Preliminary characterization of slow growing rhizobial strains isolated from Retama monosperma (L.) Boiss. root nodules from Northwest coast of Algeria

Abstract

In this paper, we did some preliminary characterization of six slow growing rhizobial strains, isolated from Retama monosperma (L.) Boiss. root nodules sampled from 3 sites along the coast of Oran (CapeFalcon, Bousfer and MersElHadjadj) in Northwestern Algeria. Results of this study showed that all strains had a very slow growth rate in yeast malt (YM) agar medium, forming colonies less than 1 mm in diameter after seven days incubation. Catalase, oxidase and urease were positive, 3-ketolactose was negative. All strains resisted alkaline pH up to 9 and salinity equal to 2% (w/v) NaCl. They grew from 14 to 30°C with optimum growth at 28°C which is related to their place of presence (marine sand dunes Mediterranean climate). The strains used are, on the one hand D-glucose and D-galactose as carbon source and on the other hand L-leucine, L-tyrosine as nitrogen source. The nodulation tests performed pointed out that the total dry weight of the plant could go up to 1.7 g per plant and the maximum number of nodules was equal to 5.6 nodules per plant for the strain RMB1 from Bousfer site. The intrinsic antibiotic resistance level in all strains was tested against nine antibiotics; they revealed a variability of resistance against spectinomycin (10 µg , erythromycin (15 µgml

Genetic and phenotypic diversity of microsymbionts nodulating promiscuous soybeans from different agro-climatic conditions

“…Soybean-nodulating bradyrhizobia are slow growers (take up to 5 days) and alkali-producing in YEMA media supplemented with BTB [ 57 ]. Hannane et al [ 14 ] while working with Retama monosperma (L.) Boiss similarly reported that bradyrhizobia are slow growers and alkaline producers hence BTB media take a characteristic blue color. Additionally, typical bradyrhizobia colonies when incubated in the dark showed little or no absorption of Congo Red [ 4 ].…”

Phylogenomic Review of Root Nitrogen-Fixing Symbiont Population Nodulating Northwestern African Wild Legumes

“…symbiotic nitrogen-fixing bacteria associated with Retama species in North Africa: Retama monosperma, R. raetam, and R. sphaerocarpa (Algeria: [35,36]; Morocco: [37]). Recently, the novel B. retamae species, in which groups with B. elkanii and B. pachyrhizi and related B. lablabi and B. jicamae type strains are included in Bradyrhizobium group II [38], has been isolated from R. sphaerocarpa and R. monosperma in Morocco [37].…”