Circular-economy-oriented medium-chain fatty acid production from organic wastes via chain elongation： artificial regulation and resource-loop pathways

WU Xuejiao; MA Haoyi; YANG Ying; ZHENG Ran; DONG Jian; CUI Han; ZHANG Yafei; ZHOU Dandan

doi:10.13205/j.hjgc.202608008

Volume 44 Issue 8

Aug. 2026

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Article Navigation > ENVIRONMENTAL ENGINEERING > 2026 > 44(8): 77-94

WU Xuejiao, MA Haoyi, YANG Ying, ZHENG Ran, DONG Jian, CUI Han, ZHANG Yafei, ZHOU Dandan. Circular-economy-oriented medium-chain fatty acid production from organic wastes via chain elongation： artificial regulation and resource-loop pathways[J]. ENVIRONMENTAL ENGINEERING , 2026, 44(8): 77-94. doi: 10.13205/j.hjgc.202608008

Citation:

WU Xuejiao, MA Haoyi, YANG Ying, ZHENG Ran, DONG Jian, CUI Han, ZHANG Yafei, ZHOU Dandan. Circular-economy-oriented medium-chain fatty acid production from organic wastes via chain elongation： artificial regulation and resource-loop pathways[J]. ENVIRONMENTAL ENGINEERING , 2026, 44(8): 77-94. doi: 10.13205/j.hjgc.202608008

Citation:

WU Xuejiao, MA Haoyi, YANG Ying, ZHENG Ran, DONG Jian, CUI Han, ZHANG Yafei, ZHOU Dandan. Circular-economy-oriented medium-chain fatty acid production from organic wastes via chain elongation： artificial regulation and resource-loop pathways[J]. ENVIRONMENTAL ENGINEERING , 2026, 44(8): 77-94. doi: 10.13205/j.hjgc.202608008

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Circular-economy-oriented medium-chain fatty acid production from organic wastes via chain elongation： artificial regulation and resource-loop pathways

doi: 10.13205/j.hjgc.202608008

1. School of Environment, Northeast Normal University, Changchun 130117, China

Received Date: 2026-05-31

Abstract

Abstract

Medium-chain fatty acids （MCFAs） are promising biobased products due to their high energy density， hydrophobicity， and significant value for chemical conversion. They represent an important link between organic waste valorization and the development of a circular economy. Compared with conventional anaerobic digestion for methane production， chain elongation （CE） can further convert short-chain intermediates， such as acetate， lactate， and ethanol， into higher-value carboxylic acids， including caproate and caprylate， through the reverse β-oxidation （RBO） pathway. This process provides a novel approach for resource recovery from sewage sludge， food waste， agricultural residues， livestock manure， and high-strength organic wastewater. However， CE systems driven by natural mixed microbial communities are still constrained by fluctuations in substrate composition， competition for electron donors， carbon diversion to methanogenesis， insufficient product selectivity， product toxicity， and high separation costs， all of which limit the stable， efficient， and targeted production of MCFAs. Focusing on the interdisciplinary demands of environmental sustainability and circular economy development， this review systematically summarizes the metabolic mechanisms， artificial regulation strategies， and engineering challenges in MCFA production via CE， with particular emphasis on the directed recovery of carbon and electron resources from organic wastes. Future perspectives are proposed regarding stable continuous-flow operation， product separation and recovery， techno-economic assessment， and life cycle evaluation. This review aims to provide insights into the high-value utilization of organic wastes and the synergistic optimization of carbon and energy resource recovery.
- chain elongation,
- medium-chain fatty acids,
- organic waste,
- circular economy,
- artificial regulation

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References(147)

