Avaliação da biossíntese de 2-feniletanol por Kluyveromyces marxianus ATCC 36907 em suco de caju

Abstract

Cashew (Anacardium occidentale L.) is a native fruit from tropical America, which processing to obtain the cashew apple nuts produces a waste of about 90 % of the cashew apple, which is discarded as an agricultural byproduct. Considering the rich nutritional composition, the cashew apple can be used as a substrate for the production of biomolecules, such as 2-phenylethanol (2-PE). 2-PE is an aromatic compound that has a characteristic rose odor and can be used as an additive in the food, cosmetics and perfumery industries. This aroma can be obtained by natural extracts from roses and by chemical synthesis, however, these two production routes bring problems as extraction cost and the toxic by-products formed by the chemical synthesis. Due to these obstacles, biotechnology pathway for 2-PE production has been studied by the scientific community and has shown a promising route. The bioconversion of 2-PE is strongly influenced by the operating conditions, mainly by the supplementation of the medium with L-phenylalanine (L-Phe) and the composition of the culture medium. In this context, the aim of this study is to evaluate the biosynthesis of 2-PE by Kluyveromyces marxianus ATCC 36907 using cashew apple juice as a substrate. In this work, fresh cashew apple juice at the concentration of 131 ± 5.7 g.L-1 of glucose + fructose, and two diluted concentrations of cashew apple juice of 106 ± 1.2 g.L-1 and 74 ± 2.8 g.L-1 were evaluated for 2-PE production. It was also carried out a fed-batch study with the addition of 50 g.L-1 of glucose in 12; 24 and 48 hours. The best results occurred when the culture was conducted using fresh cashew apple juice (131 ± 5.7 g.L-1 of glucose and fructose), with a maximum 2-PE production of 0.84 g.L-1, product yield (YP/S) of 0,0066 g.g-1 and productivity of (QP) 0,0116 g.L-1.h-1. In the fed-batch study, the 2-PE production was 0.86 g.L-1, which did not a present significant difference in relation to the previous study. Furthermore, the effect of supplementation with different L-Phe concentrations (1.0; 3.0; 4.0 and 10.0 g.L-1) was evaluated using fresh cashew apple juice. In this study stage, the results were similar for 3.0; 4.0 and 10.0 g.L-1 of L-Phe concentration in the medium, showing no significant differences in the metabolite production (p>0.05). Considering these results, sugar concentration in the cashew apple juice was shown to be important in 2-PE production, as well as the initial concentration of the precursor L-Phe. Finally, these results show that cashew juice is an unconventional culture medium suitable for the bioproduction of 2-FE by K. marxianus ATCC 36907.