Research On Metabolites Of Marine Anaerobic Bacterium SRB-22

With the wide use of antibiotics and other antibacterial agents, the problem of drug resistance became more and more serious, so it is crucial to seek new antibiotics. Terrestrial microorganisms, as the main source of new antibiotics in the early ages, seemed to be almost exhausted now and new drug source were in great demand. For their special living environment, marine microorganisms have unique genetic background and metabolic pathways, and were found to be potential to synthesize some structurally distinct antibiotics. Therefore they have become a significant source for new antibiotics of screening.In this thesis, an antimicrobial sulfate-reducing bacterium SRB-22, isolated from the sea water sample of Heishijiao sea area in Dalian, was studied on its fermentation conditions, the stability of antimicrobial activity metabolities and purification and identification of compounds. Two compounds that had stronger ultraviolet aborption were isolated and their spectral and structures were analyzed. Main results are as follows:The fermentation conditions suitable for the bioactive substance production were studied. The optimal culture condition was determined to be that the liquid medium with 10% inoculation amount was cutured at 25℃～30℃with the initial pH value of 7.2 for 28 d.The stability of the antibacterial metabolites was investigated. The results showed the bioactive substance was heat-resistant and optically stable. It was more stable if saved at 4°C for long time. But it was not stable under strong acidic or strong alkaline conditions.Two compounds were obtained by comprehesive use of column chromatographies on silica gel, Sephadex LH-20 and reverse phase silica gel as well as reverse phase high performance liquid chromatography. One of them, compound D-1 was indentified as thymidineby spectral analysis of ¹H-NMR, ¹³C-NMR and MS as well as by comparison with data reported in reference. D-2 was not ultimately identified because of its worse purity and less useful information provided by MS, one-dimensional, two-dimensional NMR of the main component.