References

[1]	SHI X，XU J，LI Y，et al. Converting biowastes into medium-chain fatty acid via microbial chain elongation：a mini review[J]. Clean Technology for Resource，Energy and Environment，2025（1）：51-59.
[2]	ZHANG Y，BAI J，ZUO J. Performance and mechanisms of medium-chain fatty acid production by anaerobic fermentation of food waste without external electron donors[J]. Bioresource Technology，2023，374：128735.
[3]	PUYOL D，BATSTONE D J，HüLSEN T，et al. Resource recovery from wastewater by biological technologies：opportunities，challenges，and prospects[J]. Frontiers in Microbiology，2017（7）：2016.
[4]	WU Q，JIANG Y，CHEN Y，et al. Opportunities and challenges in microbial medium chain fatty acids production from waste biomass[J]. Bioresource Technology，2021，340：125633.
[5]	ZHAO J，MA H，GAO M，et al. Advancements in medium chain fatty acids production through chain elongation：key mechanisms and innovative solutions for overcoming rate-limiting steps[J]. Bioresource Technology，2024，408：131133.
[6]	CAVALCANTE W D A，LEITãO R C，GEHRING T A，et al. Anaerobic fermentation for n-caproic acid production：a review[J]. Process Biochemistry，2017，54：106-119.
[7]	YUFEN W，HAIXIAO G，XUECHENG L，et al. Peracetic acid（PAA）-based pretreatment effectively improves medium-chain fatty acids（MCFAs）production from sewage sludge[J]. Environmental Science and Ecotechnology，2024，20：100355.
[8]	SONG Y，ZHANG X，KONG Z，et al. Enhancing the productivity of caproic acid in open culture chain elongation：a comparative study of biofilm systems[J]. Journal of Environmental Management，2025，394：127395.
[9]	KACPRZAK M，NECZAJ E，FIJAŁKOWSKI K，et al. Sewage sludge disposal strategies for sustainable development[J]. Environmental Research，2017，156：39-46.
[10]	WEN Z，CHEN C，AI N，et al. Environmental impact of carbon cross-media metabolism in waste management：a case study of municipal solid waste treatment systems in China[J]. Science of the Total Environment，2019，674：512-523.
[11]	PANG H，LI L，HE J，et al. New insight into enhanced production of short-chain fatty acids from waste activated sludge by cation exchange resin-induced hydrolysis[J]. Chemical Engineering Journal，2020，388：124235.
[12]	ZHOU Q，LI X，WU S，et al. Enhanced strategies for antibiotic removal from swine wastewater in anaerobic digestion[J]. Trends in Biotechnology，2021，39（1）：8-11.
[13]	WANG Z，LI X，LIU H，et al. Bioproduction and applications of short-chain fatty acids from secondary sludge anaerobic fermentation：a critical review[J]. Renewable and Sustainable Energy Reviews，2023，183：113502.
[14]	AGLER M T，WRENN B A，ZINDER S H，et al. Waste to bioproduct conversion with undefined mixed cultures：the carboxylate platform[J]. Trends in Biotechnology，2011，29（2）：70-78.
[15]	MASSIMI A，BRAGUGLIA C M，GALLIPOLI A，et al. A bacterial outlook on the caproate production from food waste[J]. Reviews in Environmental Science and Bio/Technology，2024，23（3）：679-698.
[16]	WANG J，YIN Y. Biological production of medium-chain carboxylates through chain elongation：an overview[J]. Biotechnology Advances，2022，55：107882.
[17]	WAINAINA S，AWASTHI M K，HORVáTH I S，et al. Anaerobic digestion of food waste to volatile fatty acids and hydrogen at high organic loading rates in immersed membrane bioreactors[J]. Renewable Energy，2020，152：1140-1148.
[18]	BATTISTA F，BOLZONELLA D. Beyond anaerobic digestion：new perspectives for the development of a biorefinery platform for the simultaneous production of medium-chain fatty acids by chain elongation and biogas from food wastes[J]. ACS Sustainable Chemistry& Engineering，2024，12（42）：15294-15306.
[19]	KUCEK L A，SPIRITO C M，ANGENENT L T. High n-caprylate productivities and specificities from dilute ethanol and acetate：chain elongation with microbiomes to upgrade products from syngas fermentation[J]. Energy& Environmental Science，2016，9（11）：3482-3494.
[20]	WU L，WEI W，CHEN Z，et al. Medium-chain carboxylate productions through open-culture fermentation of organic wastes[J]. Journal of Cleaner Production，2022，373：133911.
[21]	BATTISTA F，ZENI A，ANDREOLLI M，et al. Treatment of food processing wastes for the production of medium chain fatty acids via chain elongation[J]. Environmental Technology& Innovation，2024，33：103453.
