Semiselective medium for isolation of Rhizobium leguminosarum from soils

Compatibility of Rhizobial Genotypes within Natural Populations of Rhizobium leguminosarum Biovar viciae for Nodulation of Host Legumes

“…viciae isolation. Rhizobia were directly isolated from soil by a procedure previously described (29) which involves the use of a semiselective medium (including antibiotics to inhibit the growth of gram-positive bacteria and fungicides), a counterselection step (inability to grow on a NaCl-rich agar medium), and a specific identification method (colony blot hybridization with a biovar-specific DNA probe). At the same time as bacteria were isolated from bulk soils (30), samples of soils P1 and F5 were used to cultivate peas (P. sativum cv.…”

Genomics of Specificity in the Symbiotic Interaction between Rhizobium leguminosarum and Legumes

“…Furthermore, when the complete rRNA cluster, rather than the separate 16S and 23S rRNA genes, was studied, only lentil-selected subpopulations clustered together (Figure 3.12 panels A, B and C for copies 1, 2 and 3 respectively). This divergence in results between 16S/23S and the complete rRNA clusters can be attributed to differences found in the intergenic spacer (IGS) between rRNA genes (that were included for rRNA analysis); this is in line with the use of restriction enzyme IGS patterns as genotype markers in R. leguminosarum studies (Louvrier et al, 1995, Laguerre et al, 2003, Mutch and Young, 2004). …”

“…Cpn60 is a better marker than 16S rRNA in samples with high host DNA content; however this gene is often duplicated (Johnson et al, 2015) and sometimes more non-identical copies are present in the genome (Gould et al, 2007). The soil-selected population consisted of 118 strains obtained after direct soil cultivation and isolated using a semi-selective medium (Louvrier et al, 1995), followed by PCR-based screening of chromosomal (fnrN and glnII) and symbiotic markers (nodC and nifH). A total of 130 g of soil were processed in thirteen different independent isolation trials, and (1.77·10 4 ± 9.20·10 3 ) were negative for both symbiotic markers (Rhizobium sp.…”

“…Other culture-independent methods, such as direct gene amplification from soil DNA (Zeze et al, 2001, Sarita et al, 2005, Ando et al, 2005, necessarily restrict the analysis to the number of chosen markers and limits any analysis of the entire RL soil population. This leaves culture-dependent methods.Different selective medium have been developed to isolate rhizobia directly from soil, based on antimicrobial substances (Graham, 1969, Pattison and Skinner, 1974, Barber, 1979, Soberón-Chávez and Nájera, 1989, Segovia et al, 1991, Laguerre et al, 1993a, Bromfield et al, 1994, Louvrier et al, 1995 and metal resistances (Gault and Schwinghamer, 1993, Tong and Sadowsky, 1994, Kinkle et al, 1994, but a limited number of studies have been devoted to the investigation of native soil RL without recourse to trap plants. All of them combine a semi-selective media followed by some sort of screening, and have focused their efforts on different RL biovars (bv.…”

“…phaseoli (Segovia et al, 1991) and bv. viciae (Laguerre et al, 1993a, Louvrier et al, 1995, Laguerre et al, 2003, as well as on nonsymbiotic strains (Soberón-Chávez and Nájera, 1989). However, none of these studies aimed at the entire indigenous soil RL population without restriction.…”