Search

Abstract The drought can cause a decrease in food production and loss of biodiversity. In northern Mexico, an arid region, the chiltepin grows as a semi-domesticated crop that has been affected in its productivity and yield. An alternative to mitigate the effect of drought and aid in its conservation could be using Plant Growth-Promoting Bacteria (PGPB). The present study evaluated the capacity of native Bacillus spp., isolated from arid soils, as PGPBs and drought stress tolerance inducers in chiltepin under controlled conditions. Chiltepin seeds and seedlings were inoculated with native strains of Bacillus spp. isolated from arid soils, evaluating germination, vegetative, and drought stress tolerance parameters. The PGPBs improved vegetative parameters such as height, stem diameter, root length, and slenderness index in vitro. B. cereus (Bc25-7) improved in vitro survival of stressed seedlings by 68% at −1.02 MPa. Under greenhouse conditions, seedlings treated with PGPBs exhibited increases in root length (9.6%), stem diameter (13.68%), leaf fresh weight (69.87%), and chlorophyll content (38.15%). Bc25-7 alleviated severe water stress symptoms (7 days of water retention stress), and isolates B. thuringiensis (Bt24-4) and B. cereus (Bc25-7, and Bc30-2) increased Relative Water Content (RWC) by 51%. Additionally, the treated seeds showed improved germination parameters with a 46.42% increase in Germination Rate (GR). These findings suggest that using PGPBs could be an alternative to mitigate the effect of drought on chiltepin.

This study aimed to evaluate the antimicrobial effect of thymol and carvacrol in inhibiting Escherichia coli and Salmonella serovar Typhimurium inoculated on a fresh green salad through the vapor phase. A film-forming solution was prepared by dissolving starch, sorbitol, and variying concentrations of carvacrol, thymol, and a mixture of both. The film-forming solution containing the respective antimicrobial agent was then added lid, which was sealed rigidly and hermetically to achieve different concentrations (105 mg/L of air of carvacrol, 105 mg/L of air of thymol, and a mixture of 52 mg/L of air of carvacrol and 52 mg/L of air of thymol). Each active package contained fresh green salad inoculated with E. coli or Salmonella serovar Typhimurium. The active packages were then sealed and refrigerated at a temperature of 6 °C for 48 h. Growth/inhibition curves were modelled using the Weibull equation, and consumer acceptance was evaluated. Carvacrol can reduce up to 0.5 log-cycles, while thymol can reach almost 1 log cycle. Blending the components with half the concentration has a synergistic effect, inhibiting up to 2.5 log cycles. Consumer ratings revealed no significant differences between the packages. However, the average score was 5.4 on a 9-point hedonic scale, evaluators' comments did not indicate dislike or a strong taste characteristic of thymol and carvacrol.

The emergence and re-emergence of tick-borne bacteria (TBB) as a public health problem raises the uncertainty of antibiotic resistance in these pathogens, which could be dispersed to other pathogens. The impact of global warming has led to the emergence of pathogenic TBB in areas where they were not previously present and is another risk that must be taken into account under the One Health guides. This review aimed to analyze the existing information regarding antibiotic-resistant TBB and antibiotic-resistance genes (ARG) present in the tick microbiome, considering the potential to be transmitted to pathogenic microorganisms. Several Ehrlichia species have been reported to exhibit natural resistance to fluoroquinolones and typhus group Rickettsiae are naturally susceptible to erythromycin. TBB have a lower risk of acquiring ARG due to their natural habitat, but there is still a probability of acquiring them; furthermore, studies of these pathogens are limited. Pathogenic and commensal bacteria coexist within the tick microbiome along with ARGs for antibiotic deactivation, cellular protection, and efflux pumps; these ARGs confer resistance to antibiotics such as aminoglycosides, beta-lactamase, diaminopyrimidines, fluoroquinolones, glycopeptides, sulfonamides, and tetracyclines. Although with low probability, TBB can be a reservoir of ARGs.

Introduction. Fungal genera Alternaria and Fusarium include human and plant pathogenic species. Several antifungals have been used for their control, but excessive use has contributed to resistance development in pathogens. An alternative to searching for and developing new antifungal agents is using essential oils and their main components, which have biological activities of interest in medicine and food production. Objective. To evaluate in vitro and in silico the antifungal activities of terpenoids against Alternaria alternata and Fusarium oxysporum. Materials and methods. The minimum inhibitory concentration and minimum fungicidal concentration values of 27 constituents of essential oils used against Alternaria alternata and Fusarium oxysporum were evaluated in vitro. In addition, using genetic algorithms, quantitative models of the structure-activity relationship were used to identify the structural and physicochemical properties related to antifungal activity. Results. The evaluated compounds proved to be effective antifungals. Thymol was the most active with a minimum inhibitory concentration of 91.6 ± 28.8 μg/ml for A. alternata and F. oxysporum. Quantitative structure-activity relationship models revealed the octanolwater cleavage ratio as the molecular property, and the phenols as the main functional group contributing to antifungal activity. Conclusion. Terpenoids exhibit relevant antifungal activities that should be incorporated into the study of medicinal chemistry. Inclusion of in silico assays in the in vitro evaluation is a valuable tool in the search for and rational design of terpene derivatives as new potential antifungal agents.

