Background In pregnant women Streptococcus agalactiae (GBS) can be transmitted to newborn causing severe infections. It is classified into 10 serotypes (Ia, Ib, II-IX). The severity of neonatal disease is determined by the capsular serotype and virulence factors such as the polysaccharide capsule, encoded by the cps gene, protein C, which includes the Cα surface proteins (bca gene), Rib (rib gene) and Cβ (bac gene); the proteins Lmb (lmb gene), FbsB (fbsB gene), FbsA (fbsA gene), the cyl operon encoding a β-hemolysin (hylB gene), the CAMP factor (cfb gene) and the C5a peptidase (scpB gene). The aim of this work was to determine the degree of GBS colonization in pregnant women, the serotypes distribution and to investigate virulence-associated genes. Methods We worked with 3480 samples of vagino-rectal swabs of women with 35–37 weeks of gestation. The identification of the strains was carried out using conventional biochemical tests and group confirmatory serology using a commercial latex particle agglutination kit. Two hundred GBS strains were selected. Their serotype was determined by agglutination tests. The monoplex PCR technique was used to investigate nine virulence-associated genes (cps, bca, rib, bac, lmb, fbsB, fbsA, hylB and scpB). Results The maternal colonization was 9.09%. The serotypes found were: Ia (33.50%), III (19.00%), Ib (15.50%), II (14.00%), V (7.00%) and IX (5.50%). 5.50% of strains were found to be non-serotypeable (NT). The nine virulence genes investigated were detected simultaneously in 36.50% of the strains. The genes that were most frequently detected were scpB (100.00%), fbsA (100.00%), fbsB (100.00%), cylB (95.00%), lmb (94.00%) and bca (87.50%). We found associations between serotype and genes bac (p = 0.003), cylB (p = 0.02), rib (p = 0.01) and lmb (p < 0.001). Conclusions The frequency of vaginal-rectal colonization, serotypes distribution and associated virulence genes, varies widely among geographical areas. Therefore, epidemiological surveillance is necessary to provide data to guide decision-making and planning of prevention and control strategies.
Yerba mate (Ilex paraguariensis St. Hil.) is a species native to the subtropical regions of South America. Despite being an important crop for the region, there are few studies on the use of microorganisms to improve the growth of seedlings in the nursery stage. The objective of this study was to isolate spore-forming endophytic bacteria with plant growth promoting properties associated with yerba mate seedlings and determine their phytobeneficial effect under controlled laboratory conditions. Isolates were selected based on their sporulation capacity and evaluated for in vitro plant growth promoting properties (nitrogen fixation, phosphate solubilization, production of siderophores and synthesis of indolic compounds). Yerba mate seedlings were inoculated with the most promising isolates, which were identified via analyses of the sequence of their 16S rDNA gene as Bacillus circulans (12RS3) and Bacillus altitudinis (19RS3, T5S-T4). After 120 days plants showed higher root dry weight when inoculated with isolate 19RS3 and higher shoot dry weight with 19RS3 and T5S-T4. In conclusion, further studies to determine the ability of these isolates to adapt to the climatic conditions and to survive amidst the native soil microflora in yerba mate cultivated native soils, will be crucial for developing such strains as biofertilizer.
Plant growth-promoting bacteria (PGPB) are a heterogeneous group of bacteria that can exert beneficial effects on plant growth directly or indirectly by different mechanisms. PGPB-based inoculant formulation has been used to replace chemical fertilizers and pesticides. In our previous studies, two endophytic endospore-forming bacteria identified as Bacillus altitudinis were isolated from roots of Ilex paraguariensis St. Hil. seedlings and selected for their plant growth-promoting (PGP) properties shown in vitro and in vivo. The purposes of this work were to assemble the genomes of B. altitudinis 19RS3 and T5S-T4, using different assemblers available for Windows and Linux and to select the best assembly for each strain. Both genomes were also automatically annotated to detect PGP genes and compare sequences with other genomes reported. Library construction and draft genome sequencing were performed by Macrogen services. Raw reads were filtered using the Trimmomatic tool. Genomes were assembled using SPAdes, ABySS, Velvet, and SOAPdenovo2 assemblers for Linux, and Geneious and CLC Genomics Workbench assemblers for Windows. Assembly evaluation was done by the QUAST tool. The parameters evaluated were the number of contigs ≥ 500 bp and ≥ 1000 bp, the length of the longest contig, and the N50 value. For genome annotation PROKKA, RAST, and KAAS tools were used. The best assembly for both genomes was obtained using Velvet. The B. altitudinis 19RS3 genome was assembled into 15 contigs with an N50 value of 1,943,801 bp. The B. altitudinis T5S-T4 genome was assembled into 24 contigs with an N50 of 344,151 bp. Both genomes comprise several genes related to PGP mechanisms, such as those for nitrogen fixation, iron metabolism, phosphate metabolism, and auxin biosynthesis. The results obtained offer the basis for a better understanding of B. altitudinis 19RS3 and T5S-T4 and make them promissory for bioinoculant development.
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