engleski

Optimised screening of antibiotic producing strains

Since antibiotic production depends on microbial strain properties and culture conditions the effects of various culture conditions on expression of antibiotic production were studied in order to optimise the method of screening of antibiotic producing strains. To test reliability of applied screening methods Streptomyces rimosus R6-500 parental strain and its derivative strains of known properties were used applying different culture conditions designed according different fractional factorial plans. Antibiotic activities were assayed by measurement of growth inhibition zones of Bacillus cereus ATCC 11778 as test organism. Results of experiments were analysed statistically. Comparison of results of agar plate cultures with those of corresponding shaken flask cultures showed only a weak correlation between the different methodologies. Each strain showed an individual pattern of optimised antibiotic production under the conditions tested. An array of tests is therefore necessary to enhance chances for antibiotic production by strains with unknown properties. To perform different culture conditions the fractional factorial design for 8-16 combinations can be recommended if high numbers of microorganisms have to be screened for antibiotic production.

Screening of strains; antibiotics; method evaluation

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