Bdellovibrio reynosensis sp. nov., from a Mexico soil sample.

A novel predatory bacterium, strain LBG001T, has been isolated from Reynosa, Mexico. The 16S rRNA shares approximately 97 % sequence identity with many reported strains in the genus Bdellovibrio including the type strain Bdellovibrio bacteriovorus HD100T. Phylogenetic trees based on the 16S rRNA gene and on 30 concatenated housekeeping genes or core genes showed that LBG001T is on a separate branch from the B. bacteriovorus group. LBG0001T has a genome size of 3 582 323 bp with a G+C content of 43.1 mol %. The average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization values with other members of the genus Bdellovibrio (<79, <72 and <17 %, respectively) qualifies the strain to represent a new species in the genus. Strain LBG001T formed visible plaques on all 10 tested Gram-negative bacterial species. The phenotypic characteristics, phylogenetic analysis and genomic taxonomic studies support the classification of the strain as representing a new species for which the name Bdellovibrio reynosensis sp. nov. is proposed. The type strain is LBG001T(=ATCC TSD-288T =CM-CNRG 0932T).

The decolorization and degradation of azo dyes by two Stenotrophomonas strains isolated from textile effluent (Tepetitla, Mexico).

Stenotrophomonas' metabolic versatility plays important roles in the remediation of contaminated environment and plant growth promotion. We investigated two Stenotrophomonas strains isolated from textile polluted sewage for their ability to decolorize and degrade azo dyes. Two Stenotrophomonas strains (TepeL and TepeS) were isolated from textile effluents (Tepetitla, Mexico) using the selective agar Stenotrophomonas vancomycin, imipenem, amphotericin B agar (SVIA). Isolates' identity was determined by the sequencing of their partial 16S rRNA fragments. Their abilities to decolorize dyes were tested in a Luria broth supplemented with varying concentrations (50 mg/L-1 g/L) of textile dyes (acidic red, methyl orange, reactive green, acidic yellow, and reactive black). Fourier-transform infrared (FTIR) spectroscopy and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) metabolite analyses were used to determine the effect of the isolates' growth on the dyes (acidic red, methyl orange). We also identified the enzymes that may be involved in the degradation process. Phylogenetic analysis based on the 16S rDNA sequences showed that the isolates belong to the genus Stenotrophomonas. Stenotrophomonas sp. TepeL and TepeS respectively decolorize all the azo dyes at the tested concentration except at 1 g/L and degraded the azo dyes. The degradation resulted in the formation of N, N-dimethyl p-phenylenediamine, and sodium 4-amino-1-naphthalenesulfonate from methyl orange and acid red. TepeL and TepeS rapidly decolorized and degraded the azo dyes tested. This result showed that the two isolates have a good potential for the decontamination of textile effluents.

Complete Genome Sequence of Stenotrophomonas maltophilia Strain SVIA2, Isolated from Crude Oil-Contaminated Soil in Tabasco, Mexico.

Stenotrophomonas maltophilia strain SVIA2 was isolated from crude oil-contaminated soil from Tabasco, Mexico, and displayed a good potential for the degradation of polycyclic aromatic hydrocarbons (PAHs), using naphthalene, anthracene, phenanthridine, or biphenyl as the unique source of carbon. The SVIA2 genome contains essential genes involved in the degradation of PAHs.

The sequences of MinE responsible for its subcellular localization analyzed by competitive binding method in Escherichia coli.

The subcellular localization of a protein is important for its proper function. Escherichia coli MinE is a small protein with clear subcellular localization, which provides a good model to study protein localization mechanism. In the present study, a series of recombinant minEs truncated in one end or in the middle regions, fused with egfp, was constructed, and these recombinant proteins could compete to function with the chromosomal MinE. Our results showed that the sequences related to the subcellular localization of MinE span several functional domains, demonstrating that MinE positioning in cells depends on multiple factors. The eGFP fusions with some truncated MinE from N-terminal resulted in different cell phenotypes and localization features, implying that these fusions can interfere chromosomal MinE's function, similar to MinE36-88 phenotype in the previous report. The amino acid in the region (32-48) is sensitive to change MinE conformation and influence its dimerization. Some truncated protein structure could be unstable. Thus, the MinE localization is prerequisite for its proper anti-MinCD function and some new features of MinE were demonstrated. This approach can be extended for subcellular localization research for other essential proteins.

Novel protein interactions with an actin homolog (MreB) of Helicobacter pylori determined by bacterial two-hybrid system.

The bacterium Helicobacter pylori infects more than 50% of the world population and causes several gastroduodenal diseases, including gastric cancer. Nevertheless, we still need to explore some protein interactions that may be involved in pathogenesis. MreB, an actin homolog, showed some special characteristics in previous studies, indicating that it could have different functions. Protein functions could be realized via protein-protein interactions. In the present study, the MreB protein from H. pylori 26695 fused with two tags 10×His and GST in tandem was overexpressed and purified from Escherchia coli. The purified recombinant protein was used to perform a pull-down assay with H. pylori 26695 cell lysate. The pulled-down proteins were identified by mass spectrometry (MALDI-TOF), in which the known important proteins related to morphogenesis were absent but several proteins related to pathogenesis process were observed. The bacterial two-hybrid system was further used to evaluate the protein interactions and showed that new interactions of MreB respectively with VacA, UreB, HydB, HylB and AddA were confirmed but the interaction MreB-MreC was not validated. These results indicated that the protein MreB in H. pylori has a distinct interactome, does not participate in cell morphogenesis via MreB-MreC but could be related to pathogenesis.

The detection of inherent homologous recombination between repeat sequences in H. pylori 26695 by the PCR-based method.

Helicobacter pylori infects more than half of the world's population, making it the most widespread infection of bacteria. It has high genetic diversity and has been considered as one of the most variable bacterial species. In the present study, a PCR-based method was used to detect the presence and the relative frequency of homologous recombination between repeat sequences (>500 bp) in H. pylori 26695. All the recombinant structures have been confirmed by sequencing. The inversion generated between inverted repeats showed distinct features from the recombination for duplication or deletion between direct repeats. Meanwhile, we gave the mathematic reasoning of a general formula for the calculation of relative recombination frequency and indicated the conditions for its application. This formula could be extensively applied to detect the frequency of homologous recombination, site-specific recombination, and other types of predictable recombination. Our results should be helpful for better understanding the genome evolution and adaptation of bacteria.