Adsorptionand High-Value Transformation of Volatile Fatty Acids from Microbial Fermentation Products: A Review

Abstract

To mitigatethe aforementioned global environmental issues, the concept of carbon capture andstorage is crucial in addressing the necessity for carbon peaking and carbon neutrality.The buildup of volatile fatty acids during anaerobic fermentation is a primary factorcontributing to the suboptimal performance or outright failure of anaerobic digestionsystems. In response to the pressing demand for volatile organic acid recovery andhigh-value conversion, we primarily outlined the sources, recovery techniques, adsorptionmaterials, and methods for high-value conversion of volatile fatty acids. The methodsof adsorbing volatile acetic acid were presented, encompassing adsorption materials,mechanisms, and interfacial modifications of the adsorbent. Furthermore, drawingfrom recent research advancements, we have synthesized the high-value conversiontechniques for volatile fatty acids and evaluated the research challenges and futureprospects in this domain.

Keywords

Volatilefatty acid / Carbon neutrality of biomass / Adsorption / High value biotransformation

Acknowledgements

We express our thanks for funding support from the National Key Research and Development Program of China (2021YFC2103600), National Natural Science Foundation of China (22308016, 22408019), Fundamental Research Funds for the Central Universities (JD2428), Jiangxi Province Double Thousand Plan High-level Innovation Team Project (S2020CXTD0240).

Author Contributions

Conceptualization, Software, Validation, Formal Analysis, H.Z.; Investigation, Y.W.; Resources, G.X.; Data Curation, Y.Z.; Writing—Original Draft Preparation, H.Z.; Writing—Review & Editing, Y.Z.; Supervision, H.S.; Funding Acquisition, H.S. and Y.Z.

Ethics Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Relevant information and dates can be made available upon request.

Funding

We express our thanks for funding support from the National Natural Science Foundation of China (22308016, 22408019), Fundamental Research Funds for the Central Universities (JD2428), Jiangxi Province Double Thousand Plan High-level Innovation Team Project (S2020CXTD0240).

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References

[1] Tang P, Si Y, Song X, Sun G. Hierarchically porous bacterial cellulose nanofibrous membranes for selective adsorption and real-time colorimetric monitoring of volatile carboxylic acids. Cellulose 2024, 31, 381-393.

[2] Goel C, Bhunia H, Bajpai PK. Novel nitrogen enriched porous carbon adsorbents for CO₂ capture: Breakthrough adsorption study. J. Environ. Chem. Eng. 2016, 4, 346-356.

[3] Cuéllar-Franca RM, Azapagic A. Carbon capture, storage and utilisation technologies: A critical analysis and comparison of their life cycle environmental impacts. J. CO2 Util. 2015, 9, 82-102.

[4] Lee JW, Hawkins B, Day DM, Reicosky DC. Sustainability: The capacity of smokeless biomass pyrolysis for energy production, global carbon capture and sequestration. Energy Environ. Sci. 2010, 3, 1695-1705.

[5] Conesa JA, Domene A. Gasification and pyrolysis of Posidonia oceanica in the presence of dolomite. J. Anal. Appl. Pyrolysis 2015, 113, 680-689.

[6] Dupont J, Suarez PAZ, Meneghetti MR, Meneghetti SMP. Catalytic production of biodiesel and diesel-like hydrocarbons from triglycerides. Energy Environ. Sci. 2009, 2, 1258-1265.

[7] Cooney MJ, Svoboda V, Lau C, Martin G, Minteer SD. Enzyme catalysed biofuel cells. Energy Environ. Sci. 2008, 1, 320-337.

[8] Chen G, Zhao L, Qi Y. Enhancing the productivity of microalgae cultivated in wastewater toward biofuel production: A critical review. Appl. Energy 2015, 137, 282-291.

[9] Cui P, Ge J, Chen Y, Zhao Y, Wang S, Su H. The Fe₃O₄ nanoparticles-modified mycelium pellet-based anaerobic granular sludge enhanced anaerobic digestion of food waste with high salinity and organic load. Renew. Energy 2022, 185, 376-385.

[10] Cui P, Wang S, Su H. Enhanced biohydrogen production of anaerobic fermentation by the Fe₃O₄ modified mycelial pellets-based anaerobic granular sludge. Bioresour. Technol. 2022, 366, 128144.

