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Zhang Y, Li J, Lian X, Li L, Yong YC, Meng J. Efficient caproate production from lignocellulose via single-step electro-fermentation platform without organic electron donor. BIORESOURCE TECHNOLOGY 2024; 411:131319. [PMID: 39173961 DOI: 10.1016/j.biortech.2024.131319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2024] [Revised: 08/06/2024] [Accepted: 08/19/2024] [Indexed: 08/24/2024]
Abstract
Caproate production by microbial fermentation gained the advantages of sustainability and eco-friendliness, but challenged by sterile fermentation environment, necessity of organic electron donors. Here, a single-step electro-fermentation (EF) process of mixed culture was proposed for caprate production from rice straw. At the optimal potential of -0.8 V, caproate concentration, yield and selectivity in the neutral red (NR)-mediated EF system were 2.4 g/L, 0.2 g/g and 26.6%. Long-term operation accumulated 5.3 g/L caproate with the yield and selectivity of 0.2 g/g and 34.2% in the EF+NR system. Bioaugmentation by dosing chain-elongation microbial consortium further improved the caproate production, yield and selectivity to 9.1 g/L, 0.3 g/g and 41.5%, respectively. The improved caproate production in the bioaugmented EF+NR system was likely due to the enhanced interspecies electron transfer, reconstructed microbial community, multiple electron donors and suitable pH environment. Present study offers a feasible strategy for cost-effective caprate production directly from waste biomass.
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Affiliation(s)
- Yafei Zhang
- Biofuels Institute, School of Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 73 Huanghe Road, Harbin 150090, China
| | - Jianzheng Li
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 73 Huanghe Road, Harbin 150090, China
| | - Xu Lian
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 73 Huanghe Road, Harbin 150090, China
| | - Lin Li
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 73 Huanghe Road, Harbin 150090, China
| | - Yang-Chun Yong
- Biofuels Institute, School of Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Jia Meng
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 73 Huanghe Road, Harbin 150090, China.
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Fernández-Blanco C, Pereira A, Veiga MC, Kennes C, Ganigué R. Comprehensive comparative study on n-caproate production by Clostridium kluyveri: batch vs. continuous operation modes. BIORESOURCE TECHNOLOGY 2024; 408:131138. [PMID: 39043275 DOI: 10.1016/j.biortech.2024.131138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 07/06/2024] [Accepted: 07/19/2024] [Indexed: 07/25/2024]
Abstract
Recently, there has been notable interest in researching and industrially producing medium-chain carboxylic acids (MCCAs) like n-caproate and n-caprylate via chain elongation process. This study presents a comprehensive assessment of the behavior and MCCA production profiles of Clostridium kluyveri in batch and continuous modes, at different ethanol:acetate molar ratios (1.5:1, 3.5:1 and 5.5:1). The highest n-caproate concentration, 12.9 ± 0.67 g/L (92.9 ± 1.39 % MCCA selectivity), was achieved in batch mode at a 3.5:1 ratio. Interestingly, higher ratios favored batch mode selectivity over continuous mode when this was equal or higher to 3.5:1. Steady state operation yielded the highest n-caproate (9.5 ± 0.13 g/L) and n-caprylate (0.35 ± 0.020 g/L) concentrations at the 3.5:1 ratio. Increased ethanol:acetate ratios led to a higher excessive ethanol oxidation (EEO) in both operational modes, potentially limiting n-caproate production and selectivity, especially at the 5.5:1 ratio. Overall, this study reports the efficient MCCA production of both batch and continuous modes by C. kluyveri.
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Affiliation(s)
- Carla Fernández-Blanco
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química e Bioloxía (CICA), BIOENGIN Group, University of A Coruña, E-15008-A Coruña, Spain
| | - Alexandra Pereira
- Center for Microbial Ecology and Technology (CMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Ghent 9000, Belgium; Center for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Frieda Saeysstraat, Ghent 9052, Belgium
| | - María C Veiga
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química e Bioloxía (CICA), BIOENGIN Group, University of A Coruña, E-15008-A Coruña, Spain
| | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química e Bioloxía (CICA), BIOENGIN Group, University of A Coruña, E-15008-A Coruña, Spain
| | - Ramon Ganigué
- Center for Microbial Ecology and Technology (CMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Ghent 9000, Belgium; Center for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Frieda Saeysstraat, Ghent 9052, Belgium.
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Souza MFD, Akyol Ç, Willems B, Huizinga A, van Calker S, Van Dael M, De Meyer A, Guisson R, Michels E, Meers E. From grass to gas and beyond: Anaerobic digestion as a key enabling technology for a residual grass biorefinery. WASTE MANAGEMENT (NEW YORK, N.Y.) 2024; 182:1-10. [PMID: 38615638 DOI: 10.1016/j.wasman.2024.04.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 03/07/2024] [Accepted: 04/09/2024] [Indexed: 04/16/2024]
Abstract
Roadside grass clippings hold potential as a sustainable source of bioenergy as they do not compete with crops for land use, and are only partially utilized for low-value applications. In this study, we proposed using roadside grass as a sole feedstock for anaerobic digestion (AD) in three different settings, and assessed the potential of producing biomaterials and fertilizers from grass-based digestate. Wet continuous digestion at pilot scale and dry batch digestion at pilot and large scales resulted in biogas yields up to 700 Nm3.t-1 DOM with a methane content of 49-55 %. Despite promising results, wet AD had operational problems such as clogging and poor mixing; once upscaled, the dry digestion initially also presented an operational problem with acidification, which was overcome by the second trial. Digested grass fibers from the pilot dry AD were processed into biomaterials and performed similarly or better than the undigested fibers, while around 20 % performance reduction was observed when compared to reference wood fibers. A mass balance indicated reduced fiber recovery when higher biogas production was obtained. The liquid fraction from the pilot dry AD was characterized for its nutrient content and used as a biofertilizer in another study. In contrast, the leachate collected from the large-scale dry AD had a low nitrogen content and high chloride content that could hinder its further use. Finally, a regional market analysis was conducted showing that the biocomposites produced with the available grass fibers could substitute at least half of the current European market based on our results.
