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Kham NNN, Phovisay S, Unban K, Kanpiengjai A, Saenjum C, Lumyong S, Shetty K, Khanongnuch C. Valorization of Cashew Apple Waste into a Low-Alcohol, Healthy Drink Using a Co-Culture of Cyberlindnera rhodanensis DK and Lactobacillus pentosus A14-6. Foods 2024; 13:1469. [PMID: 38790769 PMCID: PMC11120566 DOI: 10.3390/foods13101469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 05/07/2024] [Accepted: 05/08/2024] [Indexed: 05/26/2024] Open
Abstract
This study investigated the potential of microbial fermentative transforming processes in valorizing the cashew apple by-product into a low-alcohol, health-benefiting beverage. We particularly investigated the use of a non-Saccharomyces yeast, Cyberlindnera rhodanensis DK, as the main targeted microbe. At 30 °C without agitation, C. rhodanensis DK caused changes in key parameters during the fermentation of cashew apple juice (CAJ) in terms of varied pH values and initial sugar concentrations. This result indicated that pure CAJ, with pH adjusted to 6 and with the original 6.85% (w/v) total sugar content, was the most feasible condition, as glucose and fructose were mostly consumed at 12 days of fermentation. A co-culture approach with either Saccharomyces cerevisiae TISTR 5088 or Lactobacillus pentosus A14-6 was investigated to improve both physicochemical and fermentation characteristics. Co-fermentation with S. cerevisiae TISTR 5088 resulted in significantly increased ethanol accumulation to 33.61 ± 0.11 g/L, but diminished bioactive compounds, antioxidant activity, and antidiabetic potential. In contrast, co-fermentation with L. pentosus A14-6 demonstrated excellent outcomes, as it significantly increased sugar consumption and finally remained at only 4.95 g/L compared to C. rhodanensis DK alone, produced lower levels of ethanol at only 19.47 ± 0.06 g/L, and higher total titratable acid (TTA), resulting in a final pH of 3.6. In addition, co-fermentation with this lactic acid bacterium significantly enhanced bioactive compounds and antioxidant activity and also retained potential antidiabetic properties. These findings highlight the feasibility of using tailored microbial fermentation strategies to produce low-alcohol beverages with enhanced health-promoting properties from CAJ; however, product-development processes following health food regulations and sensory evaluation are necessary.
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Affiliation(s)
- Nang Nwet Noon Kham
- Multidisciplinary School, Chiang Mai University, Muang, Chiang Mai 50100, Thailand; (N.N.N.K.); (S.P.)
| | - Somsay Phovisay
- Multidisciplinary School, Chiang Mai University, Muang, Chiang Mai 50100, Thailand; (N.N.N.K.); (S.P.)
| | - Kridsada Unban
- Division of Food Science and Technology, Faculty of Agro-Industry, Chiang Mai University, Mae-Hia, Chiang Mai 50100, Thailand
| | - Apinun Kanpiengjai
- Department of Chemistry, Faculty of Science, Chiang Mai University, Huay Kaew Rd., Muang, Chiang Mai 50200, Thailand;
| | - Chalermpong Saenjum
- Faculty of Pharmacy, Chiang Mai University, Muang, Chiang Mai 50200, Thailand;
| | - Saisamorn Lumyong
- Department of Biology, Faculty of Science, Chiang Mai University, Huay Kaew Rd., Muang, Chiang Mai 50200, Thailand;
| | - Kalidas Shetty
- Global Institute of Food Security and International Agriculture (GIFSIA), Department of Plant Sciences, North Dakota State University, Fargo, ND 58108, USA;
| | - Chartchai Khanongnuch
- Department of Biology, Faculty of Science, Chiang Mai University, Huay Kaew Rd., Muang, Chiang Mai 50200, Thailand;
- Research Center for Multidisciplinary Approaches to Miang, Multidisciplinary Research Institute (MDRI), Chiang Mai University, Muang, Chiang Mai 50200, Thailand
- Research Center of Microbial Diversity and Sustainable Utilization, Chiang Mai University, Huay Kaew Rd., Muang, Chiang Mai 50200, Thailand
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2
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Chen B, Rupani PF, Azman S, Dewil R, Appels L. A redox-based strategy to enhance propionic and butyric acid production during anaerobic fermentation. BIORESOURCE TECHNOLOGY 2022; 361:127672. [PMID: 35878771 DOI: 10.1016/j.biortech.2022.127672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 07/17/2022] [Accepted: 07/18/2022] [Indexed: 06/15/2023]
Abstract
This study investigated the selective production of volatile fatty acids (VFAs) during anaerobic mixed-culture fermentation. The experiment used chicken manure (CM) as a potential substrate to produce high added-value propionic acid and butyric acid under an alkaline environment. The conversion of CM into selective VFAs depends highly on operational conditions such as pH and redox balance. Therefore, the current experiment is designed to employ amino acid addition and develop a redox balance control method to control the final VFA profile. This study showed that 0.2-5.0 % valine and threonine addition successfully enhanced propionic acid and butyric acid production during alkaline fermentation and hence decreased the proportion of acetic acid from 83 % to approximately 47 %. The oxidation-reduction potential (ORP) and redox cofactor ratio (NADH/NAD+) were measured to support the selective VFA production mechanism. The results obtained in this study bring extra value to the valorization of CM within the circular economy concept for selective value-added VFA production.
