Bacteria molecular approaches

Microbial mats have been a longstanding focus of N2 fixation studies (Paerl et al., 1996, 2000) (Table 4.1). Most recently, appHed molecular approaches have revealed much more information about these systems. Zehr et al. (1995) examined a microbial mat from an intertidal mat from coastal North Carolina and found a wide variety of diazotrophic bacteria were present, with the majority of sequences related to niJH sequences of anaerobes (sulfate reducers and Clostridia), particularly deeper in the mat. 

Nitrogen fixation in the marine environment occurs in benthic (sediments and microbial mats) and pelagic environments, and in salt marsh soils (see Carpenter and Capone, Chapter 4, this volume). Since very diverse microorganisms that span the Bacteria and Archaea domains of life can fix nitrogen, it is often difficult to ascertain which organisms are responsible for observed nitrogen fixation rates. Our discussion of the application of molecular approaches to the study of marine nitrogen fixation is brief because it has been reviewed extensively elsewhere (Carpenter and Capone, Chapter 4, this volume Foster and O MuUan Chapter 27, this volume Scanlan and Post, Chapter 24, this volume Paerl and Zehr, 2000 Zehr and Ward, 2002 Zehr et al., 2003). 

Wieringa E. B. A., Overmann J., and Cypionka H. (2000) Detection of abundant sulphate-reducing bacteria in marine oxic sediment layers by a combined cultivation and molecular approach. Environ. Microbiol. 2, 417—427. 

Despite the promising performance of newly studied enzymes in the laboratory, their application in the industrial milieu might fail due to their lack of robustness. However, as anaerobic, extremophilic, and marine bacteria might be a source of enzymes with superior chances of success in biotechnological processes, a great deal of laboratory effort has been concentrated on their production and characterization. Furthermore, the design of novel enzymes as well as molecular approaches such as enzyme evolution and metagenomic approaches can be used to identify and develop novel biocatalysts from uncultured bacteria—a treasure of unknown proteins. 

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