AbstraktKunová G., Rada V., Lisová I., Ročková Š., Vlková E. (2011): In vitro fermentability of prebiotic oligosaccharides by lactobacilli. Czech J. Food Sci., 29 (Special Issue): S49-S54.Twelve strains of lactobacilli were tested for their growth and ability to utilise six prebiotics (pure substances and commercially available prebiotics) as a sole carbon source. All strains showed a considerable growth on all prebiotics tested. Inulin was the best carbohydrate source for lactobacilli, followed by lactulose and raffinose. A massive increase of viable cells on commercial prebiotic mixtures (Vivinal, Oligomate 55, and Orafti P95) was also observed. Lysozyme susceptibility was assayed in 13 strains of lactobacilli. Eight out of 13 strains were completely resistant to the lysozyme concentration of 400 µg/ml, in the rest of the strains a slight delay of the exponential phase of the growth curves was observed. Lactobacilli tolerated lysozyme well and were able to utilise all prebiotics.

Chramostová J., Mošnová R., Lisová I., Pešek E., Drbohlav J., Němečková I. (2014): Influence of cultivation conditions on the growth of Lactobacillus acidophilus, Bifidobacterium sp., and Streptococcus thermophiles, and on the production of organic acids in fermented milks. Czech J. Food Sci., 32: 422-429.The parameters influencing the formation of organic acids and the ratio between the optical isomers of lactic acid were evaluated. Five different factors were tested, namely the form of starter, inoculum, temperature of fermentation, time of fermentation, and enhanced non-fat dry matter or addition of whey protein concentrate. Out of them, optimal conditions were chosen for the preparation of fermented milk beverage with ABT culture (Lactobacillus acidophilus, Bifidobacterium sp., Streptococcus thermophilus) with a lowered content of d(-)-lactic acid. The inoculum of bifidobacteria had the only significant effect on the ratio between lactic acid isomers. When 1% v/w used, the ratio of d(-)-lactic acid to l(+)-lactic acid was 0.05. When 5% v/w used, the ratio was 0.02. The addition of dried skimmed milk (max. effect at 12% w/w) enhanced the growth of bifidobacteria, while whey protein concentrate was effective for the growth of lactobacilli. The optimal temperature and time of cultivation were 37°C and 17 ± 0.5 h, respectively.

In the current study, eight strains of bifidobacteria and seven strains of lactobacilli were tested for their ability to grow in the presence of rebaudioside A and steviol glycosides from the sweetener Natusweet M001 originating from herb Stevia rebaudiana (Bertoni). Stevia is gaining popularity as a natural, non-caloric sugar substitute, and recently, it was allowed as a food additive by European Union too. Utilisation of steviol glycosides by intestinal microbiota suggests that they might have potential prebiotic effect. Based on the evaluation of bacterial density and pH values in our in vitro study, it was found that lactobacilli and bifidobacteria tested were able to utilise steviol glycosides as a carbon source only to a very limited extent. All strains tested showed significantly lower change in the absorbance A540 (P < 0.05) and pH decrease of the growth media as compared with the positive controls (medium containing glucose as a carbon source and de Man Rogosa Sharpe broth). We concluded that a suggested prebiotic effect was not confirmed either in the case of rebaudioside A or in the case of the sweetener Natusweet M001 containing a mixture of steviol glycosides.

Lisová I., Horáčková Š., Kováčová R., Rada V., Plocková M. (2013): Emulsion encapsulation of Bifidobacterium animalis subsp. lactis Bb12 with the addition of lecithin. Czech J. Food Sci., 31: 270-274.The commercial probiotic strain Bifidobacterium animalis subsp. lactis Bb12 was encapsulated using emulsion encapsulation into milk protein matrix without and with the addition of 0.5% w/w lecithin into the oil. Different agitation speeds were used during the encapsulation process. The examination of microcapsules was carried out by optical microscope and fluorescence in situ hybridisation. The particle size distribution as volume based median d 0.5 was evaluated by the laser diffraction method. In the case of no lecithin addition, the agitation speed did not influence significantly the size of the microcapsules. The addition of 0.5% (w/w) of lecithin into the oil caused a decrease of d 0.5 value from 196 ± 37 µm to 79 ± 3 µm at an agitation speed of 500 rpm, and from 193 ± 24 µm to 39 ± 3 µm at 1200 rpm. It can improve the sensory properties of the products with the added microcapsules.