Novel Haloalkaliphilic Nitrile-Degrading Bacteria From Soda Lake Soil of Rift Valley Kenya

Nitrile biotransformation has garnered significant attention in recent years due to its widespread applications in various industries. This study is aimed at investigating the ability of haloalkaliphilic bacteria from extremely haloalkaline lakes in Kenya to produce unique nitrilases with nitrile-degrading potential.

A combination of enrichment and isolation was done on a mineral supplemented with either butyronitrile or isobutyronitrile, colorimetric assays, nesslerization method, Bertholet reaction, and molecular characterization.

Sixty bacterial isolates were recovered, of which 14 exhibited 6 nitrilase and 8 nitrile hydratase enzyme activities. The isolates, affiliated with Bacillus agaradhaerens, Bacillus halodurans, Bacillus xiamenensis, Bacillus cellulosilyticus, Nesterenkonia alba, Nesterenkonia aethopica, Nesterenkonia sp. YIM, Alkalilimnicola sp. AKP2, and Alkalilimnicola haloduran species, demonstrated optimal growth at pH 8.0-9.0, 5% salt concentration, and 28°C-40°C temperature. Notably, the nitrilase and nitrile hydratase enzymes exhibited optimal pH activity at 7.0-7.5.

This study identifies novel bacterial isolates from Kenyan soda lakes with the ability to produce nitrilase and nitrile hydratase enzymes, which can be utilized for the hydrolysis of nitrile to carboxylic acid, ammonia, and amide.

The identification of bacterial strains capable of degrading nitriles into acids and amide compounds that are environmentally safe and beneficial to the green industry highlights a promising approach for mitigating the harmful effects of toxic nitriles in the environment. Biodegradation of nitriles by bacteria from soda lakes offers a sustainable solution to reduce ecological damage. Techniques such as enzymatic assays, colorimetric methods, the Berthelot reaction, and the two-step nesslerization method are essential for isolating and characterizing nitrile-degrading bacteria. The discovery of these biocatalysts not only advances green catalyst research but also holds significant potential for applications in organic synthesis, biotechnology, and environmental remediation.