Typing of Nontypable Staphylococci by Lysogeny

Strains of coagulase-positive staphylococci which were nontypable with the routine typing set of phages could be typed by lysogeny with phage-propagating strains as indicators and with ultraviolet induction. About 10% of the strains could be typed without induction. About 36% of them could be typed by this method when ultraviolet irradiation was used as an inducing agent. The phage groups from which the majority of the nontypable staphylococci originated were easily identified by this method of typing.     

Metabolic Processes in Cytoplasmic Particles of the Avocado Fruit. IX. The Oxidation of Pyruvate and Malate during the Climacteric Cycle

Mitochondria isolated from preclimacteric avocado fruit oxidize pyruvate at a much lower rate than those separated from climacteric fruit. The external addition of thiamine pyrophosphate (TPP) increased the rate of pyruvate oxidation in both cases.The study of the influence of TPP on the rate of oxidation of malate by mitochondria obtained from both preclimacteric and climacteric fruit indicated that the effect of this cofactor could be understood by assuming that malate was converted to pyruvate. TPP stimulation of malate oxidation was prevented by arsenite, an inhibitor of keto acid oxidation. The addition of glutamate increased the rate of malate oxidation through the transamination of oxaloacetate. This suggests that the rate of oxidation of malate is highly dependent upon mechanisms which remove oxaloacetate efficiently.Incubation of mitochondria from preclimacteric fruit with malate-U-(14)C resulted in the labeling of oxaloacetate and the accumulation of labeled pyruvate. Addition of TPP to this system induced the rapid formation of citrate. This conversion was completely inhibited by arsenite.The results indicate that the ability to carry out the oxidative decarboxylation of alpha-ketoacids improves as the ripening process progresses. The idea was advanced that TPP available to the mitochondria plays an important controlling role.