Engineering the production of a conformational variant of occidiofungin that has enhanced inhibitory activity against fungal species

A method for promoting OcfN thioesterase activity in a bacterial strain of Burkholderia contaminans MS14 comprising a step of:

• contacting the bacterial strain of Burkholderia contaminans MS14 with a peptide containing more asparagine 1 than beta-hydroxy asparagine 1 to promote the OcfN thioesterase activity of the bacterial strain of Burkholderia contaminans MS14, to produce occidiofungin;
• wherein the bacterial strain of Burkholderia contaminans MS14 comprises one of the following features:
• (A) the bacterial strain of Burkholderia contaminans MS14 comprises an ocfN gene encoding the amino acid sequence of SEQ ID NO:
• 3 and the activity of the ocfN gene in the bacterial strain of Burkholderia contaminans MS14 is promoted by expressing the ocfN gene in a multicopy plasmid, integrating additional copies of the ocfN gene into the chromosome, or substituting the native promoter of the ocf gene with a promoter that increases expression of the ocfN relative to the native promoter, such that the ocfN gene in the bacterial strain of Burkholderia contaminans MS14 produces an increased OcfN thioesterase activity in comparison with the ocfN gene in a wild-type bacterial strain of Burkholderia contaminans M514;
• or
• (B) the bacterial strain of Burkholderia contaminans MS14 comprises an ocfD gene encoding the amino acid sequence of SEQ ID NO:
• 4 and the activity of the ocfD gene of the bacterial strain of Burkholderia contaminans M514 is decreased by a point mutation of the catalytic serine at position 2954 of the amino acid sequence of SEQ ID NO:
• 4, deletion, insertion or point mutations within the thioesterase motif of the amino acid sequence of SEQ ID NO:
• 4, deletion of the catalytic serine of the amino acid sequence of SEQ ID NO:
• 4, truncation of the ocfD gene, or frameshift mutation of the ocfD gene, such that the ocfD gene in the bacterial strain of Burkholderia contaminans M514 has reduced OcfD thioesterase activity in comparison with the OcfD thioesterase activity in a wild-type bacterial strain of Burkholderia contaminans M514.