Nutrient stoichiometry (N:P) controls nitrogen fixation and distribution of diazotrophs in a tropical eutrophic estuary.

Nitrogen fixation and its ecological regulation are poorly understood in the tropical estuaries, which are highly influenced by anthropogenic disturbances. In this study, we investigated the role of nutrient stoichiometry in the diversity, abundance and activity of N-fixing bacterial community and their seasonal variations in the water column of a tropical eutrophic estuary (Cochin estuary). The N fixation rates in the estuary ranged from 0.

Nitrogen fixing potential of various heterotrophic Bacillus strains from a tropical estuary and adjacent coastal regions.

In the present study, we report the nitrogen fixing potential of heterotrophic diazotrophs isolated from a tropical estuary and adjacent coastal sea. Results of the study revealed that most of the species that are capable of fixing nitrogen in the study area belongs to the genus Bacillus. The isolates from the estuary showed maximum homology with Bacillus megaterium, B.

Nitrogen fixing bacterial diversity in a tropical estuarine sediments.

Microorganisms play a significant role in biogeochemical cycles, especially in the benthic and pelagic ecosystems. Role of environmental parameters in regulating the diversity, distribution and physiology of these microorganisms in tropical marine environment is not well understood. In this study, we have identified dinitrogen (N) fixing bacterial communities in the sediments by constructing clone libraries of nitrogenase (nifH) gene from four different stations in the Cochin estuary, along the southeastern Arabian Sea.