RESUMO
In the present study, the nematicidal and acaricidal activity of three Enterobacter endophytic strains isolated from Mimosa pudica nodules was evaluated. The percentages of mortality of Enterobacter NOD4 against Panagrellus redivivus was 81.2%, and against Nacobbus aberrans 70.1%, Enterobacter NOD8 72.4% and 62.5%, and Enterobacter NOD10 64.8% and 58.7%, respectively. While against the Tyrophagus putrescentiae mite, the mortality percentages were 68.2% due to Enterobacter NOD4, 64.3% due to Enterobacter NOD8 and 77.8% due to Enterobacter NOD10. On the other hand, the ability of the three Enterobacter strains to produce indole acetic acid and phosphate solubilization, characteristics related to plant growth-promoting bacteria, was detected. Bioinformatic analysis of the genomes showed the presence of genes related to IAA production, phosphate solubilization, and nitrogen fixation. Phylogenetic analyzes of the recA gene, phylogenomics, and average nucleotide identity (ANI) allowed us to identify the strain Enterobacter NOD8 related to E. mori and Enterobacter NOD10 as E. asburiae, while Enterobacter NOD4 was identified as a possible new species of this species. The plant growth-promoting, acaricidal and nematicidal activity of the three Enterobacter strains makes them a potential agent to include in biocontrol alternatives and as growth-promoting bacteria in crops of agricultural interest.
RESUMO
A colistin-resistant mcr-1-carrying Escherichia coli strain, RC2-007, was isolated from a swine farm in Mexico. This extraintestinal and uropathogenic strain of E. coli belongs to serotype O89:H9 and sequence type 744. Assembly and annotation resulted in a 4.9-Mb draft genome that revealed the presence of plasmid-mediated mcr-1-ISApI1 genes as part of a prophage.
RESUMO
BACKGROUND: Bovine babesiosis is a tick-borne disease caused by the protozoan parasites of the genus Babesia. In their host vector, Babesia spp. undergo sexual reproduction. Therefore, the development of sexual stages and the subsequent formation of the zygote are essential for the parasite to invade the intestinal cells of the vector tick and continue its life-cycle. HAP2/GCS1 is a protein identified in plants, protozoan parasites and other organisms that has an important role during membrane fusion in fertilization processes. The identification and characterization of HAP-2 protein in Babesia would be very significant to understand the biology of the parasite and to develop a transmission-blocking vaccine in the future. RESULTS: To isolate and sequence the hap2 gene DNA from an infected bovine with Babesia bigemina was purified. The hap2 gene was amplified, cloned and sequenced. The sequences of hap2 from four geographically different strains showed high conservation at the amino acid level, including the typical structure with a signal peptide and the HAP2/GSC domain. Antisera anti-HAP2 against the conserved extracellular region of the HAP2 amino acid sequence were obtained from rabbits. The expression of hap2 in the host and vector tissues was analyzed by using semi-quantitative RT-PCR, and the protein was examined by western blot and immunofluorescence. Based on the RT-PCR and WB results, HAP2 is expressed in both, sexual stages induced in vitro, and in infected ticks as well. We did not detect any expression in asexual erythrocytic stages of B. bigemina, relevantly anti-HAP2 specific antibodies were able to block zygotes formation in vitro. CONCLUSION: Babesia bigemina HAP2 is expressed only in tick-infecting stages, and specific antibodies block zygote formation. Further studies regarding the function of HAP2 during tick infection may provide new insights into the molecular mechanisms of sexual reproduction of the parasite.
