Isolation, structure determination and antibacterial activities of succinamide conjugate diacid from Acinetobacter sp. BJ-L.

Strain BJ-L was isolated from the a water sample taken from Xiao Yue River in Beijing and identified as Acinetobacter sp. BJ-L based on the study of its morphology, physiology, biochemistry and 16S rRNA gene sequence. A new antimicrobial substance was produced after the strain was incubated in potato extract medium at 15°C for 72 h. The antimicrobial substance was sequentially purified by reduced pressure condensation, EtOAc extract, and silica gel column chromatography. The structure of the antimicrobial substance was elucidated as succinamide conjugate diacid (SCD) by spectroscopic data interpretation. Structure analysis indicated that SCD is a novel compound and that it could inhibit the growth of some tested bacterial strains with the MIC of 2mg/ml, such as Staphylococcus aureus, Bacillus subtilis, Enterobacter aerogenes and Escherichia coli. Moreover, no obvious toxicity has been found on cultured HUVEC cells with different concentrations of SCD at 5, 10, 15, and 20mg/ml.