Production of biochemicals from waste streams has been attracting increasing worldwide interest to achieve climate protection goals.Chain elongation(CE)for production of mediumchain carboxylic acids(MCCAs,especially c...Production of biochemicals from waste streams has been attracting increasing worldwide interest to achieve climate protection goals.Chain elongation(CE)for production of mediumchain carboxylic acids(MCCAs,especially caproate,enanthate and caprylate)from diverse biowaste has emerged as a potential economic and environmental technology for a sustainable society.The present mini review summarizes the research utilizing various synthetic or real waste-derived substrates available for MCCA production.Additionally,the microbial characteristics of the CE process are surveyed and discussed.Considering that a large proportion of recalcitrantly biodegradable biowaste and residues cannot be further utilized by CE systems and remain to be treated and disposed,we propose here a loop concept of bioconversion of biowaste to MCCAs making full use of the biowaste with zero emission.This could make possible an alternative technology for synthesis of value-added products from a wide range of biowaste,or even non-biodegradable waste(such as,plastics and rubbers).Meanwhile,the remaining scientific questions,unsolved problems,application potential and possible developments for this technology are discussed.展开更多
Water-saving irrigation strategies can successfully alleviate methane emissions from rice fields,but significantly stimulate nitrous oxide(N_(2)O)emissions because of variations in soil oxygen level and redox potentia...Water-saving irrigation strategies can successfully alleviate methane emissions from rice fields,but significantly stimulate nitrous oxide(N_(2)O)emissions because of variations in soil oxygen level and redox potential.However,the relationship linking soil N_(2)O emissions to nitrogen functional genes during various fertilization treatments in water-saving paddy fields has rarely been investigated.Furthermore,the mitigation potential of organic fertilizer substitution on N_(2)O emissions and the microbial mechanism in rice fields must be further elucidated.Our study examined how soil N_(2)O emissions were affected by related functional microorganisms(ammonia-oxidizing archaea(AOA),ammonia-oxidizing bacteria(AOB),nirS,nirK and nosZ)to various fertilization treatments in a rice field in southeast China over two years.In this study,three fertilization regimes were applied to rice cultivation:a no nitrogen(N)(Control),an inorganic N(Ni),and an inorganic N with partial N substitution with organic manure(N_(i)+N_(o)).Over two rice-growing seasons,cumulative N_(2)O emissions averaged 0.47,4.62 and 4.08 kg ha^(−1)for the Control,Ni and N_(i)+N_(o)treatments,respectively.In comparison to the Ni treatment,the N_(i)+N_(o)fertilization regime considerably reduced soil N_(2)O emissions by 11.6%while maintaining rice yield,with a lower N_(2)O emission factor(EF)from fertilizer N of 0.95%.Nitrogen fertilization considerably raised the AOB,nirS,nirK and nosZ gene abundances,in comparison to the Control treatment.Moreover,the substitution of organic manure for inorganic N fertilizer significantly decreased AOB and nirS gene abundances and increased nosZ gene abundance.The AOB responded to N fertilization more sensitively than the AOA.Total N_(2)O emissions significantly correlated positively with AOB and nirS gene abundances while having a negative correlation with nosZ gene abundance and the nosZ/nirS ratio across N-fertilized plots.In summary,we conclude that organic manure substitution for inorganic N fertilizer decreased soil N_(2)O emissions primarily by changing the soil NO_(3)^(−)-N,pH and DOC levels,thus inhibiting the activities of ammonia oxidation in nitrification and nitrite reduction in denitrification,and strengthening N_(2)O reduction in denitrification from water-saving rice paddies.展开更多
