114 



R. MAMELAK, J. H. OUASTEL 



VOL. 12 (1953) 



Evidence that hydrogen peroxide is involved in aerobic oxidations by resting 

 CI. sporogenes is shown by the fact that the addition of catalase to the bacterial suspension 

 brings about an increase in the rate of oxygen and of ammonia formation in presence of 

 DL-alanine. For example, i ml bacterial suspension after exposure to air at 37° for i hour 

 absorbed 9.5 [xM oxygen in 90 minutes after addition of 0.02 M DL-alanine, whereas the 

 same quantity of bacterial suspension in presence of catalase under the same conditions 

 absorbed 14.4 fjiM oxygen. 



Effects of exposure of resting CI. sporogcnes to air and to hydrogen peroxide 



On exposing resting CI. sporogenes to air, at 0°, for three of four hours a marked 

 fall in the rate of anaerobic amino acid interaction takes place. Typical results are shown 

 in Table XI (Expts. i and 2). This fall is reactivity is due to the presence of oxygen, as 

 no diminution is experienced if the suspension of organisms is exposed to nitrogen for the 

 same interval of time before addition of the amino acids (Table XI. Expt. 2). Moreover, 

 the presence of the amino acids has no protective action. The toxic effect given by 

 oxygen is given also by dilute hydrogen peroxide. Results shown in Table XI Expt. 3 

 make it clear that exposure of resting CI. sporogenes to a concentration of hydrogen 

 peroxide of less than 1/10,000 brings about an immediate drop in the rate of anaerobic 

 amino acid interaction. It is evident, therefore, that both hydrogen peroxide and oxygen 

 are toxic to the mechanisms underlying amino acid interaction in CI. sporogenes. It is 

 likely that oxygen is toxic per se as its presence induces toxicity when no consumption 

 of oxygen by the bacterial preparation in absence of added substrates is noticeable and 

 when, therefore, the production of hydrogen peroxide must be exceedingly minute. 



TABLE XI 



EFFECTS OF EXPOSURE OF CI. SpOrOgeUes TO AIR AND HYDROGEN PEROXIDE ON 



AMINO ACID INTERACTIONS 



Warburg manometer vessels contained i ml suspension CI. sporogenes (in 0.15 M KCl) ; 0.028 M 

 NaHCOj, Gas 93 % Ng + 7 % COg. Total vol. 3.2 mg. 



Expt. 



Contents of vessel 



Conditions of exposure 

 of CI. sporogenes 



HM CO., 

 formed 



/iM Glycine 

 disappeared 



1 L-Alanine (0.005 ^) 

 Time 135' + Glycine (o.oi M) 



L-Alanine (0.005 ^H 

 + Glycine (o.oi M) 



L-Alanine (0.005 ^'I) 

 -(- Glycine (o.oi M) 



2 L-Alanine (0.02 71/) 

 Time 90' -f L-l'roline (0.02 M) 



L-Alanine (0.02 M) 



+ L-Proline (0.02 .1/) 



3 L-Alanine (0.005 ^^) 

 Time 135' -1- Glycine (o.oi M) 



L-Alanine (0.005 M) 

 + Glycine (o.oi Al) 



Freshly prepared organism, used im- 

 mediately 9.9 

 Organism exposed to air for 3 h at o" 

 before addition of amino acids 5.1 

 Organism exposed to air for 3 h at o 

 in presence of alanine -|- glycine 4.3 

 Organism exposed to air for 4 h at 37" 

 before addition of amino acids 13.4 

 Organism exposed to 93% N24-7% 

 CO2 for 4 h at 37° before addition of 

 amino acids 35-6 

 Freshly prepared organism used im- 

 mediately after dilution with water, 

 centrifuging and rcsuspension in 0.15 

 AfKCl 14-5 

 Freshly prepared organism treated 

 with six times its vol. 1/10,000 hydro- 

 gen peroxide, ccntrifuged at once and 

 resuspended in 0.15 A/ KCl 4.0 



27-5 



3-2 



References p. 120. 