[11] Cui P, Wang D, Wang S, Su H, Wang Y. Regulatory mechanism of antioxidant enzymes on microbial metabolism and NADH in anaerobic fermentation of food waste for hydrogen production. J. Clean. Prod. 2024, 474, 143607.

[12] Atasoy M, Owusu-Agyeman I, Plaza E, Cetecioglu Z. Bio-based volatile fatty acid production and recovery from waste streams: Current status and future challenges. Bioresour. Technol. 2018, 268, 773-786.

[13] den Boer E, Łukaszewska A, Kluczkiewicz W, Lewandowska D, King K, Reijonen T, et al. Volatile fatty acids as an added value from biowaste. Waste Manag. 2016, 58, 62-69.

[14] Llamas M, Magdalena JA, Greses S, Tomás-Pejó E, González-Fernández C. Insights on the microbial communities developed during the anaerobic fermentation of raw and pretreated microalgae biomass. Chemosphere 2021, 263, 127942.

[15] Lu Y, Zhang Q, Wang X, Zhou X, Zhu J. Effect of pH on volatile fatty acid production from anaerobic digestion of potato peel waste. Bioresour. Technol. 2020, 316, 123851.

[16] Yu P, Tu W, Wu M, Zhang Z, Wang H. Pilot-scale fermentation of urban food waste for volatile fatty acids production: The importance of pH. Bioresour. Technol. 2021, 332, 125116.

[17] Jin Y, Lin Y, Wang P, Jin R, Gao M, Wang Q, et al. Volatile fatty acids production from saccharification residue from food waste ethanol fermentation: Effect of pH and microbial community. Bioresour. Technol. 2019, 292, 121957.

[18] Feng K, Li H, Zheng C. Shifting product spectrum by pH adjustment during long-term continuous anaerobic fermentation of food waste. Bioresour. Technol. 2018, 270, 180-188.

[19] Soomro AF, Abbasi IA, Ni Z, Ying L, Liu J. Influence of temperature on enhancement of volatile fatty acids fermentation from organic fraction of municipal solid waste: Synergism between food and paper components. Bioresour. Technol. 2020, 304, 122980.

[20] Jiang X, Qin Z, Feng L, Chen Y, Chen J, Zhang X, et al. Volatile fatty acids production from waste activated sludge during anaerobic fermentation: The effect of superfine sand. Bioresour. Technol. 2021, 319, 124249.

[21] Wang S-X, Huang Y-X, Wang H, Lu Y-Y, He W-L, Li J, et al. A comparative study of different iron minerals on phosphorus capture from municipal wastewater and subsequent recovery as vivianite through acidogenic fermentation. Chem. Eng. J. 2023, 466, 143370.

[22] Xing D, Ren N, Wang A, Li Q, Feng Y, Ma F. Continuous hydrogen production of auto-aggregative Ethanoligenens harbinense YUAN-3 under non-sterile condition. Int. J. Hydrogen Energy 2008, 33, 1489-1495.

[23] Merlin Christy P, Gopinath LR, Divya D. A review on anaerobic decomposition and enhancement of biogas production through enzymes and microorganisms. Renew. Sustain. Energy Rev. 2014, 34, 167-173.

[24] Kiely PD, Regan JM, Logan BE. The electric picnic: Synergistic requirements for exoelectrogenic microbial communities. Curr. Opin. Biotechnol. 2011, 22, 378-385.

[25] Lu L, Ren ZJ. Microbial electrolysis cells for waste biorefinery: A state of the art review. Bioresour. Technol. 2016, 215, 254-264.

[26] Hwang MH, Jang NJ, Hyun SH, Kim IS. Anaerobic bio-hydrogen production from ethanol fermentation: The role of pH. J. Biotechnol. 2004, 111, 297-309.

[27] Trček J, Mira NP, Jarboe LR. Adaptation and tolerance of bacteria against acetic acid. Appl. Microbiol. Biotechnol. 2015, 99, 6215-6229.

[28] Luo J, Huang W, Zhang Q, Guo W, Xu R, Fang F, et al. A preliminary metatranscriptomic insight of eggshells conditioning on substrates metabolism during food wastes anaerobic fermentation. Sci. Total Environ. 2021, 761, 143214.

