Transcriptome and Metabolome Profiling of a Novel Isolate Chlorella sorokiniana G32 (Chlorophyta) Displaying Enhanced Starch Accumulation at High Growth Rate Under Mixotrophic Condition
Chlorella sorokiniana is one of the most productive microalgal species with a high potential for the production of biofuels and other high value-added molecules. Many studies have focused on its capability of mixotrophic growth using reduced organic carbon and growth pattern shift between autotrophi...
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Frontiers Media S.A.
2022-01-01
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| Series: | Frontiers in Microbiology |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fmicb.2021.760307/full |
| _version_ | 1798033361979047936 |
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| author | Qingling Zhu Mengmeng Zhang Bingying Liu Fang Wen Zhili Yang Jianhua Liu Jianhua Liu |
| author_facet | Qingling Zhu Mengmeng Zhang Bingying Liu Fang Wen Zhili Yang Jianhua Liu Jianhua Liu |
| author_sort | Qingling Zhu |
| collection | DOAJ |
| description | Chlorella sorokiniana is one of the most productive microalgal species with a high potential for the production of biofuels and other high value-added molecules. Many studies have focused on its capability of mixotrophic growth using reduced organic carbon and growth pattern shift between autotrophic and mixotrophic conditions. In this study, we investigated growth patterns of a novel isolate, C. sorokiniana G32, under mixotrophic growth conditions supplemented with a low level (1.25 g L–1) and a high level (5 g L–1) of glucose. Physiological, transcriptomic (i.e., RNA-seq), and metabolomic (i.e., LC-MS/MS) methods were used. We showed that peak growth based on OD680nm absorbance is ∼4-fold higher with high glucose vs. low glucose supplementation. Photosynthetic efficiency (Fv/Fm) in G32 mixotrophic cultures with high or low glucose supplementation remains identical to that of G32 phototrophic growth. We also found that the conversion rate between absorbance-based cell density and cell dry weight with high glucose supplementation was lower than with low glucose. This suggests that more cell biomass is produced under high glucose treatment than with low glucose. The result was confirmed via sucrose density gradient centrifugation. It is likely that accumulation of high concentration of starch may account for this effect. Transcriptomic analysis of G32 cultures (i.e., via RNA-seq) in response to reciprocal change of glucose levels reveals that expression of a subset of differentially expressed genes (DEGs) is correlated with the amount of glucose supplementation. These DEGs are designated as glucose-specific responsive (GSR) genes. GSR genes are enriched for a number of energy metabolic pathways. Together with metabolomics data (i.e., LC-MS/MS), we show that under high-level supplementation, glucose is preferentially oxidized through an oxidative pentose phosphate pathway. Collectively, our results indicate the mechanism of regulation of glucose assimilation and energy metabolism in G32 under mixotrophic conditions with different levels of glucose supplementation revealed by transcriptomic and metabolomic analyses. We propose that C. sorokiniana G32 has the potential for the production of high value-added molecules. |
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| issn | 1664-302X |
| language | English |
| last_indexed | 2024-04-11T20:29:09Z |
| publishDate | 2022-01-01 |
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| spelling | doaj.art-51c663b5ff9e4862854403f65d9e8d522022-12-22T04:04:33ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2022-01-011210.3389/fmicb.2021.760307760307Transcriptome and Metabolome Profiling of a Novel Isolate Chlorella sorokiniana G32 (Chlorophyta) Displaying Enhanced Starch Accumulation at High Growth Rate Under Mixotrophic ConditionQingling Zhu0Mengmeng Zhang1Bingying Liu2Fang Wen3Zhili Yang4Jianhua Liu5Jianhua Liu6Systems Biology, School of Marine Science and Technology, Zhejiang Ocean University, Zhoushan, ChinaSystems Biology, School of Marine Science and Technology, Zhejiang Ocean University, Zhoushan, ChinaMarine Biology, Ocean College, Zhejiang University, Zhoushan, ChinaMarine Biology, Ocean College, Zhejiang University, Zhoushan, ChinaSystems Biology, School of Marine Science and Technology, Zhejiang Ocean University, Zhoushan, ChinaSystems Biology, School of