that lead to BPA transformation and degradation, and identifies research needs to advance predictive understanding of the longevity of BPA and its transformation products in environmental systems.

Enzymatic C[sbnd]C bond formation by benzylsuccinate synthases – A key step in anaerobic microbial degradation of hydrocarbons

In cases where fire debris contains soil, microorganisms can rapidly and irreversibly alter the chemical composition of any ignitable liquid residue that may be present. In this study, differences in microbial degradation due to the season in which the sample is collected was examined. Soil samples were collected from the same site during Fall, Winter, Spring and Summer and the degradation of gasoline was monitored over 30 days. Predominant viable bacterial populations enumerated using real-time PCR and reverse transcriptase polymerase chain reaction (RT-PCR) enumeration revealed the predominant viable bacterial genera to be Alcaligenes, Bacillus, and Flavobacterium. Overall, the compounds most vulnerable to microbial degradation are the n-alkanes, followed by the mono-substituted alkylbenzenes (e.g., toluene, ethylbenzene, propylbenzene and isopropylbenzene). Benzaldehyde (a degradation product of toluene) was also identified as a marker for the extent of biodegradation. Ultimately, it was determined that soil collected during an unusually hot and dry summer exhibited the least degradation with little to no change in gasoline for up to 4 days, readily detectable n-alkanes for up to 7 days and relatively high levels of resilient compounds such as o-xylene, p-xylene and 1,3,5-trimethylbenzene. These results demonstrate, however, that prompt preservation and/or analysis of soil evidence is required in order to properly classify an ignitable liquid residue.

Can PBDE natural formation and degradation processes interfere with the identification of anthropogenic trends and sources? Evidences from sediments of the Nador Lagoon (Morocco)

This paper presents the first results related to PBDE concentrations in sediments of the Nador Lagoon (N-E Morocco), an area endangered by different pollutant sources. Analyses were performed by HRGC-LRMS and confirmed by HRGC-HRMS on selected samples. Total surficial concentrations were 0.059–8.2ngg−1. The maxima were found close to Nador City. Along the sedimentary records, the highest total concentrations (11 and 2.2ngg−1) were found at depths corresponding to times (1930s–1950s) when these chemicals were not yet produced. Dehydroxylation or demethoxylation of naturally occurring structural analogues of PBDEs under reducing conditions was suggested. BDE-47 dominated the congener compositions, while BDE-209, when present, could be detected only by HRGC-HRMS, proving that analytical degradation modified the original assemblage. Microbial anaerobic degradation could have changed congener compositions in sediments deposited from the 1970s to the 2000s. Current values are not harmful, but increasing trends call for constant monitoring.

Sediment pollution and dynamic in the Mar Piccolo of Taranto (southern Italy): insights from bottom sediment traps and surficial sediments.

Major and trace element, PAH, and PCB concentrations were measured in surface sediments and particles from sediment traps collected in the First and Second Basin of the Mar Piccolo (Gulf of Taranto) in two periods (June-July and August-September, 2013). The aim of the study was to evaluate pollution degree, sediment transport and particle redistribution dynamic within the area. Results confirm the higher contamination of sediments from the First Basin observed by previous researches, particularly for Cu, Hg, Pb, total PAHs, and total PCBs. Advective transport from the First to the Second Basin appears to be the leading transfer mechanism of particles and adsorbed contaminants, as evidenced by measured fluxes and statistical analyses of contaminant concentrations in surficial sediments and particles from sediment traps. Long-range selective transports of PAHs and microbial anaerobic degradation processes for PCBs have been also observed. These results are limited to a restricted time window but are consistent with the presence of transport fluxes at the bottom of the water column. This mechanism deserves further investigation and monitoring activities, potentially being the main responsible of pollutant delivering to the less contaminated sectors of the Mar Piccolo.

