Proglacial lake is an emergent source of the second most important greenhouse gas methane as the climate continues to warm,and syntrophic bacteria play a crucial role in the sediment organic matter degradation and met...Proglacial lake is an emergent source of the second most important greenhouse gas methane as the climate continues to warm,and syntrophic bacteria play a crucial role in the sediment organic matter degradation and methane production.However,our understanding of syntrophic bacteria in the proglacial lake sediments is limited.Here,we combined 16S rRNA gene amplicon sequencing,metagenomics,and metatranscriptomics to explore the diversity,function,and activity of syntrophic propionate-and butyrate-oxidizing bacteria(SPOB and SBOB)in sediments of a glacier-fed proglacial lake on the south Qinghai-Tibet Plateau.We identified a diverse array of putative SPOB and SBOB with pronounced spatial and temporal variations,many of which were central in microbial co-occurrence networks.The most abundant SBOB were Syntrophus,Syntrophorhabdus,and unclassified_Syntrophales,and the dominant SPOB included unclassified_Syntrophobacterales,Smithella,and Syntrophobacter.Lake hydrology,water depth,and associated physicochemical properties shape the spatial patterns of sediment syntrophic bacterial communities.Genome-resolved metagenomics revealed 21 and 4 genus-level novel lineages for SPOB and SBOB,respectively.Transcriptomic evidence highlighted high activity of the uncharacterized genera UBA1429(Anaerolineae)and E44-bin15(Dehalococcoidia)in propionate oxidation,and JAPLJM01(Syntrophia)as a dominant player in butyrate oxidation.This study provides the first insight into syntrophic oxidizers in proglacial lake sediments,advancing our understanding of carbon cycling and methane emission in cryosphere aquatic ecosystems.展开更多
The degradation rate of Volatile Fatty Acids (VFAs) produced predominantly in the acidogenesis stage is a key process parameter to be optimised to ensure a successful Anaerobic digestion (AD). Thermodynamically, the o...The degradation rate of Volatile Fatty Acids (VFAs) produced predominantly in the acidogenesis stage is a key process parameter to be optimised to ensure a successful Anaerobic digestion (AD). Thermodynamically, the oxidation of the VFAs are energetically unfavourable, and as such external energy source apart from the energy derived from the hydrolysis of Adenosine Triphosphate (ATP) is needed for the initial activation of the VFAs, initial growth of the methanogens in AD process and improved degradation rate of the VFAs. Thus, this research investigated the influence of polyphosphate hydrolysis on the degradation rate of the VFAs at high concentration. Sodium-propionate, Sodium-butyrate and Sodium-acetate salts were added at the start of experiments in order to increase the concentration of the VFAs. The polyphosphate salts used were;Na-hexametaphosphate, Na-tripolyphosphate and potassium pyrophosphate. The control experiment was polyphosphate free and three process parameters (degradation rate, cumulative biogas production and specific methane content) of anaerobic digestion were investigated. The experiments were carried out at a mesophilic temperature of 37.5°C for 41 days. The results of the investigation showed that the treated reactors with the polyphosphate salt solution in low concentration performed better than the reactors with high concentration of the polyphosphate salts solution. All the treated reactors with poly-P salts performed better than reactor Nr-9 (control experiment), but reactor Nr-1 was outstanding with an improved degradation rate of 47%, cumulative biogas production of 21% and specific methane content of 23%.展开更多
Background Chlorophenoxy compounds represent a group of selective herbicides widely used around the world.Chlorophenoxy herbicides are toxic,chemically stable,and can migrate into groundwater through soil leaching,pos...Background Chlorophenoxy compounds represent a group of selective herbicides widely used around the world.Chlorophenoxy herbicides are toxic,chemically stable,and can migrate into groundwater through soil leaching,posing a significant threat to drinking water safety and human health.Chlorophenoxy herbicides in groundwater aquifers are subject to anaerobic processes;however,the pathway and microbiology involved in the attenuation of chlorophenoxy herbicides under anaerobic condition are largely unknown.Here,the anaerobic degradation process of 2,4,5-trichlorophenoxyacetic acid(2,4,5-T),a typical chlorophenoxy herbicide,was investigated.Results The initial 52.5±2.3μM 2,4,5-T was completely degraded by a sediment-derived microbial consortium,with 3,4-dichlorophenol,2,5-dichlorophenol,3-chlorophenol(3-CP)and phenol being identified as the intermediate products.Reductive dechlorination of 3-CP to phenol and the subsequent elimination of phenol were the key transformation steps in the overall degradation process of 2,4,5-T.Amplicon sequencing suggested that Dehalobacter,Sulfuricurvum,Bacteroides,Acetobacterium,and Clostridium sensu stricto 7 might contribute to the transformation of 2,4,5-T to phenol,and Smithella,Syntrophorhabdus,Methanofollis and Methanosaeta likely cooperated to accomplish the complete mineralization of phenol.Conclusions This study reported the anaerobic degradation of 2,4,5-T via reductive dechlorination and the subsequent syntrophic metabolization of phenol,an intermediate product transformed from 2,4,5-T.Dehalobacter was identified as the organohalide-respiring population catalyzing the reductive dechlorination reaction.Syntrophorhabdus and methanogenic populations were likely involved in anaerobic phenol oxidation and facilitated the complete mineralization of 2,4,5-T.展开更多
基金supported by the National Natural Science Foundation of China for Excellent Young Scientists Fund Program(Grant No.42222105)the National Natural Science Foundation of China General Program(Grant No.42171144),the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2021QZKK0100)+1 种基金the Key Research and Development Plan of Xizang Autonomous Region(Grant No.XZ202301ZY0008G)the Global Ocean Negative Carbon Emissions(Global ONCE)Program.
