The complete genome of a novel nitrogen-fixing bacterium has been recently sequenced and analyzed.
The researchers isolated and sequenced the complete genome of a species of Micromonospora, bacteria that play a role in promoting plant growth and breaking down plant cell walls, from root nodules of Sheoak trees (Casuarina equisetifolia).
Although Micormonospora bacteria are a diverse genus and an important source of antibiotics, we know little about them. This complete genome provides details about one species’ genes and the proteins they code for, which can provide further insight into how this soil-dwelling bacterium interacts with plants and other microbes in its environment.
Micromonospora are soil and water-dwelling bacteria that have been eyed for their potential in biofuel processing because of their ability to break down cell walls. Some species have even been found in the rumen of cattle and termite guts. Several Micromonospora species have already been sequenced, and this complete genome adds a unique entry to that list. In 2005, Micromonospora sp. L5 was found growing in the root nodules of C. equisetifolia in Irapuato, Mexico. It was subsequently shown to be capable of converting atmospheric nitrogen into ammonia, a process called nitrogen fixation.
Genes the researchers identified include several enzymes that degrade cell walls. However, they did not find any genes similar to the nif gene, which is responsible for nitrogen fixation in other bacteria and cyanobacteria species.
Trees of the genus Casuarina can tolerate highly saline soil and air pollutants such as sulfur dioxide and nitrogen dioxide. They are also important as nitrogen-fixing plants and fuel crop. The relationship between another sheoak species, C. glauca, and one of its nitrogen-fixing symbiotic bacteria, Frankia, is the subject of a DOE JGI 2012 Community Sequencing Project by Laurent LaPlaze of the Institute of Research for Development in France.
Ann M. Hirsch
UCLA, Los Angeles, California
DOE Office of Science, Office of Biological and Environmental Research
University of California Institute for Mexico and the United States (UC-MEXUS) and El Consejo Nacional de Ciencia y Tecnologia (CONACYT)
Hirsch AM, et al, 2013. Complete genome sequence of Micromonospora strain L5, a potential plant-growth-regulating actinomycete, originally isolated from Casuarina equisetifolia root nodules. Genome Announc. 1(5):e00759-13.