Nutritional Requirements for Hydrogenase Production by Escherichia Coli

During studies on the metabolism of Escherichia coli (Texas), it was found that hydrogenase was either entirely absent or present in relatively small quantity in cells harvested from a glucose mineral salts medium. This observa-tion suggested a nutritional approach to the study of this enzyme, and the re-sults herein presented show clearly that the production of hydrogenase during the growth of E. coli is conditioned by the presence of certain amino acids. METHODS E. coli (Texas) was carried by serial transfer on a basal medium of the fol-lowing composition: 0.1 per cent KH2PO4, 0.07 per cent MgSO4-7H20, 0.1 per cent NaCl, 0.4 per cent (NH4)2HPO4, 0.05 per cent citric acid neutralized with 10 per cent NaOH, 0.00005 per cent FeCls, and 1 per cent glucose added asepti-cally. This medium was adjusted to pH 6 to 7 before sterilization. One ml of a 24-hour culture of E. coli was introduced as inoculum into 100 to 250 ml of the growth medium, and the cultures were incubated at 37 C for 21 hours. The cells were harvested by centrifugation, washed in distilled water,