Nitrile hydrolysing activities of deep-sea and terrestrial mycolate actinomycetes

Nitrile metabolising actinomycetes previously recovered from deep-sea sediments and terrestrial soils were investigated for their nitrile transforming properties. Metabolic profiling and activity assays confirmed that all strains catalysed the hydrolysis of nitriles by a nitrile hydratase/amidase system. Acetonitrile and benzonitrile, when used as growth substrates for enzyme induction experiments, had a significant influence on the biotransformation activities towards various nitriles and amides. The specific activities of selected deep-sea and terrestrial acetonitrile-grown bacteria against a suite of nitriles and amides were higher than those of the only other reported marine nitrile-hydrolysing R. erythropolis, isolated from a shallow sediment. The increase of nitrile chain length appeared to have negative influence on the nitrile hydratase activity of acetonitrile-grown bacteria, but the same was not true for benzonitrile-grown bacteria. The nitrile hydratases and amidases were constitutive in 10 of the 16 deep-sea and terrestrial actinomycetes studied, and one strain showed an inducible hydratase and a constitutive amidase. Most of the deep-sea strains had constitutive activities and showed some of the highest activities and broadest substrate specificities of organisms included in this study.