Dichlorophenolindophenol-linked formate dehydrogenase of the methanol-utilizing Mycobacterium gastri MB19

2,6-Dichlorophenolindophenol (DCIP)-linked formate dehydrogenase activity has been demonstrated for the first time in the cell-free extract of a methylotrophic mycobacterium, Mycobacterium gastri MB19. The enzyme was produced when the strain was cultivated with methanol, glucose or mannitol as a carbon source, whereas no enzyme production occurred with other multi-carbon compounds. The enzyme was located in the particulate fraction. Although the enzyme was unstable on preservation at 4° C in potassium phosphate buffer (pH 7.0), it was stabilized under acidic conditions (pH 5.0). Glycerol and EDTA were also effective for the enzyme's stability. The optimum pH and temperature for the enzyme's activity were 7.0° and 55° C, respectively.