Nisin

Nisin is a polycyclic antibacterial peptide, a natural antimicrobial agent, formed by fermentation using the bacterium Lactococcus lactis. It is one of the few commercial food preservatives which are not chemically synthesized. Nisin is obtained by culturing milk or dextrose with L. lactis, similar to the the yoghurt-making process.
As a food additive, nisin has an E number of E234.

The benefits of Nisin are

• Cancer : Scientists found feeding rats a ‘nisin milkshake’ killed 70 to 80 per cent of head and neck tumor cells after nine weeks – and extended survival rates.
• Combat antibiotic-resistant bacteria : scientists found nisin fights deadly bacteria, including antibiotic-resistant MRSA. Nisin has a fairly broad-spectrum effect on gram-positive bacteria, successfully inhibiting listeria monocytogenes, staphylococcus aureus, clostridium botulinun and lactic acid bacteria which are commonly associated with food spoilage. It has essentially no effect on gram-negative bacteria, moulds or yeasts, by itself.