Rapid procedure for the detection of acid and gas production by bacterial cultures

Microtechnique for most-probable-number analysis

A microtechnique based on the most-probable-number (MPN) method has been developed for the enumeration of the ammonium-oxidizing population in soil samples. An MPN table for a research design ([8 by 12] i.e., 12 dilutions, 8 replicates per dilution) is presented. A correlation of 0.68 was found between MPNs determined by the microtechnique and the standard tube technique. Higher MPNs were obtained with the microtechnique with increased accuracy in endpoint determinations being a possible cause. Considerable savings of time, space, equipment, and reagents are observed using this method. The microtechnique described may be adapted to other microbial populations using various types of media and endpoint determinations.

Microtechnique for isolating fecal coliforms from soil

A most-probable-number microtitration technique for isolating fecal coliforms from soil was developed. A correlation coefficient of 0.86, with a 95% confidence interval of 0.76 less than zeta less than 0.92, was obtained when this technique was compared with the standard elevated-temperature fecal coliform most-probable-number procedure.

Automated reading of a microtitre plate: preliminary evaluation in antimicrobial susceptibility tests and Enterobacteriaceae identification

An automated microELISA Reader was evaluated for its ability to read and interpret microtitre plates. A total of 309 microtitre plates were investigated by automated and visual methods. There was disagreement between the methods in one hundred and twelve (0.6%) wells. However agreements between the two methods for susceptibility tests and Enterobacteriaceae identification were respectively 98.8% and 89.3%.

Convenient system for multiple screening of microbial carbohydrate metabolism

A rapid technique for inoculating carbohydrate oxidation and fermentation media is described. This method employs 24-well tissue culture trays and a multi-inoculator. Other applications are discussed.

Effect of dyes on bacterial growth

A rapid screening procedure was used to test the effect of 42 dyes on growth of 30 bacteria on solid media. The results indicated that many readily available dyes might have potential application for selective isolation of specific bacterial groups as well as value in differentiating between closely related bacterial taxa. Separation of Enterobacter from Escherichia, Salmonella from Shigella, and Staphylococcus from Micrococcus by selected dyes was also evaluated.

Microfermentation series for identification of single colonies of Enterobacteriaceae

Microfermentation tests for members of the family Enterobacteriaceae were devised by using agar solutions in disposable, multi-welled, plastic trays. The tests could be made directly from isolated colonies picked from agar plates and represented a considerable saving in time, labor, and materials over the conventional methods. Tests were formulated for determining carbohydrate fermentations, citrate utilization, motility, amino acid decarboxylation, and production of H(2)S, indole, urease, and acetyl-methyl-carbinol.