Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt 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 Romy Gleyse Chagas Barros, Christean Santos de Oliveira, Layana Taynara Santos Oliveira, Ubatã Corrêa Pereira, Taís Oliveira Matos Silva, Marina Denadai, Narendra Narain * Laboratory of Flavor & Chromatographic Analysis, PROCTA, Federal University of Sergipe, 49100-000, São Cristóvão, SE, Brazil ARTICLE INFO Keywords: Microorganisms Agroindustrial residues Fermentation Bioactive compounds ABSTRACT 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 po- tential 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. 1. Introduction Endophytic organisms are defined as microorganisms that colonize living tissues, internal to plants, without causing any macroscopically visible symptoms. Normally, these are located in the leaves, flowers, fruits, roots, stems, seeds, and even within nodules of legumes (Grondin et al., 2015). Previous studies have shown that some endophytic mi- croorganisms have a symbiosis relationship with the host plant, which triggers a fundamental role in promoting growth, resistance to stress, degradation of pollutants, production of phytohormones, acquisition of minerals, nitrogen fixation and natural biocontrol of plant pathogens (Rodriguez, Gonzalez, & Giordano, 2016). The various research studies undertaken on interactions between plant materials with their host organisms, have shown the development of new antibiotics, antimycotics (Felício et al., 2015), im- munosuppressants and anti-cancer compounds (Trapp, Kai, Mithöfer, & Rodrigues-Filho, 2015) isolated and purified from endophytic organ- isms. Fermentation is an ancient process that aims to develop biotechnological products (Doblado, Frias, Muñoz, & Vidal-Valverde, 2003). This bioprocess has been applied for the production and ex- traction of bioactive compounds in the food, chemical and pharma- ceutical industries. In the last years, fermentation was carried out to increase the content of phenolic compounds in several types of food, especially those obtained from agroindustrial residues (Mirabella, Castellane, & Sala, 2014). The extraction/production of bioactive compounds by fermentation according to Nigam (2009) is an interesting alternative since it is able to provide high quality of extracts with reduced toxicity associated with organic solvents. In this process, the bioactive compounds are gener- ated in the form of secondary metabolites produced by microorganisms after its growth is completed. The aim of this work was to isolate strains of endophytic micro- organisms from the fruits achachairu (Garcinia humilis), araçá-boi (Eugenia stipitata) and bacaba (Oenocarpus bacaba) and to evaluate their potential for liquid fermentation, aiming the production of bioactive compounds by using the agro-industrial residues of these fruits. https://doi.org/10.1016/j.lwt.2019.05.046 Received 25 June 2018; Received in revised form 9 April 2019; Accepted 9 May 2019 * Corresponding author. E-mail address: narendra.narain@gmail.com (N. Narain). LWT - Food Science and Technology 111 (2019) 370–377 Available online 09 May 2019 0023-6438/ © 2019 Elsevier Ltd. All rights reserved. T