TIP Revista Especializada en Ciencias QuimicoBiologicas最新文献

The influence of aeration on the fermentative activity of Brettanomyces intermedius RIVE 2-2-2 was studied in a mixed culture with Saccharomyces cerevisiae RIVE 15-1-416 in order to evaluate the production of chemical compounds of sensory importance. To achieve this, the strains were cultured in Erlenmeyer flasks containing sterilized and aroma-removed apple juice. The chemical compounds produced during fermentation under shaking (200 min⁻¹) or static cultivation were determined by gas and liquid chromatography. The results showed that the stirring during cultivation diminishes the production of glycerol (0.53±0.1 g/L) and acetic acid (94.0±10.0 mg/L) and, on the other hand, increases the production of higher alcohols (1.009 g/L) and ethyl acetate (122.0±5.0 mg/L). Additional batch cultivations carried out in a bioreactor with an air flow of 25 l/h reported a growth rate (μ) and a biomass yield (Y_x/s) of 0.05 h⁻¹ and 0.24 (g. dry biomass/g. sugar) respectively. At the end of cultivation, no presence of acetic acid was observed and furthermore, concentrations of ethanol and glycerol reached values of 0.34±0.1 g/L and 1.3±0.05 g/L respectively. The best results in terms of organoleptic quality of the cider regarding to taste and smell were obtained when fermented under static cultivation conditions. The regulation of aeration during fermentation is a useful tool to control the fermentative activity of these two strains in a mixed culture.

In this short review, our objective was to describe few new applications of a natural polysaccharide extracted from algae, the alginates. Firstly, the chemical composition is recalled and the main techniques used for characterization are cited. The role of guluronic acid blocks (GG blocks) is particularly important for gel mechanical properties in presence of calcium counterions. Then, the main applications in food and biomedicine are briefly mentioned followed by tentative applications in packaging, paper, textil and wound dressing which are described. Especially, fine fibers are produced now industrially under mixed sodium/calcium ionic form.

Fusarium verticillioides is the main fungal pathogen that affects the productivity of maize worldwide. The fungus penetrates the plant by different routes and infects roots, stem and cob. The pathogen produces several toxins in tissue and corn kernels, which affect their quality. Fumonisins are the major toxins produced by this fungus. The ability to produce them depends on the presence of several genes encoding the enzymes responsible for biosynthesis. The regulation of the synthesis is very complex and depends on environmental and nutritional factors, as well as multiple signaling pathways. This is reflected by the high variability in fumonisin production among F. verticillioides strains. Fumonisins are virulence factors because their production is associated with a greater capacity to infect maize seedlings. However, this role is not clear for ear infection and rotting. In maize, fumonisins have three molecular targets: sphinganine N-acyl-transferase, plasma membrane proton ATPase and the basic β-1,3-glucanases. These three enzymes have important physiological functions and also participate in the plant defense response against fungal pathogens.

The lake of Bosque de San Juan de Aragón (LBSJA, for its Spanish acronym), occupies a 12 hectare area. The lake is eutrophicated due to an activated sludge system, known as “Tlacos”, that carries partially treated water into the lake and contains nitrogen and phosphorus concentrations that trigger the growth of microalgae. In this study, we describe relevant aspects of the design, construction and operational start of a treatment system based on artificial wetlands (AWs) built in the LBSJA. The AWs occupies an area of about one hectare; it was designed to purify an average of 250 m³d⁻¹ of water. The system consists of a limestone aggregate filter, a settler, a subsurface flow artificial wetland (SSFAW), a surface flow artificial wetland (SFAW), and a gabion wall filter. Water that feeds the system comes from both the conventional treatment plant of “Tlacos” (WWTP-Tlacos) and that contained in the lake itself. Our results show an 80% reduction of contaminant content. The later represents a superior quality than that established in the environmental standards for treated water from water bodies used for recreational purposes.

Bromeliads have the ability to retain water in the leaf axils that are known as tanks or phytotelmata; they support complex food webs with all types of organisms from bacteria to small vertebrates. In this paper, we present the first approach to the microalgae living in the tanks of a species of bromeliad at “La Martinica” Ecological Reserve, in Banderilla, Veracruz. The collections were studied in preserved material and cultures. About 60 algae were obtained, belonging to Cyanoprokariota, Euglenophyta, Cryptophyta, Chlorophyta and Bacillariophyta, but only 16 species have been identified. We conclude Tillandsia multicaulis tanks provide suitable conditions for the development of microalgae and the location and morphology of the bromeliad influence the distribution of this biological group. The shortage of individuals did not allow a more precise identification. In the cultures, we could detect species not seen in the preserved material, indicating a much richer flora than the one we could observe directly.

