Five novel tin Schiff base complexes with histidine analogues (derived from the condensation reaction between L-histidine and 3,5-di-tert-butyl-2-hydroxybenzaldehyde) have been synthesized and characterized. Characterization has been completed by IR and high-resolution mass spectroscopy, 1D and 2D solution NMR (1H, 13C and 119Sn), as well as solid state 119Sn NMR. The spectroscopic evidence shows two types of structures: a trigonal bipyramidal stereochemistry with the tin atom coordinated to five donating atoms (two oxygen atoms, one nitrogen atom, and two carbon atoms belonging to the alkyl moieties), where one molecule of ligand is coordinated in a three dentate fashion. The second structure is spectroscopically described as a tetrahedral tin complex with four donating atoms (one oxygen atom coordinated to the metal and three carbon atoms belonging to the alkyl or aryl substituents), with one molecule of ligand attached. The antimicrobial activity of the tin compounds has been tested against the growth of bacteria in vitro to assess their bactericidal properties. While pentacoordinated compounds 1, 2, and 3 are described as moderate effective to noneffective drugs against both Gram-positive and Gram-negative bacteria, tetracoordinated tin(IV) compounds 4 and 5 are considered as moderate effective and most effective compounds, respectively, against the methicillin-resistant Staphylococcus aureus strains (Gram-positive).
Recently, studies were initiated to investigate the metagenome, which represents the genomes of cultured and uncultured microbes, as a rich source for isolation of many novel genes. The metagenomic approach originated from the molecular analysis of microbial communities, which revealed that the majority of microorganisms in nature were not cultivable by standard culturing techniques. Therefore, most microorganisms in nature have not been characterized. Although numerous methods have been reported for direct DNA isolation and purification from microorganisms in soil, the sample preparation procedures and experimental conditions used in different studies vary widely. Soils are therefore one of the most challenging environmental matrices from which to obtain microbial DNA that will support PCR. The Papaloapan River is the second largest river basin in México. For the climatic conditions of this region, there is great diversity in plants, animals and microorganisms. In the Papaloapan region different fruits are grown, however, the main crops are sugarcane and pineapple. In this work the extraction of DNA from soils of sugarcane cultivation was performed. We used PCR tests to assess the quality of DNA extracted from soil by amplifying the 16S rDNA gene. Changes in both protocols were performed; satisfactory results were obtained as to the quality of DNA and gene amplification. These results will allow continuing the metagenomic studies, such as sequencing, library construction and identification of enzymes cellulase and amylase activity. It is the first time these studies were performed in the Papaloapan region.
Proteus mirabilis, a motile Gram-negative bacterium, represents a common cause of complicated urinary tract infections. Autotransporters are a family of secreted proteins from Gram-negative bacteria that direct their own secretion across the outer membrane (type V autotransporter secretion mechanism). Serine protease autotransporters of Enterobacteriaceae (SPATEs) include adhesins, toxins, and proteases that can contribute to the virulence. Plasmid-encoded toxin (Pet) is the predominant protein in culture supernatants of enteroaggregative E. coli prototype strain 042 and has been extensively studied. Pet toxin is encoded on the 65-MDa adherence-related plasmid of EAEC 042 strain. In this work, Pet protein was found in the supernatant obtained from Proteus mirabilis RTX339 strain isolated from a psychiatric patient suffering complicated urinary tract infections (UTIs). The nucleotide sequence of pet gene was obtained using primers designed from E. coli 042 pet gene reported. The alignment of the sequence showed 100% identity with the pet gene reported. Is important to note that Proteus mirabilis RTX339 pet gene has chromosomal location. The chromosomal location of the gene was established since no plasmids were harbored by this strain
Quorum sensing is a chemical communication process that bacteria use to regulate collective behaviors. In Gram-positive bacteria, oligopeptides (called autoinducers) are the signaling molecules to elicit quorum sensing. In Bacillus thuringiensis, NprR is a transcriptional regulator whose activity depends on the NprX signalling peptide. Bacillus thuringiensis is closely related to Bacillus cereus and Bacillus anthracis. The principal difference between them is that Bacillus thuringiensis is the only one that produced Cry protein. The aim of this study is to explore the relation of nprR and 16S rRNA genes in Bacillus thuringiensis. Phylogenetic trees of nucleotide sequences of nprR and 16S rRNA genes were built. Sequences of fourteen new isolates from Papaloapan region were included in those phylogenetic trees. In order to identify the isolates, a simple and fast methodology considering the Cry protein formation was used. The 16S rRNA phylogenetic tree allows identify eight isolates as Bacillus thuringiensis and the others as Bacillus spp. The nprR phylogenetic tree does not match with the 16S rRNA phylogenetic tree. This confirms that nprR is not a molecular marker for evolution. Most of the new isolates have the same NprR sequence (WTSDIVG). However, the SKPDIVG is the most common NprR sequence in thuringiensis species.
The Desierto de los Leones National Park is a place that features recreational activities for residents and visitors to Mexico City. The Presa de los Patos (Ducks Dam) is one of the many bodies of water that are present in the park. By means of physico-chemical and microbiological analysis, it was determined that the water of the Presa de los Patos cannot be considered potable. The pH range was between 5.5 -5.9. The turbidity exceeded the values established in the standards (10.7 -32.3 Nephelometric Turbidity Units (NTU's)). Chemical Oxygen Demand (COD) showed that large amounts of oxygen are needed to oxidize organic matter (106 -450 mg/L). The amount of coliforms and fecal coliforms exceeds the values established by the standards used (total coliforms 98 -956 Colony Forming Units (CFU's), fecal coliforms 78 -807 CFU's). Five bacterial genera (Escherichia coli, Pseudomona, Klebsiella, Shigella and Salmonella) were isolated and identified. Most of the bacteria isolated were resistant to ampicillin (90%), while 25% were resistant to ciprofloxacin. The water consumption of the Presa de los Patos is a great risk for the habitants and visitors of the park.
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