文摘Proglacial lake is an emergent source of the second most important greenhouse gas methane as the climate continues to warm,and syntrophic bacteria play a crucial role in the sediment organic matter degradation and methane production.However,our understanding of syntrophic bacteria in the proglacial lake sediments is limited.Here,we combined 16S rRNA gene amplicon sequencing,metagenomics,and metatranscriptomics to explore the diversity,function,and activity of syntrophic propionate-and butyrate-oxidizing bacteria(SPOB and SBOB)in sediments of a glacier-fed proglacial lake on the south Qinghai-Tibet Plateau.We identified a diverse array of putative SPOB and SBOB with pronounced spatial and temporal variations,many of which were central in microbial co-occurrence networks.The most abundant SBOB were Syntrophus,Syntrophorhabdus,and unclassified_Syntrophales,and the dominant SPOB included unclassified_Syntrophobacterales,Smithella,and Syntrophobacter.Lake hydrology,water depth,and associated physicochemical properties shape the spatial patterns of sediment syntrophic bacterial communities.Genome-resolved metagenomics revealed 21 and 4 genus-level novel lineages for SPOB and SBOB,respectively.Transcriptomic evidence highlighted high activity of the uncharacterized genera UBA1429(Anaerolineae)and E44-bin15(Dehalococcoidia)in propionate oxidation,and JAPLJM01(Syntrophia)as a dominant player in butyrate oxidation.This study provides the first insight into syntrophic oxidizers in proglacial lake sediments,advancing our understanding of carbon cycling and methane emission in cryosphere aquatic ecosystems.
文摘The degradation rate of Volatile Fatty Acids (VFAs) produced predominantly in the acidogenesis stage is a key process parameter to be optimised to ensure a successful Anaerobic digestion (AD). Thermodynamically, the oxidation of the VFAs are energetically unfavourable, and as such external energy source apart from the energy derived from the hydrolysis of Adenosine Triphosphate (ATP) is needed for the initial activation of the VFAs, initial growth of the methanogens in AD process and improved degradation rate of the VFAs. Thus, this research investigated the influence of polyphosphate hydrolysis on the degradation rate of the VFAs at high concentration. Sodium-propionate, Sodium-butyrate and Sodium-acetate salts were added at the start of experiments in order to increase the concentration of the VFAs. The polyphosphate salts used were;Na-hexametaphosphate, Na-tripolyphosphate and potassium pyrophosphate. The control experiment was polyphosphate free and three process parameters (degradation rate, cumulative biogas production and specific methane content) of anaerobic digestion were investigated. The experiments were carried out at a mesophilic temperature of 37.5°C for 41 days. The results of the investigation showed that the treated reactors with the polyphosphate salt solution in low concentration performed better than the reactors with high concentration of the polyphosphate salts solution. All the treated reactors with poly-P salts performed better than reactor Nr-9 (control experiment), but reactor Nr-1 was outstanding with an improved degradation rate of 47%, cumulative biogas production of 21% and specific methane content of 23%.
基金supported by the Natural Science Foundation of China(42377133,42177220)with additional support from the Natural Science Foundation(Joint Fund)of Liaoning Province(2023JH2/101700354,2023JH2/101800044).
文摘Background Chlorophenoxy compounds represent a group of selective herbicides widely used around the world.Chlorophenoxy herbicides are toxic,chemically stable,and can migrate into groundwater through soil leaching,posing a significant threat to drinking water safety and human health.Chlorophenoxy herbicides in groundwater aquifers are subject to anaerobic processes;however,the pathway and microbiology involved in the attenuation of chlorophenoxy herbicides under anaerobic condition are largely unknown.Here,the anaerobic degradation process of 2,4,5-trichlorophenoxyacetic acid(2,4,5-T),a typical chlorophenoxy herbicide,was investigated.Results The initial 52.5±2.3μM 2,4,5-T was completely degraded by a sediment-derived microbial consortium,with 3,4-dichlorophenol,2,5-dichlorophenol,3-chlorophenol(3-CP)and phenol being identified as the intermediate products.Reductive dechlorination of 3-CP to phenol and the subsequent elimination of phenol were the key transformation steps in the overall degradation process of 2,4,5-T.Amplicon sequencing suggested that Dehalobacter,Sulfuricurvum,Bacteroides,Acetobacterium,and Clostridium sensu stricto 7 might contribute to the transformation of 2,4,5-T to phenol,and Smithella,Syntrophorhabdus,Methanofollis and Methanosaeta likely cooperated to accomplish the complete mineralization of phenol.Conclusions This study reported the anaerobic degradation of 2,4,5-T via reductive dechlorination and the subsequent syntrophic metabolization of phenol,an intermediate product transformed from 2,4,5-T.Dehalobacter was identified as the organohalide-respiring population catalyzing the reductive dechlorination reaction.Syntrophorhabdus and methanogenic populations were likely involved in anaerobic phenol oxidation and facilitated the complete mineralization of 2,4,5-T.
