Isolation of nitrogen fixing bacteria from sea water sample

In marine environments, the availability of nitrogen are generally limited. Therefore, nitrogen fixing prokaryotes (diazotroph) can convert N₂gas into ammonium by nitrogen fixation process and provide significant input of N into the oceans. Recent studies shows that free living N fixing bacteria have a great potential to become biofertilizer. However, their activity and regulation in the water column is largely unknown. In this thesis, molecular and microbiological methods were used to study the possible free-living N fixer isolated from the sea water around the Kelantan Beaches. Bacteria from the surface of sea water were isolated on N free medium which is selective agar for isolating the possible free living N fixer. Colony morphology of the isolates were observed through the single colony formed on NA. Cellular morphology of the selected isolates from the Gram staining was observed under the microscope. PCR amplification of three selected isolates (A6, Al 1, C7) were carried out for molecular characterizations through the amplification of 16S rDNA and nifH genes. The experimental results from the studies showed the .e xpected amplified product of 16S rDNA gene approximately 1,400 bp were obtain while for nifH gene does not obtain the targeted amplified product which is 380 bp.