[29] Wang Y, Hui X, Wang H, Chen H. Boosting Volatile fatty acids (VFAs) production in fermentation microorganisms through genes expression control: Unraveling the role of iron homeostasis transcription factors. Water Res. 2024, 259, 121850.

[30] Li H, Mei X, Liu B, Li Z, Wang B, Ren N, et al. Insights on acetate-ethanol fermentation by hydrogen-producing Ethanoligenens under acetic acid accumulation based on quantitative proteomics. Environ. Int. 2019, 129, 1-9.

[31] Talebi A, Razali YS, Ismail N, Rafatullah M, Azan Tajarudin H. Selective adsorption and recovery of volatile fatty acids from fermented landfill leachate by activated carbon process. Sci. Total Environ. 2020, 707, 134533.

[32] Zhao J, Li Y, Euverink GJW. Effect of bioaugmentation combined with activated charcoal on the mitigation of volatile fatty acids inhibition during anaerobic digestion. Chem. Eng. J. 2022, 428, 131015.

[33] Bengtsson S, Karlsson A, Alexandersson T, Quadri L, Hjort M, Johansson P, et al. A process for polyhydroxyalkanoate (PHA) production from municipal wastewater treatment with biological carbon and nitrogen removal demonstrated at pilot-scale. New Biotechnol. 2017, 35, 42-53.

[34] Liu JN, Huang X, Chen R, Yuan M, Liu J. Efficient bioconversion of high-content volatile fatty acids into microbial lipids by Cryptococcus curvatus ATCC 20509. Bioresour. Technol. 2017, 239, 394-401.

[35] Liu W, Huang S, Zhou A, Zhou G, Ren N, Wang A, et al. Hydrogen generation in microbial electrolysis cell feeding with fermentation liquid of waste activated sludge. Int. J. Hydrogen Energy 2012, 37, 13859-13864.

[36] Zhang X, Wang J, Zhang Y, Qing W, Lansing S, Shi J, et al. Anhydrous volatile fatty acid extraction through omniphobic membranes by hydrophobic deep eutectic solvents: Mechanistic understanding and future perspective. Water Res. 2024, 257, 121654.

[37] Rizzioli F, Magonara C, Mengoli G, Bolzonella D, Battista F. Production, purification and recovery of caproic acid, Volatile fatty acids and methane from Opuntia ficus indica. Renew. Sustain. Energy Rev. 2024, 190, 114083.

[38] Marták J, Schlosser Š. Extraction of lactic acid by phosphonium ionic liquids. Sep. Purif. Technol. 2007, 57, 483-494.

[39] Oliveira FS, Araújo JMM, Ferreira R, Rebelo LPN, Marrucho IM. Extraction of l-lactic, l-malic, and succinic acids using phosphonium-based ionic liquids. Sep. Purif. Technol. 2012, 85, 137-146.

[40] Tonova K, Svinyarov I, Bogdanov MG. Hydrophobic 3-alkyl-1-methylimidazolium saccharinates as extractants for l-lactic acid recovery. Sep. Purif. Technol. 2014, 125, 239-246.

[41] Cevasco G, Chiappe C. Are ionic liquids a proper solution to current environmental challenges? Green Chem. 2014, 16, 2375-2385.

[42] Reyhanitash E, Zaalberg B, Kersten SRA, Schuur B. Extraction of volatile fatty acids from fermented wastewater. Sep. Purif. Technol. 2016, 161, 61-68.

[43] Obotey Ezugbe E, Rathilal S. Membrane Technologies in Wastewater Treatment: A Review. Membranes 2020, 10, 89.

[44] Tao B, Passanha P, Kumi P, Wilson V, Jones D, Esteves S. Recovery and concentration of thermally hydrolysed waste activated sludge derived volatile fatty acids and nutrients by microfiltration, electrodialysis and struvite precipitation for polyhydroxyalkanoates production. Chem. Eng. J. 2016, 295, 11-19.

[45] Reyhanitash E, Kersten SRA, Schuur B. Recovery of Volatile Fatty Acids from Fermented Wastewater by Adsorption. ACS Sustain. Chem. Eng. 2017, 5, 9176-9184.

