THE CHARACTERIZATION OF LACTOBACILLI FROM CHEDDAR CHEESE: I. AN EVALUATION OF PHYSIOLOGICAL AND BIOCHEMICAL TESTS

Abstract

Characterization studies were conducted on 230 cultures of lactobacilli isolated from Canadian Cheddar cheese, and on an additional 15 named cultures from various sources. Preliminary investigation included reactions with 19 carbohydrates, yeast glucose litmus milk, and arginine, hippurate, and aesculin broths. This resulted in the appearance of six major groups, tentatively designated as Lactobacillus plantarum, Lactobacillus casei, Lactobacillus helveticus, Lactobacillus brevis, Lactobacillus fermenti, and an unclassifiable group. Subgroups of the divisions were noted. Sixty-eight cultures were chosen for detailed study. Tests performed included the production of catalase, nitrite, hydrogen sulphide, indole, and polysaccharide; the hydrolysis of starch, gelatin, Tweens 40 and 60, polypectate, and casein; and tolerance of growth temperatures, sodium chloride, and phenol. Titratable acidity in skim milk was determined, and morphological studies were carried out. Accumulated data indicated that the group previously designated as L. helveticus, and the unclassified group, consisted of variants of L. plantarum, L. casei, or intermediates.