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Journal Article
- Synthesis of pinene in the industrial strain Candida glycerinogenes by modification of its mevalonate pathway
- Tengfei Ma , Hong Zong , Xinyao Lu , Bin Zhuge
- J. Microbiol. 2022;60(12):1191-1200. Published online October 24, 2022
- DOI: https://doi.org/10.1007/s12275-022-2344-0
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- 7 Citations
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Abstract
- Terpenes have many applications and are widely found in nature, but recent progress in synthetic biology has enabled the use of microorganisms as chassis cells for the synthesis of these compounds. Candida glycerinogenes (C. glycerinogenes) is an industrial strain that may be developed as a chassis for the synthesis of terpenes since it has a tolerance to hyperosmolality and high sugar, and has a complete mevalonate (MVA) pathway. However, monoterpenes such as pinene are highly toxic, and the tolerance of C. glycerinogenes to pinene was investigated. We also measured the content of mevalonate and squalene to evaluate the strength of the MVA pathway. To determine terpene synthesis capacity, a pathway for the synthesis of pinene was constructed in C. glycerinogenes. Pinene production was improved by overexpression, gene knockdown and antisense RNA inhibition. Pinene production was mainly enhanced by strengthening the upstream MVA pathway and inhibiting the production of by-products from the downstream pathway. With these strategies, yield could be increased by almost 16 times, to 6.0 mg/L. Overall, we successfully constructed a pinene synthesis pathway in C. glycerinogenes and enhanced pinene production through metabolic modification.
Meta-Analysis
- Proposal of a health gut microbiome index based on a meta-analysis of Korean and global population datasets
- Hyun-Seok Oh , Uigi Min , Hyejin Jang , Namil Kim , Jeongmin Lim , Mauricio Chalita , Jongsik Chun
- J. Microbiol. 2022;60(5):533-549. Published online March 31, 2022
- DOI: https://doi.org/10.1007/s12275-022-1526-0
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- 9 Citations
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Abstract
- The disruption of the human gut microbiota has been linked to host health conditions, including various diseases. However, no reliable index for measuring and predicting a healthy microbiome is currently available. Here, the sequencing data of 1,663 Koreans were obtained from three independent studies. Furthermore, we pooled 3,490 samples from public databases and analyzed a total of 5,153 fecal samples. First, we analyzed Korean gut microbiome covariates to determine the influence of lifestyle on variation in the gut microbiota. Next, patterns of microbiota variations across geographical locations and disease statuses were confirmed using a global cohort and disease data. Based on comprehensive comparative analysis, we were able to define three enterotypes among Korean cohorts, namely, Prevotella type, Bacteroides type, and outlier type. By a thorough categorization of dysbiosis and the evaluation of microbial characteristics using multiple datasets, we identified a wide spectrum of accuracy levels in classifying health and disease states. Using the observed microbiome patterns, we devised an index named the gut microbiome index (GMI) that could consistently predict health conditions from human gut microbiome data. Compared to ecological metrics, the microbial marker index, and machine learning approaches, GMI distinguished between healthy and non-healthy individuals with a higher accuracy across various datasets. Thus, this study proposes a potential index to measure health status of gut microbiome that is verified from multiethnic data of various diseases, and we expect this model to facilitate further clinical application of gut microbiota data in future.
Journal Article
- Spot 42 RNA regulates putrescine catabolism in Escherichia coli by controlling the expression of puuE at the post-transcription level
- Xin Sun , Ruyan Li , Guochen Wan , Wanli Peng , Shuangjun Lin , Zixin Deng , Rubing Liang
- J. Microbiol. 2021;59(2):175-185. Published online February 1, 2021
- DOI: https://doi.org/10.1007/s12275-021-0421-4
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- 1 Citations
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Abstract
- Putrescine, a typical polyamine compound important for cell growth and stress resistance, can be utilized as an energy source. However, the regulation of its catabolism is unclear. Here the small RNA (sRNA) Spot 42, an essential regulator of carbon catabolite repression (CCR), was confirmed to participate in the post-transcriptional regulation of putrescine catabolism in Escherichia coli. Its encoding gene spf exclusively exists in the γ-proteobacteria and contains specific binding sites to the 5-untranslated regions of the puuE gene, which encodes transaminase in the glutamylated putrescine pathway of putrescine catabolism converting γ-aminobutyrate (GABA) into succinate semialdehyde (SSA). The transcription of the spf gene was induced by glucose, inhibited by putrescine, and unaffected by PuuR, the repressor of puu genes. Excess Spot 42 repressed the expression of PuuE significantly in an antisense mechanism through the direct and specific base-pairing between the 51–57 nt of Spot 42 and the 5- UTR of puuE. Interestingly, Spot 42 mainly influenced the stability of the puuCBE transcript. This work revealed the regulatory role of Spot 42 in putrescine catabolism, in the switch between favorable and non-favorable carbon source utilization, and in the balance of metabolism of carbon and nitrogen sources.
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