The deamidation of nicotinamide by bacteria

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Abstract
Washed suspensions and cell-free extracts of Lactobacillus arabinosus 17-5 contain an enzyme which hydrolyzes nicotinamide to ammonia and nicotinic acid. The enzyme does not attack other naturally occurring nicotinamide derivatives such as diphosphopyridine nucleotide, nicotinamide riboside and nicotinamide ribotide. The pH opt. of the enzyme is between pH 5 and 8. The apparent Mlchaelis constant is 0.0015 M. The formation of nicotinamide deamidase in Lb. arabinosus and Lb. bulgaricus is not affected by the composition of the growth medium; the enzyme is constitutive. Seven spp. of lactobacilli tested formed the enzyme. With the exception of a strain of Staphylococcus albus. strains of 11 spp. of other bacteria did not possess the enzyme. A modified Koenig reaction was used to estimate the quantity of nicotinic acid in the presence of nicotinamide. The use of the method for identifying and estimating pyridine derivatives is briefly discussed.