A ROUTINE DETERMINATION OF THE OPTICALLY ACTIVE ISOMERS OF LACTIC ACID FOR BACTERIAL CLASSIFICATION.
The quantity of L(+)-isomer of lactic acid is determined with L(+)-specific lactic dehydrogenase. Comparison with the total amount of lactic acid determined chromatographically is used as a rapid and accurate replacement for the classical determination of optically active isomers of lactic acid for classification of lactic acid bacteria.
Types and Distribution of Anaerobic Bacteria in the Large Intestine of Pigs
An examination was made of various sites along the length of the swine large intestine, using strictly anaerobic culture methods. Sites were separated by differential washing into fractions described as lumenal content, lumenal surface layer, and intestinal wall tissue. Direct microscopic clump counts averaged 13.3 × 1010 organisms per g (dry weight) of material in the lumenal content, 14.0 × 1010 in the surface layer, and 5.1 × 1010 in the intestinal wall tissue. Both direct microscopic counts and viable culture counts were higher from the lumenal content and surface layer than from the intestinal tissue at all sites sampled in the intestine. Cultural counts averaged 56.2% of the direct microscopic counts in lumenal content and surface layer and 20.2% in intestinal tissue. Over 90% of the bacteria isolated were gram positive and consisted mainly of gram-positive cocci, lactobacilli, eubacteria, and clostridia. Of 192 isolates recovered, only 124 could be assigned to recognized species.
Taxonomic Relationships of Lactobacillus Bifidus (B. Bifidus Tissier) and Bacteroides Bifidus
The so-called Bacteroides group of bacteria has almost overnight become a subject of considerable interest; this is true particularly of the members which occur normally in the intestine. There is much confusion regarding the proper classification of these organisms, due largely to the heterogeneity of the group as a whole. In a recent report' on a study of the gram-negative bacteroides of the human intestine, we proposed what appeared to us to be a more simplified rearrangement of the species. The gram-positive nonsporing anaerobes were reserved for future study. More recently our attention has been directed to this group, but specifically to one particular species or type, namely Eggerth's "Bacteroides bifidus" (group II), or Orla-Jensen's "Bacterium bifidum."