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Xu M, Zhou H, Yang X, Angelidaki I, Zhang Y. Sulfide restrains the growth of Methylocapsa acidiphila converting renewable biogas to single cell protein. WATER RESEARCH 2020; 184:116138. [PMID: 32721763 DOI: 10.1016/j.watres.2020.116138] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 06/29/2020] [Accepted: 06/30/2020] [Indexed: 06/11/2023]
Abstract
Methane-oxidizing bacteria (MOB) that can use biogas and recycled nitrogen from wastewater as a sustainable feedstock for single cell protein (SCP) synthesis are receiving increasing attention. Though promising, limited knowledge is available on the alternative strains especially the ones that can tolerant to strict environments such as acidic conditions. Furthermore, how would the hydrogen sulfide affect the MOB (especially the alternative strains) for SCP synthesis when crude biogas is used as feedstock is still unknown. In this study, the capability of an acidic-tolerant methanotrophic bacterium Methylocapsa acidiphila for SCP production using raw biogas and the associated inhibitory effect of sulfide on the bioconversion was for the first time investigated. Results showed that the inhibitory effect of sulfide on the growth of M. acidiphila was observed starting from 8.13 mg L-1 Na2S (equivalent to approximately 1000 ppm of H2S in crude biogas). The total amino acid content in the dry biomass decreased more than two times due to sulfide inhibition compared with the control samples without the presence of sulfide (585.96 mg/g dry biomass), while the proportion of essential amino acids in the total amino acid was not affected when the concentration of Na2S was lower than 5.73 mg L-1. The performance of M. acidiphila in a sulfide-rich environment was further studied at different operational conditions. The feeding gas with a CH4/O2 ratio of 6:4 could help to alleviate the sulfide inhibition, compared with other ratios (4:6 and 8:2). Moreover, the sequential supply of the feed gas could also alleviate sulfide inhibition. In addition, the MOB's growth rate was higher when applying a higher mixing rate of 120 rpm, compared with 70 rpm and 0, due to a better gas-liquid mass transfer. The inoculum size of 20% and 10% resulted in a faster growth rate compared with the 5%. Furthermore, M. acidiphila could assimilate either NH4+ or NO3- as nitrogen source with a similar growth rate, giving it the potential to recycle nitrogen from a wide range of wastewaters. The results will not only create new knowledge for better understanding the role of hydrogen sulfide in the assimilation of raw biogas by acid-tolerant M. acidiphila but also provide technical insights into the development of an efficient and robust process for the waste-to-protein conversion.
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Affiliation(s)
- Mingyi Xu
- Department of Environmental Engineering, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark
| | - Huihui Zhou
- Department of Environmental Engineering, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark; State Key Laboratory of Urban Water Resources and Environment, School of Environment, Harbin Institute of Technology, Harbin, 150090, China
| | - Xiaoyong Yang
- Department of Environmental Engineering, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark
| | - Irini Angelidaki
- Department of Environmental Engineering, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark
| | - Yifeng Zhang
- Department of Environmental Engineering, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark.
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Valverde-Pérez B, Xing W, Zachariae AA, Skadborg MM, Kjeldgaard AF, Palomo A, Smets BF. Cultivation of methanotrophic bacteria in a novel bubble-free membrane bioreactor for microbial protein production. BIORESOURCE TECHNOLOGY 2020; 310:123388. [PMID: 32335344 DOI: 10.1016/j.biortech.2020.123388] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/11/2020] [Accepted: 04/13/2020] [Indexed: 06/11/2023]
Abstract
Microbial protein is proposed as an alternative protein source with low environmental impact. Methane oxidizing bacteria are already produced at commercial scale from natural gas. However, their productivity is limited because of the creation of explosive atmospheres in the fermenters during production. This work demonstrates the applicability of bioreactors with a membrane-based gas supply via diffusion. Methanotrophic bacteria were successfully cultivated, with growth yields from 0.26 to 0.43 g-VSS g-CH4-1, slightly below those observed in analogous fermenters relying on bubbling. However, ammonia yields ranged from 5.2 to 6.9 g-VSS g-NH3-1, indicating higher nitrogen assimilation than in conventional fermenters. Indeed, protein content increased during the operational period reaching up to 51% of dry weight. The amino acid profile included the majority of the essential amino acids, demonstrating suitability as feed ingredient. Never during the operational period was an explosive atmosphere established in the reactor. Thus, bubble-free membrane bioreactors are a promising technology for microbial protein production relying on explosive gas mixtures.
