The Differences between Chromobacterium violaceum Strains in Growth and Violet Pigment Production

Abbrar Hussein Labban, Tennessee State University


Chromobacterium violaceum is a gram-negative, facultative anaerobic, small rods or coccobacilli, free-living â-proteobacterium which found in soil and water of tropical and subtropical ecosystems. One of the significant characteristics of Chromobacterium violaceum is the ability to produce violet pigments known violacein and deoxyviolacein. It was reported that C. violaceum has the ability to grow under either aerobic or anaerobic conditions. However, violacein is produced only in the presence of oxygen. Many gram negative bacteria use Quorum sensing system to regulate many physiological functions such as virulence, toxin, pigment production, and luminescence. Quorum sensing is a cell-cell signaling and a communication mechanism between bacterial cells. C. violaceum produces the signaling molecule N-acylhomoserine which is used to control population density and bioluminescence through quorum sensing. The major objective of this work reported here was to determine if the violet pigment production accompanied with bacterial growth in three different strains of C. violaceum, CV 14N23 and CV 14N1, isolated from Copper Basin, Tennessee and ATCC 12472, obtained from ATCC. The bacterial growth of ATCC 12472 and CV14N23 strains were measured for 20 hours by using CFU Drop Counting method. Violet Pigment production of the two strains were also measured every hour for 20 hours using spectrophotometer at 575 nm. CV14N1 strain was not able to produce violet pigment in LB broth media and we expect that CV 14N1 needs a high amount of the inoculation to increase the initial cell density to produce the pigment in liquid culture. CV14N23 has not only a rapid ability to produce violet pigment but also to reach the death phase than ATCC 12472. The violet pigment production was obviously not accompanied with the increase of bacterial growth. The greater violet pigment production of ATCC 12472 occurred during the stationary phase as well as in CV14N23, where the bacterial growth is stable. This illustrates that the violet pigment production of the two strains is more related to increased stress on cell growth. Moreover, the violet pigment production of CV14N23 is increased while the bacterial cells undergo the death phase. This demonstrates the violet pigment production is more closely associated with the death cells.

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Recommended Citation

Abbrar Hussein Labban, "The Differences between Chromobacterium violaceum Strains in Growth and Violet Pigment Production" (2015). ETD Collection for Tennessee State University. Paper AAI1592026.