The Production of Benzaldehyde by Rhizopus oligosporus USM R1 in a Solid State Fermentation (SSF) System of Soy Bean Meal: Rice Husks

The cultivation of Rhizopus oligosporus USM R1 for the production of benzaldehyde, a bitter cherry almond flavour was performed using soya bean meal and rice husks as the substrates. The identification of R. oligosporus USM R1 was performed based on the observation made under light microscope and scanning electron microscope (SEM). The optimum conditions for the SSF in a 250-ml Erlenmeyer flask system were 40% (v/w) water content, substrate particle size of 0.7 mm; inoculum size of 1 x 10^5 spores/g substrate; incubation temperature of 30C; substrate amount of 7 g and the ratio of soy bean meal: rice husks of 50:50%. A maximum benzaldehyde production was obtained when the substrate was agitated after 48 hour for a 96 hour fermentation time. The highest benzaldehyde production obtained after 96 hour cultivation was 5.47 mg g-1 substrate. The supplementation of carbon and nitrogen sources in the substrate mixture revealed an enhancement in the growth and benzyldehyde production. A maximum production of benzaldehyde was obtained with the supplementation of L-phenylalanine, a precursor for benzaldehyde biosynthesis which gave 38.69 mg benzaldehyde/g substrate. This is approximately 6-folds higher compared to the substrates without the supplementation of L-phenylalanine.