Enhancement of phenolic antioxidants production in submerged cultures of endophytic microorganisms isolated from achachairu (Garcinia humilis), araçá-boi (Eugenia stipitata) and bacaba (Oenocarpus bacaba) fruits

In recent years, there is a growing interest in the characterization and identification of microorganisms from different habitats due to their potential as producers of bioactive compounds. The objective of this work was to isolate endophytic strains present in the fruits of achachairu, araçá-boi and bacaba, and to evaluate their potential in production of bioactive compounds. The microorganisms were isolated and identified by the MALDI-TOFMS system, where the main strains identified were of the genera Candida, Rhodotorula and Ochrobactrum. Among the different strains isolated, Rhodotorula glutinis showed the best performance as it presented the highest production of bioactive compounds while in various residues tested, bacaba fruit residue was the best. The process optimization was performed by applying a Plackett-Burman design which leads to conclude that the medium pH and yeast extract were the two principal factors which influenced the fermentation process, leading to a maximum yield of 887.55 ± 3.61 mg GAE/100 g. In addition, when the unfermented and the fermented residue of bacaba were compared, the UHPLC-QqQ-MS/MS analysis indicated an increase in chlorogenic acid (460.00%), catechin (94.75%) and rutin (27.53%) compounds, while, the antioxidant capacity presented an increase in ORAC (118.62%), FRAP (90.32%) and ABTS (39.25%) in fermented products.