Pomegranate peel is an important source of polyphenols of remarkable interest in the food, pharmaceutical and cosmetic industry. The improved extraction of total polyphenolic compounds (TPC) from pomegranate peel by solid-state fermentation (SSF) was achieved. The Box, Hunter and Hunter (BHH) followed by the central composite design (CCD) processes were performed to assess the effect of the process variables on TPC release. The statistical designs indicate that the best TPC extraction (234.85 mg GAE/gdm) by means of SSF occurs at 42 °C, 50% moisture, 5.0 pH, mineral solution (g/L): NaNO3 (3.83), KH2PO4 (1.52), MgSO4 (4.66) and KCl (1.52) at 36 h. Under the best fermentation conditions TPC (248.78 ± 1.24 mgGAE/gdm) increased 5.96-fold more than values previously reported and antioxidant activity (AA) increased 5.81-fold compared to the value obtained before the SSF optimization. High-value citric acid, α and β punicalin, α and β punicalagin, punigluconin, galloyl-HHDP hexoside and ellagic acid molecules were identified. The increased extraction of TPC by SSF provides a suitable alternative for the valorization of pomegranate peel through the recovery of molecules with high added value with potential use in the food, pharmacy and cosmetic industries; a diversification in the use of food agroindustry by-products is obtained as an approach to the circular economy model through biotechnological processes.

Chihuahua cheese is traditionally produced in the State of Chihuahua, Mexico, with raw milk, which involves potential bacterial outbreaks. The objective of this work was to characterize the cheese-making process of Chihuahua cheese, including the determination of cheese composition and microbiological determination of pathogens, indicators and Lactic Acid Bacteria (LAB). Ten different cheese factories were sampled where cheese manufacturing protocols were documented. Also, samples of raw milk, curd, cheddaring, and final product were taken. Pathogens, indicators (total mesophilic bacteria, coliforms, coagulase-positive Staphylococci and Salmonella) and LAB were quantified in all samples. Proximal analysis of the final product was also completed. Although process steps were similar, there were significant variations in relevant parameters such as temperature, pH, and time. Regarding microbiological analysis, coliforms (5.9-7.4 Log10 CFU/g) and total mesophilic counts were high (8.8-9.2 Log10 CFU/g), while counts of S. aureus were within the range of 2.1-2.3 Log10 CFU/g. The microbial count of lactobacilli was lower in milk and higher in the final product. The highest counts of enterococci (6.97 Log10 CFU/g) and thermophilic lactobacilli (8.16 Log10 CFU/g) were observed in the final product. Microbial counts were different in all dairies and LAB groups varied during the manufacturing process. Principal Component Analysis grouped data by type of sample or process analyzed, rather than by dairy location. Manufacturing standardization, incorporation of good manufacturing practices, and milk pasteurization with the use of a starter culture, can improve the overall quality of Chihuahua cheese. The balance between the sensorial and physicochemical properties of the artisanal product will assure that Chihuahua cheese is not a risk of food-borne outbreaks for consumers.

Aedes aegypti is a vector for the arbovirus responsible for yellow fever, Zika and Chikungunya virus. Essential oils and their constituents are known for their larvicidal properties and are strong candidates for mosquito control. This work aimed to develop a quantitative structure–activity study and molecular screening for the search and design of new larvicidal agents. Twenty-five monoterpenes with previously evaluated larvicidal activity were built and optimized using computational tools. QSAR models were constructed through genetic algorithms from the larvicidal activity and the calculation of theoretical descriptors for each molecule. Docking studies on acetylcholinesterase (AChE) and sterol carrier protein (SCP-2) were also carried out. Results demonstrate that the epoxide groups in the structure of terpenes hinder larvicidal activity, while lipophilicity plays an important role in enhancing biological activity. Larvicidal activity correlates with the interaction of the sterol-carrier protein. Of the 25 compounds evaluated, carvacrol showed the highest larvicidal activity with an LC50 of 8.8 µg/mL. The information included in this work contributes to describing the molecular, topological, and quantum mechanical properties related to the larvicidal activity of monoterpenes and their derivatives.

