Abstract

COMPARATIVE ASSESSMENT OF ANTIBIOTIC PRODUCTION AND ACTIVITY BY BATCH CULTURES OF STREPTOMYCES SPECIES ISOLATED FROM SOIL UNDER SOLID-STATE AND SUBMERGED FERMENTATIONS

Ekong U. S.* and Ibezim E. C.

ABSTRACT

Antibiotic producing Streptomyces species were isolated by spread.- plating aliquots of tenfold serially diluted pre-treated soil samples on a chemically defined complex Streptomyces isolation medium, ISP1, by the crowded-plate method. The cultures were bioautographed against a sensitive Staphylococcus aureus (ATCC 25932); and nine bioactive strains (UY1- UY9) with outright antagonism, evident by clear zones of inhibition were selected and grown as pure cultures in ISP 1. Antibiotic production potential and activity by batch cultures of Streptomyces bioactive strains was comparatively assessed by solid-state (SSF) and submerged (SmF) fermentations procedures, for five days, in a chemically defined complex fermentation medium, ISP2. Fully grown and sporulated solid-state cultures were directly evaluated for antibiotic production and activity by the modified agar-block diffusion technique; while cells in the submerged cultures were harvested by centrifugation, processed into crude antibiotics filtrates for production and activity assay by the agar-well diffusion technique. The zones of inhibitory activity by the bioactive substances from the fermentation systems gave qualitative and quantitative measures of antibiotic titre and activity as relatively estimated from a chloramphenicol standard curve. The comparative sensitivity assay between the SSF and SmF systems with respect to the chloramphenicol standard, indicated significant (p<0.05) higher antibiotics production and activity in the SSF, than in the SmF; and also significant (p

Keywords: Comparative Assessment, Antibiotic Production and Activity Batch Cultures, Streptomyces Species, Solid-State and Submerged Fermentations.