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Affiliation(s)
- Boyang Chen
- KU Leuven, Department of Chemical Engineering, Process and Environmental Technology Lab, Jan Pieter De Nayerlaan 5, B-2860 Sint-Katelijne-Waver, Belgium
| | - Parveen Fatemeh Rupani
- KU Leuven, Department of Chemical Engineering, Process and Environmental Technology Lab, Jan Pieter De Nayerlaan 5, B-2860 Sint-Katelijne-Waver, Belgium
| | - Samet Azman
- Avans University of Applied Sciences, Academy of Life Sciences and Technology, Lovensdijk 61, 4818 AJ Breda, Netherlands
| | - Raf Dewil
- KU Leuven, Department of Chemical Engineering, Process and Environmental Technology Lab, Jan Pieter De Nayerlaan 5, B-2860 Sint-Katelijne-Waver, Belgium; University of Oxford, Department of Engineering Science, Parks Road, Oxford OX1 3PJ, United Kingdom
| | - Lise Appels
- KU Leuven, Department of Chemical Engineering, Process and Environmental Technology Lab, Jan Pieter De Nayerlaan 5, B-2860 Sint-Katelijne-Waver, Belgium.
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3
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Petkova T, Doykina P, Alexieva I, Mihaylova D, Popova A. Characterization of Fruit Sorbet Matrices with Added Value from Zizyphus jujuba and Stevia rebaudiana. Foods 2022; 11:foods11182748. [PMID: 36140880 PMCID: PMC9498022 DOI: 10.3390/foods11182748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 08/25/2022] [Accepted: 09/01/2022] [Indexed: 11/16/2022] Open
Abstract
Sorbets are healthy ice cream alternatives and desired frozen desserts by vegetarians and vegans. This study focuses on assessing the effects of sorbet recipe alteration through the addition of different percentages of Zizyphus jujuba powder. Stevia rebaudiana was used as a sugar substituent. A control sample and five variables were developed. Peaches from the “Laskava” (native Bulgarian) variety were used as the main ingredient. The new sorbet matrices were characterized based on their moisture and ash content, overrun, melting behavior, melting rate, water holding capacity, pH, nutritional data, soluble solids content, titratable acidity, vitamin C content, total phenolic content and antioxidant activity. The microbial load and CIELAB color of the sorbet alternatives was also evaluated. A sensory evaluation revealed the most preferred variant. Panelists evaluated the appearance (n = 6), aroma (n = 5), flavor (n = 5), mouthfeel (n = 7), and aftertaste (n = 5). The soluble solids content varied from 17.50 to 33.03%, the ash content from 0.36 to 5.21%, the moisture content from 63.77 to 80.21%. The studied sorbet matrices have an overrun in the range from 8.11 to 12.32%. Results showed that a potential for the development of peach sorbet matrices with added value and a reasonable consumer acceptability exists. Further research can perfect the recipe and provide a reference for other frozen desserts.
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Affiliation(s)
- Teodora Petkova
- Department of Catering and Nutrition, Economics Faculty, University of Food Technologies, 4002 Plovdiv, Bulgaria
| | - Pavlina Doykina
- Department of Catering and Nutrition, Economics Faculty, University of Food Technologies, 4002 Plovdiv, Bulgaria
| | - Iordanka Alexieva
- Department of Catering and Nutrition, Economics Faculty, University of Food Technologies, 4002 Plovdiv, Bulgaria
| | - Dasha Mihaylova
- Department of Biotechnology, Technological Faculty, University of Food Technologies, 4002 Plovdiv, Bulgaria
- Correspondence:
| | - Aneta Popova
- Department of Catering and Nutrition, Economics Faculty, University of Food Technologies, 4002 Plovdiv, Bulgaria
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Mihaylova D, Popova A, Goranova Z, Doykina P. Development of Healthy Vegan Bonbons Enriched with Lyophilized Peach Powder. Foods 2022; 11:1580. [PMID: 35681330 PMCID: PMC9180698 DOI: 10.3390/foods11111580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 05/14/2022] [Accepted: 05/26/2022] [Indexed: 01/27/2023] Open
Abstract
Changing nutritional demands, in combination with the global trend for snacking, sets a goal for preparing food products for direct consumption with certain beneficial properties. This study was designed to investigate the quality characteristics of raw vegan bonbons enriched with lyophilized peach powder. Three types of formulations were prepared in which 10%, 20%, and 30% of lyophilized peach powder were, respectively, added. The newly developed vegan products were characterized in terms of their physical (moisture, ash, color, water activity), microbiological, and nutritional characteristics. Their antioxidant activity, flavonoid, and phenolic content were also evaluated. Considering the content of the bonbons, the reported health claims indicate that they are sources of fiber, with no added sugar, and contain naturally occurring sugars. The color measurements demonstrated similarity in the values. This study showed that there is significant potential in the production of healthy snacks for direct consumption, with beneficial properties.