[22]	ZHANG P Y，WANG Q Y，LIANG J S，et al. Research progress on chain elongation synthesis of medium-chain fatty acids from anaerobic fermentation liquid of organic waste[J]. Journal of Environmental Engineering，2022，16（2）：363-374. 张盼月，王清谚，梁劲松，等. 有机废物厌氧发酵液链延长合成中链脂肪酸研究进展[J]. 环境工程学报，2022，16（2）：363-374.
[23]	WAN R X. Feasibility Study on the Synthesis of Medium-Chain Fatty Acids from Anaerobic Fermentation Products of Residual Sludge[D]. Shanghai：Shanghai Jiao Tong University，2020. 苑荣雪. 基于剩余污泥厌氧发酵产物合成中链脂肪酸的可行性研究[D]. 上海：上海交通大学，2020.
[24]	BALEEIRO F，RAAB J，KLEINSTEUBER S，et al. Mixotrophic chain elongation with syngas and lactate as electron donors[J]. Microbial Biotechnology，2022，16.
[25]	LIU H P，LIU C，WANG W，et al. Bio-based carbon chain elongation for the synthesis of high-value chemicals：reaction mechanisms and research progress with different electron donors[J]. Journal of Beijing University of Chemical Technology（Natural Science Edition），2020，47（5）：1-17. 刘昊鹏，刘超，王雯，等. 基于生物的碳链延长合成高价值化学品反应机理及研究进展：不同电子供体[J]. 北京化工大学学报（自然科学版），2020，47（5）：1-17.
[26]	ROGHAIR M，HOOGSTAD T，STRIK D P B T B，et al. Controlling ethanol use in chain elongation by CO₂ loading rate[J]. Environmental Science& Technology，2018，52（3）：1496-1505.
[27]	LI D，ZHOU A，MEI J，et al. Synergy among multiple electron donors in electro-fermentation chain elongation：accelerated directional electron transfer and enhanced microbial functions[J]. Bioresource Technology，2025，434：132817.
[28]	KUCEK L A，NGUYEN M，ANGENENT L T. Conversion of l-lactate into n-caproate by a continuously fed reactor microbiome[J]. Water Research，2016，93：163-171.
[29]	BALEEIRO F C F，KLEINSTEUBER S，STRäUBER H. Hydrogen as a co-electron donor for chain elongation with complex communities[J]. Frontiers in Bioengineering and Biotechnology，2021，9：650631.
[30]	ROGHAIR M，LIU Y，ADIATMA J C，et al. Effect of n-caproate concentration on chain elongation and competing processes[J]. ACS Sustainable Chemistry& Engineering，2018，6（6）：7499-7506.
[31]	QIANG H，XU X，LIU Z，et al. New insights into the interplay between chain elongation and homoacetogenesis in microbial electrosynthesis：chloroform-enhanced medium-chain carboxylate production[J]. Water Research，2026，298：125790.
[32]	YU J，DU Y，AN K，et al. A novel sustainable and microbial functional modulation strategy for directly transforming corn straw into high-value liquid biochemicals[J]. Water Research，2026，288：124628.
[33]	CANDRY P，RADIĆ L，FAVERE J，et al. Mildly acidic pH selects for chain elongation to caproic acid over alternative pathways during lactic acid fermentation[J]. Water Research，2020，186：116396.
[34]	QUINTELA C，BOUNTZIS P，REZAEI B，et al. Chain elongation in continuous microbial electrosynthesis cells：the effect of pH and precursors supply[J]. Journal of CO₂ Utilization，2024，83：102789.
[35]	ULČAR B，REGUEIRA A，PODOJSTERŠEK M，et al. Why do lactic acid bacteria thrive in chain elongation microbiomes？[J]. Frontiers in Bioengineering and Biotechnology，2024，11：1291007.
[36]	WANG Y，WEI W，DAI X，et al. Different electron donors drive the variation in the performance of medium-chain fatty acid production from waste-activated sludge[J]. ACS ES&T Engineering，2024，4（3）：650-659.
[37]	LI D，WANG Y，QIANG H，et al. Tailoring microbial communities for medium chain fatty acid production from waste activated sludge：comparative performance of endogenous vs. exogenous consortia[J]. Bioresource Technology，2026，444：134038.
[38]	LIANG Y，YU J，YAO Z，et al. Decoding microbial interactions：interaction networks and regulatory strategies for medium-chain fatty acid biosynthesis through anaerobic chain elongation[J]. Biotechnology Advances，2026，86：108735.
[39]	LIU B，STRäUBER H，CENTLER F，et al. Functional redundancy secures resilience of chain elongation communities upon pH shifts in closed bioreactor ecosystems[J]. Environmental Science& Technology，2023，57（46）：18350-18361.
[40]	DOMINGOS J M B，MARTINEZ G A，SCOMA A，et al. Effect of operational parameters in the continuous anaerobic fermentation of cheese whey on titers，yields，productivities，and microbial community structures[J]. ACS Sustainable Chemistry& Engineering，2017，5（2）：1400-1407.
[41]	LIU Y，HE P，SHAO L，et al. Significant enhancement by biochar of caproate production via chain elongation[J]. Water Research，2017，119：150-159.
[42]	ZHANG C，LIU Y，ZHANG W，et al. Modification of wheat straw to improve the caproate production in a cell immobilized system[J]. Bioresource Technology，2021，342：125984.