This review aims to evaluate the state of saffron’s main bioactive compounds and their relationship with its commercial quality. Saffron is the commercial name for the dried red stigmas of the Crocus sativus L. flower. It owes its sensory and functional properties mainly to the presence of its carotenoid derivatives, synthesized throughout flowering and also during the whole production process. These compounds include crocin, crocetin, picrocrocin, and safranal, which are bioactive metabolites. Saffron’s commercial value is determined according to the ISO/TS3632 standard that determines their main apocatotenoids. Other techniques such as chromatography (gas and liquid) are used to detect the apocarotenoids. This, together with the determination of spectral fingerprinting or chemo typing are essential for saffron identification. The determination of the specific chemical markers coupled with chemometric methods favors the discrimination of adulterated samples, possible plants, or adulterating compounds and even the concentrations at which these are obtained. Chemical characterization and concentration of various compounds could be affected by saffron’s geographical origin and harvest/postharvest characteristics. The large number of chemical compounds found in the by-products (flower parts) of saffron (catechin, quercetin, delphinidin, etc.) make it an interesting aromatic spice as a colorant, antioxidant, and source of phytochemicals, which can also bring additional economic value to the most expensive aromatic species in the world.

Leishmaniasis is a neglected vector-borne disease; there are different manifestations of the diseases and species involved, and cutaneous leishmaniasis caused by Leishmania (L.) mexicana is the most prevalent in Mexico. Currently, the drugs available for the treatment of leishmaniasis are toxic, expensive, and often ineffective; therefore, it is imperative to carry out research and development of new therapeutic alternatives, with natural products being an attractive option. In particular, oregano is a plant with worldwide distribution; in Mexico, two species: Lippia berlandieri Schauer and Poliomintha longiflora Gray are endemic. Both essential oils (EO’s) have been reported to have antimicrobial activity attributed to their main components, thymol and carvacrol. In this research, the leishmanicidal effect and mechanism of cell death induced by L. berlandieri EO, P. longiflora EO, thymol, and carvacrol in L. mexicana promastigotes were determined in vitro. Additionally, the cytotoxic activity in mammalian cells was evaluated. L. berlandieri EO presented higher leishmanicidal activity (IC50 = 41.78 µg/mL) than P. longiflora EO (IC50 = 77.90 µg/mL). Thymol and carvacrol were the major components of both Mexican oregano EO’s. Thymol presented higher leishmanial inhibitory activity (IC50 = 22.39 µg/mL), above that of carvacrol (IC50 = 61.52 µg/mL). All the EO’s and compounds evaluated presented lower cytotoxic activity than the reference drug; thymol was the compound with the best selectivity index (SI). In all cases, apoptosis was identified as the main mechanism of death induced in the parasites. The leishmanicidal capacity of the Mexican oregano EO is an accessible and affordable alternative that can be further explored.

La evaluación sensorial de alimentos es de suma importancia en la investigación y el desarrollo de alimentos. El tipo de análisis sensorial dependerá del tipo de información requerida, y en este sentido, el presente artículo provee un panorama de las estrategias utilizadas en pruebas de diferencia, que se utilizan cuando se desea conocer si dos alimentos son perceptiblemente distintos. Las pruebas de diferencia son ampliamente usadas tanto en la academia como en la industria, con aplicaciones en el control de calidad, el estudio del impacto por cambios en la formulación o el proceso, la habilidad de los consumidores para discriminar entre dos productos similares, entre otras aplicaciones. Primero, se presenta una revisión de las pruebas discriminativas, haciendo énfasis en los diferentes tipos de pruebas, para luego describir las teorías de análisis estadístico de resultados, describiendo especialmente, los diversos problemas que se presentan en este tipo de pruebas. Finalmente, se presenta la modelación Thurstoniana que puede ser usada para obtener información, considerando el procesamiento central en el cerebro. La consideración de todas estas variables permitirá la selección del protocolo más adecuado en investigaciones de evaluación sensorial con este tipo de pruebas. Abstract Food sensorial analysis is an important area in research and development of new food alternatives. The type of sensorial analysis used, will depend on the type of information required; in this sense, this article contains a panoramic view of some difference tests, which are used to determine if there are perceptible differences among two food sample. These tests are widely used both in academy and industry, in applications such as food process quality control, evaluation of the impact on changes in food process or formulation, as well as for the ability of consumers to distinguish between two similar products, among other applications. First, there is a revision of discriminative tests, emphasizing on the different test included; then, the descriptions of the theories of analysis of results are included, especially describing the problems related to those analyses. Finally, the Thurstonian modeling is explained, that can be used to obtain information, considering the central processing of information that is carried out in the brain. The consideration of all the above variables, will allow select the most appropriate protocol for the type of sensorial analysis required in a particular food analysis Keywords: Sensorial analysis, statistical tests, difference tests