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Affiliation(s)
- Dasha Mihaylova
- Department of Biotechnology, Technological Faculty, University of Food Technologies, 4002 Plovdiv, Bulgaria;
| | - Aneta Popova
- Department of Catering and Nutrition, Economics Faculty, University of Food Technologies, 4002 Plovdiv, Bulgaria;
| | - Zhivka Goranova
- Institute of Food Preservation and Quality, 4002 Plovdiv, Bulgaria;
| | - Pavlina Doykina
- Department of Catering and Nutrition, Economics Faculty, University of Food Technologies, 4002 Plovdiv, Bulgaria;
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Virdis B, Hoelzle R, Marchetti A, Boto ST, Rosenbaum MA, Blasco-Gómez R, Puig S, Freguia S, Villano M. Electro-fermentation: Sustainable bioproductions steered by electricity. Biotechnol Adv 2022; 59:107950. [PMID: 35364226 DOI: 10.1016/j.biotechadv.2022.107950] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 02/22/2022] [Accepted: 03/24/2022] [Indexed: 01/06/2023]
Abstract
The market of biobased products obtainable via fermentation processes is steadily increasing over the past few years, driven by the need to create a decarbonized economy. To date, industrial fermentation (IF) employs either pure or mixed microbial cultures (MMC) whereby the type of the microbial catalysts and the used feedstock affect metabolic pathways and, in turn, the type of product(s) generated. In many cases, especially when dealing with MMC, the economic viability of IF is hindered by factors such as the low attained product titer and selectivity, which ultimately challenge the downstream recovery and purification steps. In this context, electro-fermentation (EF) represents an innovative approach, based on the use of a polarized electrode interface to trigger changes in the rate, yield, titer or product distribution deriving from traditional fermentation processes. In principle, the electrode in EF can act as an electron acceptor (i.e., anodic electro-fermentation, AEF) or donor (i.e., cathodic electro-fermentation, CEF), or simply as a mean to control the oxidation-reduction potential of the fermentation broth. However, the molecular and biochemical basis underlying the EF process are still largely unknown. This review paper provides a comprehensive overview of recent literature studies including both AEF and CEF examples with either pure or mixed microbial cultures. A critical analysis of biochemical, microbiological, and engineering aspects which presently hamper the transition of the EF technology from the laboratory to the market is also presented.
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Affiliation(s)
- Bernardino Virdis
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, Brisbane, QLD 4072, Australia
| | - Robert Hoelzle
- School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Angela Marchetti
- Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Santiago T Boto
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute (HKI), 07745 Jena, Germany; Faculty of Biological Sciences, Friedrich Schiller University (FSU), 07743 Jena, Germany
| | - Miriam A Rosenbaum
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute (HKI), 07745 Jena, Germany; Faculty of Biological Sciences, Friedrich Schiller University (FSU), 07743 Jena, Germany
| | - Ramiro Blasco-Gómez
- LEQUIA, Institute of the Environment, University of Girona, Maria Aurèlia Capmany 69, 17003 Girona, Spain
| | - Sebastià Puig
- LEQUIA, Institute of the Environment, University of Girona, Maria Aurèlia Capmany 69, 17003 Girona, Spain
| | - Stefano Freguia
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Marianna Villano
- Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.
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6
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Atasoy M, Cetecioglu Z. Bioaugmented Mixed Culture by Clostridium aceticum to Manipulate Volatile Fatty Acids Composition From the Fermentation of Cheese Production Wastewater. Front Microbiol 2021; 12:658494. [PMID: 34539589 PMCID: PMC8446653 DOI: 10.3389/fmicb.2021.658494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 06/30/2021] [Indexed: 11/13/2022] Open
Abstract
Production of targeted volatile fatty acid (VFA) composition by fermentation is a promising approach for upstream and post-stream VFA applications. In the current study, the bioaugmented mixed microbial culture by Clostridium aceticum was used to produce an acetic acid dominant VFA mixture. For this purpose, anaerobic sequencing batch reactors (bioaugmented and control) were operated under pH 10 and fed by cheese processing wastewater. The efficiency and stability of the bioaugmentation strategy were monitored using the production and composition of VFA, the quantity of C. aceticum (by qPCR), and bacterial community profile (16S rRNA Illumina Sequencing). The bioaugmented mixed culture significantly increased acetic acid concentration in the VFA mixture (from 1170 ± 18 to 122 ± 9 mgCOD/L) compared to the control reactor. Furthermore, the total VFA production (from 1254 ± 11 to 5493 ± 36 mgCOD/L) was also enhanced. Nevertheless, the bioaugmentation could not shift the propionic acid dominancy in the VFA mixture. The most significant effect of bioaugmentation on the bacterial community profile was seen in the relative abundance of the Thermoanaerobacterales Family III. Incertae sedis, its relative abundance increased simultaneously with the gene copy number of C. aceticum during bioaugmentation. These results suggest that there might be a syntropy between species of Thermoanaerobacterales Family III. Incertae sedis and C. aceticum. The cycle analysis showed that 6 h (instead of 24 h) was adequate retention time to achieve the same acetic acid and total VFA production efficiency. Biobased acetic acid production is widely applicable and economically competitive with petroleum-based production, and this study has the potential to enable a new approach as produced acetic acid dominant VFA can replace external carbon sources for different processes (such as denitrification) in WWTPs. In this way, the higher treatment efficiency for WWTPs can be obtained by recovered substrate from the waste streams that promote a circular economy approach.
