ABSTRACT
Avoiding food-borne diseases by competitive exclusion agents is a proactive strategy. In the current paper, we report the use of Bacillus smithii TBMI12 spores as potential competitive exclusion agents. One group of mice was predosed for three successive days with 10(8) colony forming units of B. smithii TBMI12 spores followed by inoculation with 10(6) colony forming units of wild-type Salmonella enterica serotype Enteritidis cells. Microbial plate counts of the animals' livers and spleens showed that only 40% of the mice were infected with S. enterica serotype Enteritidis, while the control group was 100% infected. These results suggest that B. smithii TBMI12 spores may protect against infection by S. enterica serotype Enteritidis.
Subject(s)
Bacillus/physiology , Foodborne Diseases/prevention & control , Probiotics/administration & dosage , Protective Agents/administration & dosage , Salmonella Infections/prevention & control , Salmonella enteritidis/physiology , Spores, Bacterial/growth & development , Animals , Disease Models, Animal , Female , Foodborne Diseases/drug therapy , Foodborne Diseases/microbiology , Gastrointestinal Tract/microbiology , Humans , Male , Mice , Mice, Inbred BALB C , Salmonella Infections/drug therapy , Salmonella Infections/microbiologyABSTRACT
The increasing use of commercial multitest systems for identification of environmental bacteria creates the problem of how to compare the identification results obtained from different systems. The limited use of species designations in such comparisons is caused by low usage of environmental bacteria in the development of commercial identification schemes. Two multivariate statistical methods, the Mantel's test and the co-inertia analysis, were applied to analyze data derived from the Biolog GN and the API 20NE systems of identification for 50 environmental bacterial strains. We found these two methods to be useful for revealing the relationship between the two sets of numerical taxonomic traits. Both of these methods showed that the distances according to the Biolog GN results between the studied strains were related to those derived from the API 20NE results, despite the differences in the test sets of the two systems. In addition, the co-inertia analysis allowed us to visualise the relationships between classifications of strains derived from the two identification systems and, simultaneously, to estimate the contribution of particular tests to the differentiation of bacterial strains.
Subject(s)
Bacterial Typing Techniques , Gram-Negative Bacteria/classification , Gram-Negative Bacteria/isolation & purification , Water Microbiology , Biodegradation, Environmental , Multivariate Analysis , Phenol/metabolismABSTRACT
Horizontal transfer of genes of selective value in an environment 6 years after their introduction into a watershed has been observed. Expression of the gene pheA, which encodes phenol monooxygenase and is linked to the pheBA operon (A. Nurk, L. Kasak, and M. Kivisaar, Gene 102:13-18, 1991), allows pseudomonads to use phenol as a growth substrate. Pseudomonas putida strains carrying this operon on a plasmid were used for bioremediation after an accidental fire in the Estonia oil shale mine in Estonia in 1988. The water samples used for studying the fate of the genes introduced were collected in 1994. The same gene cluster was also detected in Pseudomonas strains isolated from water samples of a nearby watershed which has been continuously polluted with phenols due to oil shale industry leachate. Together with the more frequently existing counterparts of the dmp genes (V. Shingler, J. Powlowski, and U. Marklund, J. Bacteriol. 174:711-724, 1992), the pheA gene was also represented in the phenol-degrading strains. The area where the strains containing the pheA gene were found was restricted to the regular route of phenolic leachate to the Baltic Sea. Nine Pseudomonas strains belonging to four different species (P. corrugata, P. fragi, P. stutzeri, and P. fluorescens biotypes B, C, and F) and harboring horizontally transferred pheBA operons were investigated. The phe genes were clustered in the same manner in these nine phe operons and were connected to the same promoter as in the case of the original pheBA operon. One 10.6-kb plasmid carrying a pheBA gene cluster was sequenced, and the structure of the rearranged pheBA operon was described. This data indicates that introduced genetic material could, if it encodes a beneficial capability, enrich the natural genetic variety for biodegradation.
Subject(s)
Operon , Phenol/metabolism , Pseudomonas/genetics , Pseudomonas/metabolism , Water Pollutants, Chemical/metabolism , Base Sequence , Biodegradation, Environmental , DNA, Bacterial/genetics , Estonia , Gene Transfer, Horizontal , Genes, Bacterial , Mixed Function Oxygenases/genetics , Mixed Function Oxygenases/metabolism , Molecular Sequence Data , Plasmids/genetics , Pseudomonas/isolation & purification , Pseudomonas putida/genetics , Pseudomonas putida/metabolism , Restriction Mapping , Water MicrobiologyABSTRACT
The activity of alcohol oxidase (AO) in the cells of Candida boidinii, in actively growing cultures, depends on the stage of the cell cycle. The minimal activity of AO was found in young cells produced by budding and in cells in the process of budding. The maximal activity of AO was detected in the fraction of cells of a medium size. The activity of AO decreased abruptly when the cells proceeded to budding. The activity of catalase depended on the stage of the cell cycle only to a minor extent.
