No abstract

More than 100 facultatively and strictly anaerobic strains from 22 genera isolated from the digestive tract of the rat were tested for the ability to split glycine and taurine conjugates and to transform cholic acid. Strains belonging to 14 of these genera, of which 12 were strictly anaerobic, were capable of splitting conjugates; whereas strains from only 7 genera were capable of transforming cholic acid. None of the strains isolated could 7a‐dehydroxylate cholic acid. Twenty strains from 9 genera capable of splitting conjugates in vitro were established as monocontaminats in ex‐germfree rats. Of these, three strains from the genera Clostridium, Eubacterium and Streptococcus (strictly anaerobic species) gave approximately 80 per cent splitting of the caecal bile acids. Four strains showed no conversion of caecal bile acids, while the remainder showed splitting varying between 4 and 44 per cent of the caecal bile acids. Therie was no correlation between the viable numbers of bacteria in the caecum and the extent of splitting of caecal bile acids. Deconjugation in vitro cannot be used as a criterion for the potential deconjugation of microorganisms growing in the digestive tract.

A selective agar medium (medium J1) is proposed for the quantitative enumeration of egg yolk-positive (EYP) and egg yolk-negative (EYN) Staphylococcus pyogenes from the digestive tract and feces of the rat. This medium, buffered at pH 5.0, is composed of acid casein hydrolysate and yeast extract with 7.5% sodium chloride, 1.6% sodium pyruvate, 0.0008% 2,3,5-triphenyltetrazolium chloride (TTC), and 6% egg yolk emulsion. Inoculation is by the pour-plate method and incubation is at 38 C in a water-jacketed incubator for 36 hr. Colonies of S. pyogenes reduce YTC; EYP strains are surrounded by a halo of opacity; and EYN strains may be surrounded by a red halo, but no opacity. Small, white colonies of S. epidermidis may develop, but Micrococcus, and all other groups of Staphylococcus recognized in the rat intestinal flora, are inhibited. Other bacterial genera, notably Bacillus, Corynebacterium, Proteus, and Streptococcus, are also inhibited.

SUMMARY: Ignoring wasted material at the surface and sides, the variation in pH in six months old pit silage was smaller from side to side than from top to bottom. At the 2‐foot level, where the best quality silage was found, variation was very slight. A correlation was found between pH and the logarithm of the microscopical count of bacteria, the total number of bacteria falling with decreasing pH.