Abstract:

A Lactobacillus fusant with high activity was constructed through electro-fusion between L. helveticus SR288 with slim-producing activity and L. bulgaricus NR902 with acid-producing activity. Results indicated that the optimal electro-fusion parameters were alternative electric field intensity 300 V/cm, impulse intensity 6 kV/cm, impulse time 40 μs, and impulse number 4. The obtained fusion strain revealed excellent genetic stability up to 10 generations. Biological activity tests suggested that the fusant was superior to parental strains in acid-producing activity, apparent viscosity, and water-holding capacity.

Key words: Lactobacllus helveticus, Lactobacllus bulgaricus, protoplast, electron fusion, activity