Overexpression of a water-forming NADH oxidase improves the metabolism and stress tolerance of Saccharmyces cerevisiae in aerobic fermenation
Redox homeostasis is fundamental to the maintenance of metabolism. Redox imbalance can cause oxidative stress, which affects metabolism and growth. Water-forming NADH oxidase regulates the redox balance by oxidizing cytosolic NADH to NAD+, which relieves cytosolic NADH accumulation through rapid glu...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2016-09-01
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| Series: | Frontiers in Microbiology |
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| Online Access: | http://journal.frontiersin.org/Journal/10.3389/fmicb.2016.01427/full |
| _version_ | 1818944087625039872 |
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| author | Xinchi Shi Yanan Zou Yong Chen Cheng Zheng Hanjie Ying |
| author_facet | Xinchi Shi Yanan Zou Yong Chen Cheng Zheng Hanjie Ying |
| author_sort | Xinchi Shi |
| collection | DOAJ |
| description | Redox homeostasis is fundamental to the maintenance of metabolism. Redox imbalance can cause oxidative stress, which affects metabolism and growth. Water-forming NADH oxidase regulates the redox balance by oxidizing cytosolic NADH to NAD+, which relieves cytosolic NADH accumulation through rapid glucose consumption in Saccharomyces cerevisiae, thus decreasing the production of the byproduct glycerol in industrial ethanol production. Here, we studied the effects of overexpression of a water-forming NADH oxidase from Lactococcus lactis on the stress response of S. cerevisiae in aerobic batch fermentation, and we constructed an interaction network of transcriptional regulation and metabolic networks to study the effects of and mechanisms underlying NADH oxidase regulation. The oxidase-overexpressing strain (NOX) showed increased glucose consumption, growth, and ethanol production, while glycerol production was remarkably lower. Glucose was exhausted by NOX at 26 h, while 18.92 ± 0.94 g/L residual glucose was left in the fermentation broth of the control strain (CON) at this time point. At 29.5 h, the ethanol concentration for NOX peaked at 35.25 ± 1.76 g/L, which was 14.37 % higher than that for CON (30.82 ± 1.54 g/L). Gene expression involved in the synthesis of thiamine, which is associated with stress responses in various organisms, was increased in NOX. The transcription factor HAP4 was significantly upregulated in NOX at the late-exponential phase, indicating a diauxic shift in response to starvation. The apoptosis-inducing factor Nuc1 was downregulated while the transcription factor Sok2, which regulates the production of the small signaling molecule ammonia, was upregulated at the late-exponential phase, benefiting young cells on the rim. Reactive oxygen species production was decreased by 10% in NOX, supporting a decrease in apoptosis. The HOG pathway was not activated, although the osmotic stress was truly higher, indicating improved osmotolerance. Thus, the NADH oxidase can regulate the metabolism during aerobic fermentation in S. cerevisiae, thereby protecting cells against several stresses. Our findings indicate its suitability for use in industrial processes. |
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| institution | Directory Open Access Journal |
| issn | 1664-302X |
| language | English |
| last_indexed | 2024-12-20T07:37:39Z |
| publishDate | 2016-09-01 |
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| series | Frontiers in Microbiology |
| spelling | doaj.art-dfe9a8db4d7b4f89ae836378308e2db32022-12-21T19:48:14ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2016-09-01710.3389/fmicb.2016.01427213248Overexpression of a water-forming NADH oxidase improves the metabolism and stress tolerance of Saccharmyces cerevisiae in aerobic fermenationXinchi Shi0Yanan Zou1Yong Chen2Cheng Zheng3Hanjie Ying4Nanjing Tech UniversityNanjing Tech UniversityNanjing Tech UniversityNanjing Tech UniversityNanjing Tech UniversityRedox homeostasis is fundamental to the maintenance of metabolism. Redox imbalance can cause oxidative stress, which affects metabolism and growth. Water-forming NADH oxidase regulates the redox balance by oxidizing cytosolic NADH to NAD+, which relieves cytosolic NADH accumulation through rapid glucose consumption in Saccharomyces cerevisiae, thus decreasing the production of the byproduct glycerol in industrial ethanol production. Here, we studied the effects of overexpression of a water-forming NADH oxidase from Lactococcus lactis on the stress response of S. cerevisiae in aerobic batch fermentation, and we constructed an interaction network of transcriptional regulation and metabolic networks to study the effects of and mechanisms underlying NADH oxidase regulation. The oxidase-overexpressing strain (NOX) showed increased glucose consumption, growth, and ethanol production, while glycerol production was remarkably lower. Glucose was exhausted by NOX at 26 h, while 18.92 ± 0.94 g/L residual glucose was left in the fermentation broth of the control strain (CON) at this time point. At 29.5 h, the ethanol concentration for NOX peaked at 35.25 ± 1.76 g/L, which was 14.37 % higher than that for CON (30.82 ± 1.54 g/L). Gene expression involved in the synthesis of thiamine, which is associated with stress responses in various organisms, was increased in NOX. The transcription factor HAP4 was significantly upregulated in NOX at the late-exponential phase, indicating a diauxic shift in response to starvation. The apoptosis-inducing factor Nuc1 was downregulated while the transcription factor Sok2, which regulates the production of the small signaling molecule ammonia, was upregulated at the late-exponential phase, benefiting young cells on the rim. Reactive oxygen species production was decreased by 10% in NOX, supporting a decrease in apoptosis. The HOG pathway was not activated, although the osmotic stress was truly higher, indicating improved osmotolerance. Thus, the NADH oxidase can regulate the metabolism during aerobic fermentation in S. cerevisiae, thereby protecting cells against several stresses. Our findings indicate its suitability for use in industrial processes.http://journal.frontiersin.org/Journal/10.3389/fmicb.2016.01427/fullApoptosisSaccharomyces cerevisiaestress responsetranscriptome analysisNADH oxidaseOsmotolerance |
| spellingShingle | Xinchi Shi Yanan Zou Yong Chen Cheng Zheng Hanjie Ying Overexpression of a water-forming NADH oxidase improves the metabolism and stress tolerance of Saccharmyces cerevisiae in aerobic fermenation Frontiers in Microbiology Apoptosis Saccharomyces cerevisiae stress response transcriptome analysis NADH oxidase Osmotolerance |
| title | Overexpression of a water-forming NADH oxidase improves the metabolism and stress tolerance of Saccharmyces cerevisiae in aerobic fermenation |
| title_full | Overexpression of a water-forming NADH oxidase improves the metabolism and stress tolerance of Saccharmyces cerevisiae in aerobic fermenation |
| title_fullStr | Overexpression of a water-forming NADH oxidase improves the metabolism and stress tolerance of Saccharmyces cerevisiae in aerobic fermenation |
| title_full_unstemmed | Overexpression of a water-forming NADH oxidase improves the metabolism and stress tolerance of Saccharmyces cerevisiae in aerobic fermenation |
| title_short | Overexpression of a water-forming NADH oxidase improves the metabolism and stress tolerance of Saccharmyces cerevisiae in aerobic fermenation |
| title_sort | overexpression of a water forming nadh oxidase improves the metabolism and stress tolerance of saccharmyces cerevisiae in aerobic fermenation |
| topic | Apoptosis Saccharomyces cerevisiae stress response transcriptome analysis NADH oxidase Osmotolerance |
| url | http://journal.frontiersin.org/Journal/10.3389/fmicb.2016.01427/full |
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