SUMMARYWhen Streptococcus faecalis was grown anaerobically in a complex medium containing D-glucose, D-ribose or L-arginine as energy source the dry wt. of organism produced was proportional to the concentration of the energy source in the medium. However, S. faecalis will not grow in a defined medium with arginine as the energy source unless glucose is present at the same time. The anaerobic growth of both Saccharornyces cerevisiae and Pseudomonas lindneri was proportional to the concentration of glucose in the medium and the yield coefficient-defined as g. dry wt. organism/mole glucose-of the former was the same as that of S. fmculis grown upon glucose and approximately twice that of P . lindneri. Calculation of the g. dry wt. organism/mole adenosine triphosphate synthesized for these three organisms gave values ranging from 12.6 to 8.3 with an average of 10.5. These results suggest that, under anaerobic conditions, the yield of S . faecalis, S . cerevisiae and P. lindneri was proportional to the amount of ATP synthesized. When Propionibacterium pentosaceum was grown anaerobically with glucose, glycerol or DL-lactate as energy source there was, in all three cases, a linear relationship between the dry wt. of organisms produced and the concentration of the energy source in the medium. The values of the yield coefficients obtained were compatible with the formation of approximately 4 mole ATP/mole glucose, 2 mole ATP/mole glycerol and 1 mole ATP/mole lactate.

The end products of the metabolism of phenylalanine, tyrosine and tryptophan by growing cultures of clostridia have been identified. The species used were Clostridium aminovalericum; C. bifermentans; C. botulinum proteolytic type A; C. botulinum proteolytic type B; C. cochlearium; C. difficile; C. ghoni; C. histolyticum; C. lentoputrescens; C. limosum; C. lituseburense; C. malenomenatum; C. mangenoti; C. propionicum; C. putrefaciens; C. sordellii; C. sporogenes; C. sporosphaeroides; C. sticklandii; C. subterminale; C. tetani; C. tetanomorphum. The mixture of aromatic compounds formed, which depended upon the species, included phenyl acetic acid, phenyl propionic acid, phenyl lactic acid, phenol, p-cresol, p-hydroxy phenyl acetic acid, p-hydroxy phenyl propionic acid, indole, indole acetic acid and indole propionic acid.

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Three organisms, Clostridium kluyveri (Barker and Taha, 1942), Rhodospirillum rubrm (Kohlmiller and Gest, 1951) and an organism isolated from silage by Rosenberger (1952) and identified as Clotridium scatologenes, have been shown to synthesize fatty acids higher than n-butyrate, as end products of fermentative metabolism. In this paper we give an account of the isolation and properties of an anaerobic, gram negative organism which ferments certain carbohydrates and DL-lactic acid with the formation of hydrogen, carbon dioxide, acetate, propionate, n-butyrate, n-valerate, and n-hexanoate. The organism was isolated from the rumen contents of the sheep. MATERIALS AND METHODS Media. Except where otherwise stated the basal medium contained 0.4 per cent yeast extract (Difco), 0.05 per cent K1H2P04, 0.05 per cent NH4Cl, 0.03 per cent MgCl2.6H20, 0.03 per cent thioglycolic acid in tapwater; the pH was adjusted to 7.4. Medium A consisted of the basal medium plus 2 per cent soluble starch. Medium B consisted of basal medium plus 2 vol per cent of 70 per cent DL-sodium lactate. Rumen contents. The samples of rumen contents used were obtained from Scotch Blackface sheep fitted with rumen cannulae, and fed meadow hay and concentrates. Cultural techniques. Liquid enrichment cultures were carried out in 60-ml glass-stoppered bottles completely filled with medium. Agar plates were incubated in desiccators filled with H25 per cent C02 gas mixture and containing a capsule of