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Proceedings of the National Academy of... Jul 2017Twenty-five years ago this month, Thomas Gold published a seminal manuscript suggesting the presence of a "deep, hot biosphere" in the Earth's crust. Since this...
Twenty-five years ago this month, Thomas Gold published a seminal manuscript suggesting the presence of a "deep, hot biosphere" in the Earth's crust. Since this publication, a considerable amount of attention has been given to the study of deep biospheres, their role in geochemical cycles, and their potential to inform on the origin of life and its potential outside of Earth. Overwhelming evidence now supports the presence of a deep biosphere ubiquitously distributed on Earth in both terrestrial and marine settings. Furthermore, it has become apparent that much of this life is dependent on lithogenically sourced high-energy compounds to sustain productivity. A vast diversity of uncultivated microorganisms has been detected in subsurface environments, and we show that H, CH, and CO feature prominently in many of their predicted metabolisms. Despite 25 years of intense study, key questions remain on life in the deep subsurface, including whether it is endemic and the extent of its involvement in the anaerobic formation and degradation of hydrocarbons. Emergent data from cultivation and next-generation sequencing approaches continue to provide promising new hints to answer these questions. As Gold suggested, and as has become increasingly evident, to better understand the subsurface is critical to further understanding the Earth, life, the evolution of life, and the potential for life elsewhere. To this end, we suggest the need to develop a robust network of interdisciplinary scientists and accessible field sites for long-term monitoring of the Earth's subsurface in the form of a deep subsurface microbiome initiative.
Topics: Anaerobiosis; Gases; Hydrocarbons; Microbiota; Origin of Life
PubMed: 28674200
DOI: 10.1073/pnas.1701266114 -
Science (New York, N.Y.) Apr 2017
Topics: Anaerobiosis; Glucose; Humans; Oxygen
PubMed: 28428384
DOI: 10.1126/science.aan1505 -
Bioresource Technology Nov 2023Anaerobic digestion is an established method for the biological conversion of waste feedstocks to biogas and biomethane. While anaerobic digestion is an excellent waste...
Anaerobic digestion is an established method for the biological conversion of waste feedstocks to biogas and biomethane. While anaerobic digestion is an excellent waste management technique, it can be susceptible to toxins and pollutants from contaminated feedstocks, which may have a detrimental impact on a digester's efficiency and productivity. Ethylene glycol (EG) is readily used in the heat-transfer loops of anaerobic digestion facilities to maintain reactor temperature. Failure of the structural integrity of these heat transfer loops can cause EG to leak into the digester, potentially causing a decrease in the resultant gas yields. Batch fermentations were incubated with 0, 10, 100 and 500 ppm (parts per million) of EG, and analysis showed that the EG was completely metabolised by the digester microbiome. The concentrations of EG tested showed significant increases in gas yields, however there were no significant changes to the digester microbiome.
Topics: Anaerobiosis; Metagenome; Microbiota; Biofuels; Ethylene Glycols
PubMed: 37597572
DOI: 10.1016/j.biortech.2023.129683 -
The ISME Journal Oct 2021CO is a promising substrate for producing biochemicals and biofuels through mixed microbial cultures, where carboxydotrophs play a crucial role. The previous...
CO is a promising substrate for producing biochemicals and biofuels through mixed microbial cultures, where carboxydotrophs play a crucial role. The previous investigations of mixed microbial cultures focused primarily on overall community structures, but under-characterized taxa and intricate microbial interactions have not yet been precisely explicated. Here, we undertook DNA-SIP based metagenomics to profile the anaerobic CO-driven microbiomes under 95 and 35% CO atmospheres. The time-series analysis of the isotope-labeled amplicon sequencing revealed the essential roles of Firmicutes and Proteobacteria under high and low CO pressure, respectively, and Methanobacterium was the predominant archaeal genus. The functional enrichment analysis based on the isotope-labeled metagenomes suggested that the microbial cultures under high CO pressure had greater potential in expressing carboxylate metabolism and citrate cycle pathway. The genome-centric metagenomics reconstructed 24 discovered and 24 under-characterized metagenome-assembled genomes (MAGs), covering more than 94% of the metagenomic reads. The metabolic reconstruction of the MAGs described their potential functions in the CO-driven microbiomes. Some under-characterized taxa might be versatile in multiple processes; for example, under-characterized Rhodoplanes sp. and Desulfitobacterium_A sp. could encode the complete enzymes in CO oxidation and carboxylate production, improving functional redundancy. Finally, we proposed the putative microbial interactions in the conversion of CO to carboxylates and methane.
