Biosynthesis and transcriptional analysis of thurincin H, a tandem repeated bacteriocin genetic locus, produced by Bacillus thuringiensis SF361

Thurincin H, a bacteriocin produced by Bacillus thuringiensis SF361 isolated from honey, strongly inhibited the growth of Bacillus cereus F4552. The bacteriocin was purified by 65% ammonium sulfate precipitation of the culture supernatant, followed by octyl-sepharose CL-4B and reverse-phase HPLC. The molecular mass of the bacteriocin was determined to be 3139.51 Da and the 14 amino acids of the bacteriocin at the N-terminus were identified. The complete amino acid sequence of mature thurincin H was deduced from three structural genes, thnA1, thnA2, and thnA3 found in tandem repeats on the chromosome, all of which encode for the same bacteriocin, thurincin H. The genetic determinants for thurincin H biosynthesis consist of 10 ORFs, including three thurincin H structural genes. Northern hybridization elucidated that the transcription of all three bacteriocin structural genes was regulated by a putative promoter located upstream of thnA1.