Efficient conversion of extracts from low-cost, rejected fruits for high-valued Docosahexaenoic acid production by Aurantiochytrium sp. SW1

Abstract

Aurantiochytrium sp. has been developed for commercial docosahexaenoic (DHA) production but the production cost remains a major issue due to exorbitant cultivation substrates. In this study, we explore the capacity of locally isolated Aurantiochytrium sp. to produce DHA utilizing low-cost, safe and extensively abundant fruit extracts derived from rejected fruits as alternative carbon sources via development of several biotechnological processes including; (1) simple and cost-effective sugar extraction from the fruit extracts, (2) screening of the potential fruit extracts and (3) process optimization using selected fruit extract to enhance the DHA yield and (4) comparative study of the selected fruit extract with commercial glucose and fructose to evaluate its competency for large scale production. The capability of Aurantiochytrium sp. SW1 to utilize the fruit extracts were screened and results showed that Aurantiochytrium sp. SW1 produced 20–60% higher lipid and DHA when grown in autoclaved assisted Ananas comosus MD2 extracts in comparison to other fruit extracts. In addition, lipid and DHA production cultivated with Ananas comosus MD2 extract was also 15–50% higher than that of commercial glucose and fructose. This superior production of lipid and DHA of Aurantiochytrium sp. SW1 cultivated in Ananas comosus MD2 extract was shown to probably be caused by significant elevation of the key metabolic enzymes involved in lipid biosynthesis, including malic enzyme, glucose-6-phosphate and ATP citrate lyase and the lowering of the reactive oxygen species and lipid peroxidation activities. Efficient DHA biosynthetic capacity of 0.31 (g DHA/g Biomass) was achieved in this study, suggesting Ananas comosus MD2 extract as an ideal alternative carbon source for economic production of DHA by Aurantiochytrium sp.