Increased nitrogen(N)loading and sea-level rise(SLR)are two dominant drivers of global change that threaten tidal marshes and the ecosystem services they provide,including the sequestration of organic carbon.Neverthel...Increased nitrogen(N)loading and sea-level rise(SLR)are two dominant drivers of global change that threaten tidal marshes and the ecosystem services they provide,including the sequestration of organic carbon.Nevertheless,the mechanisms through which N loading enrichment,SLR inundation increase,and their combined effects impact the rates and pathways of soil organic carbon(SOC)mineralization in tidal marshes remain poorly understood.We utilized a factorial design in an oligohaline tidal marsh,utilizing in situ weirs to simulate SLR inundation increase by manipulating the duration of flooding with or without nitrogen enrichment as NaNO_(3)plus NH_(4)Cl or with a combination of increased flood duration and nitrogen.After nearly 2 years,the addition of N increased total SOC mineralization(CMR),soil microbial Fe(III)reduction(FeRR),NO_(3)-reduction(NRR),and SO_(4)^(2-)reduction(SRR)but decreased methanogenesis(MGR).The abiotic factor Fe(III)/Fe(II)ratio and dissolved organic carbon(DOC),and the biotic factors,β-glucosidase(BG),and phenol oxidase(PHO)activity explained the increased SOC mineralization rates following N enrichment.Increased flood duration did not change CMR,but increased flooding offset the stimulatory effects of N addition on CMR,FeRR,SRR,NRR and MGR.The contributions of Fe(III)reduction and SO_(4)^(2-)reduction pathways to SOC mineralization increased in all experimental treatments,FeRR,SRR,NRR,and MGR were significantly positively correlated with the abundance of Geobacter,dsrA,nrfA,and mcrA.SLR inundation increase did not increase soil carbon loss in this oligohaline marsh and may counteract the simulation of soil C loss due to N enrichment.展开更多
Raw-materials based broad bean paste(rmBBP)is popular among consumers.Though high salinity can select functional microbial community for fermentation,it also impaired the fermentation efficiency of rmBBP and unfavored...Raw-materials based broad bean paste(rmBBP)is popular among consumers.Though high salinity can select functional microbial community for fermentation,it also impaired the fermentation efficiency of rmBBP and unfavored human health.Therefore,this study aimed to construct a synthetic microbial community based on key functional microbes for reduced salt rmBBP fermentation based on the elucidation of the microbial community succession during fermentation.Based on the tracked determination and multivariate statistical analysis of the physicochemical parameters,metabolites and the structure of microbial community,salinity and microbial in-teractions were key drivers for the succession of microbial community.Aspergillus,Staphylococcus,Weissella and Tetragenococcus were predicted to play key roles during fermentation.After that,core species were isolated from rmBBP mash and their salinity tolerance and metabolic characteristics were evaluated.Finally,a synthetic mi-crobial community(Aspergillus oryzae,Staphylococcus carnosus,Tetragenococcus halophilus and Weissella confusa)was constructed and applied in reduced-salt rmBBP fermentation.The bioaugmentation contributed to the accumulation of volatile metabolites while effectively maintaining the acidity during rmBBP fermentation when salinity was reduced from 12%to 10%.In general,this study developed a synthetic microbial community with desired characteristics for successful reduced-salinity rmBBP fermentation.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 51622809, 51878471)
文摘Production of biochemicals from waste streams has been attracting increasing worldwide interest to achieve climate protection goals.Chain elongation(CE)for production of mediumchain carboxylic acids(MCCAs,especially caproate,enanthate and caprylate)from diverse biowaste has emerged as a potential economic and environmental technology for a sustainable society.The present mini review summarizes the research utilizing various synthetic or real waste-derived substrates available for MCCA production.Additionally,the microbial characteristics of the CE process are surveyed and discussed.Considering that a large proportion of recalcitrantly biodegradable biowaste and residues cannot be further utilized by CE systems and remain to be treated and disposed,we propose here a loop concept of bioconversion of biowaste to MCCAs making full use of the biowaste with zero emission.This could make possible an alternative technology for synthesis of value-added products from a wide range of biowaste,or even non-biodegradable waste(such as,plastics and rubbers).Meanwhile,the remaining scientific questions,unsolved problems,application potential and possible developments for this technology are discussed.
基金supported by the National Key Research and Development Program of China(2022YFD2300300)the National Natural Science Foundation of China(41907072)+1 种基金the Scientific Research Foundation of Zhejiang A&F University,China(2022LFR003)the Jiangsu Agriculture Science and Technology Innovation Fund,China(CX(21)3007).
