Double-bacteria system construction method for PHA accumulation

Abstract

The invention discloses a double-bacteria system construction method. Brewer's yeast and pseudomonas putida are adopted to form a double-bacteria system I, the brewer's yeast realizes xylose utilization, and the pseudomonas putida realizes PHA accumulation. Studies on the system mainly include: determining lactic acid as an optimal carbon source of the pseudomonas putida, and on the basis, designing a middle exchange metabolism product of double bacteria to be lactic acid; exploring an optimal inoculation proportion of the double bacteria, and setting a standard of inoculating 2 g of pseudomonas putida liquid into each 200mL of inorganic salt-xylose culture medium, wherein when the inoculation proportion of the brewer's yeast and the pseudomonas putida is 10:1, talli grow most fast and are highest in biomass; exploring adding time point of sodium caprylate which is a PHA precursor substance, wherein when adding amount is 5g / L and the adding time point is at the beginning of fermentation, PHA accumulation reaches a highest level.

Description

technical field [0001] The invention relates to a method for constructing a dual-bacteria system for PHA accumulation, which belongs to the research field of mixed flora in microbiology. Background technique [0002] Polyhydroxyalkanoate (PHA) has attracted widespread attention as an excellent substitute for traditional plastics due to its good biocompatibility, environmental friendliness, and renewability of raw materials [1], and it is also widely used in the field of biomedicine. widely used. However, the cost of PHA produced by existing methods is much higher than that of traditional plastics, which limits its large-scale production and application [1]. According to a survey by Tsinghua University, substrate consumption accounts for 50% of the cost of PHA. In order to reduce substrate costs, people have turned their attention from expensive substrates such as glucose to non-grain raw materials, such as xylose, which accounts for 18-30% of natural lignocellulose content....

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Problems solved by technology

The reason is that at present, PHA is mainly produced by the traditional fermentation of a single microbial strain [4], xylose itself cannot be rapidly utilized by microorganisms [5], and it is expected to accumulate PHA efficiently, which will bring a heavy metabolic burden to the strain [6 ], so the limitation of microbial metabolism is the bottleneck of efficient conversion of xylose to PHA

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