Efficient cyanide degradation by Aspergillus welwitschiae LOT1 isolated from industrial waste

Cyanide is a potent cytotoxin and neurotoxin largely derived from anthropogenic activities and can accumulate in the environment through industrial wastewater, posing serious ecological and health risks. This study evaluated the cyanide degradation capacity of intact Aspergillus welwitschiae LOT1 biomass under varying physicochemical and nutritional conditions. Cyanide degradation refers to the biochemical breakdown of cyanide into simpler compounds, whereas detoxification describes the conversion of cyanide into less toxic metabolites. Cyanide removal by A. welwitschiae LOT1 was influenced by pH, temperature, substrate concentration, inoculum size, and co-metabolites, with optimal degradation occurring at pH 12 (~ 80% efficiency), 50 °C (~ 36%), and an initial cyanide concentration of 60 mM (~ 75%). Agricultural wastes, particularly corn stalk, enhanced degradation efficiency (~ 84%) compared with refined sugars, while the combination of 40 mM cyanide and 40 mM glucose produced approximately 85% degradation. HPLC analysis confirmed substantial cyanide removal and detected formamide, ammonia, and carbon dioxide as detoxification products, supporting an enzymatic transformation pathway. Although alkaline conditions may contribute to abiotic cyanide loss, enhanced removal in inoculated cultures suggests biological involvement. Future studies should focus on the molecular characterisation of degradation enzymes and on the evaluation of A. welwitschiae LOT1 in pilot-scale and field-based bioremediation systems.