Expression of carotenoid pigments of haloarchaeal cultures exposed to aniline

Abstract

The effects of exposure to aniline on growth and pigmentation in three haloarchaeal isolates from the Indian subcontinent - GUSF (MTCC 3265), from the estuarine saltpans of Goa, India; and GURFT-1 and GURFP-1, both from continental shelf sediments of the west coast of India-were studied. In nutrient-rich tryptone yeast extract medium containing 25 percent NaCl/crude salt, the growth of GUSF, measured as absorbance at 600 nm, was not affected significantly at all concentrations of aniline used [0.005 percent-0.04 percent (v/v)], whereas the growth phases of GURFT-1 and GURFP-1 were affected at concentrations greater than 0.005 percent; the total yield, however, was nearly equal to the yield of cultures growing in the absence of aniline. GURFT-1 reached approximately 40 percent of total yield on the 7th day in the presence of 0.04 percent aniline, which declined thereafter. The pigmentation observed visually was completely abolished at concentrations of aniline greater than 0.01 percent. Spectral scans of acetone extracts of the pigment of each of the cultures exposed to concentrations of aniline greater than 0.01 percent showed that (i) the bacterioruberin component of the pigments (absorbance in the range 390-500 nm) was completely abolished and (ii) the pigment component(s) shifted toward squalene and phytofluene derivatives (320-360 nm). This is the first report examining the effect of an aromatic pollutant such as aniline on the growth and pigmentation of haloarchaeal cultures.