La manipulación genética del genoma de cloroplasto esta a la vanguardia en investigación biotecnológica. El pasto B. gracilis es un modelo para el estudio de estrés hídrico y oxidativo, capacidades relacionadas al cloroplasto. Es necesario tener un método que facilite la obtención de ADN de buena calidad, particularmente cuando se refiere al ADN de cloroplasto de B. gracilis. La implementación de un método para la extracción de cpADN se logró probando diferentes estrategias de extracción de cpADN reportados en la literatura y combinando las etapas más apropiadas para B. gracilis. La incorporación de un paso adicional del lavado con CTAB permitió la recuperación de cpDNA enriquecido, el cual se puede utilizar en el desarrollo de hermanitas moleculares. Debido la implementación de un protocolo de extracción también fue posible obtener una cantidad considerable de cpADN de B. gracilis. El cpADN fue digerido con varias enzimas de restricción y los fragmentos resultantes fueron analizados por Southern blot con las sondas de los genes de rADN 16S y 23S. Abstract Genetic manipulation of the chloroplast genome is at the forefront of biotechnology research. B. gracilis is a model for the study of water stress and oxidative capacities related to the chloroplast. It is requires a method to facilitate the obtaining of good quality DNA, particularly when it comes to chloroplast DNA of B. gracilis. The implementation of a method for extracting cpDNA was achieved by assaying different strategies cpDNA extraction reported in the literature and combining the most appropriate stage for B. gracilis for cpDNA extraction. The incorporation of an additional step of washing with CTAB after lysis of chloroplasts, allowed the recovery of enriched cpDNA which can be used in the development of molecular tools. Due to the implementation of an extraction protocol was also possible to obtain a considerable amount of B. gracilis cpDNA. The cpDNA was digested with several restriction enzymes and the resulting fragments were analyzed by Southern blot with probes of genes rADN 16S and 23S.

Las pectinas son polisacáridos presentes en los tejidos vegetales, compuestos principalmente por cadenas de ácido galacturónico. Las pectinas se han extraído por diferentes métodos de los tejidos vegetales de diversos frutos, principalmente de los materiales de desecho como por ejemplo de la pomaza de manzana y de las cáscaras de cítricos, en los cuales se ha encontrado un mayor rendimiento. La demanda mundial de pectinas ha ido en aumento debido a la gran aplicabilidad de esta materia, ya que se ha empleado en la industria alimentaria por su alto poder gelificante y espesante, también tienen una gran aplicación en la industria farmacéutica y cosmética. Recientemente se han encontrado reportes del empleo de pectinas para la fabricación de recubrimientos y películas de empaque como alternativa a los empaques de origen sintético, con lo cual pueden aprovecharse los desechos o subproductos de la producción agrícola. Estos materiales llegan a representar la mitad del peso fresco total del fruto y son particularmente ricos en pectinas. Abstract Pectin is a polysaccharide found in vegetable tissues, which are mainly formed by galacturonic acid chains. Extraction of pectin from vegetable tissue has been done by a variety of methods, using as starting material, either fruits or waste material derived from fruit processing, like apple pomace or citric fruit peel, that have given high extraction yields. Worldwide demand of pectin has been increased due to the great applicability in different areas, including the food industry, where pectin is used as gelling and thickening agent; it is also been used in the pharmaceutical and cosmetic industries. Recently, pectin has been utilized in the production of edible coating and films to be used as packing materials, as an alternative to synthetic materials; that, at the same time, is an alternative to use the waste material and residues from agricultural production. These materials represent nearby the half of the fruit total weight and are particularly rich in pectin. Keywords: biopolymers, agroindustrial residues, edible films.

