High-level production of violacein by the newly isolated Duganella violaceinigra str. NI28 and its impact on Staphylococcus aureus

Abstract

A violacein-producing bacterial strain was isolated and identified as a relative of Duganella violaceinigra YIM 31327 based upon phylogenetic analyses using the 16S rRNA, gyrB and vioA gene sequences and a fatty acid methyl ester (FAME) analysis. This new strain was designated D. violaceinigra str. NI28. Although these two strains appear related based upon these analyses, the new isolate was phenotypically different from the type strain as it grew 25% faster on nutrient media and produced 45-fold more violacein. When compared with several other violacein producing strains, including Janthinobacterium lividum, D. violaceinigra str. NI28 was the best violacein producer. For instance, the crude violacein yield with D. violaceinigra str. NI28 was 6.0 mg/OD at 24 hours, a value that was more than two-fold higher than all the other strains. Finally, the antibacterial activity of D. violaceinigra str. NI28 crude violacein was assayed using several multidrug resistant Staphylococcus aureus. Addition of 30 μM crude violacein led to a 96% loss in the initial S. aureus population while the minimum inhibitory concentration was 1.8 μM. Consequently, this novel isolate represents a phenotypic variant of D. violaceinigra capable of producing much greater quantities of crude violacein, an antibiotic effective against multidrug resistant S. aureus.

Chromobacterium violaceum delivers violacein, a hydrophobic antibiotic, to other microbes in membrane vesicles

“…Figure A shows the growth of C. violaceum ATCC 12742 and that this bacterium rapidly produces violacein immediately after entering the stationary phase, with a maximum concentration of around 5 mg/l. This concentration is similar with the minimum inhibitory concentrations reported for strains of S. aureus by several different groups (Subramaniam et al ., ; Choi et al ., ) and, thus, we were curious if C. violaceum ATCC 12742 could inhibit or kill S. aureus when cultured together.…”

1114 - Combined application of bacterial predation and violacein to kill polymicrobial pathogenic communities

“…Violacein was extracted from cultures of Pseudoduganella violaceinigra sp. NI28 as described previously 18 . After dissolving the violacein in ethanol, the solution was filtered using a 0.22um syringe filter (Millipore, USA) and the ethanol was evaporated (EYELA N1110, Tokyo Rikakikai Co., Japan).…”

“…To determine the antibiotic resistant nature of the bacterial strains, we used the same protocol as described previously 18 . Strain resistance was determined using the latest breakpoint tables available at the European Committee on Antimicrobial Susceptibility Testing (EUCAST) website (http:// www.eucast.org/clinical_breakpoints/).…”

Advances in Chromobacterium violaceum and properties of violacein-Its main secondary metabolite: A review

“…Violacein showed growth-inhibitory activity against Gram-positive bacteria but not against Gramnegative bacteria and fungi. Different Duganella violaceinigra from Forest soil were isolated and characterized and showed excellent productivity of violacein (Li et al, 2004, Choi et al, 2015b. Ahmad et al (2012) isolated C. violaceum from various plant waste sources, such as bagasse, fruit waste, molasses, and others, as an alternative to the rich medium normally used.…”