Mesorhizobium septentrionale sp. nov. and Mesorhizobium temperatum sp. nov., isolated from Astragalus adsurgens growing in the northern regions of China

Abstract

Ninety-five rhizobial strains isolated from Astragalus adsurgens growing in the northern regions of China were classified into three main groups, candidate species I, II and III, based on a polyphasic approach. Comparative analysis of full-length 16S rRNA gene sequences of representative strains showed that candidate species I and II were Mesorhizobium, while candidate species III, which consisted of non-nodulating strains, was closely related to Agrobacterium tumefaciens. The phylogenetic relationships of the three candidate species and some related strains were also confirmed by the sequencing of glnA genes, which were used as an alternative chromosomal marker. The DNA–DNA relatedness was between 11·3 and 47·1 % among representative strains of candidate species I and II and the type strains of defined Mesorhizobium species. Candidate III had DNA relatedness of between 4·3 and 25·2 % with type strains of Agrobacterium tumefaciens and Agrobacterium rubi. Two novel species are proposed to accommodate candidate species I and II, Mesorhizobium septentrionale sp. nov. (type strain, SDW014T=CCBAU 11014T=HAMBI 2582T) and Mesorhizobium temperatum sp. nov. (type strain, SDW018T=CCBAU 11018T=HAMBI 2583T), respectively. At least two distinct nodA sequences were identified among the strains. The numerically dominant nodA sequence type was most similar to that from the Mesorhizobium tianshanense type strain and was identified in strains belonging to the two novel species as well as other, as yet, undefined genome types. Host range studies indicate that the different nodA sequences correlate with different host ranges. Further comparative studies with the defined Agrobacterium species are needed to clarify the taxonomic identity of candidate species III.

Characterization of Rhizobial Bacteria Nodulating Astragalus corrugatus and Hippocrepis areolata in Tunisian Arid Soils

“…STM4038 which were isolated from Astragalus cruciatus and Argyrolobium uniflorum growing on the same Tunisian soils (Zakhia et al, 2004;Mahdhi et al, 2008). So, it would now be interesting to test the cross-nodulation capacity of our new isolates on A. cruciatus and A. uniflorum legumes.It has been previously reported that A. corrugatus is nodulated by strains belonging to the genera Rhizobium, Sinorhizobium, Brdyrhizobium, Mesorhizobium, Agrobacterium and Phyllobacterium (Wei et al, 2003;Gao et al, 2004;Zakhia et al, 2004;Mantelin et al, 2006;Guerrouj et al, 2013;Zheng et al, 2013;Gnat et al, 2014). Our results thus confirm the previous studies showing the large diversity of A. corrugatus rhizobia that belong to Rhizobium, Sinorhizobium, Mesorhizobium and Agrobacterium.…”

Isolation and Characterization of Nitrogen Fixing Rhizobia from Cultivated and Uncultivated Soils of Northern Tanzania

“…The studies conducted in Hawaii to examine serological relatedness of 25 strains of slow-growing Rhizobia japonicum by agglutination identified 6 somatic serogroups [143] [149] Raposeiras, and Marriel [150] in Brazil reported that SLA 2.2 native rhizobia strain and CIAT 899 commercial strains are competitive strain for bean inoculation in soils with low fertility and reduced rhizobia population. Gao and Yang [48] in China reported that strain 042B could form nodules and fix nitrogen to both alfalfa and soybeans with nodule occupancy ranging from 82% -90% while that of strain USDA110 ranged from 78% -46%. Bizarro and Giongo [151] in Brazil reported that 27/75 isolates from soybeans were similar to original strain with strong correlation obtained in their genetic variability.…”

“…However, rhizobia are thought to be present before the legumes for nodulation because Sino rhizobium-Bradyrhizobium split was reported about 500 Ma [48] [49]. Bacteria of the genus Bradyrhizobium, Rhizobium Sinorhizobium and others induce nitrogen-fixing nodules on the roots of legumes such as peas, beans, cow peas and soybeans [50].…”

Aliihoeflea aestuarii gen. nov., sp. nov., a novel bacterium isolated from tidal flat sediment

“…The G+C content of genomic DNA of the type strain was 53.4 mol%. The value of genomic DNA G+C content in the validated species belonging to the genus Mesorhizobium that showed the highest 16S rRNA gene sequence similarity with the novel strain, is in the range of 59~65.1 mol% (Jarvis et al, 1997;Gao et al, 2004). The G+C content value of strain N8 T genomic DNA is relatively lower than the values for validated species of the genus Mesorhizobium.…”