Nitrile hydratase, which occurs abundantly in cells of Rhodococcus rhodochrous Jl isolated from soil samples, catalyzes the hydration of 3-cyanopyridine to nicotinamide. By using resting cells, the reaction conditions for nicotinamide production were optimized. Under the optimum conditions, 100% of the added 12 M 3-cyanopyridine was converted to nicotinamide without the formation of nicotinic acid, and the highest yield achieved was 1,465 g of nicotinamide per liter of reaction mixture containing resting cells (1.48 g as dry cell weight) in 9 h. The nicotinamide produced was crystallized and then identified physicochemically. The further conversion of the nicotinamide to nicotinic acid was due to the low activity of nicotinamide as a substrate for the amidase(s) present in this organism. Nitrile hydratase catalyzes the hydration of nitriles to amides, whereas nitrilase catalyzes the direct cleavage of nitriles to the corresponding acids and ammonia. Thus, nitrile hydratase can be clearly distinguished from nitrilase by the mode of nitrile degradation. We previously proposed a new enzymatic production process for acrylamide, applicable on an industrial scale, involving nitrile hydratase as a catalyst (3). Pseudomonas chlororaphis B23 and Brevibacterium sp. strain R312 were selected as favorable strains (3, 6). Indeed, P. chlororaphis B23 produces more than 400 g of acrylamide per liter of reaction mixture from acrylonitrile under suitable conditions. Thus, very recently, the use of the P. chlororaphis B23 nitrile hydratase as a catalyst for the industrial production of acrylamide, an important chemical commodity, was started. Recently, we found that Rhodococcus rhodochrous J1 produces nitrile hydratase or nitrilase selectively, depending on the culture conditions (T. Nagasawa, M. Kobayashi, and H. Yamada, Arch. Microbiol., in press). Although the nitrile

The nitrilase which occurs abundantly in cells of Rhodococcus rhodochrous Jl catalyzes the direct hydrolysis of 3-cyanopyridine to nicotinic acid without forming nicotinamide. By using resting cells, the reaction conditions for nicotinic acid production were optimized. Under the optimum conditions, 100% of the added 3-cyanopyridine could be converted to nicotinic acid, the highest yield achieved being 172 mg of nicotinic acid per 1.0 ml of reaction mixture containing 2.89 mg (dry weight) of cells in 26 h.

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Extracellular alpha galactosidase (alpha galactnsidasc galactol~ydl-olase EC 3.2.1.22) producing bacteria wcre isolated fiom soil hy the enrichment culture techniyue using raffinose as the induce].. Six hacterial species were isolated hy this method hased on their morphological characteristics. Their raffinose ut.ilization rate varied fi-om 11 mgAl to 27 mgh. Enzyme acivity present in the supernatant varied from 2-11 mU/ml. Two of the isolated species did not show ally alpha galactosidase activily. Three hacterial species having 11ig11 alpha galactosidase activity were identified as K l c b s i ~l b u ~~~~. u ~~r ~~. o ~~. i i ~e ~Cifrobacter fieu~rtlii. andEsi;Ir.crichiix roli hy their colony morpholo~y and biochemical tests. They were cult,ivated a t different pH values with peptone and ammonium sulpllate as the nitrogen source. From t,l~ose studies, it was shown that the highest extracellular alpl~n galact,osidase activity of 14.7 mUIm1 could he obtained h.om Citmboclr!r frer1.17,rlii after 1811 o f cultivation in a culture medium with an i.nitial pH of 8 containing peptone as t l ~e nitrogen source. Extracellulai~ enzyme production was increased up to 1SmUIn1l hy the cullivation of Citrobur:ter f'rrlrlrdii in pH8 pllosphate Bufl'er li)~. 3611 with peptone as the nitrogen source.