Chitin in a dual role as substrate for Streptomyces griseus and as adsorbent for streptomycin produced during fermentation

Abstract

Streptomycin production from chitin by Streptomyces griseus was compared using two different types of bioreactor. The first was equipped with a combined U-shaped paddle and Rushton impeller. Also employed was a bioreactor of novel design in which the chitin was contained in a wire mesh basket that was totally submerged in a liquid salts medium. During operation the chitin was gently fluidised by air admitted into the basket. Fermentation was continued in both bioreactors until maximum antibiotic titres were achieved whereupon operation was interrupted to allow the streptomycin adsorbed to the chitin substrate to be extracted into pH 3.0 buffer before continuing fermentation of the same batch of chitin a second time. At a chitin concentration of 10 % (w/v) the highest streptomycin yields (c. 5.5 mg/L) were obtained using the stirred bioreactor, however growth occurred more rapidly in the vertical basket bioreactor.