ABSTRACT
Growth of Lactobacillus plantarum AA135 in MRS broth at 30 degrees C yielded maximal plantaricin AA13 activity of 10000 AU/ml at pH 3.8 after 16 hours. Maximal activity (10000 AU/ml) of plantaricin AA13 was recorded in MRS broth at initial pH of 5 or 5.5. Optimal production (10000 AU/ml) was recorded in the presence of tryptone (20 g/l), a combination of tryptone plus meat extract (1:0.6) or tryptone with yeast extract (1:0.6) as sole nitrogen source. Growth of Lactobacillus plantarum AA135 in the presence of 20 g/l glucose yielded bacteriocin activity of 10000 AU/ml. Moreover, when 40 g/l glucose was added, the plantaricin AA13 levels doubled to 20000 AU/ml. Concentrations of 5, 10 and 20 g/l K2HPO4 lowered bacteriocin activity by 60%. Supplementing MRS with 1 g/l or more glycerol repressed bacteriocin production. Maximal activity of 20000 AU/ml was recorded in MRS supplemented with Vitamin DL-6,8-thioctic acid.
