Experiments on Growth Media for Lactobacilli

Cox, Christopher; Briggs, Mary

doi:10.1111/j.1365-2672.1954.tb02019.x

Cited by 7 publications

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“…The contemporary use of media more adequately designed to meet the nutritional requirements of as many different Lactobacillus types as possible (e.g. Cox & Briggs, 1954) considerably reduces the chance of such selective action by the medium.…”

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The Stability of Lactobacillus Strains

Davis

Hayward

1955

Journal of General Microbiology

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SUMMARY: Reported changes of pure strains of Lactobacillus from the heterofermentative to the homofermentative type, with concomitant changes in many characters of recognized taxonomic importance, were investigated. No evidence was obtained that such gross variations occur. Inadequate initial purification and subsequent contamination between strains of different physiological types, were found to produce effects which could be mistaken for such changes.The literature contains many allusions to the morphological and physiological variability of Lactobacillus in artificial culture. Most of these reports concern minor variations in, for instance, fermentation reactions ( Rosebury, Linton & Buchbinder, 1929 ;McIntosh, James & Lazarus-Barlow, 1922, 1924. In recent years such variations have been recognized as of little taxonomic importance and do not impede the accurate classification of lactobacilli.Although Cannon (1924) stated that no appreciable variation in fermentation reaction powers occurred as a result of prolonged culture of lactobacilli, Howitt (1930) regarded prolonged culture as a necessary stabilizing process, without which reliable classification could not be attained . Harrison (1942u, b) reported a type of variation in the physiological characters of oral Lactobacillus strains during the course of prolonged artificial culture which appeared to support Howitt's theory and was clearly of major taxonomic importance.Harrison (1942 a) classified oral lactobacilli into two main types, groups A and B, on the basis of mannitol and sorbitol fermentation and acid production in milk. In the light of modern studies it is almost certain that group A represented the homofermentative L . cusei and group B, the heterofermentative L. ferrnenti (Davis, 1955). Harrison (19423) claimed that group B strains (mannitol-and sorbitol-negative) tended to acquire the morphological, physiological and serological characteristics of group A when maintained for some time in artificial culture. Although this apparent change from the group B to the group A type was observed in many strains, Harrison only found one group A strain which changed to the group B type. Possible

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