[43]	ZHAO Y，YUAN F，SU Y，et al. Metagenomic and proteomic insights into graphene oxide-boosted anaerobic co-fermentation of food waste and sewage sludge for volatile fatty acids production[J]. Chemical Engineering Journal，2025，504：158706.
[44]	XIANG J，ZHOU Z，LIU Z，et al. Constructing simplified microbial consortia that couple lactic acid and ethanol utilization to highly produce caproic acid from liquor-making wastewater[J]. Water Research，2025，284：123973.
[45]	ZAGRODNIK R，DUBER A，ŁĘŻYK M，et al. Enrichment versus bioaugmentation—microbiological production of caproate from mixed carbon sources by mixed bacterial culture and Clostridium kluyveri[J]. Environmental Science& Technology，2020，54（9）：5864-5873.
[46]	WANG Y，CHENG S，VARRONE C，et al. Selective colonization of multifunctional microbes that facilitates caproate production in microbial electrosynthesis system[J]. Chemical Engineering Journal，2024，488：150848.
[47]	ZHANG Y，LI J，LIAN X，et al. Efficient caproate production from lignocellulose via single-step electro-fermentation platform without organic electron donor[J]. Bioresource Technology，2024，411：131319.
[48]	WU S L，WU L，WEI W，et al. Challenges and enhancement technologies of medium chain carboxylates production in open culture anaerobic fermentation[J]. Chemical Engineering Journal，2024，494：153224.
[49]	GU J，CUI Z，WU Y，et al. Electricity-driven microbial production of medium-chain fatty acids from biowaste：from mechanisms to applications[J]. Chemical Engineering Journal，2025，522：167282.
[50]	WANG Q，ZHANG R，LI Y，et al. Micro-biological actions and regulation of chain elongation process for medium chain carboxylic acid production[J]. Separation and Purification Technology，2026，380：135297.
[51]	CHI X，LI J，WANG X，et al. Bioaugmentation with Clostridium tyrobutyricum to improve butyric acid production through direct rice straw bioconversion[J]. Bioresource Technology，2018，263：562-568.
[52]	ZHANG C，LIU H，WU P，et al. Clostridium kluyveri enhances caproate production by synergistically cooperating with acetogens in mixed microbial community of electro-fermentation system[J]. Bioresource Technology，2023，369：128436.
[53]	ZHANG W，YIN F，DONG H，et al. Bioconversion of swine manure into high-value products of medium chain fatty acids[J]. Waste Management，2020，113：478-487.
[54]	QIAN D K，GENG Z Q，SUN T，et al. Caproate production from xylose by mesophilic mixed culture fermentation[J]. Bioresource Technology，2020，308：123318.
[55]	WESTPHAL L，WIECHMANN A，BAKER J，et al. The Rnf complex is an energy-coupled transhydrogenase essential to reversibly link cellular NADH and ferredoxin pools in the acetogen Acetobacterium woodii[J]. Journal of Bacteriol，2018，200（21）.
[56]	SEEDORF H，FRICKE W F，VEITH B，et al. The genome of Clostridium kluyveri，a strict anaerobe with unique metabolic features[J]. Proceedings of the National Academy of Sciences，2008，105（6）：2128-2133.
[57]	LIU T，LI J，HAO X，et al. Efficient caproic acid production from lignocellulosic biomass by bio-augmented mixed microorganisms[J]. Bioresource Technology，2024，399：130565.
[58]	WEIMER P J，NERDAHL M，BRANDL D J. Production of medium-chain volatile fatty acids by mixed ruminal microorganisms is enhanced by ethanol in co-culture with Clostridium kluyveri[J]. Bioresource Technology，2015，175：97-101.
[59]	DAMS R I，VIANA M B，GUILHERME A A，et al. Production of medium-chain carboxylic acids by anaerobic fermentation of glycerol using a bioaugmented open culture[J]. Biomass and Bioenergy，2018，118：1-7.
[60]	WANG C，WEI W，WU L，et al. A novel sustainable and self-sufficient biotechnological strategy for directly transforming sewage sludge into high-value liquid biochemicals[J]. Environmental Science& Technology，2024，58（28）：12520-12531.
[61]	DENG L，LV Y，LAN T，et al. Chain elongation using native soil inocula：exceptional n-caproate biosynthesis performance and microbial mechanisms[J]. Engineering，2024，39：262-272.
[62]	BASAK B，AHN Y，KUMAR R，et al. Lignocellulolytic microbiomes for augmenting lignocellulose degradation in anaerobic digestion[J]. Trends in Microbiology，2022，30（1）：6-9.
[63]	TANG J，YANG H，PU Y，et al. Effect of inoculum sources on caproic acid production from food waste through lactate-based chain elongation：properties and microbial succession[J]. Journal of Environmental Chemical Engineering，2024，12（6）：114186.
