SUMMARY: A mutant of was isolated which showed a requirement for methionine+lysine when a fairly large inoculum of washed organisms was used. Cystathionine or homocysteine replaced methionine, and diaminopimelic acid replaced lysine; no other amino acid or growth factor was active. The amounts of the amino acids required to promote growth were only about one-tenth of the quantity of methionine and lysine found in the grown organisms. A quantitative study with C-glucose and S-sulphate confirmed that these amino acids were synthesized . Although homoserine would not replace methionine for growth, the presence of unlabelled homoserine suppressed the incorporation of isotope from C-glucose into methionine and threonine, indicating that the accepted pathways are operative and that the block in methionine synthesis was in the formation of cystathionine. Small amounts of yeast extract replaced the amino acid requirement and decreased one-thousandfold the size of the inoculum required.


Article metrics loading...

Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error