A Study of Leptotrichia buccalis. II. Biochemical and Physiological Observations

¹ W. G. Zoller Memorial Dental Clinic, University of Chicago, Chicago, Illinois

A closer look at the morphological picture of L. buccalis has been presented. It is quite definite that this species presents a very pleomorphic pattern as far as the individual bacteria are concerned. Bulbous swellings appear in different areas on individual logs, sometimes at the ends and at other times concentric or eccentric. Highly granular elements also are quite numerous. Comparison with the facultative forms definitely proves the contention of several other workers that these forms can be distinguished from each other on a purely morphological basis.

The biochemical-activities study furnishes additional evidence for the existence of a well-defined species and clearly demonstrates the differences in the physiological activities of the anaerobes and the facultative forms. The differences are distinct enough to separate the two as individual species. A suggestion is made to adopt the decision of other investigators to place these two groups into different genera—the Leptotrichia species might fit well with the Lactobacillaceae and the Bacterionema species with the Actinomycetaceae.

Further evidence for the placing of the Leptotrichia species into the Lactobacillaceae is the result obtained from the benzidine test. This test shows the definite absence of any cytochrome respiratory system, which is one of the characteristics of the lactobacillus group, as demonstrated by the work of Deibel and Evans.²⁴