[64]	ZOMORRODI A R，SEGRè D. Synthetic ecology of microbes：mathematical models and applications[J]. Journal of Molecular Biology，2016，428（5）：837-861.
[65]	LAWSON C E，HARCOMBE W R，HATZENPICHLER R，et al. Common principles and best practices for engineering microbiomes[J]. Nature Reviews Microbiology，2019，17（12）：725-741.
[66]	LYU X，NUHU M，CANDRY P，et al. Top-down and bottom-up microbiome engineering approaches to enable biomanufacturing from waste biomass[J]. Journal Industrial Microbiology and Biotechnology，2024，51：25.
[67]	XU Y，WU M，ZHAO D，et al. Simulated fermentation of strong-flavor baijiu through functional microbial combination to realize the stable synthesis of important flavor chemicals[J]. Foods，2023，12（3）：644.
[68]	KENEALY W R，CAO Y，WEIMER P J. Production of caproic acid by cocultures of ruminal cellulolytic bacteria and Clostridium kluyveri grown on cellulose and ethanol[J]. Applied Microbiology and Biotechnology，1995，44（3）：507-513.
[69]	DAI M，WANG X，WANG H，et al. Butyrogenic and caprogenic bacteria from pit mud of strong-aroma baijiu engage in mutualistic cross-feeding and promoting caproic acid biosynthesis[J]. International Journal of Food Microbiology，2025，443：111434.
[70]	PARERA OLM I，BENITO VAQUERIZO S，DUBAERE C，et al. Synthetic microbial cocultivation for targeted production of odd-chain carboxylates and alcohols from carbon monoxide[J]. Environmental Science& Technology，2025，59（35）：18706-18721.
[71]	DIENDER M，PARERA OLM I，GELDERLOOS M，et al. Metabolic shift induced by synthetic co-cultivation promotes high yield of chain elongated acids from syngas[J]. Scientific Reports，2019，9（1）：18081.
[72]	ROELL G W，ZHA J，CARR R R，et al. Engineering microbial consortia by division of labor[J]. Microbial Cell Factories，2019，18（1）：35.
[73]	SHAHAB R L，BRETHAUER S，DAVEY M P，et al. A heterogeneous microbial consortium producing short-chain fatty acids from lignocellulose[J]. Science，2020，369（6507）：eabb1214.
[74]	LI X，LEI X，GUO Z，et al. Enhancing chain-elongating microbiomes：sequential fungi-bacteria cooperation for efficient food waste upgrading using endogenous electron donors[J]. Chemical Engineering Journal，2024，488：150849.
[75]	ZHANG Z，NI B J，ZHANG L，et al. Medium-chain fatty acids production from carbohydrates-rich wastewater through two-stage yeast biofilm processes without external electron donor addition：biofilm development and pH impact[J]. Science of the Total Environment，2022，828：154428.
[76]	BAMBACE M F，NG K S，JENSEN K W，et al. Development of novel microbial synthetic consortia for the production of antimicrobial fermentates containing caproate[J]. Applied Microbiology and Biotechnology，2026，110（1）：85.
[77]	LI X，MA Y，DING Z，et al. Steering yeast-bacteria synergy by biochar to achieve enhanced endogenous ethanol-driven chain elongation[J]. Chemical Engineering Journal，2025，511：162013.
[78]	CHENG S，HU Y，GU X，et al. Magnetite-enhanced chain elongation via endogenous electron donors through a novel fungi-bacteria microbiome[J]. Water Research，2025，287：124478.
[79]	CHENG S，BAI S，XU X，et al. Ferric oxide enhances mixed fungal-bacterial microbiome for medium-chain fatty acid production via endogenous electron donors[J]. Chemical Engineering Journal，2026，533：174681.
[80]	CHEN Y J，LI Y，REN Z X，et al. Unveiling the dual role of eggshell as a pH buffer and calcium-driven promoter for enhanced caproate production via two-stage anaerobic fermentation[J]. ACS Sustainable Chemistry& Engineering，2026，14（17）：8342-8353.
[81]	LI X，CHENG S，WANG X，et al. Intrinsic waste component synergy：calcium-rich eggshell waste modulates fungal-bacterial microbiome toward selectively medium-chain fatty acid production[J]. Bioresource Technology，2026，455：134795.
[82]	VIRDIS B，HOELZLE R D.，MARCHETTI A，et al. Electro-fermentation：sustainable bioproductions steered by electricity[J]. Biotechnology Advances，2022，59：107950.
[83]	SCHIEVANO A，PEPè SCIARRIA T，VANBROEKHOVEN K，et al. Electro-fermentation-merging electrochemistry with fermentation in industrial applications[J]. Trends in biotechnology，2016，34（11）：866-878.
[84]	WU P，LIU H，LI J，et al. Acetate-to-bioproducts by chain elongation microbiome catalysis under applied voltage regulation[J]. Energy Conversion and Management，2021，248：114804.