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Affiliation(s)
- Borja Valverde-Pérez
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 115, 2800 Kgs., Lyngby, Denmark.
| | - Wei Xing
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 115, 2800 Kgs., Lyngby, Denmark; School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China
| | - August A Zachariae
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 115, 2800 Kgs., Lyngby, Denmark
| | - Monika M Skadborg
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 115, 2800 Kgs., Lyngby, Denmark
| | - Astrid F Kjeldgaard
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 115, 2800 Kgs., Lyngby, Denmark
| | - Alejandro Palomo
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 115, 2800 Kgs., Lyngby, Denmark
| | - Barth F Smets
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 115, 2800 Kgs., Lyngby, Denmark
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Tsapekos P, Khoshnevisan B, Zhu X, Zha X, Angelidaki I. Methane oxidising bacteria to upcycle effluent streams from anaerobic digestion of municipal biowaste. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2019; 251:109590. [PMID: 31550605 DOI: 10.1016/j.jenvman.2019.109590] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 09/10/2019] [Accepted: 09/16/2019] [Indexed: 06/10/2023]
Abstract
Conventional microbial protein production relies on the usage of pure chemicals and gases. Natural gas, which is a fossil resource, is the common input gas for bacterial protein production. Alternative sources for gas feedstock and nutrients can sufficiently decrease the operational cost and environmental impact of microbial protein production processes. In the present study, the effluents streams of municipal biowaste anaerobic digestion, were used to grow methane oxidising bacteria which can be used as protein source. Results demonstrated that a 40:60 CH4:O2 (v/v) gas feeding resulted in microbial biomass production of 0.95 g-DM/L by a Methylophilus dominated community. When raw biogas was used as input for methane corresponding to the same initial methane partial pressure as before, instead of pure methane, the growth was partially hindered (0.61 g-DM/L) due to the presence of H2S (IC50: 1376 ppm). Hence, desulfurization is suggested before using biogas for microbial protein production. At semi-continuous mode, results showed that the produced biomass had relatively high protein content (>40% of dry weight) and the essential amino acids lysine, valine, leucine and histidine were detected at high levels.
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Affiliation(s)
- Panagiotis Tsapekos
- Department of Environmental Engineering, Technical University of Denmark, Kgs, Lyngby, DK-2800, Denmark
| | - Benyamin Khoshnevisan
- Department of Environmental Engineering, Technical University of Denmark, Kgs, Lyngby, DK-2800, Denmark; Department of Mechanical Engineering of Agricultural Machinery, Faculty of Agricultural Engineering and Technology, College of Agriculture and Natural Resources, University of Tehran, Iran
| | - Xinyu Zhu
- Department of Environmental Engineering, Technical University of Denmark, Kgs, Lyngby, DK-2800, Denmark
| | - Xiao Zha
- Department of Environmental Engineering, Technical University of Denmark, Kgs, Lyngby, DK-2800, Denmark; School of Energy and Environment, Southeast University, No. 2 Sipailou Road, Nanjing, 210096, China
| | - Irini Angelidaki
- Department of Environmental Engineering, Technical University of Denmark, Kgs, Lyngby, DK-2800, Denmark
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Kasprzycka A, Lalak-Kańczugowska J, Walkiewicz A, Bulak P, Proc K, Stępień Ł. Biocatalytic conversion of methane – selected aspects. Curr Opin Chem Eng 2019. [DOI: 10.1016/j.coche.2019.07.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Wu YM, Yang J, Fan XL, Fu SF, Sun MT, Guo RB. Elimination of methane in exhaust gas from biogas upgrading process by immobilized methane-oxidizing bacteria. BIORESOURCE TECHNOLOGY 2017; 231:124-128. [PMID: 28254343 DOI: 10.1016/j.biortech.2017.01.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 01/08/2017] [Accepted: 01/11/2017] [Indexed: 06/06/2023]
Abstract
Biogas upgrading is essential for the comprehensive utilization of biogas as substitute of natural gas. However, the methane in the biogas can be fully recovered during the upgrading process of biogas, and the exhaust gas produced during biogas upgrading may contain a very low concentration of methane. If the exhaust gas with low concentration methane releases to atmosphere, it will be harmful to environment. In addition, the utilization of large amounts of digestate produced from biogas plant is another important issue for the development of biogas industry. In this study, solid digestate was used to produce active carbon, which was subsequently used as immobilized material for methane-oxidizing bacteria (MOB) in biofilter. Biofilter with MOB immobilized on active carbon was used to eliminate the methane in exhaust gas from biogas upgrading process. Results showed porous active carbon was successfully made from solid digestate. The final methane elimination capacity of immobilized MOB reached about 0.13molh-1m-3, which was more 4 times higher than that of MOB without immobilization.
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Affiliation(s)
- Ya-Min Wu
- State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, Shandong Province 266510, PR China; Shandong Industrial Engineering Laboratory of Biogas Production & Utilization, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong Province 266101, PR China
| | - Jing Yang
- State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, Shandong Province 266510, PR China
| | - Xiao-Lei Fan
- Shandong Industrial Engineering Laboratory of Biogas Production & Utilization, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong Province 266101, PR China
| | - Shan-Fei Fu
- Shandong Industrial Engineering Laboratory of Biogas Production & Utilization, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong Province 266101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Meng-Ting Sun
- Shandong Industrial Engineering Laboratory of Biogas Production & Utilization, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong Province 266101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Rong-Bo Guo
- Shandong Industrial Engineering Laboratory of Biogas Production & Utilization, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong Province 266101, PR China.
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Enrichment and characteristics of mixed methane-oxidizing bacteria from a Chinese coal mine. Appl Microbiol Biotechnol 2016; 100:10331-10341. [DOI: 10.1007/s00253-016-7738-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 07/11/2016] [Accepted: 07/13/2016] [Indexed: 10/21/2022]
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