Effect of Cassava-Derived Microorganisms on Cyanide Detoxification and the Sensory Properties of Fermented Cassava Products

Cassava utilization as food and feed is constrained by its high levels of cyanogenic glycosides and low protein content. This study aimed to isolate lactic acid bacteria (LAB) capable of tolerating and degrading hydrogen cyanide (HCN) from fermented cassava pulp juice. From 131 isolates obtained from cassava pulp collected at seven sites in Southern Ethiopia, 67 were confirmed as LAB based on morphological, physiological, and biochemical characteristics. Five isolates exhibiting strong HCN tolerance were selected for further evaluation. Survival assessment on media containing 400–800 mg/L HCN showed that isolates La2 and Db2 had the highest tolerance, with survival rates of 47.85% and 44.12% at 800 mg/L. Cyanide detoxification at a 1-mL inoculum level ranged from 44.86%–68%, 50.62%–69.21%, and 84.25%–87% after 24, 48, and 72 hours of fermentation, respectively. At a 2-mL inoculum level, the greatest cyanide reduction after 72 hours was observed in isolates La2 (89.33%) and Cd1 (88.77%). All isolates demonstrated moderate to high detoxification capacity. PCR and 16S rRNA sequencing identified the isolates as Lactobacillus casei (Cd2), Lactiplantibacillus plantarum (La2, Db2), and Lactobacillus plantarum (La6, Cd1). Overall, Lactiplantibacillus plantarum strain OM108155.1 (Db2) and Lactobacillus plantarum strain b36 (La6, Cd1) were the most effective cyanide-reducing strains after 72 hours, indicating their potential for improving the safety of cassava-based foods and feeds.