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Affiliation(s)
- Merve Atasoy
- Department of Chemical Engineering, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Zeynep Cetecioglu
- Department of Chemical Engineering, KTH Royal Institute of Technology, Stockholm, Sweden
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7
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Volatile Fatty Acid Production from Food Waste Leachate Using Enriched Bacterial Culture and Soil Bacteria as Co-Digester. SUSTAINABILITY 2021. [DOI: 10.3390/su13179606] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The production of volatile fatty acids (VFAs) from waste stream has been recently getting attention as a cost-effective and environmentally friendly approach in mechanical–biological treatment plants. This is the first study to explore the use of a functional bacterium, AM5 isolated from forest soil, which is capable of enhancing the production of VFAs in the presence of soil bacteria as a co-digester in non-strict anaerobic fermentation processes of food waste leachates. Batch laboratory-scale trials were conducted under thermophilic conditions at 55 °C and different pH values ranging from approximately 5 to 11, as well as under uncontrolled pH for 15 days. Total solid content (TS) and volatile solid content (VS) were observed with 58.42% and 65.17% removal, respectively. An effluent with a VFA concentration of up to 33,849 mg/L (2365.57 mg/g VS; 2244.45 mg/g chemical oxygen demand (COD)-VFA VS; 1249 mg/g VSremoved) was obtained at pH 10.5 on the second day of the batch culture. The pH resulted in a significant effect on VFA concentration and composition at various values. Additionally, all types of VFAs were produced under pH no-adjustment (approximately 5) and at pH 10.5. This research might lead to interesting questions and ideas for further studies on the complex metabolic pathways of microbial communities in the mixture of a soil solution and food waste leachate.
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8
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JABEEN S, HUMA N, SAMEEN A, ZIA MA. Formulation and characterization of protein-energy bars prepared by using dates, apricots, cheese and whey protein isolate. FOOD SCIENCE AND TECHNOLOGY 2021. [DOI: 10.1590/fst.12220] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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9
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Hoelzle RD, Puyol D, Virdis B, Batstone D. Substrate availability drives mixed culture fermentation of glucose to lactate at steady state. Biotechnol Bioeng 2021; 118:1636-1648. [PMID: 33438216 DOI: 10.1002/bit.27678] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 12/16/2020] [Accepted: 12/20/2020] [Indexed: 11/10/2022]
Abstract
Mixed-culture fermentation (MCF) enables carbon recycling from complex organic waste streams into valuable feedstock chemicals. Using complex microbial consortia, MCF systems can be tuned to produce a range of biochemicals to meet market demand. However, the metabolic mechanisms and community interactions which drive biochemical production changes under differing conditions are currently poorly understood. These mechanisms are critical to useful MCF production models. Furthermore, predictable product transitions are currently limited to pH-driven changes between butyrate and ethanol, and chain-elongation (fed by lactate, acetate, and ethanol) to butyrate, valerate, and hexanoate. Lactate, a high-value biopolymer feedstock chemical, has been observed in transition states, but sustained production has not been described. In this study, steady state lactate production was achieved by increasing the organic loading rate of a butyrate-producing system from limiting to nonlimiting conditions at pH 5.5. Crucially, butyrate production resumed upon return to substrate-limited conditions. 16S ribosomal DNA community profiling combined with metaproteomics demonstrated that the butyrate-producing lineage Megasphaera redirected carbon flow through the methylglyoxal bypass when substrate was nonlimiting, which altered the community structure and metabolic expression toward lactate production. This metabolic mechanism can be included in future MCF models to describe the changes in product generation in substrate nonlimiting conditions.
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Affiliation(s)
- Robert D Hoelzle
- Advanced Water Management Centre, The University of Queensland, Brisbane, Queensland, Australia.,Australian Centre for Ecogenomics, The University of Queensland, Brisbane, Queensland, Australia.,School of Earth and Environmental Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Daniel Puyol
- Australian Centre for Ecogenomics, The University of Queensland, Brisbane, Queensland, Australia.,Group of Chemical and Environmental Engineering, King Juan Carlos University, Móstoles, Madrid, Spain
| | - Bernardino Virdis
- Advanced Water Management Centre, The University of Queensland, Brisbane, Queensland, Australia
| | - Damien Batstone
- Advanced Water Management Centre, The University of Queensland, Brisbane, Queensland, Australia
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10
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Bevilacqua R, Regueira A, Mauricio-Iglesias M, Lema JM, Carballa M. Steering the conversion of protein residues to volatile fatty acids by adjusting pH. BIORESOURCE TECHNOLOGY 2021; 320:124315. [PMID: 33189039 DOI: 10.1016/j.biortech.2020.124315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/21/2020] [Accepted: 10/22/2020] [Indexed: 06/11/2023]
Abstract
This study investigates the influence of pH on protein conversion into volatile fatty acids by anaerobic mixed-culture fermentation, a topic that, in contrast to glucose fermentation, only had scarce and contradictory information available. Several experiments were performed with two model proteins (casein and gelatin) at three different pH values (5, 7 and 9) using chemostats and batch tests. Highest conversion was reached at neutral pH although complete acidification was never achieved. Longer chain carboxylates production was favoured at low pH, while acetic acid was the main product at pH 7 and 9. Amino acids preferential consumption also varied with pH and protein composition. In fact, protein conversion stoichiometry is mainly driven by energetic yields and amino acid molecular configuration. Overall, this study identifies pH adjustment as a way to steer volatile fatty acid production during mixed-culture fermentation of proteins.
