Insights into the microbiomes for medium-chain carboxylic acids production from biowastes through chain elongation

Shi, Xingdong; Wu, Lan; Wei, Wei; Ni, Bing‐Jie

doi:10.1080/10643389.2021.1957342

Cited by 32 publications

(10 citation statements)

References 133 publications

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Section: Medium-chain Carboxylic Acid From Wastewatermentioning

confidence: 99%

“…Medium-chain carboxylic acids (MCCA) such as hexanoic acid (caproic acid, C6), heptanoic acid (enanthic acid, C7), and octanoic acid (caprylic acid, C8) are the most common MCCAs produced by anaerobic fermentation [62]. They can be used as a biopolymer precursor, as a food additive, as an antimicrobial agent, and as a precursor for bio-fuel production [62]. In comparison to VFAs, MCCAs hold higher commercial value as bio-based fuel due to their lower oxygen to carbon ratio and consequently high energy density [60,62], while their value as intermediate for polymers is expected to be higher than as fuel.…”

Section: Medium-chain Carboxylic Acid From Wastewatermentioning

confidence: 99%

“…They can be used as a biopolymer precursor, as a food additive, as an antimicrobial agent, and as a precursor for bio-fuel production [62]. In comparison to VFAs, MCCAs hold higher commercial value as bio-based fuel due to their lower oxygen to carbon ratio and consequently high energy density [60,62], while their value as intermediate for polymers is expected to be higher than as fuel.…”

Section: Medium-chain Carboxylic Acid From Wastewatermentioning

confidence: 99%

“…As shown in Figure 2, during anaerobic digestion of an organic waste/wastewater to MCCAs, first, the macromolecules in the biowaste must be converted to small intermediate molecules (e.g., lactic acid, ethanol, and VFAs) through hydrolysis and acidification, followed by microbial chain elongation from VFAs to MCCAs [62,63]. Chain elongation (CE) can be conducted through two routes; Reverse β-oxidation and fatty acid bio-synthesis, which are recently reviewed [27,62]. Reverse β-oxidation is the main CE pathway that requires an electron donor compound to add two carbon atoms to the carbon chain of the carboxylic acids during each elongation step.…”

Section: Medium-chain Carboxylic Acid From Wastewatermentioning

confidence: 99%

“…For instance, odd carbon number VFAs as substrates result in mainly odd carbon number MCCAs using ethanol as an electron donor. Due to the unavoidable oxidation of ethanol to acetate, it is not possible to avoid even carbon number acid production during the odd-CE process [62].…”

Section: Medium-chain Carboxylic Acid From Wastewatermentioning

confidence: 99%

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Recovery Techniques Enabling Circular Chemistry from Wastewater

et al. 2022

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In an era where it becomes less and less accepted to just send waste to landfills and release wastewater into the environment without treatment, numerous initiatives are pursued to facilitate chemical production from waste. This includes microbial conversions of waste in digesters, and with this type of approach, a variety of chemicals can be produced. Typical for digestion systems is that the products are present only in (very) dilute amounts. For such productions to be technically and economically interesting to pursue, it is of key importance that effective product recovery strategies are being developed. In this review, we focus on the recovery of biologically produced carboxylic acids, including volatile fatty acids (VFAs), medium-chain carboxylic acids (MCCAs), long-chain dicarboxylic acids (LCDAs) being directly produced by microorganisms, and indirectly produced unsaturated short-chain acids (USCA), as well as polymers. Key recovery techniques for carboxylic acids in solution include liquid-liquid extraction, adsorption, and membrane separations. The route toward USCA is discussed, including their production by thermal treatment of intracellular polyhydroxyalkanoates (PHA) polymers and the downstream separations. Polymers included in this review are extracellular polymeric substances (EPS). Strategies for fractionation of the different fractions of EPS are discussed, aiming at the valorization of both polysaccharides and proteins. It is concluded that several separation strategies have the potential to further develop the wastewater valorization chains.

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Section: Medium-chain Carboxylic Acid From Wastewatermentioning

confidence: 99%

Section: Medium-chain Carboxylic Acid From Wastewatermentioning

confidence: 99%

Section: Medium-chain Carboxylic Acid From Wastewatermentioning

confidence: 99%

Section: Medium-chain Carboxylic Acid From Wastewatermentioning

confidence: 99%

Section: Medium-chain Carboxylic Acid From Wastewatermentioning

confidence: 99%

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Recovery Techniques Enabling Circular Chemistry from Wastewater

et al. 2022

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Microbial dynamics with the introduction of brewery waste in a long‐term chain elongation process for caproate production

Yang

Leng

2023

J of Chemical Tech & Biotech

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BACKGROUND: The long-term cultivation of sewage sludge in a chain elongation process was performed, and brewery wastewater (BW) was gradually introduced as ethanol source for medium-chain carboxylate (MCC) production. RESULTS:The results showed that the introduction of BW promoted ethanol utilization and electron recovery efficiency of the system. The improvement was mainly due to the readily available organics, such as yeast cells and leftover grain biomass, supplied along with BW as feedstock. In addition, the microbes introduced from BW and long-term cultivation facilitated the enrichment of MCC-forming microbes and the enhancement of microbial diversity. Microbial analysis revealed that the supply of BW was correlated with acetate-and butyrate-forming Proteiniclasticum, ethanol-oxidating Desulfovibrio, as well as biofilmforming Pseudomonas, which are beneficial to the chain elongation reactions. Further metabolic pathway analysis suggested that, other than reverse ⊎-oxidation, fatty acid biosynthesis was identified as the primary pathway for MCC formation in this system. Also, the introduction of BW promoted the chain elongation process by stimulating the rate-limiting steps involved in the conversion of ethanol to acetyl-CoA and the circular fatty acid biosynthesis pathway, thereby enhancing MCC formation.CONCLUSION: Generally, the enhancement of MCC production with BW was attributed to the microbes and organics leftover introduced from BW.

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