Construction method of pediococcus acidilactici for producing L-lactic acid through co-fermentation of glucose and xylose

Abstract

The invention discloses a construction method of pediococcus acidilactici for producing L-lactic acid through co-fermentation of glucose and xylose, and belongs to the technical field of gene engineering. The construction method comprises the following construction steps: integrating heterogenous xylose isomerase, xylulokinase, transketolase and transaldolase coding genes on a genome of a strain pediococcus acidilactici TY112 (with the accession number of CGMCC NO.8664) for producing L-lactic acid by utilizing a thermosensitive knockout system; knocking out phosphoketolase and acetokinase coding genes; and carrying out adaptive evolution for improving the capacity of co-fermentation of glucose and xylose. With the construction method, an engineering strain capable of efficiently producingoptically pure L-lactic acid through co-fermentation of glucose and xylose is successfully obtained, the engineering strain is named P.acidilactici ZY271, and the accession number is CGMCC NO.13611.

Description

technical field [0001] The invention belongs to the field of genetic engineering, and in particular relates to a construction method of Pediococcus lactis producing L-lactic acid by co-fermenting glucose and xylose using a heat-sensitive knockout system based on the principle of homologous recombination. Background technique [0002] Lactic acid is an important industrial chemical, which is widely used in food, medicine, leather and textile industries. In recent years, the use of optically pure L-lactic acid as a precursor to produce biodegradable plastic polylactic acid has greatly increased the demand for optically pure L-lactic acid. At present, lactic acid production mainly includes two routes: chemical synthesis and microbial fermentation. The main disadvantage of chemical synthesis is that the lactic acid it produces is D / L mixed lactic acid, while the advantage of microbial fermentation is that it can produce optically pure lactic acid, low production temperature and...

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Problems solved by technology

However, the xylRAB in this document is expressed in a plasmid and is not integrated into the genome. The resulting engineering strain is not a stable engineering strain. During the fermentation process, antibiotics need to be added to maintain the normal growth of the recombinant bacteria. Addition will increase the cost of fermentation, which is an important drawback for large-scale industrial applications

In addition, the literature and the author's later research did not use lignocellulosic raw materials for co-fermentation to produce L-lactic acid, and there is no actual proof that the engineering strain has the ability to co-ferment glucose and xylose to produce L-lactic acid

[0005] At present, there is no report on the co-fermentation of glucose and xylose by Pediococcus lactis to produce L-lactic acid. Therefore, a xylose metabolic pathway was constructed in Pediococcus lactis to produce L-lactic acid. L-lactic acid production has important practical significance

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