Production of carotenoids by Arthrobacter arilaitensis strains isolated from smear-ripened cheeses

Arthrobacter arilaitensis is one of the major microorganisms responsible for the coloration of cheese surface, particularly in smear-ripened cheeses. This study investigated the occurrence of pigment synthesis among A. arilaitensis strains in several aspects covering (1) UV-Vis absorption spectra and HPLC chromatograms of pigment extracts, (2) diversity of pigment production among strains, (3) influence of light on the production of pigment, and (4) kinetic of pigment synthesis. Based on absorption spectra and HPLC analysis, the 14 A. arilaitensis strains studied could be divided into two groups depending on their ability to produce carotenoids, carotenoid-producing, and nonpigmented strains. The methanolic extracts prepared from eight carotenoid-producing strains contained at least four carotenoids represented mainly as polar molecules. The diversity of pigment concentrations among these strains was low, with carotenoids ranging from 0.40 to 0.76 mg L(-1) culture and specific productivities from 0.14 to 0.25 mg pigment per g dry biomass, under light condition. When cultivating these A. arilaitensis strains under darkness condition, carotenoid biosynthesis was lower within a 0.17-0.25 mg L(-1) range. The pigment production time curve of a representative colored A. arilaitensis strain displayed a sigmoid shape which paralleled cell growth, probably indicating a growth-associated pigmentation.