The Arc two-component system comprises the sensor kinase ArcB and the response regulator ArcA. In Escherichia coli, this system regulates the transcriptional network involved in energy metabolism according to the redox conditions of their environment. Under anoxic growth conditions, ArcB autophosphorylates and transphosphorylates ArcA, which in turn represses or activates the expression of its target operons. Under aerobic conditions, ArcB acts as a phosphatase that catalyzes the dephosphorylation of ArcA-P and thereby releasing its transcriptional regulation. This review describes the key structural features of ArcB, and the main events for Arc signaling, including signal reception and kinase regulation. It also compares the ArcB sequence of E. coli with the one of other bacteria and reveals similarities and differences that may be of foremost importance for the regulation of this sensor kinase protein.

The role of some leaf characters (specific area, thickness, trichome density, water content and latex production) on the defence against insect herbivores and fungal pathogens was analyzed in three species of Cnidoscolus (Euphorbiaceae). Foliar damage was examined in adults of the tree species C. spinosus and C. megacanthus, and the herbaceous species C. urens, in populations located in the Biosphere Biological Reserve of Chamela-Cuixmala (Jal.) and in the Huatulco-Zimatán region (Oax.), Mexico. Seedlings of C. spinosus were also analysed. We assessed the following leaf traits: specific area, thickness, density of trichomes on both sides of the leaf, as well as latex and hydric content. In the three Cnidoscolus species, levels of damage caused by grazer insects were higher than the ones caused by pathogens. The lowest level of foliar damage was detected in C. spinosus, but the levels of damage in seedlings were higher than those in the adults. The two tree species showed higher levels of damage by grazers than the herbaceous species. We only detected a direct significant relation between leaf thickness and herbivory levels in seedlings of C. spinousus. No other significant relations were found. This study suggests that the assessed leaf characters do not seem to play a key role in defence of these three Cnidoscolus species.

In this work, a xerophytic garden was designed and established for science popularization purposes. This was made on a green area of the Facultad de Estudios Superiores Zaragoza of the National University, at the East of Mexico City. The garden design was outlined by drawing on the soil surface, a logarithmic spiral, a Vitrubius star, a fractal pentagon and a golden rectangle. For this, white painted 10 cm high stakes were buried to delimit the curves, and succulent plants were planted to remark the geometric figures. Twenty nine plant species were transplanted, with 144 total individuals, and a catch-fog mesh device was installed with a view to exhibit an atmospheric water harvesting model for plant irrigation. The science popularization of geometric concepts was made by means of guided visits. It was concluded that it is feasible to establish an urban garden without irrigation in the East of Mexico City. Nevertheless, it is necessary to strengthen the structure of geometric curves. Also, it is required to install information panels about the soil drawings and technical fact sheets on plant species in order to facilitate popularization of the underlying scientific concepts of garden design and the explanation of catch-fog device function.

Some studies have found a positive relationship between the concentration of blood cells and metabolic alterations, suggesting that the concentration of blood cells should be included as a component of metabolic syndrome. However, these studies have been done at a low altitude, and it is unknown if this relationship is maintained at a high altitude, where the low atmospheric pressure and the high hypoxia affect the number of red cells and the presence of metabolic alterations. The aim of the present study was to determine the relationship between red blood cells and metabolic variables in Otomi women from Ixtenco-Tlaxcala living at 2500 meters above sea level. METHODS. The body mass index (BMI), concentration of total cholesterol, triglycerides, and complete blood count were measured in 309 women. Data were analyzed through correlations and binary logistic regressions. RESULTS.The BMI was positively correlated with the concentration of erythrocytes and hemoglobin, as well as with hematocrit. Independently of the age, women with overweight/obesity and dislipidemias have a big risk to have erythrocitosis, and low risk to have anemia. DISCUSSION. The relationship between the concentration of blood cells and obesity/ dislipidemias is affected by the altitude.

In this work a 30 item questionnaire was made in order to estimate the ecological footprint (EF) of Mexican university students, taking into account the lifestyle and the consumption pattern in Mexican culture. First, from statistical yearbooks, the average productivity (in ton/ha/year) of the most popular agricultural, farming and fish products, and paper for notebooks was obtained, with a view to determine the production area of the different goods to be consumed by the typical Mexican in a year. We also calculated the mean surface to absorb the carbon dioxide produced by energy comsuption directly (use of transportation, electronic devices, warm water to take a shower and daily tap water), and indirectly (production, distribution and marketing of goods). Second, the obtained surfaces were translated to global hectares (gha) through conversion factors. Subsequently, the questionnaire was answered by 125 university students with the following results: 1.48 gha of mean ecological footprint, with the highest value corresponding to food consumption (0.42 gha) due to meat products, followed by energy use (0.35 gha), essentially by home gas utilization in daily showers. This EF is inside the limits of global sustainability (< 1.61 gha). No significant differences were found due to study level, age or sex of the sample. Finally, it was concluded that the questionnaire is coherent in relation to the results obtained in other calculators available on line and made in countries with a high consumption level of goods and services, and that this represents the first ecological footprint calculator that takes account of Mexican idiosyncrasy.