[85]	YU D，CHENG S，CAO F，et al. Unveiling the bioelectrocatalyzing behaviors and microbial ecological mechanisms behind caproate production without exogenous electron donor[J]. Environmental Research，2022，215：114077.
[86]	JOURDIN L，RAES S M T，BUISMAN C J N，et al. Critical biofilm growth throughout unmodified carbon felts allows continuous bioelectrochemical chain elongation from CO₂ up to caproate at high current density[J]. Frontiers in Energy Research，2018，6：7.
[87]	van EERTEN-JANSEN M C A A，TER H A，GROOTSCHOLTEN T I M，et al. Bioelectrochemical production of caproate and caprylate from acetate by mixed cultures[J]. ACS Sustainable Chemistry& Engineering，2013，1（5）：513-518.
[88]	CHENG S，LIU Z，VARRONE C，et al. Elucidating the microbial ecological mechanisms on the electro-fermentation of caproate production from acetate via ethanol-driven chain elongation[J]. Environmental Research，2022，203：111875.
[89]	JIANG Y，CHU N，QIAN D K，et al. Microbial electrochemical stimulation of caproate production from ethanol and carbon dioxide[J]. Bioresource Technology，2020，295：122266.
[90]	SU W，LI D，TAN H，et al. Boosting the biosynthesis of medium-chain fatty acids from waste activated sludge electro-fermentation：roles of syngas and ethanol serving as co-electron donors[J]. Journal of Cleaner Production，2025，502：145383.
[91]	QIANG H，LIU Z，DONG Z，et al. Deciphering the role and mechanism of zero-valent iron on medium-chain fatty acid production from acetate via chain elongation in microbial electro-fermentation[J]. Chemical Engineering Journal，2025，515：163712.
[92]	BAEK G，KIM J，KIM J，et al. Role and potential of direct interspecies electron transfer in anaerobic digestion[J]. Energies，2018，11（1）：107
[93]	PARK J H，KANG H J，PARK K H，et al. Direct interspecies electron transfer via conductive materials：a perspective for anaerobic digestion applications[J]. Bioresource Technology，2018，254：300-311.
[94]	BURNS C，RISHAN M，STEVENS L，et al. A living semiartificial photoelectrocatalytic biohybrid for solar CO₂ fixation and fermentation to fatty acids[J]. ACS Applied Materials Interfaces，2025，17（46）：63363-63373.
[95]	RISHAN M，PUNATHIL P，BURNS C，et al. Cu₂ZnSnS₄–Sporomusa ovata photobiohybrids coupled with Clostridium kluyveri fermentation for CO₂ conversion to C₄-C₆ fatty acids[J]. Materials Horizons，2026，13（8）：3853-3867.
[96]	FAN H，WANG J，MEI X，et al. Energetic photoexcited electrons and enhancement of metabolic function and electron transport promote carbon chain elongation in bacterium-cadmium sulfide biohybrid systems[J]. Chemical Engineering Journal，2025，521：166901.
[97]	BAO Z，JI X，LIU Q，et al. Light-driven N-doped carbon quantum dots facilitate microbial chain elongation：bridging process enhancement to functional metagenomics[J]. Bioresource Technology，2026，449：134393.
[98]	HA P T，LINDEMANN S R，SHI L，et al. Syntrophic anaerobic photosynthesis via direct interspecies electron transfer[J]. Nature Communications，2017，8（1）：13924.
[99]	WANG Y，WEI W，WU S L，et al. Zerovalent iron effectively enhances medium-chain fatty acids production from waste activated sludge through improving sludge biodegradability and electron transfer efficiency[J]. Environmental Science& Technology，2020，54（17）：10904-10915.
[100]	DU J，XU P P，REN H Y，et al. Improved sequential production of hydrogen and caproate by addition of biochar prepared from cornstalk residues[J]. Bioresource Technology，2023，387：129702.
[101]	LIM E Y，LEE J T E，ZHANG L，et al. Abrogating the inhibitory effects of volatile fatty acids and ammonia in overloaded food waste anaerobic digesters via the supplementation of nano-zero valent iron modified biochar[J]. Science of the Total Environment，2022，817：152968.
[102]	FU X，YE R，JIN X，et al. Effect of nano zero-valent iron addition on caproate fermentation in carboxylate chain elongation system[J]. Science of the Total Environment，2020，743：140664.
[103]	MA J，ZHAO Q，HE Q，et al. Enhanced medium-chain fatty acids production by iron–carbon microelectrolysis：performance and mechanisms[J]. ACS ES&T Engineering，2025，5（4）：991-1002.
[104]	LI X，YANG P，LIU M，et al. Performance and mechanism of iron-carbon enhancing medium chain fatty acids production from waste sludge[J]. Journal of Environmental Chemical Engineering，2024，12（3）：112935.
