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Pedraz L, Torrents E. An easy method for quantification of anaerobic and microaerobic gene expression with fluorescent reporter proteins. Biotechniques 2023; 75:250-255. [PMID: 37880975 DOI: 10.2144/btn-2023-0064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2023] Open
Abstract
Fluorescent proteins, such as green fluorescent proteins, are invaluable tools for detecting and quantifying gene expression in high-throughput reporter gene assays. However, they introduce significant inaccuracies in studies involving microaerobiosis or anaerobiosis, as oxygen is required for the maturation of these proteins' chromophores. In this study, the authors highlight the errors incurred by using fluorescent proteins under limited oxygenation by comparing standard fluorescence-based reporter gene assays to quantitative real-time PCR data in the study of a complex oxygen-regulated gene network. Furthermore, a solution to perform quantification of anaerobic and microaerobic gene expression with fluorescent reporter proteins using a microplate reader with an oxygen control system and applying pulses of full oxygenation before fluorescence measurements is provided.
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Affiliation(s)
- Lucas Pedraz
- Bacterial Infections & Antimicrobial Therapies Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science & Technology (BIST), Baldiri Reixac 15-21, 08028 Barcelona, Spain
- Present address: Department of Microbiology & Immunology, University of British Columbia (UBC), Lower Mall Research Station, Vancouver, BC, V6T 1Z4, Canada
| | - Eduard Torrents
- Bacterial Infections & Antimicrobial Therapies Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science & Technology (BIST), Baldiri Reixac 15-21, 08028 Barcelona, Spain
- Microbiology Section, Department of Genetics, Microbiology & Statistics, University of Barcelona, 643 Diagonal Avenue, 08028, Barcelona, Spain
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Yamauchi R, Fujisawa M, Koyanagi S, Muramatsu A, Kobayashi T, Wada Y, Akama K, Tanaka M, Kurashige H, Sato A, Horiuchi H, Mukai T, Yamamoto Y, Sasaki Y. Formate-producing capacity provided by reducing ability of Streptococcus thermophilus nicotinamide adenine dinucleotide oxidase determines yogurt acidification rate. J Dairy Sci 2023; 106:6710-6722. [PMID: 37211485 DOI: 10.3168/jds.2023-23245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 04/19/2023] [Indexed: 05/23/2023]
Abstract
Yogurt is made by fermenting milk with 2 lactic acid bacteria, Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus. To comprehensively understand the protocooperation mechanism between S. thermophilus and L. bulgaricus in yogurt fermentation, we examined 24 combinations of cocultures comprising 7 fast- or slow-acidifying S. thermophilus strains with 6 fast- or slow-acidifying L. bulgaricus strains. Furthermore, 3 NADH oxidase (Nox)-deficient mutants (Δnox) and one pyruvate formate-lyase deficient mutant (ΔpflB) of S. thermophilus were used to evaluate the factor that determines the acidification rate of S. thermophilus. The results revealed that the acidification rate of S. thermophilus monoculture determined the yogurt fermentation rates, despite the coexistence of L. bulgaricus, whose acidification rate was either fast or slow. Significant correlation was found between the acidification rate of S. thermophilus monoculture and the amount of formate production. Result using ΔpflB showed that the formate was indispensable for the acidification of S. thermophilus. Moreover, results of the Δnox experiments revealed that formate production required Nox activity, which not only regulated dissolved oxygen, but also the redox potential. The Nox provided the large decrease in redox potential required by pyruvate formate-lyase to produce formate. A highly significant correlation was found between formate accumulation and Nox activity in S. thermophilus. In conclusion, the formate production ability provided by the action of Nox activity determines the acidification rate of S. thermophilus, and consequently, regulates yogurt coculture fermentation.
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Affiliation(s)
- R Yamauchi
- Graduate School of Agriculture, University of Meiji, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - M Fujisawa
- Graduate School of Agriculture, University of Meiji, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - S Koyanagi
- Graduate School of Agriculture, University of Meiji, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - A Muramatsu
- Graduate School of Agriculture, University of Meiji, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - T Kobayashi
- Graduate School of Agriculture, University of Meiji, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Y Wada
- Graduate School of Agriculture, University of Meiji, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - K Akama
- Graduate School of Agriculture, University of Meiji, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - M Tanaka
- Graduate School of Agriculture, University of Meiji, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - H Kurashige
- Department of Animal Science, School of Veterinary Medicine, Kitasato University, 35-1 Higashi 23, Towada, Aomori 034-8628, Japan
| | - A Sato
- Department of Animal Science, School of Veterinary Medicine, Kitasato University, 35-1 Higashi 23, Towada, Aomori 034-8628, Japan
| | - H Horiuchi
- Food Science and Technology Research Laboratories, R&D Division, Meiji Co. Ltd., 1-29-1 Nanakuni, Hachioji, Tokyo 192-0919, Japan
| | - T Mukai
- Department of Animal Science, School of Veterinary Medicine, Kitasato University, 35-1 Higashi 23, Towada, Aomori 034-8628, Japan
| | - Y Yamamoto
- Department of Animal Science, School of Veterinary Medicine, Kitasato University, 35-1 Higashi 23, Towada, Aomori 034-8628, Japan
| | - Y Sasaki
- Graduate School of Agriculture, University of Meiji, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.
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