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Affiliation(s)
- R Bevilacqua
- CRETUS Institute, Department of Chemical Engineering, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - A Regueira
- CRETUS Institute, Department of Chemical Engineering, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - M Mauricio-Iglesias
- CRETUS Institute, Department of Chemical Engineering, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
| | - J M Lema
- CRETUS Institute, Department of Chemical Engineering, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - M Carballa
- CRETUS Institute, Department of Chemical Engineering, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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11
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Noh MH, Cha S, Kim M, Jung GY. Recent Advances in Microbial Cell Growth Regulation Strategies for Metabolic Engineering. BIOTECHNOL BIOPROC E 2020. [DOI: 10.1007/s12257-019-0511-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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12
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Stefanski FS, Camargo AF, Scapini T, Bonatto C, Venturin B, Weirich SN, Ulkovski C, Carezia C, Ulrich A, Michelon W, Soares HM, Mathiensen A, Fongaro G, Mossi AJ, Treichel H. Potential Use of Biological Herbicides in a Circular Economy Context: A Sustainable Approach. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2020. [DOI: 10.3389/fsufs.2020.521102] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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13
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Simulation of Mixing Intensity Profile for Bioethanol Production via Two-Step Fermentation in an Unbaffled Agitator Reactor. ENERGIES 2020. [DOI: 10.3390/en13205457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Bioethanol synthesis techniques have been studied intensively due to the energy crisis and various environmental concerns. A two-step bioethanol production process was carried out multiple times in an unbaffled agitator tank. The parameters varied, including the fermentation temperature, the pH level, the amount of yeast, and the impeller type. Then, a simulation was used to obtain an image of the agitation behavior inside the agitator tank to compare the velocity profile of each type of impeller design. The impeller with eight blades was found to produce the highest flow velocity: 0.28 m/s. The highest concentration of bioethanol generated from the fermentation was 34 g/L, which was produced by using an eight-blade impeller at 30 °C, a pH level of 5, an agitation speed of 70 rpm, and 2 wt % yeast. The two-blade impeller produced the lowest bioethanol concentration, 18 g/L, under the same conditions. Ethanol concentration was found to peak at 40 °C and a pH level of 5. The geometry of the impeller, the fermentation temperature, and the pH level were each found to have a significant effect on the resulting bioethanol concentration according to the results of an ANOVA test. The amount of yeast had no effect on the fermentation reaction. Finally, the results demonstrated the possibility of using computational fluid dynamic modeling to determine the impeller’s behavior for the development of the bioethanol fermentation process. The simulation and experimental results from this research support the scaling up of a bioethanol production facility.
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14
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Li W, He L, Cheng C, Cao G, Ren N. Effects of biochar on ethanol-type and butyrate-type fermentative hydrogen productions. BIORESOURCE TECHNOLOGY 2020; 306:123088. [PMID: 32169508 DOI: 10.1016/j.biortech.2020.123088] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 02/25/2020] [Accepted: 02/26/2020] [Indexed: 06/10/2023]
Abstract
Low hydrogen yield was the bottleneck of dark fermentative hydrogen production. To solve this problem, the effects of rice straw-derived biochar on hydrogen production was investigated in different fermentation types. Ethanol-type and butyrate-type fermentations, two dominant types of dark fermentation, were carried out in batch fermentations with different concentrations of biochar. The results revealed that 3 g/L was the best concentration for both types of fermentations. Hydrogen production increased by 118.4% and 79.6% in ethanol-type and butyrate-type fermentations, respectively. The maximal hydrogen yields of ethanol-type and butyrate-type fermentations were 1.34 and 2.36 mol/mol-glucose, respectively. The addition of biochar buffered the broth pH, lowered the redox potential, and released mineral nutrients. The porosity of biochar boosted cell immobilization and thus improved the H2 productivity. This study demonstrated the enhancement effect of biochar on ethanol- and butyrate-type fermentative hydrogen productions, and enhanced the understanding of the functional mechanisms of biochar.
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Affiliation(s)
- Weiming Li
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Lei He
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Chi Cheng
- School of Bioengineering, Dalian University of Technology, Dalian 116024, China
| | - Guangli Cao
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Nanqi Ren
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
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15
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Kim HJ, Jeong H, Lee SJ. Short-Term Adaptation Modulates Anaerobic Metabolic Flux to Succinate by Activating ExuT, a Novel D-Glucose Transporter in Escherichia coli. Front Microbiol 2020; 11:27. [PMID: 32038601 PMCID: PMC6989600 DOI: 10.3389/fmicb.2020.00027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 01/08/2020] [Indexed: 11/18/2022] Open
Abstract
The sugar phosphotransferase system (PTS) is an essential energy-saving mechanism, particularly under anaerobic conditions. Since the PTS consumes equimolar phosphoenolpyruvate to phosphorylate each molecule of internalized glucose in the process of pyruvate generation, its absence can adversely affect the mixed acid fermentation profile and cell growth under anaerobic conditions. In this study, we report that the ΔptsG mutant cells of Escherichia coli K-12 strain exhibited inefficient glucose utilization, produced a significant amount of succinate, and exhibited a low growth rate. However, cells adapted soon after and started to grow rapidly in the same batch culture. As a result, the adapted ΔptsG cells showed the same mixed acid fermentation profiles as the wild-type cells, which was attributed to the mutation of the mlc gene, a repressor of the D-mannose PTS, another transporter for D-glucose. Similar adaptations were observed in the cells with ΔptsGΔmanX and the cells with ΔptsI that resulted in the production of a substantial amount of succinate and fast growth rate. The genome sequencing showed the presence of null mutations in the exuR gene, which encodes a modulator of exuT-encoded non-PTS sugar transporter, in adapted ΔptsGΔmanX and ΔptsI strains. Results from the RT-qPCR analysis and genetic test confirmed that the enhanced expression of ExuT, a non-PTS sugar transporter, was responsible for the uptake of D-glucose, increased succinate production, and fast growth of adapted cells. In conclusion, our study showed that the regulatory network of sugar transporters can be modulated by short-term adaptation and that downstream metabolic flux could be significantly determined by the choice of sugar transporters.
