Inhibition of Bacillus licheniformis LMG 19409 from ropy cider by enterocin AS-48

To determine the activity of enterocin AS-48 against ropy-forming Bacillus licheniformis from cider. Enterocin AS-48 was tested on B. licheniformis LMG 19409 from ropy cider in MRS-G broth, fresh-made apple juice and in two commercial apple ciders (A and B). Bacillus licheniformis was rapidly inactivated in MRS-G by 0·5 μg ml⁻¹AS-48 and in fresh-made apple juice by 3 μg ml⁻¹. Concentration-dependent inactivation of this bacterium in two commercial apple ciders (A and B) stored at 4, 15 and 30°C for 15 days was also demonstrated. Counts from heat-activated endospores in cider A plus AS-48 decreased very slowly. Application of combined treatments of heat (95°C) and enterocin AS-48 reduced the time required to achieved complete inactivation of intact spores in cider A to 4 min for 6 μg ml⁻¹ and to 1 min for 12 μg ml⁻¹. D and z values also decreased as the bacteriocin concentration increased. Enterocin AS-48 can inhibit ropy-forming B. licheniformis in apple cider and increase the heat sensitivity of spores. Results from this study support the potential use of enterocin AS-48 to control B. licheniformis in apple cider.