Isolation of Nitrogen Fixing Bacteria from Water Sample

This study was aimed to isolate the nitrogen fixing bacteria from water samples. Through this study, the characterization of the nitrogen fixing bacteria had been classified into morphology and molecular characterization. The sample was collected at Universiti Malaysia Kelantan (UMK) pond and had been grow on Burk's nitrogen free medium. Six potential nitrogen fixing bacteria had been isolated from pond. These isolates are A'A6, A'A8, A'A9, B19, B26 and B33. The growth of isolates on the selective media indicates these isolates capable to fix atmospheric nitrogen. These isolates were characterized through morphology characterization and molecular characterization. All the isolate showed transparent colour after streaking on selective media. Gram staining test was conducted in order to observe the cell morphology of isolates. As a result, A'A6 and B26 were identified as Gram negative bacteria. While four others isolates, A'A8, A'A9, B19 and B33, distinguished as Gram positive bacteria. Biochemical test such as catalase test was carried out in order to know the bacteria able to degrade the hydrogen peroxide in the cell or otherwise. The result obtained show negative for all isolates as there is no rection occur. Motility test also was carried out using S.I.M media. Isolate B26 and A'A9 showed positive motility test which indicates the movement of bacteria. Through the molecular characterization, genomic DNA of the three isolates A'A9, B26 and B33 were extracted. Isolate B26 has higher density of DNA among others isolate. PCR was conducted to amplify 16S rDNA and nifH gene of the isolates. The size of amplification 16S rDNA showed 1.324 kb. The expected size for amplification nifH gene was not successfully obtained as the size obtained 100 bp. This is due to unsuitable primer use and primer dimer occurred during the reaction process. As conclusion, there was nitrogen fixing bacteria found in the UMK pond water and have high potential as biofertilizer.