Production of violet pigment by a newly isolated psychrotrophic bacterium from a glacier in Xinjiang, China

A psychrotrophic XT1 strain (CGMCC 1194) isolated from a glacier in China's Xinjiang province produced violet pigments at a high content. This strain was identified as Janthinobacterium lividum XT1 by API kit and 16S rDNA analysis. The main fraction of violet pigment was violacein based on the analysis by HPLC-MS and 1H NMR. The pigment production by J. lividum XT1 was not associated with the cell growth, and a cultivation temperature lower than 20 °C was required for the cell growth and pigment production. Sucrose was the most suitable carbon source, and casein was the best nitrogen source for cell growth and pigment formation. Mineral components in the medium, including CaNO3, FeSO4, riboflavin, MgSO4 and nicotinic acid, showed different effects on the cell growth and pigment production. The maximum pigment productivity reached 0.8 g pigment per dry cell weight. The pigment production pattern by our isolate was different from that by other strains such as J. lividum reported so far.