- Volume 22, Issue 1, 1960

SUMMARY: A method is described for simultaneous estimation of pool constituents, protein, nucleic acids, cell-wall mucopeptide, and possibly teichoic acid in a single sample of S. aureus. The method makes possible isolation of the cell-wall mucopeptide contaminated by less than 5% of the cytoplasmic protein. It is suitable for studies of biosynthesis, with radioactive precursors, and requires approximately 3 mg. cell/sample.

SUMMARY: The morphological and physiological characteristics of an amylolytic rumen bacterium are described. The organism is an obligate anaerobic coccus which occurs in extremely long chains and exhibits marked pleomorphism. It is considered best placed in the genus Peptostreptococcus. The physiological characteristics and numbers in which the organism occurs suggest an important role in the rumen, especially under the conditions imposed by high-starch feeding.

SUMMARY: A method is presented for the estimation of uridine pyrophosphoglu- cose dehydrogenase activity in extracts of pneumococci; this utilizes 14C-labelled uridine pyrophosphoglucose (UPPG). This method overcomes the difficulty of the spectrophotometric assay caused by the presence of reduced diphosphopyridine nucleotide (DPNH) oxidase in such extracts. An investigation was made of the protective effects of catalase and thioglycollate on pneumococcal UPPG dehydrogenase. Both these substances prevented inactivation of this enzyme. The results suggest that inactivation is caused by hydrogen peroxide and that the point of attack on the enzyme is upon sulphydryl groups. The UPPG dehydrogenase activity of some capsulated and non-capsulated strains of type I pneumococcus was determined. The capsulated and some of the non-capsulated strains examined had considerable UPPG dehydrogenase activity except one strain which had negligible activity. The enzyme UPPglucuronic acid-4-epimerase from a type I pneumococcus required diphosphopyridine nucleotide for activity.

SUMMARY: The proteolytic activity of the whole rumen fluid of sheep does not depend on the diet of the animals. The optimum pH value for proteolysis lies between 6 and 7, with an irregular maximum at about pH 6·5. All fractions of rumen contents (protozoa, large bacteria and small bacteria) show activity. Proteolytic activity can be demonstrated in the supernatant liquid after disruption of the microorganisms. The proteolytic activity of the whole rumen fluid was enhanced by cysteine at 0·06 and 0·006 % (w/v) unless the rumen fluid had been collected and processed under highly anaerobic conditions. Potassium cyanide and ascorbic acid were also slightly stimulatory, but sodium thiosulphate, thioglycollic acid, sodium sulphide and Fe++, Ca++ and Mg++ ions had no effect.

SUMMARY: Several different culture media were used in attempts to isolate the bacteria from the sheep rumen. Only a small proportion of the bacteria which developed were actively proteolytic, and these belonged to a limited number of types. These bacteria were found in sheep on different diets, but comparison with the proteolytic activity of whole rumen contents suggests that they represented only a fraction of the proteolytic organisms of the rumen.

SUMMARY: In sheep fed on a partially-‘defined' diet the dietary protein was broken down in the rumen very rapidly after feeding. In conformity with this, the proteolytic activity of the rumen micro-organisms was relatively constant and comparatively high even before feeding. The number of proteolytic bacteria which were cultured from the rumen was relatively low at all times, although it increased after feeding.

SUMMARY: Observations on living colonies of Streptomyces coelicolor strain A3(2) growing on cellophan films were made by phase-contrast microscopy. Particular attention was paid to the mode of origin of the aerial mycelium. It was shown conclusively that aerial hyphae can originate as simple branches of the substrate mycelium, without any previous fusion of hyphae. The pattern of development of the substrate mycelium is markedly influenced by the composition of the medium.

SUMMARY: The characteristics of fifty-nine strains of Pasteurella septica, mostly derived from human lesions, were analysed by an electronic computer. The cat strains showed a high degree of similarity to each other, while the dog strains were more variable. Most human infections other than those due to bites seem to be due to strains which probably originated from cats. The analysis suggests that P. septica is distantly related to P. pestis and P. pseudotuberculosis but that the two latter are closely related to each other.