Abstract
Recent work in this laboratory 1 has demonstrated the requirement by a strain of Cl. tetani for a component of liver extract originally described in another connection by Snell and Peterson 2 and subsequently studied by Stokstad. 3 This material, together with thiamine and riboflavine, fully accounted for the activity of a fraction of liver extract which had been found essential to the growth of our tetanus organism. The active component of Snell and Peterson's fraction has been further investigated by Mitchell, Snell and Williams. 4 who have carried the purification considerably further, and have named the agent “folic acid” since they find green leaves to be a convenient source. Its chemical constitution has not yet been determined.
Through the courtesy of Professor Williams it has been possible to test his purified material as to its growth-promoting effect on the tetanus bacillus. Three specimens, representing varying degrees of concentration have been made available. The amounts required to produce half maximum growth of L. helveticus were given as follows:
These preparations were used in varying quantities to replace the Snell and Peterson or Stokstad factor in an otherwise complete medium. 1 After seeding with our strain of Cl. tetani and anaerobic incubation for 24 hours, relative growths were determined in a photoelectric nephelometer. The results, expressing degree of growth approximately as percentage of maximum are shown in Table I.
It is evident that “folic acid” is essential to the growth of this strain of tetanus, and that its effect is exerted by extremely minute quantities.
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