Isolation, characterization, and identification of endophytic bacteria by 16S rRNA partial sequencing technique from leaves of carica papaya and its potential as an antioxidant

A study about the Carica papaya plant has been reported producing antioxidants. The secondary metabolites can be isolated from plants and endophytic bacteria that are symbiotic with papaya plants. The endophytic mycobacteria have many advantages to produce bioactive compounds. This study aims to isolate the endophytic microbes which are symbiotic with papaya, obtaining data of antioxidant activity with the DPPH method and obtaining phytochemical screening qualitative data of secondary metabolites production of the endophytic bacteria. The results from this study are isolated endophytic bacteria which are symbiotic with papaya leave, named Q1. Obtained bacterial isolate has staphylococcus shape and is a type of gram-negative bacteria. The antioxidant activity of secondary metabolites of endophytic bacteria isolates using the DPPH method has IC50 of 22.472 ppm. Phytochemical screening shows that the production of secondary metabolites of endophytic bacteria which were isolated from papaya leave contains alkaloids, flavonoids, tannins, and saponins. Genotypic identification is done by isolation and purification chromosomal DNA using the helix saponin approach, then amplification fragments of 16S rRNA gene with PCR, electrophoresis of 16S rRNA gene, sequencing with Sanger method and phylogeny construction with a distance-based method. The study shows Q1 has the closest correlation with Pseudomonas deceptionensis, Pseudomonas endophytic, Pseudomonas psychrophile, Pseudomonas fragi ATCC 4973, Pseudomonas fragi NBRC 3458 from Pseudomonas genus.