Identification of Endophytic Bacteria Producing Red Pigment Isolated from the Holoparasitic Plant Rafflesia arnoldii R.Br from Bengkulu Province

The holoparasitic plant Rafflesia spp. often found on the island of Sumatra, including Bengkulu Province. This plant has been known for a long time as an ethnomedicinal plant to treat various diseases, including stopping internal bleeding and is also used by men as an aphrodisiac. Several studies show that secondary metabolites from the Rafflesia plant have potential as antimicrobial, antioxidant, and anticancer. Rafflesia has a distinctive red color which is thought to produce red pigment as a potential secondary metabolite. However, this plant is protected under government regulations and is a rare plant in the critically endangered category according to the IUCN. So this plant cannot be taken freely. Therefore, the alternative is to isolate endophytic bacteria from Rafflesia arnoldi. This endophytic bacteria is thought to be able to produce metabolite compounds in the form of the same red pigment as its host with faster growth. This study aimed to isolate and characterize endophytic bacteria from Rafflesia arnoldii with the ability to produce red pigment. Bacterial isolation was performed using the dilution method, followed by purification and identification of the growing isolates based on morphological characteristics, Gram staining, and biochemical tests. A total of 20 endophytic bacterial isolates were successfully obtained, among which two isolates, designated ER1 and ER2, exhibited red colony morphology and demonstrated red pigment production, as indicated by a color change of the medium to red. Both isolates were identified as Gram-negative bacilli. Identification based on Bergey’s Manual of Determinative Bacteriology suggested that isolate ER1 is closely related to the genus Serratia marcescens, while isolate ER2 is closely related to the genus Enterobacter cloacae.