[46] Wu H, Wei H, Yang X, Jin C, Sun W, Deng K, et al. Spherical activated carbons derived from resin-microspheres for the adsorption of acetic acid. J. Environ. Chem. Eng. 2023, 11, 109394.

[47] Zhang YD. Application of Activated Carbon Adsorption Method in Industrial Wastewater Treatment. Hebei Chem. Indust. 2011, 34, 74-76.

[48] Zhang Y, Liu Y. Harnessing Carbonaceous materials' multifaceted roles for enhanced anaerobic digestion performance. Chem. Eng. J. 2023, 477, 146931.

[49] Ma J, Tan L, Xie S, Feng Y, Shi Z, Ke S, et al. The role of hydrochloric acid pretreated activated carbon in chain elongation of D-lactate to caproate: Adsorption and facilitation. Environ. Res. 2023, 233, 116387.

[50] Rebecchi S, Pinelli D, Bertin L, Zama F, Fava F, Frascari D. Volatile fatty acids recovery from the effluent of an acidogenic digestion process fed with grape pomace by adsorption on ion exchange resins. Chem. Eng. J. 2016, 306, 629-639.

[51] Bhandari VM, Yonemoto T, Juvekar VA. Investigating the differences in acid separation behaviour on weak base ion exchange resins. Chem. Eng. Sci. 2000, 55, 6197-6208.

[52] Kanazawa N, Urano K, Kokado N, Urushigawa Y. Adsorption Equilibrium Equation of Carboxylic Acids on Anion-Exchange Resins in Water. J. Colloid Interface Sci. 2001, 238, 196-202.

[53] Bertin L, Martinez G, Domingos JMB, Rebecchi S, Fava F. Recovery of volatile fatty acids by solid phase extraction and their employment in concentrated feeding solution for polyhydroxyalkanoates production. New Biotechnol. 2016, 33, S18.

[54] Saboe PO, Manker LP, Monroe HR, Michener WE, Haugen S, Tan ECD, et al. Energy and techno-economic analysis of bio-based carboxylic acid recovery by adsorption. Green Chem. 2021, 23, 4386-4402.

[55] Singh R, Palar S, Kowalczewski A, Swope C, Parameswaran P, Sun N. Adsorptive recovery of volatile fatty acids from wastewater fermentation broth. J. Environ. Chem. Eng. 2023, 11, 110507.

[56] da Silva AH, Miranda EA. Adsorption/Desorption of Organic Acids onto Different Adsorbents for Their Recovery from Fermentation Broths. J. Chem. Eng. Data 2013, 58, 1454-1463.

[57] Rizzioli F, Battista F, Bolzonella D, Frison N. Volatile Fatty Acid Recovery from Anaerobic Fermentate: Focusing on Adsorption and Desorption Performances. Ind. Eng. Chem. Res. 2021, 60, 13701-13709.

[58] Yousuf A, Bonk F, Bastidas-Oyanedel J-R, Schmidt JE. Recovery of carboxylic acids produced during dark fermentation of food waste by adsorption on Amberlite IRA-67 and activated carbon. Bioresour. Technol. 2016, 217, 137-140.

[59] Chen GR. Encyclopedia of Chemical Engineering; Chemical Industry Press: Beijing, China, 1996; Volume 9.

[60] Shah MS, Tsapatsis M, Siepmann JI. Hydrogen Sulfide Capture: From Absorption in Polar Liquids to Oxide, Zeolite, and Metal–Organic Framework Adsorbents and Membranes. Chem. Rev. 2017, 117, 9755-9803.

[61] Caro J. Quo Vadis, MOF? Chem. Ing. Tech. 2018, 90, 1759-1768.

[62] Dedecker K, Pillai RS, Nouar F, Pires J, Steunou N, Dumas E, et al. Metal-Organic Frameworks for Cultural Heritage Preservation: The Case of Acetic Acid Removal. ACS Appl. Mater. Interfaces 2018, 10, 13886-13894.

[63] Dasgupta S, Biswas S, Dedecker K, Dumas E, Menguy N, Berini B, et al. In Operando Spectroscopic Ellipsometry Investigation of MOF Thin Films for the Selective Capture of Acetic Acid. ACS Appl. Mater. Interfaces 2023, 15, 6069-6078.

