Biosynthesis And Activity Of Secondary Metabolites Of Bacillus Atrophaeus C89 Associated With Marine Sponge

The red tide caused by algae is serious,and studies have shown that compounds of the bacillamides family and their analogues are potential excellent algicides.Recent studies found that these compounds also have anti-tumor and anti-inflammatory biological activities.The chemical synthesis of these compounds will cause environmental pollution,in order to obtain these compounds and their analogs,biosynthesis studies of the compounds are urgently needed.Previous studies have shown that Bacillus atrophaeus C89 can produce bacillamide C.In this study,a novel natural product was isolated from B.atrophaeus C89 by column chromatography and HPLC.The structure of the new compound was determined with high resolution mass spectrometry and nuclear magnetic resonance analysis,then it was named bacillamide F.The biosynthesis process of B.atrophaeus C89 was presumed based on the structure of the compound.The anti-tumor activity of bacillamide F showed that bacillamide F had low inhibitory effect on the five pancreatic cancer cells selected for this study.Studies have shown that halogen-containing compounds tend to have higher biological activity,in order to obtain highly active bacillamdies compounds,this study added a halogenated tryptophan precursor to the medium of B.atrophaeus C89 by the precursor-directed biological method.Halogenated-bacillamide C and halogenated-bacillamide F were detected by HPLC and mass spectrometry.In this study,not only the halogenated-bacillamides compounds were obtained,but also the participation of tryptophan in the biosynthesis of bacillamide C and bacillamide F was verified,which laid the foundation for further analysis of the biosynthetic pathways of these two compounds.Previous studies have speculated that bacillamide C’s biosynthesis involved acetylation.The aromatic L-amino acid decarboxylase（AADC）gene which involved in biosynthesis of bacilamdie C,was transferred into Streptomyces lividans GX28,and N-acetyltryptamine,analogue product of bacillamide C,was detected.Based on the genomic information of S.lividans GX28,it was speculated that AADC,which is heterologously expressed in S.lividans GX28,catalyzes the decarboxylation of L-tryptophan to form tryptamine,and then the tryptamine is acetylated to N-acetyltryptamine by AANAT.Toxicity of N-acetyltryptamine to three red tide microalgae was tested.The results showed that N-acetyltryptamine had a strong inhibitory effect on the growth of Prorocentrum mexicanum(IC₅₀9.6 mg/L).The purpose of this study was to study the biosynthetic pathway and biological activity of secondary metabolites of B.atrophaeus C89,and to obtain more valuable bacillamides analogs by using precursor-directed biological methods.