Previous studies on the physiological aspects of violacein biosynthesis (DeMoss and Evans, 1959) suggested that only L-tryptophan would serve as the primary source of carbon for pigment formation by Chromobacterium violaceum. In view of the pigment structure suggested by Ballantine et al. (1958), 5-[3-(5-hydroxyindolyl)]-3-(3-isatinyl)-2-pyrrolone, it seemed advisable to determine the actual so...

UNLABELLED Studies describing the use of essential oil constituents as antimicrobial agents have steadily increased; however, some phyto-constituents are often overlooked due to unfavourable minimum inhibitory concentration (MIC) values. Virulence depends on transcriptional factors which are regulated by cell-to-cell communication called quorum sensing (QS). This study was undertaken to evaluat...

The polyhydroxyalkanoic acid synthase gene from Chromobacterium violaceum (phaC(Cv)) was cloned and characterized. A 6.3-kb BamHI fragment was found to contain both phaC(Cv) and the polyhydroxyalkanoic acid (PHA)-specific 3-ketothiolase (phaA(Cv)). Escherichia coli strains harboring this fragment produced significant levels of PHA synthase and 3-ketothiolase, as judged by their activities. Whil...

An ethyl acetate (EtOAc) extract isolated from the marine bacterium, Rheinheimera aquimaris QSI02, was found to exhibit anti-quorum sensing (anti-QS) activity. A subsequent bioassay-guided isolation protocol led to the detection of an active diketopiperazine factor, cyclo(Trp-Ser). Biosensor assay data showed that the minimum inhibitory concentration (MIC) of cyclo(Trp-Ser) ranged from 3.2 mg/m...