文摘Water-saving irrigation strategies can successfully alleviate methane emissions from rice fields,but significantly stimulate nitrous oxide(N_(2)O)emissions because of variations in soil oxygen level and redox potential.However,the relationship linking soil N_(2)O emissions to nitrogen functional genes during various fertilization treatments in water-saving paddy fields has rarely been investigated.Furthermore,the mitigation potential of organic fertilizer substitution on N_(2)O emissions and the microbial mechanism in rice fields must be further elucidated.Our study examined how soil N_(2)O emissions were affected by related functional microorganisms(ammonia-oxidizing archaea(AOA),ammonia-oxidizing bacteria(AOB),nirS,nirK and nosZ)to various fertilization treatments in a rice field in southeast China over two years.In this study,three fertilization regimes were applied to rice cultivation:a no nitrogen(N)(Control),an inorganic N(Ni),and an inorganic N with partial N substitution with organic manure(N_(i)+N_(o)).Over two rice-growing seasons,cumulative N_(2)O emissions averaged 0.47,4.62 and 4.08 kg ha^(−1)for the Control,Ni and N_(i)+N_(o)treatments,respectively.In comparison to the Ni treatment,the N_(i)+N_(o)fertilization regime considerably reduced soil N_(2)O emissions by 11.6%while maintaining rice yield,with a lower N_(2)O emission factor(EF)from fertilizer N of 0.95%.Nitrogen fertilization considerably raised the AOB,nirS,nirK and nosZ gene abundances,in comparison to the Control treatment.Moreover,the substitution of organic manure for inorganic N fertilizer significantly decreased AOB and nirS gene abundances and increased nosZ gene abundance.The AOB responded to N fertilization more sensitively than the AOA.Total N_(2)O emissions significantly correlated positively with AOB and nirS gene abundances while having a negative correlation with nosZ gene abundance and the nosZ/nirS ratio across N-fertilized plots.In summary,we conclude that organic manure substitution for inorganic N fertilizer decreased soil N_(2)O emissions primarily by changing the soil NO_(3)^(−)-N,pH and DOC levels,thus inhibiting the activities of ammonia oxidation in nitrification and nitrite reduction in denitrification,and strengthening N_(2)O reduction in denitrification from water-saving rice paddies.
基金supported by grants from the National Sci-ence Foundation of China(42177213 and 41877335)the National Key Research and Development Program of China(2022YFC3105401。)。
文摘Increased nitrogen(N)loading and sea-level rise(SLR)are two dominant drivers of global change that threaten tidal marshes and the ecosystem services they provide,including the sequestration of organic carbon.Nevertheless,the mechanisms through which N loading enrichment,SLR inundation increase,and their combined effects impact the rates and pathways of soil organic carbon(SOC)mineralization in tidal marshes remain poorly understood.We utilized a factorial design in an oligohaline tidal marsh,utilizing in situ weirs to simulate SLR inundation increase by manipulating the duration of flooding with or without nitrogen enrichment as NaNO_(3)plus NH_(4)Cl or with a combination of increased flood duration and nitrogen.After nearly 2 years,the addition of N increased total SOC mineralization(CMR),soil microbial Fe(III)reduction(FeRR),NO_(3)-reduction(NRR),and SO_(4)^(2-)reduction(SRR)but decreased methanogenesis(MGR).The abiotic factor Fe(III)/Fe(II)ratio and dissolved organic carbon(DOC),and the biotic factors,β-glucosidase(BG),and phenol oxidase(PHO)activity explained the increased SOC mineralization rates following N enrichment.Increased flood duration did not change CMR,but increased flooding offset the stimulatory effects of N addition on CMR,FeRR,SRR,NRR and MGR.The contributions of Fe(III)reduction and SO_(4)^(2-)reduction pathways to SOC mineralization increased in all experimental treatments,FeRR,SRR,NRR,and MGR were significantly positively correlated with the abundance of Geobacter,dsrA,nrfA,and mcrA.SLR inundation increase did not increase soil carbon loss in this oligohaline marsh and may counteract the simulation of soil C loss due to N enrichment.
基金supported by the National Natural Science Foundation of China(No.32272282)Yunnan Province Science and Technology department(No.202305AF150007)Key Laboratory of Industrial Biotechnology of Ministry of Education in Jiangnan Univer-sity(No.KLIB-KF202208).
文摘Raw-materials based broad bean paste(rmBBP)is popular among consumers.Though high salinity can select functional microbial community for fermentation,it also impaired the fermentation efficiency of rmBBP and unfavored human health.Therefore,this study aimed to construct a synthetic microbial community based on key functional microbes for reduced salt rmBBP fermentation based on the elucidation of the microbial community succession during fermentation.Based on the tracked determination and multivariate statistical analysis of the physicochemical parameters,metabolites and the structure of microbial community,salinity and microbial in-teractions were key drivers for the succession of microbial community.Aspergillus,Staphylococcus,Weissella and Tetragenococcus were predicted to play key roles during fermentation.After that,core species were isolated from rmBBP mash and their salinity tolerance and metabolic characteristics were evaluated.Finally,a synthetic mi-crobial community(Aspergillus oryzae,Staphylococcus carnosus,Tetragenococcus halophilus and Weissella confusa)was constructed and applied in reduced-salt rmBBP fermentation.The bioaugmentation contributed to the accumulation of volatile metabolites while effectively maintaining the acidity during rmBBP fermentation when salinity was reduced from 12%to 10%.In general,this study developed a synthetic microbial community with desired characteristics for successful reduced-salinity rmBBP fermentation.
