Production of d-lactate from glucose using Klebsiella pneumoniae mutants

Xinjun Feng, Liqun Jiang, Xiaojuan Han, Xiutao Liu, Zhiqiang Zhao, Huizhou Liu, Mo Xian, Guang Zhao
2017 Microbial Cell Factories  
d-Lactate is a valued chemical which can be produced by some bacteria including Klebsiella pneumoniae. However, only a few studies have focused on K. pneumoniae for d-lactate production with a significant amount of by-products, which complicated the purification process and decreased the yield of d-lactate. Results: Based on the redirection of carbon towards by-product formation, the effects of single-gene and multiplegene deletions in K. pneumoniae on d-lactate production from glucose via
more » ... lactate synthase (budB), acetate kinase (ackA), and alcohol dehydrogenase (adhE) were tested. Klebsiella pneumoniae mutants had different production behaviours. The accumulation of the main by-products was decreased in the mutants. The triple mutant strain had the most powerful ability to produce optically pure d-lactate from glucose, and was tested with xylose and arabinose as carbon sources. Fed-batch fermentation was also carried out under various aeration rates, and the strain accumulated 125.1 g/L d-lactate with a yield of 0.91 g/g glucose at 2.5 vvm. Conclusions: Knocking out by-product synthesis genes had a remarkable influence on the production and yield of d-lactate. This study demonstrated, for the first time, that K. pneumoniae has great potential to convert monosaccharides into d-lactate. The results provide new insights for industrial production of d-lactate by K. pneumoniae.
doi:10.1186/s12934-017-0822-6 pmid:29162110 pmcid:PMC5697408 fatcat:2x2csm7eybgnbn6bj6kbi6ieju