Abstract: L-carnitine is produced by bringing apocarnitine into contact with hydrase produced by a strain of Enterobacter in an aqueous medium having a pH of 4-10 at a temperature of 20.degree.-60.degree. C., whereby apocarnitine is converted to L-carnitine.

Abstract: Novel 1,5-benzothiazepine derivatives having the formula; ##STR1## (wherein R.sub.1, R.sub.2 and R.sub.3 each denotes hydrogen, a halogen, a lower alkyl group, a lower alkoxy group or a hydroxy group; R.sub.4 denotes a lower alkyl group, an allyl group, a lower alkoxyalkyl group, a lower alkyl group substituted with a hydroxy group or a halogen, a lower alkylaminoalkyl group or a morpholino lower alkyl group; X denotes a halogen or hydrogen) are produced from corresponding 1,4-benzothiazine by a ring expansion reaction with trimethylhalosilane, hydrogen peroxide and water. The derivatives have analgesic, antipyretic and antiarrythmic activities.