| Summary: | The outbreak of leaf blight disease in Malaysia affects the sustainability of rice production in supporting the growing population. Bactronophorus thoracites is a wood-boring shipworm with high protein and possesses numerous bioactive compounds. The present study investigated the effects of enzymatic hydrolysis for generating molluscs protein hydrolysates (MPH) from B. thoracites and their efficacy against rice pathogens. The inhibition percentage against rice pathogens was significantly (p<0.05) increased when enzyme concentration was increased from 1.75% to 2.05% (w/v) but slightly decreased at a concentration exceeding 2.35%. The inhibition percentage was also found to increase when the temperature increased to 55°C. However, the hydrolysis at 65°C produced a lower inhibition percentage. Prolonging the incubation time from 120 to 240 minutes significantly (p<0.05) increased the inhibition percentage. The inhibition percentage of hydrolysates was significantly (p<0.05) increased when pH increased from 9.0 to 9.5. However, increasing pH to 10.0 resulted in a reduction in inhibition percentage. Subsequently, the MPH with optimum condition (2.05% w/v, 55°C, 240 min and pH 9.5) was lyophilised and analysed for antimicrobial activities. The MIC and MBC values for MPH were 500 μg/mL and 1000 μg/mL against P. ananatis and 250 μg/mL and 1000 μg/mL against P. stewartii. The zones of inhibition value for MPH were 20.76 mm (1000 μg/mL) and 11.53 mm (500 μg/mL) for P. ananatis and 21.1 mm (1000 μg/mL), 14.03 mm (500 μg/mL) and 8.16 mm (250 μg/mL) for P. stewartii. At MIC, 2 MIC, and 4 MIC, the MPH exhibited a longer lag phase. Nonetheless, at a lower MIC concentration, a progressive rise in bacterial growth for P. ananatis and P. stewartii at 12 hours was observed. This study shows that enzymatic hydrolysis using alcalase can produce potential antimicrobial agent applicable to the agricultural sector. © 2022 Malaysian Society for Biochemistry and Molecular Biology. All rights reserved.
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