JOURNAL OF BIOTECHNOLOGY
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2020
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IF 3.503
Hengqian Lu,Haiqin Chen,Xin Tang,Qin Yang,Hao Zhang,Yong Q. Chen,Wei Chen
Lipid hyperaccumulation in oleaginous microorganisms is generally induced by nitrogen limitation, while oxygen supply can influence biomass growth and cell metabolism. Although strategies based on nitrogen limitation or oxygen control have been extensively explored and applied in various oleaginous microorganisms, the role of oxygen supply in nitrogen limitation induced lipid hyperaccumulation still remains unclear. Here, we systematically surveyed the effects of oxygen supply on the oleaginous fungus M. alpina cultured in nitrogen limited conditions through integration of physiochemical parameters and metabolomics analysis. Our results indicated that a high oxygen supply promoted carbon/nitrogen consumption and was used for rapid biomass synthesis, while either high or low oxygen supply conditions were adverse to lipid and ARA accumulation. Different oxygen supply level significantly affected the balance between fermentation for lipid synthesis and respiration for energy generation. Under nitrogen limitation, a suitable oxygen supply promoted the recycling of preformed nitrogen and increased the redirection of carbon towards fatty acid synthesis through the hub centred around glutamic acid coupled to the intermediate metabolism of carbon in the TCA cycle, while a high oxygen supply favored the respiration process and enhanced the degradation of LC-PUFAs, rather than fermentation for fatty acid synthesis. This system-level insight reveals the underlying metabolic mechanism of oxygen control in nitrogen limitation induced lipid accumulation, and provides theoretical support for the integration of oxygen control with nutrient supply for efficient microbial oil production.
研究领域:
微生物学
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代谢生物学
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DOI
PubMed
高影响因子
Food & Function
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2023
·Vol. 14
·期 14
·6363-6375
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IF 6.1
Mengyang Liu,Haitao Wang,Xu Yan,Sufang Zhang,Chaofan Ji,Yingxi Chen,Beiwei Zhu,Xinping Lin
A carotenoid production strain Rhodosporidium toruloides NP11 and its mutant strain R. toruloides A1-15 were studied under chemostat nitrogen-limited cultivation. Multi-omics analysis (metabolomics, lipidomics and transcriptomics) was used to investigate the different mechanisms of torularhodin accumulation between NP11 and A1-15. The results showed that the carotenoid synthesis pathway was significantly enhanced in A1-15 compared to NP11 under nitrogen limitation, due to the significant increase of torularhodin. Under nitrogen-limited conditions, higher levels of β-oxidation were present in A1-15 compared to those in NP11, which provided sufficient precursors for carotenoid synthesis. In addition, ROS stress accelerated the intracellular transport of iron ions, promoted the expression of CRTI and CRTY genes, and reduced the transcript levels of FNTB1 and FNTB2 in the bypass pathway, and these factors may be responsible for the regulation of high torularhodin production in A1-15. This study provided insights into the selective production of torularhodin.
研究领域:
微生物学
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代谢组学
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脂质组学
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转录组学
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生物技术
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产品关联
DOI
PubMed
高影响因子
Environmental Technology & Innovation
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2024
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IF 6.7
Lu Huang,Weilai Lu,Yunkai Yu,Haoning Qiu,Yan Zeng,Lida Wang,Ying Liu,Lei Yan,Yu Vincent Fu,Yanning Zheng
Ammonium (NH 4 + ) transport across cell membranes plays an important role in assimilation or removal of the environmental nitrogen. The membrane protein AmtB has been considered to be the NH 4 + transporter that is responsible for the NH 4 + uptake. The phototrophic diazotroph Rhodopseudomonas palustris harboring two amtB genes has been widely used in wastewater treatment and bioremediation. However, the role of AmtB in NH 4 + uptake remains unclear in R. palustris . Here, we employed an innovative approach combining stable isotope probing (SIP) with Raman spectroscopy to determine the physiological functions of AmtB1 and AmtB2 in R. palustris. This powerful technique allowed us to investigate NH 4 + uptake at the single-cell level. The generated R. palustris Δ amtB1 Δ amtB2 mutant lacking AmtB1 and AmtB2 proteins was still capable of utilizing 15 NH 4 + even the 15 NH 4 + concentration was as low as 5 μM. These data demonstrate that both of the AmtB proteins are not essential for R. palustris to take up NH 4 + regardless of environmental NH 4 + levels. However, both AmtB1 and AmtB2 can contribute to NH 4 + uptake under nitrogen-limiting conditions. Given that R. palustris primarily expresses AmtB2 in these conditions, AmtB2 plays a more important role in NH 4 + uptake compared to AmtB1. In addition, transcriptomic analysis showed that the deletion of the amtB1 and amtB2 genes resulted in the upregulation of many transporter genes, providing potential targets for future investigation of alternative NH 4 + uptake systems.
研究领域:
微生物学
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环境科学
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分子生物学
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产品关联
DOI
高影响因子
ACS Synthetic Biology
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2023
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IF 4.7
Ruosi Zhang,Mingdong Yao,Haidi Ma,Wenhai Xiao,Ying Wang,Yingjin Yuan
Substrate competition within a metabolic network constitutes a common challenge in microbial biosynthesis system engineering, especially if indispensable enzymes can produce multiple intermediates from a single substrate. Androstenedione (4AD) is a central intermediate in the production of a series of steroidal pharmaceuticals; however, its yield via the coexpression of 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17α-hydroxylase/17,20-lyase (CYP17A1) in a microbial chassis affords a nonlinear pathway in which these enzymes compete for substrates and produce structurally similar unwanted intermediates, thereby reducing 4AD yields. To avoid substrate competition, we split the competing 3β-HSD and CYP17A1 pathway components into two separate Yarrowia lipolytica strains to linearize the pathway. This spatial segregation increased substrate availability for 3β-HSD in the upstream strain, consequently decreasing the accumulation of the unwanted intermediate 17-hydroxypregnenolone (17OHP5) from 94.8 ± 4.4% in single-chassis monocultures to 24.8 ± 12.6% in cocultures of strains expressing 3β-HSD and CYP17A1 separately. Orthologue screening to increase CYP17A1 catalytic efficiency and the preferential production of desired intermediates increased the biotransformation capacity in the downstream pathway, further decreasing 17OHP5 accumulation to 3.9%. Furthermore, nitrogen limitation induced early 4AD accumulation (final titer, 7.71 mg/L). This study provides a framework for reducing intrapathway competition between essential enzymes during natural product biosynthesis as well as a proof-of-concept platform for linear steroid production.
研究领域:
代谢工程
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生物技术
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药学
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微生物生物技术
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产品关联
DOI
PubMed
高影响因子
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