Nisin is produced commercially in the UK by Aplin and Barrett
Ltd, 15, North Street, Beaminster, Dorset, DT6 3JZ. They have
a sister company in the US too. Try talking to Joss
Delves-Broughton, their Technical Services Manager; he's very
helpful. Otherwise, try reading the ATCC catalogue, antibiotic
producing strains should be listed.