CHARACTERIZATION OF NATURAL ISOLATE LACTOBACILLUS-ACIDOPHILUS BGRA43 USEFUL FOR ACIDOPHILUS MILK-PRODUCTION

Lactobacillus acidophilus BGRA43 was selected from a set of human orig in isolates of Lact. acidophilus strains for the highest growth rates and antagonistic effect against both Gram-positive and Gram-negative b acteria. The strain BGRA43 also exhibited an inhibitory effect on the growth of Clostridium sporogenes. Inhibition of this strain seems to b e due to lactic acid production rather than hydrogen peroxide or bacte riocin. Growth of Lact. acidophilus BGRA43 in non-fat skim milk for 6 h at 37 degrees C resulted in a lowering of the pH value to 4.53. Besi des the fast acidification, this strain generated a high viscosity of skim milk. These characteristics make the strain BGRA43 attractive for acidophilus milk production. Lactobacillus acidophilus BGRA43 produce s an extracellular proteinase. Whole cells efficiently degraded casein for 3 h at 37 degrees C especially alpha- and beta-casein fractions. Total DNA isolated from the strain BGRA43 did not show any hybridizati on with lactococcal proteinase probes indicating that this strain prod uces a distinctive proteinase.