Influence of inoculum type, inorganic salt and nitrogen to carbon ratio on sclerotium formation and carotenoid production in surface culture of Penicillium sp. PT95

Abstract

This study examined the respective effect of inoculum type, inorganic salt and nitrogen to carbon ratio on sclerotium formation and carotenoid production in surface culture of Penicillium sp. PT95. Neither the spore inoculum nor the mycelial pellet inoculum could result in the formation of sclerotium on a modified CZAPEK agar medium after incubation of 28 days, whereas the inoculum in the form of sclerotium caused the formation of numerous orange, sand-shaped sclerotia after incubation of 14 days. Among four inorganic salts tested, K2HPO4 was more essential to the sclerotium formation and carotenoid production of strain PT95 as compared to KCl, MgSO4 or FeSO4. It was also shown that the combination of K2HPO4, KCl and MgSO4 could produce the best positive cooperation and give the highest sclerotia biomass (782 mg/plate) and carotenoid content in sclerotium (420 μg/g of dry sclerotia) as well as pigment yield (328 μg/plate). The medium containing 0.24∼0.48 g/1 sodium nitrate-nitrogen was effective to both the sclerotium formation and carotenoid production of strain PT95 when available maltose-carbon concentrations were at 5.26∼21.05 g/l. The optimal N:C ratio was found to be 1:25.