Viability of bifidobacterium longum grown alone or in association with some strains of lactic acid bacteria under refrigeration

الملخص EN

This work was undertaken to characterize the interaction between Bifidobacterium longum DSM 20097 and 6 strains oflactic acid bacteria belonging to Streptococcus thermophilus, Lactococcus lactis subsp.

lactis, Lactobacilllus delbrueckii subsp.

bulgaricus, Lactobacillus casei subsp.

paracasei, Lactobacillus acidophilus and Lactobacillus plantarum.

Bifidobacterium longum was grown in sterilized skim milk supplemented with 2% glucose, 1 % yeast extract and 0.05% L-cysteine hydrochloride either separately or in co-culture with one of the above listed strains of lactic acid bacteria.

Following 18hr of incubation at 37°C, milk cultures were stored at 5±1 °C for 28 days.

Changes in titratable acidity, pH, organic acids, soluble tyrosine, viable counts and antibacteria c 'vity of various milk cultures were monitored at regular intervals during refrigeration storage.

Results reveale a, 10 gum survived better in the presence of Lb.

plantarum, while its viability was drastically declined in the peen of' b.

Bulgaricus.

Among tested lactic acid organisms, Lb.

plantarum proved to be the highest proteolytic or nisf termined in terms of soluble tyyrosine, and the least acid producer.

These activities might be responsible 'reverent of viability of B.

longum during refrigeration storage, Also, combining B.

longum with Lb.

plant m 1 proved the antimicrobial activity of the former against Staphylococcus aureus and Bacillus subtilis a s ssed 13 e well-diffusion agar method