In vitro Degradation of Extracted Cassava Linamarin by Bacillus Species Isolated from cassava wastewater

Linamarin is the most abundant cyanoglucoside present in cassava cells and may generate the equivalent amount of hydrocyanic acid. This study was aimed to assess degradative capacities of Bacillus pumilus strain WOB3 and WOB7on linamarin. The test organisms for linamarase activity were identified on the basis of phenotype, biochemical properties and 16S rDNA gene sequencing as: Bacillus pumilus strain WOB3 KX774195 and Bacillus pumilus strain WOB7 KX774196. Growth studies showed that the strains grew in all the substrates tested. The doubling times of Bacillus pumilus strain WOB3 and Bacillus pumilus strain WOB7 were 8.25 d and 7.53 d on cassava effluent, 6.30 dand 5.78 d on supplemented cassava effluent, 8.66 dand 9.90 d on waste leachate and 6.30 d and 9.24 d on supplemented waste leachate respectively; with specific growth rates of 0.084 d-1 and 0.092 d-1 on cassava effluent, 0.11 d-1 and 0.12 d-1 on supplemented cassava effluent, 0.080 d-1 and 0.070 d-1 on waste leachate and 0.11 d-1 and 0.075 d-1 on supplemented waste leachate respectively. High-performance liquid chromatographic analysis studies revealed that linamarin degradation by the strains followed a linamarase pathway involving CO2 and HCN as metabolic intermediates. Based on HPLC analysis, linamarin residual concentration at day 12 by the strains WOB3 and WOB7 was 26.73 mgL-1(19.79 %) and 29.79 mgL-1 (21.92 %). These novel features make the bacteria suitable candidates for in-situ application on sites contaminated with cassava processing wastes.