Isolating Miliusa velutina endophytic bacteria to generate antioxidants and optimizing culture conditions for antioxidant production

•Miliusa velutina should be conserved and protected since it belongs to an endangered or critically endangered genus.•Endophytes associated with the plant can reduce harvesting and are promising sources of bioactive compounds.•Pantoea sp., can generate bioactive compounds and optimal conditions to boost bacterial productivity was identified.•Provide knowledge about endophytic bacteria producing bioactive compounds and the fermentation of endophytic bacteria.•Modify to apply the bacterium to vast fermentation to develop novel drugs and functional foods produced by fermentation. Miliusa velutina (MV) antioxidants are being used for food or medical purposes, However, the use of the plant is limited since some Miliusa genus are endangered or critically endangered species. This study aims to find the MV endophytic bacteria that can produce the antioxidants (total phenol content (TPC), total flavonoid content (TFC), total antioxidant capacity (TAC), reducing power (RP); and ferric reducing antioxidative power (FRAP)) and their optimum fermentation condition by utilizing morphology, SEM, 16S rRNA, and CCD model. Results found that 44 endophytic bacterial strains isolated from various parts of the plant showed promising antioxidative activities, with the highest produced by Pantoea sp. MV-R3. The model indicated that 15.41 g/L of glucose in pH 7.72 at 29.19 °C for 46.54 h was the optimal fermentation condition. The maximal activities reached 89.1 % to 129.0 % compared with the predictions. The activities of TPC, TFC, TAC, RP, and FRAP were 41.54 ± 7.69, 33.18 ± 4.55, 207.36 ± 30.89, 119.55 ± 14.34, and 57.02 ± 9.15 mg per mL, respectively. Hence, the MV endophyte and its optimum fermentation condition were successfully identified.