Mar., 1921
T H E JOURLVAL O F I X D U S T R I A L A N D ELVGIATEERING C H E M I S T R Y
I
265
NOTES AND CORRESPONDENCE THE ACTION OF ULTRAVIOLET RAYS ON THE SACCHAROMYCETES
Editor of the Journal of Industrial and Engineering Chemistry: I n THISJOURNAL, 12 (1920). 740, Messrs. Feuer and Tanner state that when ordinary brewers’ yeast as well as other species of the Saccharomycetes, were exposed to the action of ultraviolet light they did not survive the exposure for more than 1 min. I t is very difficult to understand this result, since it is entirely opposed, not only t o the results of my own experiments, but t o those of a good many other observers. Among the latter I may mention: Menri and Stodel, Compt. rend., 148 (19091, 582 Henri and P. Cernovodeanu, I b i d . , 150 (1910), 5 2 Gabriel Vallet, Ibid., 160 (1910), 632 Maurice Lombard, Ibid., 150 (1910), 227 Van Aubel, I b i d . , 149 (1909), 983
1:might also mention articles in the DezLtsche Essig Industvie, 1910, 214 Bvswing Trade Review, 1915, 67 Chem. Zentr., 1918 [II],51.
During the years 1915 to 1917, I carried out a long series of observations on the differential effect of the ultraviolet rays on the bacieria and the Saccharomycetes, and my results are published in detail in the A n n u l i d i Chzmica Applicata, Ig15, 301; 1916, 221; and 1917, 93. In my experiments I exposed brewers’ yeast for 12 hrs. to the ultraviolet rays from a 1200-candle power lamp a t a distance of 20 cm. Not only was the yeast not injured by this treatment, but its fermentative activity was actually increased. All the bacteria present in the yeast were destroyed after a brief exposure. In addition to this laboratory result, I may point out that, since 1918, the Peroni Brewery in Rome (which is perhaps the most important brewery in Italy) has installed a plant for the Freeing of yeast from bacteria by submitting it to the action of ultraviolet rays, and the results obtained on this large industrial scale fully confirm my own experiments. ROMOLO DE FAZI VIA SICILIA 43 ROME(25), ITALY November 3, 1920
..........
Editor of the Journal of Industrial and Engineering Chemistry: We wish to point out that Fazi has indicated the subject for discussion by selecting as the topic for his polemic “The Action of‘Ultraviolet Rays on the Saccharomycetes.” Fazi states that we found the brewers’ yeast, as well as other species of Saccharomycetes, unable to endure the action of ultraviolet rays for more than 1 min. Such is not the case, for Fig. 1 of our paper shows that Saccharomyces of Binot lived For 4 min., one strain of Saccharomyces ellipsoideus for 7 min., and Saccharomyces marxianus for 7 min. under the conditions maintained in our experiment. To anyone having any knowledge of microorganisms, it is evident that no two strains of the same organism react in the same manner to any unfavorable condition. The conditions under which the endurance of microorganisms to various types of disinfectants is tested determine the results. Our suspensions were not heavy, merely a loop of growth in 9 cc. of water spread out in a very thin layer and exposed to the action of the ultraviolet rays a t a distance of 25 cm. with nothing intervening. Scharffl has shown that disinfection by ultraviolet rays is an orderly time process and that, consequently, if the initial number of cells is small, the point will be reached more quickly where 1
J . rnf. D ~ s . io , ( i g i z ) , 30s.
the unit volume will contain no living cells. Our unit was the platinum loop, while Fazi’s was a much larger one. Unfortunately we have not had access to Fazi’s original papers in the A n n u l i dz Chimica Applicata, but having seen abstracts of them in the abstract journals of three languages, we feel that we have sufficiently accurate information upon which to base this discussjon. Fazi’s method consisted in exposing the yeast cells in dextrose solution and water to the action of ultraviolet rays emitted from a lamp of 1200 candle power operating a t 110 volts and 4 amperes. The distance was 20 cm. After exposure, the fermenting activity of the cells was determined by measuring the amount of carbon dioxide formed, Burgel found that the ultraviolet rays would not destroy the endoenzyme of bacteria, for there was little difference between the amount of gelatin liquefied by the sterile filtrate secured from crushed cells which had been exposed to ultraviolet rays, and cells which were in the active growing stage. Stassano and Lematte2 found this to be true for endoenzymes and also for those other bodies so much like enzymes, the agglutinins, toxins, etc. It is not, therefore, to be expected that the enzymes in yeasts would be destroyed; when the exposed material such as Fazi used’to test the viability of yeasts is added to a fermentable substrate, the formation of carbon dioxide would be expected, since the endoenzymes responsible for fermentation would not be destroyed. There is no reason to assume that the enzymes in yeast cells are less resistant to ultraviolet rays. The most interesting part of Fazi’s discussion to us is the imposing list of references which he cites. “Among others” he mentions the following: M. Lombard, “Sur les effets chimique et biologique des rayons ultraviolets.” E. van Aubel, “Sur la production d’ozone sous l’influence de l a lumisre ultraviolette.” G. Vallet, “Penetration et action bactericide des rayons ultraviolets par rapport a la constitution chimique des mileux.” P. Cernovodeanu and V. Henri, “Etude de l’action des rayons ultraviolets sur les microbes.” V. Henri and G. Stodel, “Sterilization du lait par les rayons ultraviolets.”
From the context of Fazi’s polernic, the reader is led to believe that all OF these papers support Fazi by statements or data indicating that the Saccharomycetes are very resistant to ultraviolet rays. A careful reading of these papers did not reveal even the word yeast or Saccharomycete, or any reference to the budding fungi. I n one or two of the papers there are references to bacteria, B. coli in particular, but none with regard to the yeasts. Fazi also mentions articles in the Deutsche Essig Industrie, the Brewing Trade Review, and the Chemisches Zentralblatt. The last reference in this group is a four- or five-line abstract of one of the papers by Fazi himself. We have made no serious effort to look up the first two papers, since they are not available in the University of Illinois Library, and more on account of the nature of the other paper to which Fazi refers, Fazi’s imposing array of references to support his claim of the great enduring power of Saccharomycetes to ultraviolet rays dwindle down to practically nothing, since every paper to which he refers, with the exception of his own work, has no relation to the topic under discussion. It is strange that Fazi overlooks the excellent paper by Buchta a in which he states: The ultraviolet rays check the growth even with the minimum exposure of 10 sec.; by an exposure longer than 3 min., the cells are killed. 1 2
Am. J . Physiol , 43 (1917), 429. Compt. r e n d , 162 (1911), 623.
8 “Uber den Einfluss des Lichtes auf die Sprossung der Hefe,” Cenl. Bakl. A b t . , 41, 1111 (1914), 340.
