Respiratory Activity and Biosynthesis of Alkaloids by the Fungus Penicillium citrinum Thom

The fungus Penicillium citrinum VKM F-4043D isolated from ancient permafrost deposits in the Arctic is an active producer of quinoline alkaloids (quinocitrinines A and B) and clavine ergot alkaloids (agroclavine-I and epoxyagroclavine-I). The dynamics of respiratory activity was studied during fungal growth in a medium with two non-fermentable substrates: succinate and mannitol. Oxygen consumption by cells was shown to be associated with the dynamics of two-phase synthesis of biomass and alkaloids; the maximum respiratory activity coincided with the maximum rates of alkaloid synthesis and biomass accumulation. As shown by inhibitory analysis of fungal respiration, along with the main, cytochrome, respiratory chain, an alternative, cyanide-resistant, electron transfer pathway functions, which is suppressed by benzhydroxamic acid. It has been shown that the fungus P. citrinum is capable of growing in the presence of antimycin A, an inhibitor of electron transfer in the cytochrome region of the respiratory chain. In this case, the alternative oxidase functions as the only terminal oxidase capable of providing fungal growth and alkaloid biosynthesis. When glucose was used as a growth substrate, biosynthesis of both alkaloids and cyanide-resistant oxidase was not observed.