[105]	LI J，LIU H，WU P，et al. Quorum sensing signals enhanced caproate production by changing microbial community in chain elongation enrichments[J]. Journal of Environmental Chemical Engineering，2021，9（6）：106623.
[106]	CHEN Y，CHEN T，YIN J. Impact of N-butyryl-l-homoserine lactone–mediated quorum sensing on acidogenic fermentation under saline conditions：insights into volatile fatty acids production and microbial community[J]. Bioresource Technology，2023，368：128354.
[107]	ZHAO S，SONG G，LIU S，et al. Anaerobic acidogenesis improvement and fermentation-type regulation by quorum sensing[J]. ACS ES&T Engineering，2024，4（10）：2358-2369.
[108]	LI J，LIU H，WU P，et al. Quorum sensing signals stimulate biofilm formation and its electroactivity for chain elongation：system performance and underlying mechanisms[J]. Science of the Total Environment，2023，859：160192.
[109]	ZHAO J，MA H，SU F，et al. Quorum sensing enhances microbial resistance to substrate toxicity during anaerobic caproate production[J]. Chemical Engineering Journal，2025，520：166049.
[110]	LI J，LIU H，ZHAO C，et al. Autoinducer-2 quorum sensing regulates biofilm formation and chain elongation metabolic pathways to enhance caproate synthesis in microbial electrochemical system[J]. Chemosphere，2023，344：140384.
[111]	JARBOE L R，ROYCE L A，LIU P. Understanding biocatalyst inhibition by carboxylic acids[J]. Frontiers in Microbiology，2013（4）：272.
[112]	STAMATOPOULOU P，MALKOWSKI J，CONRADO L，et al. Fermentation of organic residues to beneficial chemicals：a review of medium-chain fatty acid production[J] Processes，2020，8（12）：1571.
[113]	ALLAART M T，STOUTEN G R，SOUSA D Z，et al. Product inhibition and pH affect stoichiometry and kinetics of chain elongating microbial communities in sequencing batch bioreactors[J]. Frontiers in Bioengineering and Biotechnology，2021（9）：693030.
[114]	DE GROOF V，COMA M，ARNOT T，et al. Medium chain carboxylic acids from complex organic feedstocks by mixed culture fermentation[J]. Molecules，2019，24（3）：337.
[115]	CARVAJAL-ARROYO J M，ANDERSEN S J，GANIGUÉ R，et al. Production and extraction of medium chain carboxylic acids at a semi-pilot scale[J]. Chemical Engineering Journal，2021，416：127886.
[116]	XU J，GUZMAN J，ANDERSEN S，et al. In-line and selective phase separation of medium-chain carboxylic acids using membrane electrolysis[J]. Chemical Communications，2015，51.
[117]	BAK C，YUN Y M，KIM J H，et al. Electrodialytic separation of volatile fatty acids from hydrogen fermented food wastes[J]. International Journal of Hydrogen Energy，2019，44（6）：3356-3362.
[118]	REYHANITASH E，KERSTEN S R A，SCHUUR B. Recovery of volatile fatty acids from fermented wastewater by adsorption[J]. ACS Sustainable Chemistry& Engineering，2017，5（10）：9176-9184.
[119]	ANGENENT L T，RICHTER H，BUCKEL W，et al. Chain elongation with reactor microbiomes：open-culture biotechnology to produce biochemicals[J]. Environmental Science& Technology，2016，50（6）：2796-2810.
[120]	PALOMO BRIONES R，XU J，SPIRITO C M，et al. Near-neutral pH increased n-caprylate production in a microbiome with product inhibition of methanogenesis[J]. Chemical Engineering Journal，2022，446：137170.
[121]	GE S，USACK J G，SPIRITO C M，et al. Long-term n-caproic acid production from yeast-fermentation beer in an anaerobic bioreactor with continuous product extraction[J]. Environmental Science& Technology，2015，49（13）：8012-8021.
[122]	XU J，BIAN B，ANGENENT L T，et al. Long-term continuous extraction of medium-chain carboxylates by pertraction with submerged hollow-fiber membranes[J]. Frontiers in Bioengineering and Biotechnology，2021（9）：726946.
[123]	WU Q，GUO W，BAO X，et al. Upgrading liquor-making wastewater into medium chain fatty acid：insights into co-electron donors，key microflora，and energy harvest[J]. Water Research，2018，145：650-659.
[124]	CHEN Y，CHENG J J，CREAMER K S. Inhibition of anaerobic digestion process：a review[J]. Bioresource Technology，2008，99（10）：4044-4064.
[125]	RAJAGOPAL R，MASSé D I，SINGH G. A critical review on inhibition of anaerobic digestion process by excess ammonia[J]. Bioresource Technology，2013，143：632-641.
[126]	SPIRITO C M，RICHTER H，RABAEY K，et al. Chain elongation in anaerobic reactor microbiomes to recover resources from waste[J]. Current Opinion in Biotechnology，2014，27：115-122.
