Forty-seven strains of Streptococcus bovis were tested for bacteriocin production. Fourteen were found to produce bacteriocins, while all 47 were sensitive to at least one of these bacteriocins. The bacteriocins, on the basis of their host range on S. bovis strains, formed six groups. A representative of each group was selected and characterized by temperature stability, sensitivity to trypsin and lipase, sedimentation by centrifugation, ability to pass through dialysis tubing, host range on other bacterial species, and conditions for production in liquid media. A correlation between mannitol fermentation and bacteriocin production was noted.
About 25 Streptococcus bovis bacteriophages were isolated from abattoir wastes, bovine rumen fluid, and lysogenic strains of S. bovis. Eight phages were selected and characterized by morphology, stability, rate of adsorption, single-step growth curve, serum neutralization, and antigenic relationship. Two distinct morphological phage types were found, one of which has not been previously reported for group D streptococci.
The nutrition of ruminants is intimately connected with microbial digestion in the rumen. Because a substantial proportion of the diet ultimately utilized by the animal exists as bacterial substance for a time, the fate of the bacterial cell in the alimentary tract is of interest. We are at present investigating the possible significance of the bacterial cell wall in the nutrition of the sheep as such walls constitute from Io to 3o 7o of the dry weight of the cell and are known to contain carbohydrate (1). As a part of the investigation a general survey by electron microscopy of bacterial types present in rumen contents was made. Phage particles both free and attached to cells were found to be present. Many empty bacterial cell envelopes and fragments of cell walls were also found. A brief report (2) of the occurrence of phage in the rumen liquor of bovines indicated that the phenomenon is of more than local interest and may be a constant feature of the bacterial population in the rumen.Rumen contents were obtained from fistulated sheep fed a diet of lucerne chaff, and from freshly slaughtered sheep fed a diet of unknown composition. The contents were filtered through muslin and samples were examined in the electron microscope in negative contrast using potassium phosphotungstate. In order to exclude selective removal of large micro-organisms during the staining procedure, the agar stripping technique (3) was also used. Bacteriophages were present in samples of rumen contents from both sources and were present both free in the rumen liquor and attached to cells of different types. The most common had polyhedral heads (P1. I, fig. I) and were associated with a very small coccus (< I/z in diameter) which was present in large numbers. Plate 2, fig. 3, shows part of a lysed curved rod shaped organism associated with phage particles. A number of full and empty bacteriophages are associated with the bacterial body. Most of the phage particles occurring free in the rumen liquor were single. Occasionally, however, we found some also with polyhedral heads, clustered together (P1. 2, fig. 4). The tails of these particles have a common attachment to an unknown fibril. Of particular interest was the discovery of groups of spirochaetes with surfaces heavily lined with bacteriophages (P1. 2, fig. 4). The fibrillar structure of the spirochaetes is discernible and some of the phage heads appear to have discharged their contents. The association of phages with spirochaetes seems not to have been previously described.A further feature brought out by the survey was the large number of cell walls seen in each rumen sample (P1.2, fig. 4)-At times these represented up to about 1o 70 of the total number of bacterial bodies present. Lysis of bacteria in the rumen was indicated by the presence of these cell walls. (PI. 2, fig. 4 shows a complete cell wall and P1. 2, fig-3, shows isolated fragments of cell envelope possessing the 'honeycomb' appearance (4).Although it is difficult to make quantitative measurements of the numbers of phage ...
By using metabolically altered mutants and acrylate, novel putative intermediates of alpha-pinene metabolism by Pseudomonas putida PIN11 were detected. They were characterized as 3-isopropylbut-3-enoic acid and (zeta)-2-methyl-5-isopropylhexa-2,5-dienoic acid.
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