Ensifer meliloti L6-AK89, an Effective Inoculant of Medicago lupulina Varieties: Phenotypic and Deep-Genome Screening

Abstract

This paper presents a deep analysis of the accessory genome of an economically promising strain of Ensifer (Sinorhizobium) meliloti, L6-AK89, obtained as a result of next-generation high-throughput sequencing (MiSeq, MinIon). Strain L6-AK89 is a StrR mutant of the native strain CIAM1775, a symbiont of Medicago lupulina that adapted to a saline and arid habitat in NW Kazakhstan. CIAM1775 is an effective inoculant of M. lupulina cv. Mira (fodder type standard), cultivated on moderately acid soils in the NW agricultural region of Russia. Strain L6-AK89 makes it possible to obtain the expected high (>150%) increases in dry mass of the same plant variety in plant tests. The L6-AK89 genome has an increased proportion of sequences related to the accessory elements relative to reference strain Rm1021, 7.4% versus 4.8%. A set of 53 nod/noe/nol/nif/fdx/fix genes and 32 genes involved in stress tolerance together with 16S rRNA and recA–atpD–glnII–gyrB–dnaJ were evaluated. The high symbiotic efficiency of L6-АК89 with hop clover is most likely due to unique features of its genome, in combination with structural differences in its nod and stress-related genes, as well as unique clusters of quorum-sensing genes and osmoprotector synthesis.

A Temperate Sinorhizobium Phage, AP-16-3, Closely Related to Phage 16-3: Mosaic Genome and Prophage Analysis

“…The same media with 0.6% agar was used as the top layer for titration of phages [ 42 ]. The spectrum of lytic activity of Sinorhizobium phage AP-16-3 was assessed according to the protocol described by [ 43 , 44 , 45 ].…”

“…S. meliloti strains were cultivated on solid LB media (agar concentration 2%) at 28 • C. The same media with 0.6% agar was used as the top layer for titration of phages [42]. The spectrum of lytic activity of Sinorhizobium phage AP-16-3 was assessed according to the protocol described by [43][44][45].…”

Engineered Bacterium DF4-8 Achieves Specific Phenol Detection via a unique mopR-like Regulatory Pathway

“…CENSOR analysis identi ed a transposable element (TE), BEL-20_ArCe-I, within mopR-ORF, suggesting its potential in uence [10]. BLAST analysis of the intergenic spacers further revealed remarkable connections -mopR-ORF perfectly matched the ISSgl1 transposon [11], while DF4-ORF8 and DF4-ORF10 displayed strong matches with ISSme2 [12] and ISHahy5 [13], respectively. These ndings hint at potential evolutionary links or past TE insertions within the region.…”