Chemotaxis in thermophilic bacterium PS-3

Abstract

Depositing the thermophilic bacterium PS-3 on semi-solid agar plate containing rich medium, several chemotactic rings were formed as in the cases of Escherichia coli and Salmonella typhimurium, indicating that the bacterium is chemotactic. The cells were attracted to L-amino acids: L-alanine, tryptophan, L-aspartate, and glutamate; and to sugars: D-glucose, maltose, D-fructose, and sucrose. In order to find out some sort of methylatable proteins were present, which has been proven to be important in the case of Escherichia coli, the PS-3 cells were labeled with radioactive methionine under conditions in which the protein synthesis had been inhibited. The results showed that the cells contained methylatable proteins of 60,000 to 88,000 daltons. The banding pattern of these methylated proteins was very similar to that of Escherichia coli when the proteins were analyzed by SDS-polyacrylamide gel electrophoresis. In addition, the methyl groups attached onto the proteins were alkaline labile, indicating that the site of methylation was on carboxyl group. The methylation and demethylation reactions of these proteins were affected by the presence of attractants.