Several cases of consumer complaints to the still soft beverages – fruit drinks and ice teas were analysed. The visible impurities and slight sensory changes were observed, sediment was formed by microbial cells. The bacteria were isolated and identified as <I>Asaia</I> sp. The identification was confirmed by PCR technique. The sensitivity of bacteria to preservative agents especially to the sodium benzoate, potassium sorbate and dimethyldicarbonate was evaluated in model samples and in the real conditions of the beverage. The minimal inhibitory concentrations were estimated as well as the factors affecting the sensitivity of bacteria. Besides the stabilisation of drinks the general possibilities of decay prevention were considered, the efficiency of cleaning and sanitation procedures were evaluated, including the comparison of various sanitation agents.

Sedláčková P., Horáčková Š., Shi T., Kosová M., Plocková M. (2015): Two different methods for screening of bile salt hydrolase activity in Lactobacillus strains. Czech J. Food Sci., 33: 13-18.Bile salt hydrolase (BSH) activity of intestinal bacteria (including lactobacilli) is one of the indirect ways of decreasing a cholesterol level in human body. Tested Lactobacillus strains were isolated from various sources (faeces of fully breast-fed infants, cow's colostrum, cow's raw milk cheeses, and cow's raw milk) and identified by genotypic and phenotypic methods. All strains, including three commercial probiotic strains and six culture collection strains, were subsequently tested for their BSH activity via two methods -thin layer chromatography (TLC) and plate assay. Among all the 59 Lactobacillus strains, 15 strains were shown to be BSH positive by TLC method and only 8 of them by plate assay. Most of the BSH positive strains (9 strains) were isolated from faeces. Differences between BSH activities for sodium salts of cholyltaurine and cholylglycine were demonstrated. The TLC method was shown to be more sensitive compared to the plate assay for BSH activity determination.

Horáčková Š., Sedláčková P., Sluková M., Plocková M. (2014): Influence of whey, whey component and malt on the growth and acids production of lactobacilli in milk. Czech J. Food Sci., 32: 526-531.The effect of whey powder, whey protein concentrate, caseinomacropeptide, and malt addition into milk on the growth and acid production of lactobacilli (Lactobacillus casei Lafti L-26, Lactobacillus acidophilus CCDM 151, and Lactobacillus casei CCDM 198) was evaluated. The ability of these strains to use different types of saccharides from milk and plant sources was also tested. Glucose, galactose, fructose and maltose were utilised by all tested strains. The results showed that the addition of malt positively affected the growth of lactobacilli strains compared to the growth in milk enriched by whey ingredients. The addition of malt increased significantly the production of d(-) isomer of lactic acid by Lactobacillus acidophilus CCDM 151 and Lactobacillus casei CCDM 198 and the production of acetic acid by Lactobacillus casei CCDM 198.

Sedláčková P., Čeřovský M., Horsáková I., Voldřich M. (2011): Cell surface characteristic of Asaia bogorensis -spoilage microorganism of bottled water. Czech J. Food Sci., 29: 457-461.The ability of bacteria to attach to a surface and develop a biofilm has been of considerable interest for many groups in the food industry. Biofilms may serve as a chronic source of microbial contamination and the research into biofilms and cells interactions might help to improve general understanding of the biofilm resistance mechanisms. Multitude of factors, including surface conditioning, surface charge and roughness and hydrophobicity, are thought to be involved in the initial attachment. Hydrophobic interactions have been widely suggested as responsible for much of the adherence of cells to surfaces. Cell-surface hydrophobicity is an important factor in the adherence and subsequent proliferation of microorganisms on solid surfaces and at interfaces. In the present study, we have estimated the cell-surface characteristics of Asaia bogorensis -isolated contamination of flavoured bottled water and compared its ability to colonise surfaces which are typical in the beverage production -stainless steel, glass and plastic materials.