Mesorhizobium soli sp. nov., a novel species isolated from the rhizosphere of Robinia pseudoacacia L. in South Korea by using a modified culture method

Abstract

Strain NHI-8(T) was isolated from a forest soil sample, collected in South Korea, by using a modified culture method. Comparative analysis of its nearly full-length 16S rRNA gene sequence showed that strain NHI-8(T) belongs to the genus Mesorhizobium and to be closely related to Mesorhizobium chacoense PR5(T) (97.32 %). The levels of DNA-DNA relatedness between strain NHI-8(T) and reference type strains of the genus Mesorhizobium were 32.28-53.65 %. SDS-PAGE of total soluble proteins and the sequences of the housekeeping genes recA, glnII, and atpD were also used to support the clade grouping in rhizobia. The new strain contained summed feature 8 (57.0 %), cyclo-C19:0ω8c (17.3 %), and C18:0 (11.0 %) as the major fatty acids, as in genus Mesorhizobium. The strain contained cardiolipin, phosphatidylglycerol, ornithine-containing lipid, phosphatidylethanolamine, phosphatidyl-N-dimethylethanolamine, and phosphatidylcholine. Morphological and physiological analyses were performed to compare the characteristics of our strain with those of the reference type strains. Based on the results, strain NHI-8(T) was determined to represent a novel member of the genus Mesorhizobium, and the name Mesorhizobium soli is proposed. The type strain is NHI-8(T) (=KEMB 9005-153(T) = KACC 17916(T) = JCM 19897(T)).

Mesorhizobium microcysteis sp. nov., isolated from a culture of Microcystis aeruginosa

“…The only respiratory quinone identified in strain MaA-C15 T was Q-10, in agreement with those of other species of the genus Mesorhizobium [2–6]. C 16 : 0 , 11-methyl-C 18 : 1 ω 7 c , cyclo-C 19 : 0 ω 8 c and summed feature 8 (C 18 : 1 ω 6 c and/or C 18 : 1 ω 7 c ) were identified in strain MaA-C15 T as the major cellular fatty acids (>5 % of the total fatty acids) ().…”

“…Phosphatidylethanolamine, phosphatidylmonomethylethanolamine, an unidentified aminophospholipid, an unidentified glycolipid and three unidentified phospholipids were detected as the major polar lipids (Fig. S4), which was different from other closely related members of the genus Mesorhizobium [2–11]. For instance, one of the reference strains, M.…”

“…Symbols: +, positive; -, negative. Mesorhizobium [2][3][4][5][6]. C 16 : 0 , 11-methyl-C 18 : 1 ω7c, cyclo-C 19 : 0 ω8c and summed feature 8 (C 18 : 1 ω6c and/or C 18 : 1 ω7c) were identified in strain MaA-C15 T as the major cellular fatty acids (>5 % of the total fatty acids) (Table 3).…”

“…The genus Mesorhizobium , known to have the ability to engage in nitrogen-fixing endosymbiosis with leguminous plants, was first proposed as a member of the family Phyllobacteriaceae through reclassifying five Rhizobium species based on fatty acid composition and phylogenetic analysis of 16S rRNA gene sequences in 1997 [1]. At the time of writing, the genus Mesorhizobium comprises 57 validly published species that have been mostly isolated from root nodules of various host plants in soil environments [2–11]. Only two Mesorhizobium species were isolated from marine habitats [12, 13] and currently no Mesorhizobium type strain has been isolated from freshwater.…”

“…genus Mesorhizobium[2][3][4][5][6][7][8][9][10][11]. For instance, one of the reference strains, M. sediminum KCTC 42205 T , does not contain phosphatidylmonomethylethanolamine and glycolipid.…”