365 1 Filamentous fungi, as well as other microorgan isms, synthesize structurally diverse, biologically active compounds. Formation of secondary metabo lites by producers is controlled by the regulatory mechanisms affected by changing environmental con ditions. Since the conditions favorable for the maxi mum rate of a producer do not necessarily favor the synthesis of secondary metabolites, a balance between the growth rates and the maximum product yield is required [1,2]. In the production of antibiotics, this problem is solved by using two stage processes. The conditions for rapid vegetative growth and for efficient product formation are created at the first and second stage of cultivation, respectively (the tropho and idiophasic kinetics). Growth of the overwhelming majority of fungal producer strains of the genus Peni cillium in a synthetic medium with mannitol, succinic acid, mineral salts, and ammonium nitrogen (optimal for secondary metabolite synthesis) was accompanied by the synthesis of nitrogen containing compounds [3]. It is known that the genes involved in the synthesis of secondary metabolites are clustered, and these clus ters are controlled by transcription regulators (DNA bound proteins) having either specific effects on the genes within the cluster or on the genes of the com mon metabolic pathways [4]. Secondary metabolite biosynthesis involves multifunctional enzyme com plexes: a polyketide synthase, a nonribosomal peptide synthetase, and their hybrid [5]. Expression of the genes of secondary metabolism depends on the medium composition, cultivation conditions, meta bolic products, and trace elements. During the culti 1 Corresponding author; e mail: kozlovski@ibpm.pushchino.ru vation of producers, production of the bioactive com pounds is sometimes substantially enhanced by opti mizing the physical (temperature, pH, aeration) and chemical factors (medium components, precursors, inducers, etc.) [6].Penicillium citrinum VKM F 4043 D isolated from ancient permafrost deposits forms two classes of bio logically active compounds: clavine ergot alkaloids (EA) (epoxyagroclavine I and agroclavine I) and quinoline alkaloids, quinocitrinines (QC) [7,8].The goal of this work was to study the effects of cul tivation temperature, pO 2 , and the concentrations of NaCl and the carbon substrate (mannitol) on the for mation of secondary metabolites by P. citrinum VKM F 4043 D.
MATERIALS AND METHODSThe fungus P. citrinum VKM F 4043 D used in the work was provided by the All Russian Collection of Microorganisms, the Institute of Biochemistry and Physiology of Microorganisms of the Russian Acad emy of Sciences (VKM). The effects of growth tem perature (20, 24, and 28°C) and dissolved oxygen con centration (pO 2 10, 20, 40, and 80% of air saturation at 24°C) were studied during the cultivation of the fun gus in a 10 L ANKUM 2M fermenter (Biopribor, Russia) with a 6 L working volume. Constant temper ature and the pH changes were recorded automati cally. The pO 2 values were regulated by rotational velocity of the st...