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Affiliation(s)
- Marcella Fernandes de Souza
- Lab for Bioresource Recovery, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000 Gent, Belgium.
| | - Çağrı Akyol
- Lab for Bioresource Recovery, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000 Gent, Belgium
| | | | - Alex Huizinga
- Millvision, Ramgatseweg 11i, 4941 VN Raamsdonksveer, the Netherlands
| | - Sander van Calker
- Millvision, Ramgatseweg 11i, 4941 VN Raamsdonksveer, the Netherlands
| | | | | | | | - Evi Michels
- Lab for Bioresource Recovery, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000 Gent, Belgium
| | - Erik Meers
- Lab for Bioresource Recovery, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000 Gent, Belgium
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Fernández-Blanco C, Veiga MC, Kennes C. Carbon dioxide as key player in chain elongation and growth of Clostridium kluyveri: Insights from batch and bioreactor studies. BIORESOURCE TECHNOLOGY 2024; 394:130192. [PMID: 38081469 DOI: 10.1016/j.biortech.2023.130192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/07/2023] [Accepted: 12/08/2023] [Indexed: 02/04/2024]
Abstract
Chain elongation technology allows medium-chain fatty acids (MCFAs) production as an alternative to fossil resources. Clostridium kluyveri generates n-caproate primarily from ethanol and acetate, presumably requiring CO2 for growth. Here, the impact of CO2 on C. kluyveri was explored. Bottle studies revealed the bacterium's adaptability to low CO2 levels, even in conditions with minimal dissolved NaHCO3 (0.0003 M) and unfavorable pH (below 6) under 1 bar CO2. Bioreactor investigations demonstrated a direct correlation between CO2 availability and bacterial growth. The highest n-caproate production (11.0 g/L) with 90.1 % selectivity was achieved in a bioreactor with continuous CO2 supply at 3 mL/min. Additional bottle experiments pressurized with 1 bar CO2 and varying ethanol:acetate ratios (1:1, 2:1, 4:1) also confirmed CO2 consumption by C. kluyveri. However, increasing the ethanol:acetate ratio did not enhance n-caproate selectivity, likely due to overly acidic pH conditions. These findings provide insights into chain-elongators responses under diverse conditions.
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Affiliation(s)
- Carla Fernández-Blanco
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology, Centro Interdisciplinar de Química e Bioloxía (CICA), BIOENGIN Group, University of A Coruña, E-15008-A Coruña, Spain
| | - María C Veiga
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology, Centro Interdisciplinar de Química e Bioloxía (CICA), BIOENGIN Group, University of A Coruña, E-15008-A Coruña, Spain
| | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology, Centro Interdisciplinar de Química e Bioloxía (CICA), BIOENGIN Group, University of A Coruña, E-15008-A Coruña, Spain.
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Liu H, Zhen F, Wu D, Wang Z, Kong X, Li Y, Xing T, Sun Y. Co-production of lactate and volatile fatty acids through repeated-batch fermentation of fruit and vegetable waste: Effect of cycle time and replacement ratio. BIORESOURCE TECHNOLOGY 2023; 387:129678. [PMID: 37579859 DOI: 10.1016/j.biortech.2023.129678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 08/10/2023] [Accepted: 08/11/2023] [Indexed: 08/16/2023]
Abstract
In this study, repeated-batch fermentation was used to convert fruit and vegetable waste to lactate and volatile fatty acids (VFAs), which are essential carbon sources for medium-chain fatty acids (MCFAs) production. The effect of cycle time and replacement ratio on acidification in long-term fermentation was investigated. The results showed that they had a significant impact on product yield, productivity, and type of products. Considering the yield, productivity, and lactate/VFAs ratio, a replacement ratio of 30% and a cycle time of 2 d may be more suitable for further production of MCFAs. Its productivity and lactate/VFAs ratio were 4.07 ± 0.24 g/(L·d) and 5 ± 0.6, respectively. The lactic acid bacteria, such as Enterococcus (63%) and Lactobacillus (33%), stabilized in the reactor, resulting in the generation of both lactate and VFAs by heterolactic fermentation. The present study demonstrated a new strategy with the potential to recover high-value products from organic waste streams.
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Affiliation(s)
- Huiliang Liu
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Feng Zhen
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China
| | - Di Wu
- Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences, Chongqing 400714, China
| | - Zhi Wang
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China; University of Science and Technology of China, Hefei 230026, China
| | - Xiaoying Kong
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China
| | - Ying Li
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China
| | - Tao Xing
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China.
| | - Yongming Sun
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China
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