Topics: Anaerobiosis; Bacteria; Metagenome; Metagenomics; Microbiota
PubMed: 33911204
DOI: 10.1038/s41396-021-00983-1 -
Bioresource Technology Sep 2023The valorisation of whiskey by-products was assessed and compared in three anaerobic digestion systems. The systems produced similar methane yields, which could satisfy...
The valorisation of whiskey by-products was assessed and compared in three anaerobic digestion systems. The systems produced similar methane yields, which could satisfy up to 44% of the thermal energy demand at a distillery. Using methane generated from by-products would displace natural gas and reduce the distillery's carbon footprint. Two-phase systems had higher methane content (ca. 75 %vol) than the traditional system (54 %vol) and furthermore, unlocked opportunities for volatile fatty acid production. The potential value that could be generated from the extraction of butyric acid and caproic acid was approximately €6.76 million for a 50 million litre alcohol facility (0.14 € per litre of whiskey). All three anaerobic digestion systems showed the potential to valorise whiskey by-products and convert current linear distillery production processes into circular repurpose and reuse production processes.
Topics: Anaerobiosis; Bioreactors; Alcoholic Beverages; Alcohols; Methane; Biofuels
PubMed: 37247792
DOI: 10.1016/j.biortech.2023.129239 -
Bioresource Technology Feb 2018Ammonium chloride (NHCl) was usually used as a model ammonia source to simulate ammonia inhibition during anaerobic digestion (AD) of nitrogen-rich feedstocks. However,...
Ammonium chloride (NHCl) was usually used as a model ammonia source to simulate ammonia inhibition during anaerobic digestion (AD) of nitrogen-rich feedstocks. However, ammonia in AD originates mainly from degradation of proteins, urea and nucleic acids, which is distinct from NHCl. Thus, in this study, the inhibitory effect of a "natural" ammonia source (urea) and NHCl, on four pure methanogenic strains (aceticlastic: Methanosarcina thermophila, Methanosarcina barkeri; hydrogenotrophic: Methanoculleus bourgensis, Methanoculleus thermophilus), was assessed under mesophilic (37 °C) and thermophilic (55 °C) conditions. The results showed that urea hydrolysis increased pH significantly to unsuitable levels for methanogenic growth, while NHCl had a negligible effect on pH. After adjusting initial pH to 7 and 8, urea was significantly stronger inhibitor with longer lag phases to methanogenesis compared to NHCl. Overall, urea seems to be more toxic on both aceticlastic and hydrogenotrophic methanogens compared to NHCl under the same total and free ammonia levels.
Topics: Ammonia; Ammonium Chloride; Anaerobiosis; Methane; Methanomicrobiaceae; Methanosarcina
PubMed: 29195150
DOI: 10.1016/j.biortech.2017.11.081 -
Bioresource Technology Jan 2022This study investigated for the first time if ammonia tolerant methanogenic consortia can be stored in gel (biogel) and used in a later time on-demand as bioaugmentation...
This study investigated for the first time if ammonia tolerant methanogenic consortia can be stored in gel (biogel) and used in a later time on-demand as bioaugmentation inocula, to efficiently relieve ammonia inhibition in continuous biomethanation systems. Moreover, wood biochar was assessed as a potential enhancer of the novel biogel bioaugmentation process. Three thermophilic (55 °C), continuous stirred-tank reactors (R, R and R), operated at 4.5 g NH-N L were exposed to biogel, biochar and mixture of biogel and biochar, respectively, while a fourth reactor (R) was used as control. The results showed that the methane production yields of R, R and R increased by 28.6%, 20.2% and 10.7%, respectively compared to R. The highest methane yield was achieved by the synergistic interaction between biogel and biochar. Additionally, biogel stimulated a rapid recovery of Methanoculleus thermophilus sp. and syntrophic acetate oxidising bacteria populations.