Monsoonal influence on variation of hydrochemistry and isotopic signatures: Implications for associated arsenic release in groundwater

Summary The present study examines the groundwater and surface water geochemistry of two different geomorphic domains within the Chakdaha block, West Bengal, in an attempt to decipher potential influences of groundwater abstraction on the hydrochemical evolution of the aquifer, the effect of different water inputs (monsoon rain, irrigation and downward percolation from surface water impoundments) to the groundwater system and concomitant As release. A low-land flood plain and a natural levee have been selected for this purpose. Although the stable isotopic signatures of oxygen (δ18O) and hydrogen (δ2H) are largely controlled by local precipitation, the isotopic composition falls sub-parallel to the Global Meteoric Water Line (GMWL). The Cl/Br molar ratio indicates vertical recharge into the wells within the flood plain area, especially during the post-monsoon season, while influences of both evaporation and vertical mixing are visible within the natural levee wells. Increase in mean DOC concentrations (from 1.33 to 6.29 mg/L), from pre- to post-monsoon season, indicates possible inflow of organic carbon to the aquifer during the monsoonal recharge. Concomitant increase in AsT, Fe(II) and HCO3− highlights a possible initial episode of reductive dissolution of As-rich Fe-oxyhydroxides. The subsequent sharp increase in the mean As(III) proportions (by 223%), particularly in the flood plain samples during the post-monsoon season, which is accompanied by a slight increase in mean AsT (7%) may refer to anaerobic microbial degradation of DOC coupled with the reduction of As(V) to As(III) without triggering additional As release from the aquifer sediments.

Aerobic and anaerobic microbial degradation of crude (4-methylcyclohexyl)methanol in river sediments

Cyclohexane and some of its derivatives have been a major concern because of their significant adverse human health effects and widespread occurrence in the environment. The 2014 West Virginia chemical spill has raised public attention to (4-methylcyclohexyl)methanol (4-MCHM), one cyclohexane derivative, which is widely used in coal processing but largely ignored. In particular, the environmental fate of its primary components, cis- and trans-4-MCHM, remains largely unexplored. This study aimed to investigate the degradation kinetics and mineralization of cis- and trans-4-MCHM by sediment microorganisms under aerobic and anaerobic conditions. We found the removal of cis- and trans-4-MCHM was mainly attributed to biodegradation with little contribution from sorption. A nearly complete aerobic degradation of 4-MCHM occurred within 14days, whereas the anaerobic degradation was reluctant with residual percentages of 62.6% of cis-4-MCHM and 85.0% of trans-4-MCHM after 16-day incubation. The cis-4-MCHM was degraded faster than the trans under both aerobic and anaerobic conditions, indicating an isomer-specific degradation could occur during the 4-MCHM degradation. Nitrate addition enhanced 4-MCHM mineralization by about 50% under both aerobic and anaerobic conditions. Both cis- and trans-4-MCHM fit well with the first-order kinetic model with respective degradation rates of 0.46–0.52 and 0.19–0.31day−1 under aerobic condition. Respective degradation rates of 0.041–0.095 and 0.013–0.052day−1 occurred under anaerobic condition. One bacterial strain capable of effectively degrading 4-MCHM isomers was isolated from river sediments and identified as Bacillus pumilus at the species level based on 16S rRNA gene sequence and 97% identity. Our findings will provide critical information for improving the prediction of the environmental fate of 4-MCHM and other cyclohexane derivatives with similar structure as well as enhancing the development of feasible treatment technologies to mitigate these compounds.

Bacterial community structure and predicted alginate metabolic pathway in an alginate-degrading bacterial consortium

Methane fermentation is one of the effective approaches for utilization of brown algae; however, this process is limited by the microbial capability to degrade alginate, a main polysaccharide found in these algae. Despite its potential, little is known about anaerobic microbial degradation of alginate. Here we constructed a bacterial consortium able to anaerobically degrade alginate. Taxonomic classification of 16S rRNA gene, based on high-throughput sequencing data, revealed that this consortium included two dominant strains, designated HUA-1 and HUA-2; these strains were related to Clostridiaceae bacterium SK082 (99%) and Dysgonomonas capnocytophagoides (95%), respectively. Alginate lyase activity and metagenomic analyses, based on high-throughput sequencing data, revealed that this bacterial consortium possessed putative genes related to a predicted alginate metabolic pathway. However, HUA-1 and 2 did not grow on agar medium with alginate by using roll-tube method, suggesting the existence of bacterial interactions like symbiosis for anaerobic alginate degradation.