Docosahexaenoic Acid (DHA)-Rich Lipid Production by Aurantiochytrium sp. SW1 using Pineapple Peel Waste as an Alternative Carbon Source

Thraustochytrids such as Aurantiochytrium sp. have drawn the attention of researchers and industries due to their ability to produce high-value polyunsaturated fatty acids (PUFAs), especially docosahexaenoic acid ( DHA , C22:6 omega-3) from its total fatty acids. However, the requirement for expensive substrates, particularly refined carbon sources during the cultivation process, has contributed to the increased commercialization costs of DHA from thraustochytrids. Therefore, in this study, the potential use of pineapple peel waste (PPW), which is among the major agricultural wastes in Malaysia, as a cheaper alternative carbon source for DHA production from Aurantiochytrium sp. SW1 was investigated. Considering that PPW contains relatively complex lignin, cellulose, and hemicellulose, autoclave, acidic, and alkaline treatment methods at different concentrations were examined to obtain the optimal sugar content from PPW. The results showed that autoclave treatment yielded the highest sugar concentration (39.6 f 0.39 g/L) significantly (p<0.05), compared to acidic and alkaline treatments, each of which could extract sugar within the range of 31-38 g/L. Subsequently, the ability of Aurantiochytrium sp. SW1 to utilize all PPW hydrolysates as a sole carbon source was compared. It was found that the use of PPW hydrolysate with 100 mM H2SO4 treatment along with additional nutrients produced the maximum biomass (7.74 f 0.39 g/L) significantly (p<0.05), and outstanding lipid content (60.7 +/- 3.04%) was obtained when SW1 was cultured using autoclaved PPW hydrolysate without nutrient supplementation. The maximum DHA production (0.68 +/- 0.034 g/L) was achieved when Aurantiochytrium sp. SW1 was cultured using PPW hydrolysate with 100 mM H2SO4 treatment along with additional nutrients, which was 10-35% higher compared to production using other PPW hydrolysates. This study could serve as a foundation towards cheaper DHA production from thraustochytrids using PPW as an alternative carbon source.