Endophytic phosphate solubilization and potential nitrogen-fixing bacteria in the leaf and root of rice planted on the conventional wetland

Abstract

Endophytic bacteria inhabit internal plant tissue and generally promote plant growth, showing no external sign of infection or negative effect on their host plant. Endophytes play diverse roles including nutrient acquisition, production of phytohormones and siderophores, protection against abiotic stresses. The purpose of this study was to isolate and characterize endophytic bacteria which have the specific capability of the acquisition of nutrients especially Phosphate Solubilizing Bacteria (PSB) and potentially Nitrogen Fixing Bacteria (NFB) from the leaf and root of rice planted on the conventional wetland of Inceptisol. Isolation of endophytic bacteria was conducted by sterilizing the surface of plant samples and then inoculating using the spread plate method on pikovskaya and yeast extract mannitol agar media. The growing bacterial colonies on the media showed that the diversity and population density of endophytic PSB in the root was higher than in the leaf tissue, namely 4 types of isolates with 1,526x105 CFU/g in the root and 2 types of isolates with 0.0395x105 CFU/g in the leaf. On the other hand, the diversity of endophytic potentially NFB in the leaf was higher than in the root tissue namely 5 and 3 types of isolates, but the population density was higher in the root at the level 11,55x105 CFU/g than in the leaf at 5,976x105 CFU/g. The next research is necessary to compare endophytic bacteria from rice planted in inorganic and organic cultivation systems, and continued with the examination of the effect of inoculation of those endophytic bacteria to the targeted crops.