[127]	WU Q L，YUAN K X，REN W T，et al. Unveiling the mechanism underlying the effects of ammonia on n-caproate production：influenced pathways，key enzymes，and microbiota functions[J]. Engineering，2024，35：180-190.
[128]	WEI Y，REN B，ZHENG S，et al. Effect of high concentration of ammonium on production of n-caproate：recovery of a high-value biochemical from food waste via lactate-driven chain elongation[J]. Waste Management，2021，128：25-35.
[129]	ZHANG C，YANG L，TSAPEKOS P，et al. Immobilization of Clostridium kluyveri on wheat straw to alleviate ammonia inhibition during chain elongation for n-caproate production[J]. Environment International，2019，127：134-141.
[130]	ZHAO J，MA H，GAO M，et al. Production of caproate from lactate by chain elongation under electro-fermentation：dual role of exogenous ethanol electron donor[J]. Bioresource Technology，2025，424：132272.
[131]	XIONG B J，KLEINSTEUBER S，STRÄUBER H，et al. Impact of fungal hyphae on growth and dispersal of obligate anaerobic bacteria in aerated habitats[J]. mBio，2022，13（3）：e0076922.
[132]	SOMPONG O，ZHU X，ANGELIDAKI I，et al. Medium chain fatty acids production by microbial chain elongation：recent advances[J]. Advances in Bioenergy，2020（5）：63-99.
[133]	JI X，ZHU K，ZHANG Y，et al. Mixed culture chain elongation for consumption of acetate and ethanol in anaerobic fermentation：the impact of salt type，dosage and acclimation[J]. Waste Management，2022，152：48-58.
[134]	SHRESTHA S，XUE S，RASKIN L. Competitive reactions during ethanol chain elongation were temporarily suppressed by increasing hydrogen partial pressure through methanogenesis inhibition[J]. Environmental Science& Technology，2023，57（8）：3369-3379.
[135]	CANDRY P，ULCAR B，PETROGNANI C，et al. Ethanol：propionate ratio drives product selectivity in odd-chain elongation with Clostridium kluyveri and mixed communities[J]. Bioresource Technology，2020，313：123651.
[136]	GROOTSCHOLTEN T I M，STEINBUSCH K J J，HAMELERS H V M，et al. Chain elongation of acetate and ethanol in an upflow anaerobic filter for high rate MCFA production[J]. Bioresource Technology，2013，135：440-445.
[137]	DAIGGER G T，KUO J，DERLON N，et al. Biological and physical selectors for mobile biofilms，aerobic granules，and densified-biological flocs in continuously flowing wastewater treatment processes：a state-of-the-art review[J]. Water Research，2023，242：120245.
[138]	CHEN Y，LI Y，CHENG S，et al. Brief aerobic pretreatment for stabilizing long-term caproate production from food waste via fungi-bacteria chain-elongating consortia[J]. Bioresource Technology，2026，455：134810.
[139]	CHEN W S，STRIK D，BUISMAN C J N，et al. Production of caproic acid from mixed organic waste：an environmental life cycle perspective[J]. Environmental Science& Technology，2017，51（12）：7159-7168.
[140]	XU J，HAO J，GUZMAN J J L，et al. Temperature-phased conversion of acid whey waste into medium-chain carboxylic acids via lactic acid：no external e-donor[J]. Joule，2018，2（2）：280-295.
[141]	WU S L，SUN J，CHEN X，et al. Unveiling the mechanisms of medium-chain fatty acid production from waste activated sludge alkaline fermentation liquor through physiological，thermodynamic and metagenomic investigations[J]. Water Research，2020，169：115218.
[142]	CHANG B R，DENG L，WU Q L，et al. A review：carbon-based materials as effective additives in anaerobic fermentation，focusing on microbial chain elongation and medium chain fatty acids production[J]. Chinese Chemical Letters，2025，36（7）：110411.
[143]	MCDOWALL S C，BRAUNE M，NITZSCHE R. Recovery of bio-based medium-chain fatty acids with membrane filtration[J]. Separation and Purification Technology，2022，286：120430.
[144]	ZAMPIERI G，CAMPANARO S，ANGIONE C，et al. Metatranscriptomics-guided genome-scale metabolic modeling of microbial communities[J]. Cell Reports Methods，2023，3（1）：100383.
[145]	LONG F，FAN J，LIU H. Prediction and optimization of medium-chain carboxylic acids production from food waste using machine learning models[J]. Bioresource Technology，2023，370：128533.
[146]	MA H，LIU Y，ZHAO J，et al. Explainable machine learning-driven predictive performance and process parameter optimization for caproic acid production[J]. Bioresource Technology，2024，410：131311.
[147]	SØRENSEN H M，CUNNINGHAM D，BALAKRISHNAN R，et al. Steps toward a digital twin for functional food production with increased health benefits[J]. Current Research in Food Science，2023，7：100593.