Xenorhabdus nematophila producing Xcn1 in high yield and application thereof

Abstract

The invention relates to a strain of Xenorhabdus nematophila producing Xenocoumacin1 (Xcn1) in high yield. On the basis of a homologous recombination technology, genes related to anabolism of Xcn1 in a wild type strain of Xenorhabdus nematophila CB6 are subjected to engineering transformation to finally obtain an improved strain not producing Xcn2 but producing Xcn1 in high yield, named as CB6-T2. Studies show that an enzyme gene xcnM for mediating degradation and transformation of Xcn1 in the CB6-T2 strain is deleted and mutated, and a first gene xcnA promoter of an Xcn1 synthetic gene cluster is replaced with a promoter Promoter-g3509 that is derived from Xenorhabdus nematophila and has higher expression intensity. Tests show that the yield of Xcn1 obtained by fermenting the strain CB6-T2 in an LB culture medium is at least 782 mg / L or above, much higher than the fermentation yield of a wild strain of Xenorhabdus nematophila CB6. The strain can effectively reduce production cost in industrial development of Xcn1.

Description

technical field [0001] The invention relates to the technical field of microbes, in particular to a high-yield Xcn1 pathogenic nematophila strain and application thereof. Background technique [0002] Entomopathogenic nematode symbionts are a class of bacteria that exist in the intestinal tract of entomopathogenic nematodes, belonging to the family Enterobacteriaceae, including Xenorhabdus and Xenorhabdus that live in symbiosis with Steinernema nematodes Nematode symbiotic Photorhabdus. Symbiotic bacteria secrete a variety of enzymes, degrade insect tissues, release nutrients, and produce antibacterial substances to inhibit the growth of other bacteria, which is conducive to the growth and reproduction of nematodes. Symbiotic bacteria originate from special habitats, and there are a variety of new compounds with biological activity in their metabolites. At present, the main ones that have been isolated and identified are antibacterial substances, insecticidal proteins, and ...

AI Technical Summary

Problems solved by technology

Xcn1 is the main active substance produced by Xcn1, Xcn1 is the main active substance produced by Xcn1, but during the metabolism of the strain, the excessively accumulated Xcn1 will activate the degradation and metabolism pathway of Xcn1, and Xcn1 will be converted into low-activity derivatives such as Xcn2, which are produced by fermentation The production of Xcn1 further decreased with the passage of time, resulting in the inability to accumulate a large amount of Xcn1

In addition, the level of Xcn1 produced by fermentation of the wild-type CB6 strain is low, and it is speculated that the low expression levels of various enzymes in the Xcn1 synthetic gene cluster are the key limiting factors

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