Effects Of Iron-deficiency Stree On The Expression Of The Secondary Metabolite Synthetase In Brevibacillus Brevis GZDF3 Strain

Objective:To study the effect of iron-deficiency on the expression of secondary metabolite synthetase of Brevibacillus brevis GZDF3 for laying the foundation for further study on the synthesis and regulation of secondary metabolites.Methods:Brevibacillus brevis GZDF3 was cultured in NA medium,Fe-free medium?SA medium?and Fe-low medium(SA+10?mol/L Fe³⁺),and the growth curve was drawn.The isotope labeling relative and absolute quantification technique?iTRAQ?was used to analysis the expression of the secondary metabolite synthetase in the GZDF3 strain cultured in three media.RT-PCR was adopted to validated the results at the transcript level.Results:1.The results of growth curve showed that iron deficiency-stress did not affect the growth of GZDF3 strain in short time;2.The supernatant of GZDF3 cultured in three media had obvious inhibitory effect on Candida albicans.The diameter of the inhibition zone of NA medium,Fe-free medium and Fe-low medium suppendment were 21±0.5 mm,32±0.5 mm and 24±0.5 mm,respectively.3.A total number of 3892 trusted differentially expressed proteins were screened from the three kinds of medium,including 1313 differentially expressed proteins from NA and Fe-free medium,1312 differentially expressed proteins from NA and Fe-low medium,and 1267 differentially expressed proteins from Fe-free medium and Fe-low medium;4.iTRAQ differential protein analysis showed that chitinase D?GENE6369?,linear gramicidin synthase A?GENE677?,linear gramicidin synthaseB?GENE676?,and tyrocidine synthaseB?GENE796?,associated with bacteriostatic activity,were up-regulated in Fe-free medium,while chitinase A?GENE2828?was down-regulated in Fe-free medium.5.Chitinase chiA gene2828,gramicidin LgrA gene677,tyrocidine TycB gene796 and NRPS synthetase Peptidase S8 gene1818 were selected for RT-PCR validation.Gene2828 and gene1818 were down-regulated in Fe-free medium,and gene796 and gene677 were up-regulated in Fe-free medium.Conclusion:Iron deficiency-stress can promote the synthesis of LgrA,B,C of linear gramicidin and TycB of Tyrocidine from strain GZDF3,and inhibited the synthesis of chitinase chiA.