Search PubMed⌕ Search

Biomedical subjects

G W Reinbold

Publications and source records attributed to G W Reinbold.

16 recordsLinked to original sources
PubMed1973

Sulfonamide resistance of propionibacteria: nutrition and transport.

Three variations of a synthetic growth medium were used to study the folic acid and p-aminobenzoic acid (PABA) requirements of Propionibacterium. P. shermanii, P. freudenreichii, P. thoenii, and P. arabinosum synthesize folic acid and do not require PABA or folic acid. P. pentosaceum, P. jensenii, and P. rubrum are stimulated by folic acid or PABA, but do not show an absolute requirement. P. peterssonii shows a requirement for either PABA or folic acid. The addition of 300 mug of sulfadiazine per ml did not inhibit growth of propionibacteria in the synthetic medium, synthetic medium plus PABA, or synthetic medium plus folic acid. P. freudenreichii was not inhibited even when 500 mug of sulfadiazine per ml was added to the synthetic medium, nor did it degrade sulfadiazine significantly. Trimethoprim totally inhibited the growth of Propionibacterium. Radioactive sulfadiazine was transported by sulfadiazine-sensitive Escherichia coli but not by P. freudenreichii, indicating that the sulfadiazine resistance of propionibacteria could be mainly due to their inability to transport sulfonamides.

Aminobenzoates↗
PubMed1972

Agar medium for differential enumeration of lactic streptococci.

An agar medium containing arginine and calcium citrate as specific substrates, diffusible (K(2)HPO(4)) and undiffusible (CaCO(3)) buffer systems, and bromocresol purple as the pH indicator was developed to differentiate among lactic streptococci in pure and mixed cultures. Milk was added as the sole source of carbohydrate (lactose) and to provide growth-stimulating factors. Production of acid from lactose caused developing bacterial colonies to seem yellow. Subsequent arginine utilization by Streptococcus lactis and S. diacetilactis liberated ammonia, resulting in a localized pH shift back toward neutrality and a return of the original purple indicator hue. The effects of production of acid from lactose and ammonia were fixed around individual colonies by the buffering capacity of CaCO(3). After 36 hr at 32 C in a candle oats jar, colonies of S. cremoris were yellow, whereas colonies of S. lactis and S. diacetilactis were white. S. diacetilactis, on further incubation, utilized suspended calcium citrate, and, after 6 days, the citrate-degrading colonies exhibited clear zoning against a turbid background, making them easily distinguishable from the colonies of the other two species. The medium proved suitable for quantitative differential enumeration when compared with another widely used general agar medium for lactic streptococci.

Journal Article↗
PubMed1972

Associative growth studies in three-strain mixtures of lactic streptococci.

A recently developed differential agar medium was used to study associative growth patterns in 17 different heterologous, three-strain mixtures of Streptococcus lactis, S. cremoris, and S. diacetilactis grown in milk. Mixtures were made by combining equal volumes of 18-hr milk cultures of the three species. Relative populations of component species were followed through three successive transfers in milk after the initial mixed propagation. Direct evidence for strain dominance and compatibility was obtained. A procedure also was developed to estimate the extent of suppression of S. lactis and S. diacetilactis in a mixture containing a dominant S. cremoris strain. The technique described could be successfully applied in quality-control work in the dairy-starter manufacturing industry.

Journal Article↗
PubMed1971

Isolation of inhibitory factor in raw milk whey active against propionibacteria.

Preparative isolation of the active component(s) in skim milk whey inhibitory for propionibacteria was made by using (NH(4))(2)SO(4) salt fractionation. The crude preparation was further purified by Sephadex G-100 column separation. Disc-gel electrophoresis of the active peak from the Sephadex elution pattern (peak I) showed that this fraction contained almost all of the immune globulin in the column sample. The biologically inactive peaks did not contain any immune globulin. Starch-gel electrophoresis of the active peak revealed the presence of three separate immune globulin fractions. A correlation was also observed between hemolytic reaction of propionibacterial strains and relative resistance to whey inhibition. The investigation showed that one of the immune globulins of milk, pseudoglobulin, was mainly responsible for the suppressive activity of whey.

Ammonium Sulfate↗
PubMed1969

Differential agar medium for separating Streptococcus lactis and Streptococcus cremoris.

The characteristic ability of Streptococcus lactis and inability of Streptococcus cremoris to hydrolyze arginine formed the basis for the development of a differential agar medium to separate these species in pure and mixed cultures. Ammonia liberated from arginine was detected by the pH changes occurring in the medium. The agar contained milk as the sole source of carbohydrate, arginine as the specific substrate, diffusible (K(2)HPO(4)) and nondiffusible (CaCO(3)) buffer systems, and a suitable pH indicator in addition to other ingredients. The nondiffusible buffer system afforded the localization of pH changes, and, hence, the indicator color changes immediately around individual colonies appearing on the medium. S. cremoris produced yellow colonies surrounded by yellow zones on this purple medium because of their ability to produce acid from lactose in the milk. S. lactis, on the other hand, first produced colonies similar to S. cremoris, but subsequent color reversal of pH indicator with the liberation of NH(3) resulted in the discharge of the yellow color. Hence, S. lactis colonies were white and devoid of zones. The difference in their colony color allowed the identification of the species in a mixture of S. cremoris and S. lactis strains. The medium was found suitable for both qualitative and quantitative differentiation.

Agar↗