RETRACTED ARTICLE: Engineering Bacillus licheniformis as a thermophilic platform for the production of l-lactic acid from lignocellulose-derived sugars
Abstract Background Bacillus licheniformis MW3 as a GRAS and thermophilic strain is a promising microorganism for chemical and biofuel production. However, its capacity to co-utilize glucose and xylose, the major sugars found in lignocellulosic biomass, is severely impaired by glucose-mediated carbo...
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| Format: | Article |
| Language: | English |
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BMC
2017-10-01
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| Series: | Biotechnology for Biofuels |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s13068-017-0920-z |
| _version_ | 1818554296328781824 |
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| author | Chao Li Zhongchao Gai Kai Wang Liping Jin |
| author_facet | Chao Li Zhongchao Gai Kai Wang Liping Jin |
| author_sort | Chao Li |
| collection | DOAJ |
| description | Abstract Background Bacillus licheniformis MW3 as a GRAS and thermophilic strain is a promising microorganism for chemical and biofuel production. However, its capacity to co-utilize glucose and xylose, the major sugars found in lignocellulosic biomass, is severely impaired by glucose-mediated carbon catabolite repression (CCR). In this study, a “dual-channel” process was implemented to engineer strain MW3 for simultaneous utilization of glucose and xylose, using l-lactic acid as a target product. Results A non-phosphotransferase system (PTS) glucose uptake route was activated via deletion of the glucose transporter gene ptsG and introduction of the galactose permease gene galP. After replacing the promoter of glucokinase gene glck with the strong promoter P als, the engineered strain recovered glucose consumption and utilized glucose and xylose simultaneously. Meanwhile, to improve the consumption rate of xylose in this strain, several measures were undertaken, such as relieving the regulation of the xylose repressor XylR, reducing the catabolite-responsive element, and optimizing the rate-limiting step. Knockout of ethanol and acetic acid pathway genes further increased lactic acid yield by 6.2%. The resultant strain, RH15, was capable of producing 121.9 g/L l-lactic acid at high yield (95.3%) after 40 h of fermentation from a mixture of glucose and xylose. When a lignocellulosic hydrolysate was used as the substrate, 99.3 g/L l-lactic acid was produced within 40 h, with a specific productivity of 2.48 g/[L h] and a yield of 94.6%. Conclusions Our engineered strain B. licheniformis RH15 could thermophilically produced l-lactic acid from lignocellulosic hydrolysate with relatively high concentration and productivity at levels that were competitive with most reported cases of l-lactic acid-producers. Thus, the engineered strain might be used as a platform for the production of other chemicals. In addition to engineering the B. licheniformis strain, the “dual-channel” process might serve as an alternative method for engineering a variety of other strains. |
| first_indexed | 2024-12-12T09:37:30Z |
| format | Article |
| id | doaj.art-07ad28df15a8417895072af43f5ad533 |
| institution | Directory Open Access Journal |
| issn | 1754-6834 |
| language | English |
| last_indexed | 2024-12-12T09:37:30Z |
| publishDate | 2017-10-01 |
| publisher | BMC |
| record_format | Article |
| series | Biotechnology for Biofuels |
| spelling | doaj.art-07ad28df15a8417895072af43f5ad5332022-12-22T00:28:40ZengBMCBiotechnology for Biofuels1754-68342017-10-0110111310.1186/s13068-017-0920-zRETRACTED ARTICLE: Engineering Bacillus licheniformis as a thermophilic platform for the production of l-lactic acid from lignocellulose-derived sugarsChao Li0Zhongchao Gai1Kai Wang2Liping Jin3Clinical and Translational Research Center, Shanghai First Maternity and Infant Hospital, Tongji University School of MedicineState Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong UniversityClinical and Translational Research Center, Shanghai First Maternity and Infant Hospital, Tongji University School of MedicineClinical and Translational Research Center, Shanghai First Maternity and Infant Hospital, Tongji University School of MedicineAbstract Background Bacillus licheniformis MW3 as a GRAS and thermophilic strain is a promising microorganism for chemical and biofuel production. However, its capacity to co-utilize glucose and xylose, the major sugars found in lignocellulosic biomass, is severely impaired by glucose-mediated carbon catabolite repression (CCR). In this study, a “dual-channel” process was implemented to engineer strain MW3 for simultaneous utilization of glucose and xylose, using l-lactic acid as a target product. Results A non-phosphotransferase system (PTS) glucose uptake route was activated via deletion of the glucose transporter gene ptsG and introduction of the galactose permease gene galP. After replacing the promoter of glucokinase gene glck with the strong promoter P als, the engineered strain recovered glucose consumption and utilized glucose and xylose simultaneously. Meanwhile, to improve the consumption rate of xylose in this strain, several measures were undertaken, such as relieving the regulation of the xylose repressor XylR, reducing the catabolite-responsive element, and optimizing the rate-limiting step. Knockout of ethanol and acetic acid pathway genes further increased lactic acid yield by 6.2%. The resultant strain, RH15, was capable of producing 121.9 g/L l-lactic acid at high yield (95.3%) after 40 h of fermentation from a mixture of glucose and xylose. When a lignocellulosic hydrolysate was used as the substrate, 99.3 g/L l-lactic acid was produced within 40 h, with a specific productivity of 2.48 g/[L h] and a yield of 94.6%. Conclusions Our engineered strain B. licheniformis RH15 could thermophilically produced l-lactic acid from lignocellulosic hydrolysate with relatively high concentration and productivity at levels that were competitive with most reported cases of l-lactic acid-producers. Thus, the engineered strain might be used as a platform for the production of other chemicals. In addition to engineering the B. licheniformis strain, the “dual-channel” process might serve as an alternative method for engineering a variety of other strains.http://link.springer.com/article/10.1186/s13068-017-0920-zLignocellulosic biomassThermophilesBacillus licheniformisl-Lactic acidMetabolic engineering |
| spellingShingle | Chao Li Zhongchao Gai Kai Wang Liping Jin RETRACTED ARTICLE: Engineering Bacillus licheniformis as a thermophilic platform for the production of l-lactic acid from lignocellulose-derived sugars Biotechnology for Biofuels Lignocellulosic biomass Thermophiles Bacillus licheniformis l-Lactic acid Metabolic engineering |
| title | RETRACTED ARTICLE: Engineering Bacillus licheniformis as a thermophilic platform for the production of l-lactic acid from lignocellulose-derived sugars |
| title_full | RETRACTED ARTICLE: Engineering Bacillus licheniformis as a thermophilic platform for the production of l-lactic acid from lignocellulose-derived sugars |
| title_fullStr | RETRACTED ARTICLE: Engineering Bacillus licheniformis as a thermophilic platform for the production of l-lactic acid from lignocellulose-derived sugars |
| title_full_unstemmed | RETRACTED ARTICLE: Engineering Bacillus licheniformis as a thermophilic platform for the production of l-lactic acid from lignocellulose-derived sugars |
| title_short | RETRACTED ARTICLE: Engineering Bacillus licheniformis as a thermophilic platform for the production of l-lactic acid from lignocellulose-derived sugars |
| title_sort | retracted article engineering bacillus licheniformis as a thermophilic platform for the production of l lactic acid from lignocellulose derived sugars |
| topic | Lignocellulosic biomass Thermophiles Bacillus licheniformis l-Lactic acid Metabolic engineering |
| url | http://link.springer.com/article/10.1186/s13068-017-0920-z |
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