RESUMEN
It has been shown that vitamin B12 in fermented food is synthesized by a wide range of bacteria. Miang is a native food product made from whole leaves which is commonly consumed mainly in the Northern part of Thailand. Studies on 48 sample of Miang showed that they contained relatively high vitamin B12 content, ranged from 3.9 to 30.1 ng/g. Miang Som contained the highest vitamin B12 while Miang Van had the lowest vitamin B12 content. Three species of bacteria, i.e., Bacillus subtilis, B. megaterium and B. sphaericus were isolated from 5 samples of Miang. Re-inoculation of these species of bacteria into the broth, medium for vitamin B12 production and soybean showed that B. subtilis could not produce vitamin B12 in these media. Only B. megaterium and B.sphaericus synthesized vitamin B12. This is the first report to show that B.sphaericus has such ability.