[64] Cui G, Wang J, Zhang S. Active chemisorption sites in functionalized ionic liquids for carbon capture. Chem. Soc. Rev. 2016, 45, 4307-4339.

[65] Liu C, Zhang B, Zhang J, Peng L, Kang X, Han B, et al. Gas promotes the crystallization of nano-sized metal–organic frameworks in ionic liquid. Chem. Commun. 2015, 51, 11445-11448.

[66] Asadi M, Babamiri B, Hallaj R, Salimi A. Unusual synthesis of nanostructured Zn-MOF by bipolar electrochemistry in ionic liquid-based electrolyte: Intrinsic alkaline phosphatase-like activity. J. Electroanal. Chem. 2022, 914, 116306.

[67] Liu B-Y, Chen M-J, Yang L, Zhao B, Xia T, Chang G-G. Hollow MOF capsule encapsulated amino-functionalized ionic liquid for excellent CO₂ catalytic conversion. Chin. J. Chem. Eng. 2021, 40, 124-130.

[68] Huo Q, Li J, Qi X, Liu G, Zhang X, Zhang B, et al. Cu, Zn-embedded MOF-derived bimetallic porous carbon for adsorption desulfurization. Chem. Eng. J. 2019, 378, 122106.

[69] Yuan X, Zhong J, Xiong J, Lou W. Cysteine-functionalization zirconium-organic framework for efficient adsorption 2,4-dichlorophenylacetic acid from water. J. Environ. Chem. Eng. 2023, 11, 110162.

[70] Zuliani A, Bandelli D, Chelazzi D, Giorgi R, Baglioni P. Environmentally friendly ZnO/Castor oil polyurethane composites for the gas-phase adsorption of acetic acid. J. Colloid Interface Sci. 2022, 614, 451-459.

[71] Zuliani A, Chelazzi D, Mastrangelo R, Giorgi R, Baglioni P. Adsorption kinetics of acetic acid into ZnO/castor oil-derived polyurethanes. J. Colloid Interface Sci. 2023, 632, 74-86.

[72] Elhami V, Hempenius MA, Vancso GJ, Krooshoop EJG, Alic L, Qian X, et al. Recovery of dilute (bio-based) volatile fatty acids by adsorption with magnetic hyperthermal swing desorption. Sep. Purif. Technol. 2023, 323, 124273.

[73] El-Qanni A, Nassar NN, Vitale G. A combined experimental and computational modeling study on adsorption of propionic acid onto silica-embedded NiO/MgO nanoparticles. Chem. Eng. J. 2017, 327, 666-677.

[74] Deng Z, Zhang Q, Deng Q, Guo Z, Seok I. Modification of coconut shell activated carbon and purification of volatile organic waste gas acetone. Adv. Compos. Hybrid Mater. 2022, 5, 491-503.

[75] Li Z, Li Y, Zhu J. Straw-Based Activated Carbon: Optimization of the Preparation Procedure and Performance of Volatile Organic Compounds Adsorption. Materials 2021, 14, 3284.

[76] Liang D, Yu F, Xie Q, Chen Q, Liu Y, Zheng Y, et al. Volatile Organic Compounds Adsorption Capacities of Zeolite/Activated Carbon Composites Formed by Electrostatic Self-Assembly. ACS Appl. Mater. Interfaces 2023, 15, 38781-38794.

[77] Guo X, Li X, Gan G, Wang L, Fan S, Wang P, et al. Functionalized Activated Carbon for Competing Adsorption of Volatile Organic Compounds and Water. ACS Appl. Mater. Interfaces 2021, 13, 56510-56518.

[78] Ma L, He M, Fu P, Jiang X, Lv W, Huang Y, et al. Adsorption of volatile organic compounds on modified spherical activated carbon in a new cyclonic fluidized bed. Sep. Purif. Technol. 2020, 235, 116146.

[79] Dong N, Wang Z, Wang J, Song W, Du L, Gu X, et al. Preparation of CPVC-based activated carbon spheres and insight into the adsorption-desorption performance for typical volatile organic compounds. Environ. Pollut. 2024, 343, 123177.

[80] Yoshimaru S, Sadakiyo M, Maeda N, Yamauchi M, Kato K, Pirillo J, et al. Support Effect of Metal–Organic Frameworks on Ethanol Production through Acetic Acid Hydrogenation. ACS Appl. Mater. Interfaces 2021, 13, 19992-20001.

