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[Effect of growth medium content on antagonistic characteristics of Bacillus pumilus].

AIM
To study the effect of growth medium content on antagonistic characteristics of "Pashkov" strain of B. pumilus.


MATERIALS AND METHODS
The following strains were used in the study: B. subtitlis 3H, B. subtitlis 534, B. subtitlis 1719, B. pumilus "Pashkov". Test strains from collection of Tarasevich State Institute for Standardization and Control of Medical Biological Preparations were used for determination of antagonistic activity. Growing of B. pumilus cultures on medium (No. 9, No. 5, VK-2, Spizeisen, and L-broth) was performed by periodic cultivation during 72 h in conditions of continuous aeration at 37 degrees C. Inhibiting effect of obtained samples was assessed on growth kinetics of test strains using microbiological analyzer with plan-table photometer "BIOSCREEN/iEMS--reader MF" (LabMetod, Finland).


RESULTS
Expressed antagonistic characteristics were revealed during cultivation on media No. 9 and No. 5 with maximal expression on day 3. Addition of lactose to medium No. 9 resulted in increase of bacteriostatic effect (BSE) against both individual strains and all test strains--up to 16% in average. Selection of optimal concentrations of different components allowed to develop a new growth medium which provides maximal antagonistic activity in studied strain of B. pumilus.


CONCLUSION
Effect of growth medium content on antagonistic characteristics against pathogenic and opportunistic bacteria was confirmed on the example of cultivation of spore-forming strain "Pashkov" of B. pumilus. Optimization of carbohydrate, salt and other components of growth medium allowed to increase up to 100% the BSE of "Pashkov" strain of B. pumilus against both individual and all test strains. This study opens perspectives for generation of compounds with directional probiotic effect.