Marine Science and Technology, Zhejiang Ocean University, Zhoushan, ChinaNational Engineering Research Center for Marine Aquaculture, Zhejiang Ocean University, Zhoushan, ChinaChlorella sorokiniana is one of the most productive microalgal species with a high potential for the production of biofuels and other high value-added molecules. Many studies have focused on its capability of mixotrophic growth using reduced organic carbon and growth pattern shift between autotrophic and mixotrophic conditions. In this study, we investigated growth patterns of a novel isolate, C. sorokiniana G32, under mixotrophic growth conditions supplemented with a low level (1.25 g L–1) and a high level (5 g L–1) of glucose. Physiological, transcriptomic (i.e., RNA-seq), and metabolomic (i.e., LC-MS/MS) methods were used. We showed that peak growth based on OD680nm absorbance is ∼4-fold higher with high glucose vs. low glucose supplementation. Photosynthetic efficiency (Fv/Fm) in G32 mixotrophic cultures with high or low glucose supplementation remains identical to that of G32 phototrophic growth. We also found that the conversion rate between absorbance-based cell density and cell dry weight with high glucose supplementation was lower than with low glucose. This suggests that more cell biomass is produced under high glucose treatment than with low glucose. The result was confirmed via sucrose density gradient centrifugation. It is likely that accumulation of high concentration of starch may account for this effect. Transcriptomic analysis of G32 cultures (i.e., via RNA-seq) in response to reciprocal change of glucose levels reveals that expression of a subset of differentially expressed genes (DEGs) is correlated with the amount of glucose supplementation. These DEGs are designated as glucose-specific responsive (GSR) genes. GSR genes are enriched for a number of energy metabolic pathways. Together with metabolomics data (i.e., LC-MS/MS), we show that under high-level supplementation, glucose is preferentially oxidized through an oxidative pentose phosphate pathway. Collectively, our results indicate the mechanism of regulation of glucose assimilation and energy metabolism in G32 under mixotrophic conditions with different levels of glucose supplementation revealed by transcriptomic and metabolomic analyses. We propose that C. sorokiniana G32 has the potential for the production of high value-added molecules.https://www.frontiersin.org/articles/10.3389/fmicb.2021.760307/fullChlorella sorokinianaglucose-responsive genesmetabolomemixotrophic growthtranscriptome (RNA-seq) |
| spellingShingle | Qingling Zhu Mengmeng Zhang Bingying Liu Fang Wen Zhili Yang Jianhua Liu Jianhua Liu Transcriptome and Metabolome Profiling of a Novel Isolate Chlorella sorokiniana G32 (Chlorophyta) Displaying Enhanced Starch Accumulation at High Growth Rate Under Mixotrophic Condition Frontiers in Microbiology Chlorella sorokiniana glucose-responsive genes metabolome mixotrophic growth transcriptome (RNA-seq) |
| title | Transcriptome and Metabolome Profiling of a Novel Isolate Chlorella sorokiniana G32 (Chlorophyta) Displaying Enhanced Starch Accumulation at High Growth Rate Under Mixotrophic Condition |
| title_full | Transcriptome and Metabolome Profiling of a Novel Isolate Chlorella sorokiniana G32 (Chlorophyta) Displaying Enhanced Starch Accumulation at High Growth Rate Under Mixotrophic Condition |
| title_fullStr | Transcriptome and Metabolome Profiling of a Novel Isolate Chlorella sorokiniana G32 (Chlorophyta) Displaying Enhanced Starch Accumulation at High Growth Rate Under Mixotrophic Condition |
| title_full_unstemmed | Transcriptome and Metabolome Profiling of a Novel Isolate Chlorella sorokiniana G32 (Chlorophyta) Displaying Enhanced Starch Accumulation at High Growth Rate Under Mixotrophic Condition |
| title_short | Transcriptome and Metabolome Profiling of a Novel Isolate Chlorella sorokiniana G32 (Chlorophyta) Displaying Enhanced Starch Accumulation at High Growth Rate Under Mixotrophic Condition |
| title_sort | transcriptome and metabolome profiling of a novel isolate chlorella sorokiniana g32 chlorophyta displaying enhanced starch accumulation at high growth rate under mixotrophic condition |
| topic | Chlorella sorokiniana glucose-responsive genes metabolome mixotrophic growth transcriptome (RNA-seq) |
| url | https://www.frontiersin.org/articles/10.3389/fmicb.2021.760307/full |
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