The influence of cultural conditions on the production of diphtheria toxin / A.F. Watson and Elsie Langstaff.

  • Watson, A. F.
Date:
[1927?]
Catalogue details

Licence: In copyright

Credit: The influence of cultural conditions on the production of diphtheria toxin / A.F. Watson and Elsie Langstaff. Source: Wellcome Collection.

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    Table II. shows the classification of results from eight typical preparations of filtered digest medium made by method 2. Similar records have been obtained from nearly two hundred batches of medium representing the analysis of results from about four thousand individual filtrates. These records have indicated the relative importance of several factors involved in routine production of toxin. (i) From horizontal readings, the influence of sowing a medium at different times is shown. Change of inoculum and slight temperature differences during growth would seem to have little effect. The definite gradation in value from higher to lower obtained with many batches would point to some deterioration of medium after storage over the period tested (not exceeding 6 weeks). (ii) From vertical readings, comparisons between batches of media made from the same consignment of muscle on different days, also between batches of media prepared from different consignments of muscle, are possible. Although the technique was never consciously changed, the value of media made at different times from the same muscle batch varied. This may of course be due to bacterial interference during digestion rather than to the personal factor. The differences between meat batches are also emphasised and shown more markedly in chart I. (iii) From diagonal readings, we may see differences in media sown at the same time, every condition possible being the same for each batch, so that here the relative values of the media may be compared. Consecutive sowings show little variation in this relative order and these combined give a definite index to the value of the media. Table II. Method of control. Classification ofi results for eight batches ofi media {method 2) sown in sub-batches on different occasions. Harvesting date of “ A ” sub-batch. Average Lf value per c.c. of filtrates. Sub-batches. Sowing date of “A sub-batch. Medium number. Muscle batch. Trypsin batch. Total N.mgrms. per 10 c.c. Amino N.mgrms. per 10 c.c. A. B. C. D. F. 12.10.25 is 14 12 8 2.10 25 46 77 94 25-5 6*3 12.10.25 8 4 4 2 . • • 2.10.25 47 77 94 24-1 5-0 19.10.25 5 5 4 2 2 9.10.25 48 78 94 21*1 4-3 19.10.25 11 12 11 ... . . . 9.10.25 49 78 94 25-3 6-3 26.10.25 12 10 8 8 • • • 16.10.25 50 79 94 19-3 6-0 26.10.25 12 15 7 ... 16.10.25 51 79 94 24*6 6-5 2.11.25 18 16 15 15 ... 23.10.25 52 80 94 19-1 4*7 2.11.25 20 ... 14 14 ... 23.10.25 53 1 80 94 26*5 7-1