Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

A large amount of wastes is generated by agro-industry and can be valorized to obtain useful products with higher added value, thus reducing environmental impact. There are alternatives to valorize these wastes and the production of bioenergy has been a great precedent, from the production of biodiesel, bioethanol and biogas that is possible by the use of biomass. Biogas production by methanogenesis is an alternative for the generating biofuels and energy. However, a problem arises during biogas production due to the presence of hydrogen sulfide (and other compounds), which is toxic and can damage the biogas plant (up concentrations of 658 ppmv), increase SOx emissions and inhibit the fermentation process of biogas production, so it is necessary to eliminate them. The biological removal method of this compound is included, by oxidization through microorganisms. The objective of this review is to expose the trends in the use of the microorganisms mentioned in environmental biotechnology, particularly their role in biogas purification.

Dahlias (Dahlia spp.) are flowers native to Mesoamerica and endemic to Mexico. Its consumption as food is an ancient practice, at present there is little health information and regulation for its marketing and consumption. The objective of the study was to identify enteric bacteria associated morphologically, biochemically and molecularly with Dahlia flowers. The results of the morphological characterization revealed the predominance of short Gram-negative bacilli. From the observation of colonial morphology in selective and differential culture media Escherichia coli and Salmonella spp. were identified. However, the use of an automated commercial method classifieds them as Enterobacter cancerogenus. Due to the fact that the two tests used gave different results when identifying the isolated microorganism, the findings were inconclusive. Therefore molecular characterization was used to identify the bacterial isolate. Thus, the predominant bacterium in Dahlia flowers was Pantoea vagans (Access Number CP002206. 1). This is the first report of Pantoea vagans isolated from Dahlia flowers. 

We examined several buildings of nine archaeological sites in Mexico for the presence of mycobacteria and we could isolate forty-five nontuberculous mycobacteria (NTM). These were isolated from biofilms using selective media containing different antibiotics and dyes. Identification of the isolated mycobacteria was carried out, first, by a molecular identification by means of a mycobacteria-specific PCR using bacterial lysates of the acid-fast bacilli followed by species identification by comparing of three molecular markers: genes rrs (16SrRNA), hsp65 and rpoB. Furthermore, the physiographic data of the archaeological zones under study was related to the number of acid-fast microorganisms using a univariate analysis of variance. From the 45 isolated mycobacteria, 21 were Mycobacteroides chelonae; seven, Mycobacteroides abscessus; five, Mycolicibacterium flavescens; four, Mycobacterium alvei; two, Mycobacterium fortuitum; and six, Mycobacterium sp. Most NTM were isolated from two archaeological sites: 25 from Guachimontones (Jalisco), and 13 from Atetelco (Estado de México). The statistical analysis showed that environmental factors such as climate and the temperature-humidity-precipitation interaction had the greatest influence on the presence of NTM in these archaeological zones.

In this paper we describe four new fossil associations of “reef” and “reef”-like environments of the St. Cassian Formation (Ladinian-Carnian, Dolomites, NE Italy), based on thirty thin sections from 10 “Cipit boulders” olistoliths, which slided from the Cassian platform into coeval basin sediments. The fossil associations were determined by means of microfacies analysis using point-counting and visual estimation, as well as with aid of statistical methods, based on all fractions with a biotic significance (biomorpha and microbialites). Cluster Analyses in Q-Mode were performed, coupling three algorithms and two indices. In all samples, the main components of the framework are microbialite (average of 75%), and macrofossils (average of 20%), whereas cements and allochtonous components, such as allomicrite, do not represent a significant fraction. Based on both microbialite and fossil content, Chaetetid–microencruster Association, Microbialite–microencruster Association, Dual-type Microbialite Association and Microbialite–Terebella Association, were differentiated. The palaeoenvironmental settings where the associations come from are separately discussed. Microencrusters helped determine energy and luminosity settings. Microencruster abundance and diversity, in addition to the conspicuousness of microbialite, indicate that all associations come either from a deep, or from a cryptic setting.

The plasmid-encoded toxin (Pet) is one of the most studied Enterobacteriaceae autotransporters produced by the enteroaggregative Escherichia coli (EAEC). It is responsible of morphological changes in enterocytes during EAEC infection. Recently, Pet was found in the genome of the Proteus mirabilis RTX339 strain [P. mirabilis (Pet+)]. P. mirabilis causes complicated urinary tract infections (UTI) in patients having urinary catheters and structural or functional abnormalities. In this study, an UTI was induced in BALB/c female mice with the P. mirabilis (Pet+) strain. Mice infected by P. mirabilis (Pet+) showed bacterial colonization in bladder and kidney, from the second up to the tenth day post-infection. Morphological changes were evidenced by histology. Multiple exfoliated rounded cells were observed in the bladder transitional epithelium, as well as, structural cell alterations in the kidney cortex. The presence of Pet into exfoliated and parenchymal cells was confirmed by confocal microscopy. Cytoskeleton alterations were observed in those sites where Pet was detected. Pet expressed by P. mirabilis (Pet+) strain, contributes to its pathogenicity, affecting urinary tissues during the course of the infection. 