[81] Liu H, Li N, Feng M, Li G, Zhang W, An T. Near-infrared light induced adsorption–desorption cycle for VOC recovery by integration of metal–organic frameworks with graphene oxide nanosheets. Environ. Sci. Nano 2022, 9, 1858-1868.

[82] Biswas S, Haouas M, Freitas C, Vieira Soares C, Al Mohtar A, Saad A, et al. Engineering of Metal–Organic Frameworks/Gelatin Hydrogel Composites Mediated by the Coacervation Process for the Capture of Acetic Acid. Chem. Mater. 2022, 34, 9760-9774.

[83] Zhang Y, Chen S, Shi R, Du P, Qiu X, Gu X. Pervaporation dehydration of acetic acid through hollow fiber supported DD3R zeolite membrane. Sep. Purif. Technol. 2018, 204, 234-242.

[84] Peng Y, Huang M, Hu Y, Li G, Xia L. Microwave-assisted synthesis of porphyrin conjugated microporous polymers for microextraction of volatile organic acids in tobaccos. J. Chromatogr. A 2019, 1594, 45-53.

[85] Kim SH, Huang Y, Sawatdeenarunat C, Sung S, Lin SY. Selective sequestration of carboxylic acids from biomass fermentation by surface-functionalized mesoporous silica nanoparticles. J. Mater. Chem. 2011, 21, 12103-12109.

[86] Yang F, Li W, Zhong X, Tu W, Cheng J, Chen L, et al. The alkaline sites integrated into biomass-carbon reinforce selective adsorption of acetic acid: In situ implanting MgO during activation operation. Sep. Purif. Technol. 2022, 297, 121415.

[87] Suzuki M, Misic DM, Koyama O, Kawazoe K. Study of thermal regeneration of spent activated carbons: Thermogravimetric measurement of various single component organics loaded on activated carbons. Chem. Eng. Sci. 1978, 33, 271-279.

[88] Fufachev EV, Weckhuysen BM, Bruijnincx PCA. Tandem catalytic aromatization of volatile fatty acids. Green Chem. 2020, 22, 3229-3238.

[89] Jung J-M, Cho J, Kim K-H, Kwon EE. Pseudo catalytic transformation of volatile fatty acids into fatty acid methyl esters. Bioresour. Technol. 2016, 203, 26-31.

[90] Chang CD, Silvestri AJ. The conversion of methanol and other O-compounds to hydrocarbons over zeolite catalysts. J. Catal. 1977, 47, 249-259.

[91] Gayubo AG, Aguayo AT, Atutxa A, Aguado R, Bilbao J. Transformation of Oxygenate Components of Biomass Pyrolysis Oil on a HZSM-5 Zeolite. I. Alcohols and Phenols. Ind. Eng. Chem. Res. 2004, 43, 2610-2618.

[92] Wang X, Ding S, Wang H, Liu X, Han J, Ge Q, et al. Conversion of propionic acid and 3-pentanone to hydrocarbons on ZSM-5 catalysts: Reaction pathway and active site. Appl. Catal. A Gen. 2017, 545, 79-89.

[93] Fuhse J, Bandermann F. Conversion of organic oxygen compounds and their mixtures on H-ZSM-5. Chem. Eng. Tech. 1987, 10, 323-329.

[94] Steinbusch KJJ, Hamelers HVM, Plugge CM, Buisman CJN. Biological formation of caproate and caprylate from acetate: Fuel and chemical production from low grade biomass. Energy Environ. Sci. 2011, 4, 216-224.

[95] Reyhanitash E, Fufachev E, van Munster KD, van Beek MBM, Sprakel LMJ, Edelijn CN, et al. Recovery and conversion of acetic acid from a phosphonium phosphinate ionic liquid to enable valorization of fermented wastewater. Green Chem. 2019, 21, 2023-2034.

[96] Wang Y, Peng M, Zhang J, Zhang Z, An J, Du S, et al. Selective production of phase-separable product from a mixture of biomass-derived aqueous oxygenates. Nat. Commun. 2018, 9, 5183.

[97] Beld J, Lee DJ, Burkart MD. Fatty acid biosynthesis revisited: Structure elucidation and metabolic engineering. Mol. BioSystems 2015, 11, 38-59.