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Affiliation(s)
- Hyun Ju Kim
- Department of Systems Biotechnology, Chung-Ang University, Anseong, South Korea
| | - Haeyoung Jeong
- Gwanggyo R&D Center, Medytox Inc., Suwon, South Korea.,Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea
| | - Sang Jun Lee
- Department of Systems Biotechnology, Chung-Ang University, Anseong, South Korea
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16
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Li Z, Lou Y, Ding J, Liu BF, Xie GJ, Ren NQ, Xing D. Metabolic regulation of ethanol-type fermentation of anaerobic acidogenesis at different pH based on transcriptome analysis of Ethanoligenens harbinense. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:101. [PMID: 32518589 PMCID: PMC7268672 DOI: 10.1186/s13068-020-01740-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 05/25/2020] [Indexed: 05/04/2023]
Abstract
BACKGROUND Ethanol-type fermentation, one of the fermentation types in mixed cultures of acidogenesis with obvious advantages such as low pH tolerance and high efficiency of H2 production, has attracted widespread attentions. pH level greatly influences the establishment of the fermentation of carbohydrate acidogenesis by shaping community assembly and the metabolic activity of keystone populations. To explore the adaptation mechanisms of ethanol-type fermentation to low pH, we report the effects of initial pH on the physiological metabolism and transcriptomes of Ethanoligenens harbinense-a representative species of ethanol-type fermentation. RESULTS Different initial pH levels significantly changed the cell growth and fermentation products of E. harbinense. Using transcriptomic analysis, we identified and functionally categorized 1753 differentially expressed genes (DEGs). By mining information on metabolic pathways, we probed the transcriptional regulation of ethanol-H2 metabolism relating to pH responses. Multiple pathways of E. harbinense were co-regulated by changing gene expression patterns. Low initial pH down-regulated the expression of cell growth- and acidogenesis-related genes but did not affect the expression of H2 evolution-related hydrogenase and ferredoxin genes. High pH down-regulated the expression of H2 evolution- and acidogenesis-related genes. Multiple resistance mechanisms, including chemotaxis, the phosphotransferase system (PTS), and the antioxidant system, were regulated at the transcriptional level under pH stress. CONCLUSIONS Ethanoligenens adapted to low pH by regulating the gene expression networks of cell growth, basic metabolism, chemotaxis and resistance but not H2 evolution-related genes. Regulation based on pH shifts can represent an important approach to establish and enhance ethanol-type fermentation. The complete gene expression network of ethanol fermentative bacteria for pH response provides valuable insights into the acidogenic fermentation, and offers an effective regulation strategy for the sustainable energy recovery from wastewater and solid waste.
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Affiliation(s)
- Zhen Li
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, 73 Huanghe Road, Nangang District, P.O. Box 2614, Harbin, Heilongjiang 150090 China
| | - Yu Lou
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, 73 Huanghe Road, Nangang District, P.O. Box 2614, Harbin, Heilongjiang 150090 China
| | - Jie Ding
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, 73 Huanghe Road, Nangang District, P.O. Box 2614, Harbin, Heilongjiang 150090 China
| | - Bing-Feng Liu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, 73 Huanghe Road, Nangang District, P.O. Box 2614, Harbin, Heilongjiang 150090 China
| | - Guo-Jun Xie
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, 73 Huanghe Road, Nangang District, P.O. Box 2614, Harbin, Heilongjiang 150090 China
| | - Nan-Qi Ren
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, 73 Huanghe Road, Nangang District, P.O. Box 2614, Harbin, Heilongjiang 150090 China
| | - Defeng Xing
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, 73 Huanghe Road, Nangang District, P.O. Box 2614, Harbin, Heilongjiang 150090 China
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17
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Atasoy M, Eyice O, Schnürer A, Cetecioglu Z. Volatile fatty acids production via mixed culture fermentation: Revealing the link between pH, inoculum type and bacterial composition. BIORESOURCE TECHNOLOGY 2019; 292:121889. [PMID: 31394468 DOI: 10.1016/j.biortech.2019.121889] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 07/09/2019] [Accepted: 07/24/2019] [Indexed: 06/10/2023]
Abstract
The aim of the study was to investigate the effects of operational parameters, inoculum type and bacterial community on mixed culture fermentation to produce one dominant acid type in the mixture of volatile fatty acids (VFA). The study was performed using three different inocula (large&small granular and slurry) with glucose under various initial pH. The VFA production efficiency reached to 0,97 (gCOD/gSCOD) by granular sludge. VFA composition was changed by initial pH: in neutral conditions, acetic acid; in acidic conditions, acetic and butyric acids, in alkali conditions butyric acid were dominated, respectively. The VFA production was positively affected by the high relative abundance of Firmicutes. On the contrary, a negative correlation was seen between VFA production and the relative abundance of Chloroflexi. The results revealed the physical sludge structure of inoculum was the key factor for production efficiency, whereas, pH was the most important parameter to affect VFA composition.
