The invention relates to the technical field of
gene engineering, in particular to a recombinant
plasmid, a construction method and application of the recombinant
plasmid to improvement of the synthesis capacity of
nostoc flagelliforme pseudocladodin. The recombinant
plasmid comprises a vector plasmid, and an sgRNA target sequence, an HR
homologous sequence, a psbA
promoter sequence and an ScyR
regulator gene which are connected to the vector plasmid. The recombinant plasmid can over-express the key
regulator gene at the MAAs
gene cluster site of the
nostoc flagelliforme, so that the pseudocladostin synthesis capability of the
nostoc flagelliforme is remarkably improved. The recombinant plasmid is transformed into nostoc flagelliforme to obtain a nostoc flagelliforme
mutant, and after the nostoc flagelliforme
mutant is cultured for 15 days, the content of cladosporin is 2.4 times that of wild nostoc flagelliforme.