Los microambientes son estructuras complejas, en donde se encuentran en equilibrio una gran cantidad de organismos microscópicos, tanto eucariotes como procariotes, que interaccionan entre ellos y con los factores abióticos del medio. Para lograr el equilibrio entre los miembros de una comunidad microbiana, se establecen interacciones que resultan benéficas o perjudiciales para una de las especies que interaccionan, o para ambas. Entre estas interacciones, se encuentran: comensalismo, simbiosis, y parasitismo, entre otras. Estas interacciones les facilita a los microorganismos la obtención de compuestos que pueden ser utilizados como substratos o como complementos, asegurando así su sobrevivencia y mantenimiento en un ecosistema. Para sobrevivir, algunos microorganismos deben producir compuestos capaces de inhibir el desarrollo de microorganismos competidores. Estos compuestos, conocidos como antimicrobianos, pueden causar daño a la célula bacteriana competidora a través de diversos mecanismos de acción, pero el fin es cumplir con el mismo objetivo, la eliminación de la competencia microbiana. La producción industrial de algunos de estos antimicrobianos, han revolucionado nuestra forma de vida, al proporcionarnos herramientas para el control de enfermedades infecciosas. Abstract Microenvironments are natural complex structures, where microscopic organisms (both, eukaryotic and prokaryotic organisms) are in balance, by way of interactions among them and with the abiotic factors present in the environment. In order to achieve equilibrium between the members of a microbial community, different interactions are established, that are either beneficial or prejudicial to one or both interaction species. Among those interactions are commensalism, symbiosis and parasitism. The interactions support the acquirement of compounds that can be used as substrates or complements for microbial growth, assuring in this way, its survival and maintenance in the ecosystem. To survive, some microorganisms produce compounds capable of inhibiting the development of competitive microbiota. Those compounds, known as antimicrobials, can cause damage to the competitive microbial cell through different mechanisms of action, but the final goal is the same: to eliminate the competitive microbiota. Industrial production of some of those antimicrobials, have revolutionized our society, since they can be used to control infectious diseases. Keywords: microbial interactions, symbiosis, parasitism, competition, bacteria.

Los plásticos, particularmente aquellos producidos a partir del petróleo, son utilizados ampliamente debido a sus propiedades mecánicas y fisicoquímicas. Sin embargo, estos materiales son poco biocompatibles y muestran resistencia a procesos de degradación, por lo que tienden a acumularse ocasionando efectos detrimentales al ambiente. Como sustituto a los petroplásticos (plásticos derivados del petróleo) se pueden emplear polímeros de origen biológico, que poseen propiedades similares a sus contrapartes sintéticas, pero una mayor biocompatibilidad. La mayoría de los bioplásticos (plásticos de origen biológico) muestran costos de producción más elevados que petroplásticos similares, lo que constituye una gran desventaja. En esta revisión se presenta una breve reseña de la biosíntesis bacteriana de polihidroxibutiratos (PHB) y polihidroxivaleratos (PHV ) a partir de fuentes de carbono consideradas como subproductos o desechos de actividades agrícolas o industriales. La selección de una fuente de carbono económica puede cerrar parcialmente la brecha económica entre la producción de bioplásticos y la producción de petroplásticos. Abstract Plastics, particularly those produced f rom crude oil, are widely used due to their mechanical, physical and chemical properties. Nevertheless, these materials are poorly biocompatible and show resistance to degradation processes; therefore, they tend to accumulate, causing detrimental effects on the environment. Polymers of biological origin that have similar properties but higher biocompatibility, can be used as a substitute to petroplastics (petroleum-based plastics). Most bioplastics (biologically obtained plastics) have higher production costs than similar petroplastics, which represents a great disadvantage. In this review, a brief account of bacterial polyhydroxybutirate (PHB) and polyhydroxyvalerate (PHV ) biosynthesis using carbon sources deemed as byproducts or waste of agricultural or industrial activities is presented. Choosing an economical carbon source can partially close the economic gap between bioplastic and petroplastic production. Keywords: Polyhydroxybutirate, polyhydroxyvalerate, bioplastics, biocompatibility, biosynthesis.

Hurdle technologies are among the novel food processing techniques for food preservation, where there is a combination of mild antimicrobial factors, which can interact on the inhibition of microbial spoilage. Spices essential oils are widely known as antimicrobial compounds that can have a preservation effect on food, but their effect can be affected by food components. In order to evaluate the effect of pH (4.5–7.0) and protein content (2–8%) on the antifungal effect of Mexican oregano essential oil (150–600 mg/L), a Box-Benkhen design was used to test the effect of the treatments on the radial growth of two food-related fungi, Penicillium expansum (NRRL 2304) and Aspergillus ochraceus (ATCC 22947). Three essential oils were used, these with a different chemical composition. The first chemotype of Lippia berlandieri Schauer, presented a higher proportion of carvacrol (58.23%). The second Lippia berlandieri Schauer essential oil presented a higher concentration of thymol (60.15%). Essential oil from Poliomintha longiflora Gray contained a 43.02% of thymol. Kinetic growth parameters were obtained using the modified Gompertz equation. The maximum mold growth (A) of the molds was affected in a lineal concentration-dependent effect by the three Mexican oregano essential oils and protein concentration. This phenomenon is independent of the chemistry variability in the composition of the three OEO. The higher concentration of protein (8%) was also related to an increase in lag time (λ). These two growth parameters were mainly statistically significant of all treatments evaluated, when considering as intrinsic parameters in food such as pH and protein content. The action of OEO was higher against A. ochraceus, positioning itself as the most sensitive microorganism. The use of predictive modeling can provide valuable information on the interaction of food components to enhance or decrease the antifungal capacity of essential oils.

