Aims: To evaluate the probiotic properties of strains isolated from boza, a traditional beverage produced from cereals.Methods and results: The strains survived low pH conditions (pH 3.0), grew well at pH 9.0 and were not inhibited by the presence of 0.3% (w/v) oxbile. Cytotoxicity levels of the bacteriocins, expressed as CC50, ranged from 38 to 3776 mu g ml(-1). Bacteriocin bacST284BZ revealed high activity (EC50 = 735 mu g ml(-1)) against herpes simplex virus type 1. Growth of Mycobacterium tuberculosis was 69% repressed after 5 days in the presence of bacST194BZ. Various levels of auto-cell aggregation and co-aggregation with Listeria innocua LMG 13568 were observed. Adhesion of the probiotic strains to HT-29 cells ranged from 18 to 22%.Conclusions: Boza is a rich source of probiotic lactic acid bacteria. All strains survived conditions simulating the gastrointestinal tract and produced bacteriocins active against a number of pathogens. Adherence to HT-29 and Caco-2 cells was within the range reported for Lactobacillus rhamnosus GG, a well-known probiotic. In addition, the high hydrophobicity readings recorded define the strains as good probiotics.Significance and Impact of the Study: Boza contains a number of different probiotic lactic acid bacteria and could be marketed as a functional food product.

This study compared selected probiotic properties of 9 strains of the Lactobacillus acidophilus group (6 L. acidophilus and 3 L. johnsonii) and 9 strains of the L. casei group, isolated from probiotic dairy products sold on the German market or supplied by a producer of starter cultures. Using an in vitro system simulating gastric transit, strains of the L. acidophilus group were more tolerant to the low pH 2.0 than strains of L. paracasei and L. rhamnosus which rapidly lost their viability after exposure to the simulated gastric juice containing pepsin. Milk showed a protective effect on strains less resistant to the gastric acidity. Bile salt hydrolase activity was detected in all strains of L. acidophilus/L. johnsonii but not in strains of the L. casei group. All lactobacilli were able to adhere to mucus secreting HT29 MTX cells and to human collagen type IV, fibrinogen and fibronectin although differences in the percentage of adhering bacteria were observed between different strains.

Das in Plfanzen vorkommende Flavonol Quercetin und die zu den Triazinen gehörenden Herbizide Atrazin, Cyanazin und Gesamprim® wurden einzeln und in Kombination miteinander auf genotoxische Wirkungen untersucht. Es wurden die Induktion von Schwesterchromatidaustauschen (SCE-Test) und von Mutationen zur 6-Thioguaninresistenz (HPRT-Test) an Ovarzellen des Chinesischen Hamsters (CHO-Zellen) bestimmt. Während sich in SCE-Test keine Hinweise auf genotoxische Wirkungen ergaben, verursachten die Prüfsubstanzen im HPRT-Test nach metabolischer Aktivierung durch zugesetzte subzelluläre Enzympräparate der Rattenleber (S9-Mix) leicht erhöhte Mutationsraten. Die Kombinationen von zwei oder drei Prüfsubstanzen verursachten keine deutliche Zunahme der genotoxischen Wirkung.

The well known and previously widespread insecticide lindane has been re-assessed for DNA-damaging activity. A first group of investigations using standard in vitro and in vivo mutagenicity assays did not indicate any genotoxic effects of lindane at all. The assay systems used were for the induction of HPRT mutations and sister chromatid exchanges in CHO cells cultured in vitro, and for micronuclei induction in vivo in bone marrow cells of rats, hamsters and mice. Also, lindane was assessed for its potential to induce sister chromatid exchanges in vivo in the bone marrow of Chinese hamsters. These specific assay systems had not been used previously for elucidating the genotoxic effects of this compound, but they are basically similar to other standard mutagenicity assays in which lindane has been shown to be devoid of genotoxic activity. The second part of the investigations was directed at re-evaluating a previously reported positive effect of the compound in primary rat hepatocytes in vitro. We performed in vitro and in vivo studies with hepatocytes from the rat liver and used alkaline elution to detect DNA damage. However, we could not demonstrate that lindane induced genotoxicity, unless considerable concomitant cytotoxicity was apparent as well. Finally, since lindane can be ingested and inhaled by humans, we also measured the induction of DNA damage in local target organs of absorption using single cell microgelelectrophoresis (the comet assay). In these cases lindane was genotoxic in cells of the gastric and nasal mucosa in vitro and also in vivo following appropriate routes of application (oral and inhalational exposure).

The plant flavonol quercetin and the triazine herbicides atrazine, cyanazine, and gesamprim were examined individually and in combination for the induction of genotoxic effects. The sister chromatid exchange (SCE) assay and the gene mutation assay for 6-thioguanine resistance (HPRT) were carried out with Chinese hamster ovary (CHO) cells. Whereas no evidence of an increased SCE rate was found, the test substances caused a slightly increased mutation rate in the HPRT assay after metabolic activation with a subcellular liver enzyme preparation. Combination studies with two or three of the test substances did not result in higher mutation rates than those observed for the individual compounds tested singly.

Potassium sorbate and sodium sorbate were investigated for possible genotoxic actions using the Salmonella/mammalian-microsome test, HGPRT and sister chromatid exchange (SCE) test with Chinese hamster ovary cells, the micronucleus test on bone marrow cells of mice and Chinese hamsters, and the chromosome aberration and SCE test on Chinese hamsters. In all the in vitro tests no signs of genotoxicity were detected. Whereas no in vivo mutagenicity of potassium sorbate and sodium sorbate with freshly prepared aqueous solutions and with stored potassium sorbate was found, investigations with stored sodium sorbate revealed weak clastogenic activity by increased chromosome aberrations and elevated numbers of micronuclei at doses of 200 mg/kg body weight, but no induction of SCEs.