No abstract

The composition of a synthetic medium supporting the growth of lactobacilli is given (Table 1). The medium, containing glucose, amino acids, vitamins, mineral salts, purines and pyrimidines, allows the study of nutritional requirements of different strains of lactobacilli under identical environmental conditions. It was found that all the strains tested needed L‐glutamic acid, L‐valine and L‐leucine, and a group of them also required L‐arginine, L‐tyrosine and L‐tryptophan. Some strains required vitamins, e.g. L. bulgaricus (pantothenic acid), L. fermenti (pantothenic acid and niacin). These results are compared with those found by others employing different media.

Summary. We demonstrated that a washed suspension of E.coli does not subsist in Vittel mine• water more than one to four days depending on the size of the inoculum.On the other hand, P.vulgaris and especially K.pneumoniae can survive much longer in this water. Thereafter we showed that the longevity of E.coli and S.faecalis introduced into mineral water by fecal matters may be 1.5 months if the amount of feces is too small to allow multiplication of the bacteria, and 3 -4 months if the amount of feces is sufficient to allow multiplication.Our results also show that various organic products introduced into mineral water have the same protective effect as feces upon E.coli and S.faecalis, notably if they allow these bacteria to proliferate.The importance of the time interval between bottling the water and sampling for bacteriological analysis is discussed with the aim of understanding the significance of the presence or absence of test-bacteria as indicator of fecal pollution of bottled mineral water.

Adult gnotobiotic mice and rats, monoassociated with a homofermentative strain of Lactobacillus sp. of intestinal origin, were fed either a commercial rodent chow A or a semisynthetic diet B. Similar numbers of lactobacilli were established in their gastrointestinal tract whatever diet they ate. The lactobacilli were established in the digestive tract of the newborn of A mothers at 2 days but were hardly established in mouse or rat pups of A mothers than in their mouse homologues. Comparative analysis of milk lipids in the A and B series showed a linoleic acid (18:2 n-6) content which was three times higher in the B than in the A series. Two diets S and H differing only by their lipid fractions, which, respectively, presented the same fatty acid compositions as lipids from diets A and B were then given to two others lots of Lactobacillus monoassociated mice. The establishment kinetics of the strain were the same in the mouse pups of these two lots precedently observed in the B series. The difference observed in the establishment kinetics of the Lactobacillus strain in the digestive tract of suckling gnotobiotic mice was thus attributed to other dietary factors than the fatty acid composition of the maternal diet.