Growth and product formation of actinomycetes cultivated at increased total pressure and oxygen partial pressure

Summary

Influence of pressure (P) and oxygen partial pressure ($P_{O_2 }$) on cultivation of various Streptomyces spp. and Micromonospora purpurea was examined in pressurized air-lift and stirred tank fermenters. The maximum $P_{O_2 }$ was 2100 mbar. Growth and product formation of all cultures tested were markedly influenced by $P_{O_2 }$ higher than 1000 mbar. There is evidence that wild strains are more oxygen tolerant than production strains. At a certain $P_{O_2 }$ the metabolic activities of all cultures were inhibited. However, results obtained with S. aureofaciens and S. rimosus indicated an increase in specific product formation rate at elevated pressure. With increase in oxygen tension incorporation of oxygen into tetracycline molecules was enhanced. Since elevated oxygen tension can either show inhibiting effects or may be used for regulation of product formation and selectivity, the influence of $P_{O_2 }$ should be determined in an appropriate experimental set-up for each process.