Хранителна химия, микробиология, биотехнология и безопасност

Секция „Хранителна химия и хранителна микробиология”

A selective medium for the enumeration and differentiation of Lactobacillus delbrueckii ssp. bulgaricus
Селективна среда за изброяване и диференциране на Lactobacillus delbrueckii ssp. Bulgaricus
Lactobacillus delbrueckii subsp. bulgaricus is an important species of lactic acid bacteria used as a starter culture in the production of yogurt and some cheeses. Given the importance of this strain in dairy industry, it is necessary to have an efficient medium to be able to study this bacterium and isolate new strains. DeMan Rogosa and Sharpe (MRS) has been used for decades to enumerate lactic acid bacteria. However, the viability of lactic acid bacteria is restricted in MRS because of rapid nutrient depletion. In this study, we have developed Modified Reinforced Clostridial Medium Blue (mRCM-BLUE) based on specific nutritional and biochemical requirements of L. bulgaricus; in order to meet industry need for a more superior growth medium for the bacteria. Two strains of L. bulgaricus and three species of probiotic bacteria were used for the present study. MRS, Reinforced Clostridial Medium (RCM) and Lactic Agar (LA) media were prepared according to manufacturers’ instructions. mRCM-BLUE was developed by supplementing RCM with 0.025% CaCl2 , 0.2% Tween 80, 0.01% uracil and 0.01% aniline blue dye. Bacterial growth rate on the different media was monitored for 12 h at 42°C. Bacterial cells from pure strains and mixed cultures were enumerated using the cell count method. Colonies of L. bulgaricus that appeared on the different media plates were observed and compared based on colony morphology and appearance. Our results demonstrated that mRCM-BLUE (RCM supplemented with CaCl2, uracil, Tween 80 and aniline blue dye) significantly (P < 0.5) enhanced the growth and differentiate L. bulgaricus compared to MRS, LA and RCM in mixed lactic acid bacterial cultures. Therefore, mRCM-BLUE can be used in dairy industry to rapidly grow and isolate L. bulgaricus strains from natural sources to meet the high demand of this bacteria. mRCM-BLUE may also be used microbiologically for the analyses of new strains of L. bulgaricus.
Автори: Nwadiuto Nwamaioha, Rabin Gyawali, Tahl Zimmerman, Salam A. Ibrahim

Секция „Хранителни биотехнологии и нанотехнологии”

Секция „Анализ и контрол на хранителните продукти”

Секция „Безопасност на храните”