Improved KCN Medium

A semisolid tetrazolium salt agar medium developed for testing sensitivity to KCN is easier to interpret, has a longer storage life, and is less critical in the size of inoculum than is Moeller KCN broth medium.     

Improved Motility Medium

An improved motility medium which permits additional cultural characterization is described. Advantages include maximal motility due to a change in the physical state of the medium from solid to liquid at incubation temperatures, a definitive stab line, preservation of the stab line with nonmotile organisms, and visual delineation of culture motility. In addition, nitrate reduction, nitrogen gas production, and gelatin liquefaction may be demonstrated.     

Modified Decarboxylase-Dihydrolase Medium

A modified base medium for amino acids is described which has advantages over Moeller and Falkow media.     

Improved Motility Medium

An improved motility medium which permits additional cultural characterization is described. Advantages include maximal motility due to a change in the physical state of the medium from solid to liquid at incubation temperatures, a definitive stab line, preservation of the stab line with nonmotile organisms, and visual delineation of culture motility. In addition, nitrate reduction, nitrogen gas production, and gelatin liquefaction may be demonstrated.     

Improved KCN Medium

A semisolid tetrazolium salt agar medium developed for testing sensitivity to KCN is easier to interpret, has a longer storage life, and is less critical in the size of inoculum than is Moeller KCN broth medium.     

Medium Promoting Sporulation of Bacillus larvae and Metabolism of Medium Components

A new medium, designated TMYGP broth, was developed that allowed the honeybee pathogen Bacillus larvae NRRL B-3650 to produce up to 5 × 10⁸ spores per ml of culture (microscopic count). This species normally sporulates poorly, if at all, in artificial broth media. An aeration rate lower than that normally used to cultivate other Bacillus species was required for sporulation. During the exponential growth phase, acids were produced by catabolism of yeast extract components, causing a decrease in pH of the medium. Thereafter, the pH began to increase, probably because of derepression of the citric acid cycle and consumption of the acids. Only after this time did usage of glucose from the medium occur. Thus, glucose usage seems to be regulated by catabolite repression. The presence of glucose was needed for one or more of the later events of sporulation. Of many substances tested, only gluconic acid and glucosamine partially substituted for glucose as a requirement for sporulation. Pyruvate was also required for good sporulation. It was metabolized during the late-exponential phase of growth.     

Culture Medium for Enterobacteria

A new minimal medium for enterobacteria has been developed. It supports growth of Escherichia coli and Salmonella typhimurium at rates comparable to those of any of the traditional media that have high phosphate concentrations, but each of the macronutrients (phosphate, sulfate, and nitrogen) is present at a sufficiently low level to permit isotopic labeling. Buffering capacity is provided by an organic dipolar ion, morpholinopropane sulfonate, which has a desirable pK (7.2) and no apparent inhibitory effect on growth. The medium has been developed with the objectives of (i) providing reproducibility of chemical composition, (ii) meeting the experimentally determined nutritional needs of the cell, (iii) avoiding an unnecessary excess of the major ionic species, (iv) facilitating the adjustment of the levels of individual ionic species, both for isotopic labeling and for nutritional studies, (v) supplying a complete array of micronutrients, (vi) setting a particular ion as the crop-limiting factor when the carbon and energy source is in excess, and (vii) providing maximal convenience in the manufacture and storage of the medium.     

The Venetian Turpentine Mounting Medium

As a mounting medium to follow aceto-carmine the following modification of Zirkle's is suggested: Venetian turpentine, 25 ml.; phenol, 50 ml.; propionic acid, 35 ml.; acetic acid, 10 ml.; water, 20 ml. The technic can be employed with either root-tip or pollen-mother smears, and has been used with quite a variety of plants. It is especially valuable where it is desired to make temporary mounts permanent. The method is simple, and with reasonable care no displacement of marked cells occurs.     

New Medium for Blood Cultures

A new medium suitable for blood cultures is described. It contains dextrose, cysteine, iron, and magnesium, in a tris(hydroxymethyl)aminomethane buffer, and a mixture of peptones derived from animal tissues, casein, and yeast. In comparison with Trypticase Soy Broth, the growth rate constants of Staphylococcus aureus, Streptococcus (Viridans group), enterococcus, and Escherichia coli were higher in this medium, and growth appeared earlier in a significant number of clinical blood cultures.     

Comparison of Sulfite-Polymyxin-Sulfadiazine Medium and Tryptose-Sulfite-Cycloserine Medium Without Egg Yolk for Recovering Clostridium perfringens

The overall recoveries of spores and of actively growing, heat-stressed, coldshocked, and frozen cells of five strains of Clostridium perfringens were significantly greater (95% confidence limits) on tryptose-sulfite-cycloserine medium without egg yolk than on sulfite-polymyxin-sulfadiazine medium.     

Selective Medium for Moraxella nonliquefaciens

A medium is described which selectively inhibits most bacteria from the normal flora of the conjunctiva, the lid-margin, and the upper respiratory tract but permits growth of Moraxella nonliquefaciens, M. liquefaciens, and the less fastidious strains of M. lacunata. The selective conditions are obtained with thiostrepton, tyrothricin, and sodium nalidixinate as inhibitors. Incubation under increased CO(2) pressure increased the number of primary isolations. M. nonliquefaciens was isolated on the selective medium twice as many times as on other media.