[Effect of different pH values on the medium on the synthesis of antibiotics in the joint cultivation of Actinomyces levoris with yeasts].

Changes in the pH level of the fermentation medium used for preliminary cultivation of C. tropicalis were studied with respect to its initial aciditv or alkalinitv. When C. tropicalis was grown on the medium used for levorin fermentation with ph 5.1--10.3, the yeast changed it in 24 hours to the level of 6.2--7.9. As dependent on the initial pH values for cultivation of C. trophicalis, production of levorin on subsequent inoculation of Act. levoris changed. The antibiotic activity increased and ranged within 120--178% of the control. Synthesis of levoristatin, a non-polyenic antibiotic equally increased under such conditions and ranged within 153--163% of the control. The pH values of 9.4--10.3 of the initial fermentation medium were optimal for mixed cultivation of Act levoris and C. tropicalis and maxium production of levorin and levoristatin.