Saffron is derived from the stigmas of the flower Crocus sativus L. The drying process is the most important post-harvest step for converting C. sativus stigmas into saffron. The aim of this review is to evaluate saffron’s post-harvest conditions in the development of volatile compounds and its aroma descriptors. It describes saffron’s compound generation by enzymatic pathways and degradation reactions. Saffron quality is described by their metabolite’s solubility and the determination of picrocrocin, crocins, and safranal. The drying process induce various modifications in terms of color, flavor and aroma, which take place in the spice. It affects the aromatic species chemical profile. In the food industry, saffron is employed for its sensory attributes, such as coloring, related mainly to crocins (mono-glycosyl esters or di-glycosyl polyene).

More than half of the human population is exposed to mosquito-borne infections. Climate change and the emergence of strains resistant to traditionally used insecticides have motivated the search of new agents for mosquito population control. Essential oils have been effective repellents and larvicidal agents. The aim of this work was to review research studies conducted in recent years on the larvicidal activity of essential oils and their components against Aedes, Anopheles and Culex mosquitoes, as well as the latest reports about their possible mechanism of action.

The biological activity of essential oils and their major components is well documented. Essential oils such as oregano and cinnamon are known for their effect against bacteria, fungi, and even viruses. The mechanism of action is proposed to be related to membrane and external cell structures, including cell walls. This study aimed to evaluate the biological activity of seven essential oils and eight of their major components against Gram-negative and Gram-positive bacteria, filamentous fungi, and protozoans. The antimicrobial activity was evaluated by determination of the Minimal Inhibitory Concentration for Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Salmonella Typhimurium, Shigella sonnei, Aspergillus niger, Aspergillus ochraceus, Alternaria alternata, and Fusarium oxysporium, the half-maximal inhibitory concentration (IC50) for Trypanosoma cruzi and Leishmania mexicana, and the median lethal dose (LD50) for Giardia lamblia. Results showed that oregano essential oil showed the best antibacterial activity (66–100 µg/mL), while cinnamon essential oil had the best fungicidal activity (66–116 µg/mL), and both showed excellent antiprotozoal activity (22–108 µg/mL). Regarding the major components, thymol and carvacrol were also good antimicrobials (23–200 µg/mL), and cinnamaldehyde was an antifungal compound (41–75 µg/mL). The major components were grouped according to their chemical structure as phenylpropanoids, terpenoids, and terpinenes. The statistical analysis of the grouped data demonstrated that protozoans were more susceptible to the essential oils, followed by fungi, Gram-positive bacteria, and Gram-negative bacteria. The analysis for the major components showed that the most resistant microbial group was fungi, which was followed by bacteria, and protozoans were also more susceptible. Principal Component Analysis for the essential oils demonstrated the relationship between the biological activity and the microbial group tested, with the first three components explaining 94.3% of the data variability. The chemical structure of the major components was also related to the biological activity presented against the microbial groups tested, where the three first principal components accounted for 91.9% of the variability. The external structures and the characteristics of the cell membranes in the different microbial groups are determinant for their susceptibility to essential oils and their major components

Lactic acid bacteria (LAB) are an important source of bioactive metabolites and enzymes. LAB isolates from fresh vegetable sources were evaluated to determine their antimicrobial, enzymatic, and adhesion activities. A saline solution from the rinse of each sample was inoculated in De Man, Rogosa and Sharpe Agar (MRS Agar) for isolates recovery. Antimicrobial activity of cell-free supernatants from presumptive LAB isolates was evaluated by microtitration against Gram-positive, Gram-negative, LAB, mold, and yeast strains. Protease, lipase, amylase, citrate metabolism and adhesion activities were also evaluated. Data were grouped using cluster analysis, with 85% of similarity. A total of 76 LAB isolates were recovered, and 13 clusters were formed based on growth inhibition of the tested microorganisms. One cluster had antimicrobial activity against Gram-positive bacteria, molds and yeasts. Several LAB strains, PIM4, ELO8, PIM5 and CAL14 strongly inhibited the growth of L. monocytogenes and JAV15 and TOV9 strongly inhibited the growth of F. oxysporum. Based on enzymatic activities, 5 clusters were formed. Seven isolates hydrolyzed starch, 46 proteins, 14 lipids, and 36 metabolized citrate. LAB isolates with the best activities were molecularly identified as Leuconostoc mesenteroides, Enterococcus mundtii and Enterococcus faecium. Overall, LAB isolated from vegetables showed potential technological applications and should be further evaluated.