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Affiliation(s)
- Merve Atasoy
- Department of Chemical Engineering, KTH Royal Institute of Technology, SE-100 44, Sweden
| | - Ozge Eyice
- School of Biological and Chemical Sciences, Queen Mary University of London, E1 4NS, UK
| | - Anna Schnürer
- Department of Molecular Sciences, Biocenter, Swedish University of Agricultural Sciences, SE 750 07, Sweden
| | - Zeynep Cetecioglu
- Department of Chemical Engineering, KTH Royal Institute of Technology, SE-100 44, Sweden.
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18
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Park MK, Seo JA, Kim YS. Comparative study on metabolic changes of Aspergillus oryzae isolated from fermented foods according to culture conditions. Int J Food Microbiol 2019; 307:108270. [DOI: 10.1016/j.ijfoodmicro.2019.108270] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 07/13/2019] [Accepted: 07/19/2019] [Indexed: 12/22/2022]
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19
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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. BIORESOURCE TECHNOLOGY 2018; 268:773-786. [PMID: 30030049 DOI: 10.1016/j.biortech.2018.07.042] [Citation(s) in RCA: 198] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 07/06/2018] [Accepted: 07/08/2018] [Indexed: 05/28/2023]
Abstract
Bio-based volatile fatty acid (VFA) production from waste-stream is getting attention due to increasing market demand and wide range usage area as well as its cost-effective and environmentally friendly approach. The aim of this paper is to give a comprehensive review of bio-based VFA production and recovery methods and to give an opinion on future research outlook. Effects of operation conditions including pH, temperature, retention time, type of substrate and mixed microbial cultures on VFA production and composition were reviewed. The recovery methods in terms of gas stripping with absorption, adsorption, solvent extraction, electrodialysis, reverse osmosis, nanofiltration, and membrane contractor of VFA were evaluated. Furthermore, strategies to enhance bio-based VFA production and recovery from waste streams, specifically, in-line VFA recovery and bioaugmentation, which are currently not used in common practice, are seen as some of the approaches to enhance bio-based VFA production.
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Affiliation(s)
- Merve Atasoy
- Department of Chemical Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Isaac Owusu-Agyeman
- Department of Chemical Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Elzbieta Plaza
- Department of Sustainable Development, Environmental Science and Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Zeynep Cetecioglu
- Department of Chemical Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
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20
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Regueira A, González-Cabaleiro R, Ofiţeru ID, Rodríguez J, Lema JM. Electron bifurcation mechanism and homoacetogenesis explain products yields in mixed culture anaerobic fermentations. WATER RESEARCH 2018; 141:349-356. [PMID: 29804021 DOI: 10.1016/j.watres.2018.05.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 05/09/2018] [Accepted: 05/09/2018] [Indexed: 06/08/2023]
Abstract
Anaerobic fermentation of organic wastes using microbial mixed cultures is a promising avenue to treat residues and obtain added-value products. However, the process has some important limitations that prevented so far any industrial application. One of the main issues is that we are not able to predict reliably the product spectrum (i.e. the stoichiometry of the process) because the complex microbial community behaviour is not completely understood. To address this issue, in this work we propose a new metabolic network of glucose fermentation by microbial mixed cultures that incorporates electron bifurcation and homoacetogenesis. Our methodology uses NADH balances to analyse published experimental data and evaluate the new stoichiometry proposed. Our results prove for the first time the inclusion of electron bifurcation in the metabolic network as a better description of the experimental results. Homoacetogenesis has been used to explain the discrepancies between observed and theoretically predicted yields of gaseous H2 and CO2 and it appears as the best solution among other options studied. Overall, this work supports the consideration of electron bifurcation as an important biochemical mechanism in microbial mixed cultures fermentations and underlines the importance of considering homoacetogenesis when analysing anaerobic fermentations.
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Affiliation(s)
- A Regueira
- Dep. of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782, Santiago de Compostela, Spain; School of Engineering, Newcastle University, NE1 7RU, Newcastle upon Tyne, United Kingdom.
| | - R González-Cabaleiro
- School of Engineering, Newcastle University, NE1 7RU, Newcastle upon Tyne, United Kingdom; GENOCOV, Departament d'Enginyeria Química, Biològica i Ambiental, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.
| | - I D Ofiţeru
- School of Engineering, Newcastle University, NE1 7RU, Newcastle upon Tyne, United Kingdom.
| | - J Rodríguez
- Khalifa University of Science and Technology Masdar Institute, PO Box 54244, Abu Dhabi, United Arab Emirates.
| | - J M Lema
- Dep. of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782, Santiago de Compostela, Spain.
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21
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Yu JL, Qian ZG, Zhong JJ. Advances in bio-based production of dicarboxylic acids longer than C4. Eng Life Sci 2018; 18:668-681. [PMID: 32624947 DOI: 10.1002/elsc.201800023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 05/18/2018] [Accepted: 06/13/2018] [Indexed: 12/15/2022] Open
Abstract
Growing concerns of environmental pollution and fossil resource shortage are major driving forces for bio-based production of chemicals traditionally from petrochemical industry. Dicarboxylic acids (DCAs) are important platform chemicals with large market and wide applications, and here the recent advances in bio-based production of straight-chain DCAs longer than C4 from biological approaches, especially by synthetic biology, are reviewed. A couple of pathways were recently designed and demonstrated for producing DCAs, even those ranging from C5 to C15, by employing respective starting units, extending units, and appropriate enzymes. Furthermore, in order to achieve higher production of DCAs, enormous efforts were made in engineering microbial hosts that harbored the biosynthetic pathways and in improving properties of biocatalytic elements to enhance metabolic fluxes toward target DCAs. Here we summarize and discuss the current advantages and limitations of related pathways, and also provide perspectives on synthetic pathway design and optimization for hyper-production of DCAs.
