# Isolation and Characterization Identification of Edophytic Nitrogen-Fixing Bacteria from Peanut Nodules

## TL;DR

This study isolates and identifies nitrogen-fixing bacteria from peanut nodules in Vietnam for potential use as biofertilizers.

## Contribution

The paper presents the isolation and characterization of novel endophytic nitrogen-fixing bacteria with biofertilizer potential.

## Key findings

- Ten rod-shaped, Gram-negative, non-spore-forming isolates were identified as potential nitrogen-fixing bacteria.
- Most isolates showed salt tolerance up to 5% salinity and temperature adaptability between 25°C and 45°C.
- Three isolates were selected for further study due to their nitrogen-fixing potential and biofertilizer suitability.

## Abstract

This work was carried out to isolate and perform molecular identification and selection of endophytic nitrogen-fixing bacteria (ENFB) to be utilized as biofertilizer. In this research, nodulous samples of peanuts were collected from inside dyke areas, namely, Phuoc Hung of An Phu, An Giang, Vietnam. Ten colonies were isolated from nutrient agar plates containing YMA's medium. All isolates were rod shaped, Gram negative, and no spore creation. Biochemical tests indicated that they were obligate aerobes, catalase, oxidase, urea hydrolysis, well motile ability, and no nitrate reduction. The salt tolerance observed that most survived at 0.5% and 2% salinity (except Enterobacter cloacae subsp. dissolvens strain LMG 2683), while at 4%, only 3 isolates (Bacillus aryabhattai strain CM44, Enterobacter asburiae strain IIWM-JS-07L, and Bacillus songklensis strain KCa6) and at 5% only, 2 isolates survived, namely, Enterobacter asburiae strain IIWM-JS-07L and Bacillus songklensis strain KCa6. The result showed that most of ten ENFB strains could adapt to the range of 25°C and 45°C (except Enterobacter cloacae subsp. dissolvens strain LMG 2683 and Enterobacter mori strain cjy13 at 25°C). Out of ten isolates, three were finally selected for the next studies, which potentially have N-fixing ability and are utilized as biofertilizer in agricultural cultivation.