Forty strains designated as
Lactobacillus acidophilus were examined for the electrophoretic patterns of lactic acid dehydrogenase (LDH) with a commercial kit for serological LDH isozyme, since
L. gasseri was recently separated as a new species from
L. acidophilus. They were divided into four groups; groups A, B, C and D. Only nine strains belonged to the group A, including the neotype strain of
L. acidophilus (ATCC4353) and most strains belonged to group B including the type strain of
L. gasseri (DSM 20243).
Subsequently, all the strains of group A gave positive reaction in inulin but negative in starch fermentation tests. In addition, they were generally large in the cell size and showed rapid coagulation of milk, but they showed no growth in 4% NaCl broth. On the other hand, with respect to inulin and starch fermentation tests, the strains belonging to group B were not the same; they showed three fermentation patterns, all bering different from that of group A. Therefore,
L. gasseri can be separated clearly from
L. acidophilus by electrophoresis of LDH and several sugar fermentation tests.
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