Study On The Bioactive Compounds Of Bacillus Vallismortis C89 Associated With Sponge Dysidea Avara

Sponge associated bacteria are important sources for novel natural bioactive compounds. In our previous research work, a Bacillus vallismortis C89 was isolated from marine sponge Dysidea avara, which was found to have multiple antimicrobial activities. Some literatures also documented that bacteria of Bacillus sp. could generate a series of antibiotics.Six compounds were isolated from the culture of Bacillus vallismortis C89 by using thin-layer chromatography, gel exclusion chromatography, silica column chromatography, reverse phase HPLC etc. The structures of all the compounds were elucidated by 1D-NMR and 2D-NMR and MS spectra. CompoundⅠ: Bacillamide D CompoundⅡ: Bacillamide C CompoundⅢ: Cyclo-(S-Pro-S-Val) CompoundⅣ:Cyclo-(S-Pro-R-Ile) CompoundⅤ:Cyclo-(S-Pro-R-Leu) CompoundⅥ:Cyclo-(S-Pro-R-Phe).All of the six compounds were first found in Dysidea avara associated bacterium. In particular, compoundⅠhas novel structure and compoundⅡwas the third discovery in the world. Due to the large potential in application of CompoundⅡand its stability and relatively high yield in fermentation, we screened its antimicrobial activities, voltage-gated potassium current inhibition and in vitro anti-tumor activities. In a voltage-gated potassium current test of Sprague-Dawley Rat hippocampus, CompoundⅡ(100μM in DMSO) showed an inhibition of 37.2±7.1 (%) to delayed rectifier potassium current and 11.9±3.7 (%) to fast transient potassium current, which represented little inhibition effect. What's more, a low cytotoxic effect of CompoundⅡ(10-4M in DMSO) was presented with HL60 human leukemia cells and A-549 human lung cancer cells with an inhibition of 57.1% and 32.4% respectively.It was reported that compoundⅡshowed antiproliferative and cytotoxic effects on several tumor cells. It analog had significant inhibition against a marine dinoflagellate Cochlodinium polykrikoides which is cause of red tide and mass mortalities of cultured fishes and bivalves. This suggests that Bacillus vallismortis C89 plays a considerable role in the chemical defence of marine sponge Dysidea avara.