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Affiliation(s)
- Jia-Le Yu
- State Key Laboratory of Microbial Metabolism Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology Shanghai Jiao Tong University Shanghai P. R. China.,State Key Laboratory of Bioreactor Engineering, School of Biotechnology East China University of Science and Technology Shanghai P. R. China
| | - Zhi-Gang Qian
- State Key Laboratory of Microbial Metabolism Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology Shanghai Jiao Tong University Shanghai P. R. China.,Shanghai Collaborative Innovation Center for Biomanufacturing Technology (SCICBT) East China University of Science and Technology Shanghai P. R. China
| | - Jian-Jiang Zhong
- State Key Laboratory of Microbial Metabolism Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology Shanghai Jiao Tong University Shanghai P. R. China.,State Key Laboratory of Bioreactor Engineering, School of Biotechnology East China University of Science and Technology Shanghai P. R. China.,Shanghai Collaborative Innovation Center for Biomanufacturing Technology (SCICBT) East China University of Science and Technology Shanghai P. R. China
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22
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Chen Y, Wang T, Shen N, Zhang F, Zeng RJ. High-purity propionate production from glycerol in mixed culture fermentation. BIORESOURCE TECHNOLOGY 2016; 219:659-667. [PMID: 27544916 DOI: 10.1016/j.biortech.2016.08.026] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 08/08/2016] [Accepted: 08/09/2016] [Indexed: 06/06/2023]
Abstract
High-purity propionate production from glycerol in mixed culture fermentation (MCF) induced by high ammonium concentration was investigated. Fed-batch experiments revealed that higher ammonium concentration (>2.9g/L) had simultaneous negative effects on acetate and propionate degradation. Propionate production and yield was up to 22.6g/L and 0.45g COD/g COD glycerol, respectively, with a purity of 96%. Sequential batch experiments demonstrated that the yields of propionate were 0.3±0.05, 0.32±0.01, and 0.34±0.03g COD/g COD at a glycerol concentration of 2.78, 4.38, and 5.56g/L, respectively, and the purity of propionate was 91-100%. Microbial community analysis showed that the phylum Firmicutes dominated the bacterial community at different glycerol concentrations. However, the Methanosaeta population decreased from 46% to 6% when glycerol concentration increased from 2.78 to 5.56g/L, resulting in lower acetate degradation rate. Thus, the present study might provide an alternative option for the production of propionate from glycerol via MCF.
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Affiliation(s)
- Yun Chen
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Ting Wang
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Nan Shen
- School of Environmental Engineering and Science, Yangzhou University, 196 West Huayang Road, Yangzhou, Jiangsu 225127, People's Republic of China
| | - Fang Zhang
- Hebei Key Laboratory of Applied Chemistry, School of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao, Hebei 066004, People's Republic of China
| | - Raymond J Zeng
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China; Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou, Jiangsu 215123, People's Republic of China.
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23
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Santini TC, Malcolm LI, Tyson GW, Warren LA. pH and Organic Carbon Dose Rates Control Microbially Driven Bioremediation Efficacy in Alkaline Bauxite Residue. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:11164-11173. [PMID: 27681196 DOI: 10.1021/acs.est.6b01973] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Bioremediation of alkaline tailings, based on fermentative microbial metabolisms, is a novel strategy for achieving rapid pH neutralization and thus improving environmental outcomes associated with mining and refining activities. Laboratory-scale bioreactors containing bauxite residue (an alkaline, saline tailings material generated as a byproduct of alumina refining), to which a diverse microbial inoculum was added, were used in this study to identify key factors (pH, salinity, organic carbon supply) controlling the rates and extent of microbially driven pH neutralization (bioremediation) in alkaline tailings. Initial tailings pH and organic carbon dose rates both significantly affected bioremediation extent and efficiency with lower minimum pHs and higher extents of pH neutralization occurring under low initial pH or high organic carbon conditions. Rates of pH neutralization (up to 0.13 mM H+ produced per day with pH decreasing from 9.5 to ≤6.5 in three days) were significantly higher in low initial pH treatments. Representatives of the Bacillaceae and Enterobacteriaceae, which contain many known facultative anaerobes and fermenters, were identified as key contributors to 2,3-butanediol and/or mixed acid fermentation as the major mechanism(s) of pH neutralization. Initial pH and salinity significantly influenced microbial community successional trajectories, and microbial community structure was significantly related to markers of fermentation activity. This study provides the first experimental demonstration of bioremediation in bauxite residue, identifying pH and organic carbon dose rates as key controls on bioremediation efficacy, and will enable future development of bioreactor technologies at full field scale.
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Affiliation(s)
| | | | | | - Lesley A Warren
- Lassonde Institute of Mining, The University of Toronto , 35 Saint George Street, Toronto, Ontario M5S 1A4, Canada
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