Aspects of nitrogen‐fixing Actinobacteria, in particular free‐living and symbiotic Frankia. Issue 2 (28th March 2013)

• Record Type: Journal Article
• Authors: Sellstedt, Anita; Richau, Kerstin H.
• Is Part Of: FEMS microbiology letters. Volume 342:Issue 2(2013:May)
• Page Start: 179
• Page End: 186
• Publication Date: 2013-03-28
• Subjects: Microbiology -- Periodicals; 579
• DOI: 10.1111/1574-6968.12116
• Languages: English
• ISSNs: 0378-1097

Abstract

<abstract abstract-type="main" xml:lang="en" id="fml12116-abs-0001"> <title>Abstract</title> <p>Studies of nitrogen‐fixing properties among the Gram‐positive <italic>Actinobacteria</italic> revealed that some species of <italic>Arthrobacter, Agromyces, Corynebacterium, Mycobacterium, Micromonospora, Propionibacteria</italic> and <italic>Streptomyces</italic> have nitrogen‐fixing capacity. This is also valid for <italic>Frankia</italic> that fix nitrogen both in free‐living and in symbiotic conditions. Frankia symbiosis results from interaction between the <italic>Frankia</italic> bacteria and dicotyledonous plants, that is, actinorhiza. These plants, which are important in forestry and agroforestry, form, together with the legumes (<italic>Fabales</italic>), a single nitrogen‐fixing clade. It has been shown that a receptor‐like kinase gene, <italic>SymRK</italic>, is necessary for nodulation in actinorhizal plants as well as in legumes and arbuscular mycorrhizal fungi. Recently, the involvement of isoflavonoids as signal molecules during nodulation of an actinorhizal plant was shown. The genome sizes of three <italic>Frankia</italic> species, <italic>Frankia</italic> EANpec, ACN14a and CcI3, are different, revealing a relationship between genome size and geographical distribution. Recent genomic sequencing data of <italic>Frankia</italic> represent genomes from cluster I to IV, indicating that the genome of DgI is one of the smallest genomes in <italic>Frankia</italic>. In addition, nonsymbiotic Frankiales such as <italic>Acidothermus cellulolyticus</italic>, <italic> Blastococcus saxoobsidens</italic>, <italic> Geodermatophilus obscurus</italic> and <italic>Modestobacter marinus</italic> have a variety of genome sizes ranging from 2.4 to 5.57 Mb.</p> </abstract>