PROBLEMS AND PROMISES OF ASSAYING THE GENETIC POTENTIAL FOR NITROGEN-FIXATION IN THE MARINE-ENVIRONMENT

Nitrogen fixation in the sea has attracted the attention of ecologists for decades. Much is known about the habitats in which it occurs and some of the factors that limit N-2 fixation activity in different envi ronments, but we still know little about the organisms that fix nitrog en, and what limits the growth and distribution of these organisms in marine environments. Molecular biology technological developments have provided tools for detecting and characterizing N-2-fixing organisms in the environment. These techniques hold great promise for unraveling the mysteries and paradoxes of N-2 fixation in the sea. In this revie w, we address the theoretical basis for the use of a molecular approac h to N-2 fixation, highlight the strengths and weaknesses of the appro ach, and provide case studies that demonstrate the potential contribut ion of molecular biology approaches to studies of N-2 fixation in the sea.