Candidatus Liberibacter solanacearum is a Gram-negative bacterium, obligate parasite of the phloem in Solanaceus crops, not cultivable in vitro. It is transmitted vertical and horizontally by Bactericera cockerelli. In Mexico, CLso is a pathogen asociated with the diseases "permanente del tomate", "punta morada de la papa" (Zebra chip) and "variegado del chile". The symptoms caused by CLso depend on the farming and the stage of growth of the host but it mainly consists in yellowing and deformation of the leaf blade, due to the feeding of the vector and the colonization of the pathogen. Infections caused by CLso reduce the quality and the commercial value of the product in the market. The presence of this bacterium has been detected in the states of Coahuila, Sinaloa and Guanajuato Mexico through molecular techniques, the control of the diseases is focused on the control of the vector, by means of cultural practices and the application of chemical and biological agents. Therefore, the objective of this work is to stand out the current situation of the distribution of CLso in Mexico, the diagnostic methods and the strategies for the integrated management of the disease and the vector.

Mexico is the main exporter of tomato worldwide. The use of greenhouses favors the protection and production of vegetables, however; tomato seedlings are sensitive to necrotrophic fungi such as Alternaria sp. The use of fungicides for disease control has been effective, however; the damage to the environment and the appearance of resistant strains leads the investigation of safe alternatives to the use of synthetic fungicides. Chitosan possesses antifungal activity in addition to the ability to activate defense mechanisms in plants. In this study, tomato seedlings were treated with chitosan at different concentrations. The percentage of foliar damage, spore´s germination, induction of hydrogen peroxide and enzymatic activity (peroxidase and polyphenoloxidase) was determined. A statistically significant reduction in leaf damage and germination of spores was obtained in plants treated with 0.01% chitosan (up to 80%) compared to the control. The production of H2O2 and the enzymatic activity was induced in treated plants. Thus, the application of chitosan can be a viable alternative for rot control caused by Alternaria sp. in tomato.

Plant hormones are signaling molecules that are localized in different plant tissues and in specific amounts according to the process that they regulate. Changes in the concentration and distribution of plant hormones modulate the development and responses to biotic and abiotic stress.Autophagy, which means self-digestion, is a mechanism that degrades damaged or toxic components that arise from the metabolism, in order to recycle them and maintain the health of the cell. The most studied type of autophagy is macroautophagy which will be referred in this review as autophagy. In this process, double membrane vesicles called autophagosomes are formed to enclose damaged or unwanted cell cargo, which is later deposited for its degradation into the vacuole, from where the cell recovers amino acids, lipids and proteins. Indeed, communication between plant hormones and autophagy has been observed during development and growth, senescence and programmed cell death.In this review we discuss the advances in the understanding of the role of plant hormones involved in the modulation of autophagy in plants.

N-Succinyl-L, L-diaminopimelate desuccinylase (DapE) is a strictly dimeric zinc-dependent amidohydrolase, which catalyzes the decomposition of N-succinyl-L, L-2,6-diaminopimelate (NSDAP), into succinate and diaminopimelate (DAP). This reaction constitutes the only source of meso-diaminopimelate (mDAP) and L-Lys in most bacteria. DapE is essential for bacterial growth and a pharmacological antimicrobial target. The development of anti-DapE inhibitors must take into account the dynamic properties of the enzyme. There is a special interest in compounds that block the formation of the oxyanion hole, where is assembled with groups of both subunits of the dimer and accommodated in its catalytic position by the conformational change of the enzyme from an open to a closed state, upon productive substrate binding. The hole stabilizes reaction intermediaries, thus contributing to the decrease in the activation energy. Based on the crystallographic analysis and the coupling of the substrate into DapE presented in this work, the role of the conformational flexibility of the enzyme in substrate hydrolysis is discussed. It is observed that the susceptible carbonyl group of the substrate and a water molecule located in the active site are near to the trajectory of attack, the Bürgi-Dunitz angle.

500 species of macromycetes mushrooms have been registered in Chihuahua, 73 of them are considered edible worldwide. The objective of this study was to determine the proximate and mineral composition of four edible ectomycorrhizal fungi species of the Sierra Tarahumara in Chihuahua. Carpophores of Astraeus hygrometricus, Laccaria laccata, Amanita caesarea and Pisolithus tinctorius were collected in two areas of the municipality of Bocoyna, Chihuahua. A proximal analysis was done to determine the percentage of humidity, ash, carbohydrates, proteins and total fats, as well as a mineral analysis to quantify the percentage of total nitrogen (Nt), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn). The results show that P. tinctorius is the species with the highest content of minerals, A. hygrometricus in carbohydrate content, A. caesarea in fat content and L. laccata in protein. Of the 10 different minerals evaluated, A. caesarea has the highest content in N, P, K and Zn, while A. hygrometricus has the highest values of Ca and Mn. Laccaria laccata shows the highest contents in Mg, Na and Cu. Finally, P. tinctorius was found with the highest values in Fe. In general, the proximal and mineral results of these fungi is within the established range for edible fungi, so these fungi are a good alternative food for the inhabitants of the area.