Topics: Ammonia; Anaerobiosis; Bioreactors; Charcoal; Methane
PubMed: 34673199
DOI: 10.1016/j.biortech.2021.126146 -
Journal of Environmental Management Jan 2023Mechanical solid-liquid separation is an emerging closed-loop technology to recover and recycle carbon, nutrients and water from dilute livestock manure. This...
Mechanical solid-liquid separation is an emerging closed-loop technology to recover and recycle carbon, nutrients and water from dilute livestock manure. This closed-loop concept is tested using a modular separation technology (Z-Filter) applied at full-scale for the first time to treat effluent from a pasture-based dairy. Effluent flow rates were 200-400 L min at a total solids (TS) content of 0.52% (pH 7.2). Separation efficiency and composition of the separated solid fraction were determined, and chemically-assisted separation with cationic polymer flocculant with/without hydrated lime was also tested. Without flocculant and lime, 25.9% of TS and 33.4% of volatile solids (VS) ended up in the solid fraction, but total Kjeldahl nitrogen (TKN), phosphorus (P) and potassium recovery was not significant, likely being in poorly separable fine particle or soluble fractions. With a 5% flow-based dosage of flocculant, most of the TS (69%) and VS (85%), and notable amounts of TKN (52-56%) and P (40%) ended up in the solid fraction. Phosphorus recovery was further increased to 91% when both flocculant and hydrated lime was added up to pH 9.2. The solid fraction was stackable with 16-20% TS, making transport more economical to enable further processing and beneficial reuse of nutrients and organic matter. Removal of VS also reduces fugitive methane emissions from uncovered anaerobic effluent ponds. Overall, the results indicated that solid-liquid separation could provide improved environmental management options for dairy farmers with dilute manure effluent to beneficially utilise organic matter and nutrients.
Topics: Animals; Manure; Livestock; Conservation of Natural Resources; Phosphorus; Nitrogen; Anaerobiosis
PubMed: 36265233
DOI: 10.1016/j.jenvman.2022.116254 -
Journal of Environmental Management Apr 2022Commercial digesters handling complex waste and organic overloading often encounter unbalanced conditions or failures. With limited studies on the digester recovery from...
Commercial digesters handling complex waste and organic overloading often encounter unbalanced conditions or failures. With limited studies on the digester recovery from an industry-based waste stream, a complex and high-strength digestate containing up to 79 g COD l from acidified commercial digester was investigated for biochar and alkaline treatments. The addition of biochar and calcium hydroxide successfully decomposed excessive volatile fatty acid up to 18.9 ± 2.5 g l and resumed methane production. The maximum methane yield was obtained from the digester amended with biochar (373.4 ± 6.0 ml g COD), followed by calcium hydroxide (350.1 ± 2.5 ml g COD). Calcium hydroxide treatment showed a shorter lag phase than the biochar by 44%. Methane production could not be recovered by using sodium hydroxide or untreated digester. This study provides a strategic approach to justify the use of alkalis for restoring sour digesters from industry-based waste streams.
Topics: Alkalies; Anaerobiosis; Bioreactors; Charcoal; Methane
PubMed: 35066196
DOI: 10.1016/j.jenvman.2022.114538 -
Environmental Microbiology Reports Apr 2024The integrated fixed-film activated sludge (IFAS) process is considered one of the cutting-edge solutions to the traditional wastewater treatment challenges, allowing... (Review)
Review
The integrated fixed-film activated sludge (IFAS) process is considered one of the cutting-edge solutions to the traditional wastewater treatment challenges, allowing suspended sludge and attached biofilm to grow in the same system. In addition, the coupling of IFAS with anaerobic ammonium oxidation (Anammox) can further improve the efficiency of biological denitrification. This paper summarises the research progress of IFAS coupled with the anammox process, including partial nitrification anammox, simultaneous partial nitrification anammox and denitrification, and partial denitrification anammox technologies, and describes the factors that limit the development of related processes. The effects of dissolved oxygen, influent carbon source, sludge retention time, temperature, microbial community, and nitrite-oxidising bacteria inhibition methods on the anammox of IFAS are presented. At the same time, this paper gives an outlook on future research focus and engineering practice direction of the process.
Topics: Anaerobic Ammonia Oxidation; Anaerobiosis; Sewage; Biofilms; Ammonium Compounds
PubMed: 38444262
DOI: 10.1111/1758-2229.13235