[98] Liu H, Zhou P, Qi M, Guo L, Gao C, Hu G, et al. Enhancing biofuels production by engineering the actin cytoskeleton in Saccharomyces cerevisiae. Nat. Commun. 2022, 13, 1886.

[99] Yan Q, Cordell WT, Jindra MA, Courtney DK, Kuckuk MK, Chen X, et al. Metabolic engineering strategies to produce medium-chain oleochemicals via acyl-ACP:CoA transacylase activity. Nat. Commun. 2022, 13, 1619.

[100] Grootscholten TIM, Strik DPBTB, Steinbusch KJJ, Buisman CJN, Hamelers HVM. Two-stage medium chain fatty acid (MCFA) production from municipal solid waste and ethanol. Appl. Energy 2014, 116, 223-229.

[101] Liang S, Wan C. Carboxylic acid production from brewer’s spent grain via mixed culture fermentation. Bioresour. Technol. 2015, 182, 179-183.

[102] Bevilacqua R, Regueira A, Mauricio-Iglesias M, Lema JM, Carballa M. Chain elongation may occur in protein mixed-culture fermentation without supplementing electron donor compounds. J. Environ. Chem. Eng. 2022, 10, 106943.

[103] Wang X, Han J, Zeng M, Chen Y, Jiang F, Zhang L, et al. Total ammonia nitrogen inhibits medium-chain fatty acid biosynthesis by disrupting hydrolysis, acidification, chain elongation, substrate transmembrane transport and ATP synthesis processes. Bioresour. Technol. 2024, 409, 131236.

[104] Gu X, Sun J, Wang T, Li J, Wang H, Wang J, Wang Y. Comprehensive review of microbial production of medium-chain fatty acids from waste activated sludge and enhancement strategy. Bioresour. Technol. 2024, 402, 130782.

[105] Li D, Yin F, Ma X. Towards biodegradable polyhydroxyalkanoate production from wood waste: Using volatile fatty acids as conversion medium. Bioresour. Technol. 2020, 299, 122629.

[106] Zhang Z, Lin Y, Wu S, Li X, Cheng JJ, Yang C. Effect of composition of volatile fatty acids on yield of polyhydroxyalkanoates and mechanisms of bioconversion from activated sludge. Bioresour. Technol. 2023, 385, 129445.

[107] Liu J, Liu J-N, Yuan M, Shen Z-H, Peng K-M, Lu L-J, et al. Bioconversion of volatile fatty acids derived from waste activated sludge into lipids by Cryptococcus curvatus. Bioresour. Technol. 2016, 211, 548-555.

[108] Bi H, Wang K, Xu C, Wang M, Chen B, Fang Y, et al. Biofuel synthesis from carbon dioxide via a bio-electrocatalysis system. Chem Catal. 2023, 3, 100557.

[109] Liu L-P, Zong M-H, Hu Y, Li N, Lou W-Y, Wu H. Efficient microbial oil production on crude glycerol by Lipomyces starkeyi AS 2.1560 and its kinetics. Process Biochem. 2017, 58, 230-238.

[110] Llamas M, Magdalena JA, González-Fernández C, Tomás-Pejó E. Volatile fatty acids as novel building blocks for oil-based chemistry via oleaginous yeast fermentation. Biotechnol. Bioeng. 2020, 117, 238-250.

[111] Lu J, Zhang X, Jiang Y, Zhang W, XIin F, Jiang M. Research Progress in the Biosynthesis of Short-Chain Fatty Acid Esters. J. Biol. 2021, 38, 1-11.

[112] Kruis AJ, Bohnenkamp AC, Patinios C, van Nuland YM, Levisson M, Mars AE, et al. Microbial production of short and medium chain esters: Enzymes, pathways, and applications. Biotechnol. Adv. 2019, 37, 107407.

[113] Varma MN, Madras G. Kinetics of synthesis of butyl butyrate by esterification and transesterification in supercritical carbon dioxide. J. Chem. Tech. Biotech. 2008, 83, 1135-1144.

[114] Freguia S, Teh EH, Boon N, Leung KM, Keller J, Rabaey K. Microbial fuel cells operating on mixed fatty acids. Bioresour. Technol. 2010, 101, 1233-1238.