The multifunctional properties of autochthonous lactic acid bacteria can be of use for enhancing the sensorial properties of food, as well as in food preservation. An initial screening for antimicrobial, proteolytic, and lipolytic capacities was done in 214 presumptive lactic acid bacteria isolates obtained from Chihuahua cheese manufacturing and during a ripening period of nine months. The antimicrobial screening was done by spot-on-the-lawn tests, using Listeria monocytogenes and Escherichia coli as indicator microorganisms; proteolysis was tested in casein-peptone agar and lipolysis in Mann−Rogosa−Sharpe (MRS)-tributyrin agar. More than 90% of the isolates hydrolyzed the casein, but only 30% hydrolyzed tributyrin; the inhibition of L. monocytogenes in the spot-on-the-lawn assay was used to select 39 isolates that had a bigger inhibition zone (>11.15 mm ± 0.3) than the control (Nisin producer Lactococcus lactis BS-10 Chr Hansen). The selected isolates were grown in MRS to obtain the neutralized cell-free supernatants and verify their antimicrobial activity by agar diffusion and the percentage of growth inhibition techniques. The selected isolates were also growth in casein peptone broth, and the cell-free supernatants were used for the determination of antioxidant activity by the radical scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) techniques. The results were analyzed to identify similarities by cluster analysis, based on their antimicrobial and antioxidant capacities. The isolates were arranged into six clusters; one cluster that included 12 isolates demonstrated L. monocytogenes (784−2811 mm2/mL AU by agar diffusion assay) and E. coli (41%−47% growth inhibition) antimicrobial activity. The isolates clustered in these groups also showed competitive inhibition of both radicals (11%−19% of DPPH and 50%−60% of ABTS). The isolates from cluster one were also identified by 16S rDNA amplification and were identified as Enterococcus faecium. Traditional products such as Chihuahua cheese can be a source or lactic acid bacteria with metabolic properties that can be used in food preparation and preservation.

Se evaluó el efecto de materiales de soporte de baja densidad sobre la eficiencia de un reactor de lecho fluidizado para el tratamiento de aguas residuales. Primero se seleccionaron varios materiales de origen mineral, con densidad específica menor que la densidad de la arena sílica. Después se evaluaron otros materiales porosos de densidad específica ligeramente menor a la densidad de la arena sílica, pero con una densidad aparente significativamente menor. De un total de 10 materiales evaluados, sobresalieron la mezcla de poliéster-perlita expandida y la perlita vitrificada como los mejores materiales. La fluidización del lecho de poliéster-perlita se obtuvo con una velocidad de recirculación de 0.45 y la de perlita vitrificada con 0.55 cm seg-1. Ambas velocidades de recirculación son menores a las reportadas para materiales de densidad similar. El régimen de fluidización favoreció la operación del reactor en forma continua sin la necesidad de aplicar lavados del lecho y sin llegar a la saturación del mismo. DOI: https://doi.org/10.54167/tecnociencia.v2i2.74

Chihuahua cheese is a local artisanal cheese traditionally produced from raw milk. When this cheese is produced with pasteurized milk, cheesemakers complain that there are differences in taste and aroma as compared with traditional manufacturing. This work aimed to obtain a descriptive sensory analysis of Chihuahua cheese manufactured with raw milk under traditional conditions. Samples were collected in five cheese dairies at two different seasons (summer and autumn), and a Quantitative Descriptive Sensorial Analysis was done by a panel of trained judges. For aroma descriptors, cooked descriptor showed differences between dairies, and whey was different among dairies and sampling seasons (P

Antibiotic resistance along with biofilm formation increases the difficulty for antibiotic therapy in urinary tract infections. Bioactive molecules derived from plants, such as those present in essential oils, can be used to treat bacterial infections. Oregano is one of the spices to have antimicrobial activity. Therefore, three Mexican oregano essential oils (two Lippia berlandieri Schauer and one Poliomintha longiflora) were tested for antimicrobial capacity against multidrug-resistant, biofilm-forming bacterial isolates. Clinical isolates from urinary tract infections were tested for antibiotic resistance. Multidrug-resistant isolates were evaluated for biofilm formation, and Mexican oregano antimicrobial effect was determined by the minimal inhibitory (CMI) and minimal bactericidal concentrations (CMB). The selected isolates were identified by molecular phylogenetic analysis. Sixty-one isolates were included in the study; twenty were characterized as multidrug-resistant and from those, six were strong biofilm formers. Three isolates were identified as Escherichia coli, two as Pseudomonas aeruginosa and one as Enterococcus faecalis based on the phylogenetic analysis of 16 S rRNA gene sequences. The antimicrobial effect was bactericidal; E. faecalis was the most susceptible (P. aeruginosa was the most resistant (>2,000 mg/L CMI/CMB). There was a range of 500-1000 mg/L (CMI/CMB) for the E. coli isolates. Mexican oregano essential oils demonstrated antimicrobial efficacy against multidrug-resistant clinical isolates.

