Influence of Amino Acids, Carboxylic Acids and Sugars on the Growth of Methylococcus capsulatus on Methane

SUMMARY The influence of 3 types of compounds (L‐amino acids, carboxylic acids and sugars) on the growth of Methylococcus capsulatus in Petri dishes was investigated. Increase in colony diameter was used as the growth parameter. L‐amino acids and carboxylic acids which are normal metabolic intermediates prevented growth in low concentrations. Threonine, leucine, histidine and glycine were especially inhibitory; c. 0.01% was sufficient to suppress growth completely. Glutamic acid at 0.1 % concentration completely suppressed growth but at 0.005% markedly stimulated growth; similar effects were shown by lysine, methionine, glutamic acid, tryptophane, tyrosine, proline and citric acid. Among the sugars, glucose was the most potent growth inhibitor; maltose and sucrose had practically no effect.