BACTERIOLOGICAL EXAMINATION OF SOUR AND SOUND HAMS.
In all of the sour hams which were examined bacteriologically a large anaerobic bacillus was found to be constantly present. From several of the hams this bacillus was obtained in pure culture; that is, it was the only organism present in cultures made from the sour meat and from the bone marrow of the femur. Such cultures, when held at room temperature, gave, at three days, a sour-meat odor exactly resembling that obtained from sour hams.
In many of the sour hams other bacteria were found in association with the anaerobic bacillus noted above. These other bacteria, however, were not constant, being sometimes present and sometimes absent. Among the other bacteria noted in the sour hams, the following forms occurred most frequently:
1. A nonmotile, gram-positive bacillus, measuring from 1.5 to 4 microns in length by 0.5 micron in breadth, sometimes in chains and filaments.
2. A small, nonmotile, gram-negative bacillus, about the size of Bacillus coli and usually in pairs.
3. A large micrococcus.
Sometimes one and sometimes all of these bacteria were present in a given ham. They were encountered most frequently in hams which had been pumped in both body and shank, and were probably ordinary pickle bacteria. They were not strict anaerobes, but belonged to the class of facultative or optional anaerobes; that is, organisms which will grow either with or without free oxygen. These bacteria were isolated and grown on the egg-pork medium, but failed to give any characteristic sour or putrefactive odors, and were therefore discarded.
A series of sound hams, all of them of mild cure—that is, hams which had been pumped in the shank only—were also examined bacteriologically. In examining these hams cultures were taken at varying depths, beginning at the skinned surface and going backward toward the fat. Cultures were also taken from the bone marrow of the femur. In the cultures taken near the skinned surfaces the ordinary pickle bacteria were obtained, but these did not, as a rule, extend beyond a depth of 3 centimeters below the skinned surface. The cultures taken from the deeper portions of the hams and from the bone marrow of the femur were entirely negative—that is, failed to show any growth—and the anaerobic bacillus noted in the sour hams was not encountered in any of the cultures made from these hams.
The anaerobic bacillus isolated from the sour hams was found to correspond in morphology with the organism noted in the microscopic sections made from the muscular tissue. In view of this fact and the fact that it was constantly present in the sour hams examined, and was capable of producing in egg-pork cultures a sour-meat odor of the same nature as that obtained from sour hams, this organism was subjected to further study and experimentation.