- Volume 13, Issue 1, 1955

Summary: Fifty-six strains of non-lactose fermenting coliform organisms belonging to the Providence group were obtained from the National Collection of Type Cultures and examined for their nutritional requirements. Fifty-five of these strains formed a nutritionally homogeneous group. The simplest medium supporting growth was a basal salt medium with added glucose, glutamic acid and cystine. Pantothenate usually improved growth and appeared to be nearly essential for two strains. The remaining strain possessed the nutritional pattern of Proteus morganii and in this and other characters appeared to be a typical strain of that species. Twenty-two of the fifty-five strains gave a positive amine test using the ninhydrin test-paper technique; previously only Proteus species in the family Enterobacteriaceae had been observed to produce amines. The classification of the Providence group is discussed in the light of these findings.

Summary: The bactericidal activities of mixtures of various chemotherapeutic drugs were tested against the H37Rv strain of Mycobacterium tuberculosis when growing in Tween albumin medium. Oxytetracycline (terramycin) antagonized the bactericidal activities of streptomycin, isoniazid and viomycin, whereas p-aminosalicylic acid (PAS) was slightly synergistic or did not influence their activities. Mixtures of viomycin and streptomycin were slightly less bactericidal than streptomycin alone, but more bactericidal than viomycin alone. Viomycin acted synergistically with isoniazid, and with isoniazid + streptomycin. The emergence of strains resistant to streptomycin, isoniazid or viomycin was not prevented in the cultures by the presence of oxytetracycline, probably because of its rapid inactivation. Drug resistance emerged in dual mixtures which included PAS, where the concentrations of streptomycin, isoniazid or PAS were low, but not when these concentrations were high. Resistant strains did not emerge in cultures containing viomycin + streptomycin or viomycin + isoniazid.

Summary: In the production of high titre staphylococcus phage K lysates from concentrated liquid bacterial cultures the upper limit of phage concentration appears to be at about 1010 particles/ml. This concentration, the ‘ceiling titre’, can be raised to 4 × 1011 particles/ml. by the addition of ammonium sulphate to the medium after phage infection. It is concluded that this effect depends upon the ability of ammonium sulphate to lower the rate of adsorption of phage upon host cells, thus preventing a high rate of phage loss by adsorption and inactivation towards the end of lysis. The possibility is discussed that this mechanism may explain some puzzling observations in lysing systems.

Summary: Four strains of lactobacilli, isolated from the contaminant flora of English top fermentation brewers’ yeasts, were found to be heterofermentative. Two strains were tentatively identified as Lactobacillus brevis. For growth, all the strains required exogenous supplies of a number of growth factors of the vitamin B complex, a pyrimidine, at least one purine and at least 14 amino acids. The ability of hypoxanthine to substitute for both adenine and guinane in one strain of L. brevis is especially notable. l-Arginine, essential for the growth of all strains, increased the rate and final amount of growth in glucose medium of both strains of L. brevis, when it was supplied in relatively high concentration. Suspensions of the organisms converted arginine into ornithine, ammonia and a small amount of citrulline. Maltose, fructose and l-arabinose were better substrates for the growth of all strains than glucose, which, as major source of energy, supported little or no growth of the two unidentified strains. All the strains transformed fructose into mannitol. The rate and extent of growth of most strains on hexoses and the rate of growth of all strains on maltose were increased by the presence of acetate. Whereas the strains of L. brevis formed only little acid from glucose, all strains produced considerable amounts of volatile and non-volatile acids from l-arabinose.

Summary: Tomato juice Yeastrel Tween 80 broth was found to contain two haptene substances, one a component of tomato juice and the other of Yeastrel. These caused difficulties in the use of lactobacillus antisera. Methods were devised for eliminating the effects of these haptenes.