Bacillus Cereus Strains (bacillus + cereus_strain)

Distribution by Scientific Domains


Selected Abstracts


Impact of different pasteurization temperatures on the survival of microbial contaminants isolated from pasteurized milk

INTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 2 2005
PHOLISA DUMALISILE
The thermal inactivation of selected microbes was studied using the low temperature long time (LTLT), high temperature short time (HTST) and ,pot' pasteurization methods. Survivors were enumerated after heating for up to 40 min for the LTLT and HTST pasteurization methods and after heating for up to 30 min for the ,pot' pasteurization method. With the exception of the Bacillus cereus strain, the selected microbes did not survive the LTLT and HTST pasteurization methods. The results from the ,pot' pasteurizer showed that B. cereus, Chryseobacterium meningosepticum, Pseudomonas putida, Acinetobacter baumannii and Escherichia coli strains survived the pasteurization conditions applied, showing that the ,pot' pasteurizer does not pasteurize effectively. [source]


Distribution of S-layers on the surface of Bacillus cereus strains: phylogenetic origin and ecological pressure

ENVIRONMENTAL MICROBIOLOGY, Issue 8 2001
Tâm Mignot
Bacillus anthracis, Bacillus cereus and Bacillus thuringiensis have been described as members of the Bacillus cereus group but are, in fact, one species. B. anthracis is a mammal pathogen, B. thuringiensis an entomopathogen and B. cereus a ubiquitous soil bacterium and an occasional human pathogen. In two clinical isolates of B. cereus, in some B. thuringiensis strains and in B. anthracis, an S-layer has been described. We investigated how the S-layer is distributed in B. cereus, and whether phylogeny or ecology could explain its presence on the surface of some but not all strains. We first developed a simple biochemical assay to test for the presence of the S-layer. We then used the assay with 51 strains of known genetic relationship: 26 genetically diverse B. cereus and 25 non- B. anthracis of the B. anthracis cluster. When present, the genetic organization of the S-layer locus was analysed further. It was identical in B. cereus and B. anthracis. Nineteen strains harboured an S-layer, 16 of which belonged to the B. anthracis cluster. All 19 were B. cereus clinical isolates or B. thuringiensis, except for one soil and one dairy strain. These findings suggest a common phylogenetic origin for the S-layer at the surface of B. cereus strains and, presumably, ecological pressure on its maintenance. [source]


An assay system for the detection of phospholipase C activity

EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 10 2003
Markus Durban
Abstract Phospholipase C (PLC, EC 3.1.4.3) enzymes specifically hydrolyze the C-O-P-bond in phospholipids, yielding sn -1, 2(2, 3)-diglycerides and a phosphate residue bearing the corresponding head group. Biochemical characterization of PLC requires methods for determination of activity. During characterization and purification, proteins are separated by polyacrylamide gel electrophoresis (PAGE). For direct identification and visualization of PLC, a new assay for activity staining in native and renatured SDS-PAGE is described. Incubation of a gel containing an active PLC in the presence of ,-naphthylphosphorylcholine leads to ,-naphthol formation. This reacts with the diazonium salt Fast Red, forming a red dye which allows clear determination of PLC purity, molecular weight and substrate specificity. The assay was verified using commercially available PC-PLC and new PC-PLC-producing Bacillus cereus strains. The substrate ,-NPC was prepared by chemical synthesis at an overall yield of 12%. [source]


Characterization of spore appendages from Bacillus cereus strains

JOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2001
T. Stalheim
Aims:,Further characterization and comparison of spore appendages from Bacillus cereus strains. Methods and Results:,Appendages were isolated from 10 B. cereus strains from the food industry and food-borne outbreaks. The appendage proteins were dissolved in sample buffer containing 2% SDS and 5% mercaptoethanol at 100°C, and subjected to SDS-PAGE. None of the appendages showed identical protein patterns. Western blots, using antibodies raised against a 3·5 kDa appendage protein, showed that the majority of the appendage proteins reacted with the antibody. Removal of the appendages by sonic treatment of the spores did not alter their heat resistance. The appendages were digested by proteinase K, pepsin, and the enzymes in the detergent Paradigm 10, but not by trypsin or chymotrypsin. Spore adhesion to stainless steel was scarcely affected by removal of the appendages. Digestion of adhered intact spores (with appendages) with Paradigm 10 showed a high degree of variation. Conclusions:,Spore appendages from B. cereus are complex proteinaceous structures that differ among strains. Significance and Impact of the Study:,Information about spore appendages and their involvement in spore adhesion is crucial for improving cleaning methods used for control of bacterial spores in the food industry. [source]