Effect of cultural conditions on the growth and linamarase production by a local species of Lactobacillus fermentum isolated from cassava effluent

Background This study was designed to investigate the effect of cultural conditions on growth and production of linamarase by a local species of Lactobacillus fermentum isolated from cassava effluent. Isolation and identification of bacteria from cassava effluent were carried out using the culture-dependent method and polyphasic taxonomy, respectively, while screening for cyanide degradation, and the effects of cultural conditions on the growth and linamarase activity of L. fermentum were investigated based on standard procedures. Results A total of twenty-one bacterial isolates were obtained from cassava effluent, and isolate MA 9 had the highest growth of 2.8 × 10 10 cfu/ml in minimum medium, confirmed as safe, identified as Lactobacillus fermentum and selected for further study. The highest growth of 2.498 OD and linamarase activity of 2.49 U/ml were observed at inoculums volume of 0.10 ml at 48-h incubation period, while optimum growth of 1.926 OD and linamarase activity of 1.66 U/ml occurred at pH 5.5. At 37 °C, the optimum growth of 0.34 OD was recorded with the highest linamarase activity of 0.81 U/ml at 30 °C. However, the incubation period of 48 h stimulated an optimum growth of 3.091 OD with corresponding linamarase activity of 1.81 U/ml, while the substrate concentration of 400 ppm favours a maximum growth of 2.783 OD with linamarase activity of 1.86 U/ml at 48 h of incubation. The supplemented of 10 mM calcium ions stimulated optimum linamarase activity of 2.65 U/ml. Conclusion Lactobacillus fermentum could be used as starter culture in cassava fermentation for the production cassava-based product with reduced cyanide content.