Preliminary analysis of endophytic plant growth promoting (PGP) methylobacterium sp. Isolated from palm oil (Elaeis guineensis) leaves

Abstract

The genus Methylobacterium is known for its pink- pigmented facultative methylotrophs (PPFMs). They are able to utilize methanol emitted from plants and in return produce plant growth promoting substances. The genus Methylobacterium can be found in diverse habitats and they are known particularly for their close association with plants. The aims of this study are to isolate and characterize endophythic Methylobacterium sp. from palm oil leaves. Isolation of Methylobacterium sp was conducted using Ammonia Mineral Salts (AMS) agar supplemented with methanol. Three isolates were selected namely ENPM1, ENPM2 and ENPM3. Production of IAA by the selected isolates was evaluated under different concentration of L-tryptophan as an inducer. It was observed that the amount of(IAA) produced increased when higher concentration of tryptophan was used and ENPM1 recorded the highest amount of IAA production (1.930 μg/mL) at the 1000 μg/mL concentration of L-tryptophan. The ability to solubilized inorganic phosphate was investigated using Solubilisation Index (SI) assay on phosphate solubilisation media (PSM). The largest clear zone formation on PSM agar was shown by ENPM3 with the SI 1.5. As for nitrogen fixation, the growth of the selected isolates on two nitrogen free media namely Burk's and Jensen media indicates potential nitrogen fixing activity.