[Not available]

Poliomintha longiflora is a Mexican oregano, which has not been widely studied. This work aimed to describe the chemical composition, antimicrobial and antioxidant activities present in P. longiflora essential oil (EO), the hydrosol from EO extraction and extracts from waste solid residues (WSRs), identified as ethanol extract, ethyl acetate extract and the subfractions of ethanol and ethyl acetate extracts. The chemical characterization of the EO, hydrosol and WSR extracts was performed by GC–MS and HPLC. Their antioxidant activity was evaluated using two methods, and their antimicrobial activity was evaluated against Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, and Salmonella Typhimurium. Thirty-one chemical components were identified in the EO. The subfractions from the ethanol and ethyl acetate extracts contain methylmaleic anhydride, thymoquinone, thymol, carvacrol, thymol acetate, carvacrol acetate, and phenolic acids. The EO presented the highest biological activities for antioxidant (136.05 mg equivalent of ascorbic acid/g (AAE/g); IC50 83.70 μg/mL of 2, 2-diphenyl-1-picrylhydrazyl (DPPH)) and antimicrobial tests (minimal inhibitory concentration (MIC) value of 250–750 mg/L), while the hydrosol and the ethyl acetate extract from WSRs had the lowest antioxidant activity (14.16 and 12.29 mg AAE/g respectively), and the hydrosol had the lowest antimicrobial activity (MIC of 3000 mg/L). The data suggest that Mexican oregano P. longiflora hydrosol and extracts from waste solid residues can still have compounds with antimicrobial and antioxidant capacities.

Chihuahua cheese is a traditional cheese produced in Northwest Mexico that is consumed shortly after production. Cheeses prepared during autumn, winter and summer were collected from five dairies, and analyzed to determine seasonal influence on proximate analysis, texture profile and the microbiological dynamic during a ripening period of 270 days. Coliforms, coagulase-positive staphylococci, molds, yeast, as well as presumptive mesophilic lactobacilli, thermophilic lactobacilli, lactococci, thermophilic cocci and enterococci, were enumerated by plate count on selective agar. Manufacturing dairy had an effect on Chihuahua cheese composition and texture profile. Seasonality influence on the microbial dynamic was observed, since the highest initial counts of coliforms (5.14 log CFU/g), coagulase-positive staphylococci (4.13 log CFU/g) and mesophilic lactobacilli (7.86 log CFU/g) were detected on summer samples. Also, ripening time affected the survival of coliforms and presumptive lactococci after 270 days (1.24 and 5.89 log CFU/g respectively) while from day 90th, coagulase-positive staphylococci were absent. Microbial changes and seasonal influence provide information on the microbiota that can influence the sensorial characteristics of Chihuahua cheese.

The larvicidal activity of essential oils cinnamon (Cinnamomum verum J. Presl), Mexican lime (Citrus aurantifolia Swingle) cumin (Cuminum cyminum Linnaeus), clove (Syzygium aromaticum (L.) Merr. & L.M.Perry), laurel (Laurus nobilis Linnaeus), Mexican oregano (Lippia berlandieri Schauer) and anise (Pimpinella anisum Linnaeus)) and their major components are tested against larvae and pupae of Culex quinquefasciatus Say. Third instar larvae and pupae are used for determination of lethality and mortality. Essential oils with more than 90% mortality after a 30-min treatment are evaluated at different time intervals. Of the essential oils tested, anise and Mexican oregano are effective against larvae, with a median lethal concentration (LC50) of 4.7 and 6.5 µg/mL, respectively. Anise essential oil and t-anethole are effective against pupae, with LC50 values of 102 and 48.7 µg/mL, respectively. Oregano essential oil and carvacrol also have relevant activities. A kinetic analysis of the larvicidal activity, the oviposition deterrent effect and assays of the effects of the binary mixtures of chemical components are undertaken. Results show that anethole has synergistic effects with other constituents. This same effect is observed for carvacrol and thymol. Limonene shows antagonistic effect with β-pinene. The high larvicidal and pupaecidal activities of essential oils and its components demonstrate that they can be potential substitutes for chemical compounds used in mosquitoes control programs.