Influence of Culture Media Formulated with Agroindustrial Wastes on the Antimicrobial Activity of Lactic Acid Bacteria.

The discarding of wastes into the environment is a significant problem for many communities. Still, food waste can be used for lactic acid bacteria (LAB) growth. Here, we evaluated three growth media equivalent to de Mann Rogosa Sharpe (MRS), using apple bagasse, yeast waste, fish flour, forage oats, and cheese whey. Cell-free supernatants of eight LAB strains were tested for antimicrobial activity against nine indicator microorganisms. The supernatants were also evaluated for protein content, reducing sugars, pH, and lactic acid concentration. Cell-free supernatants from fish flour broth (FFB) LAB growth were the most effective. The strain Leuconostoc mesenteroides PIM5 presented the best activity in all media. L. mesenteroides CAL14 completely inhibited L. monocytogenes and strongly inhibited Bacillus cereus (91.1%). The strain L. mesenteroides PIM5 consumed more proteins (77.42%) and reducing sugars (56.08%) in FFB than in MRS broth (51.78% and 30.58%, respectively). Culture media formulated with agroindustrial wastes positively improved the antimicrobial activity of selected LAB, probably due to the production of antimicrobial peptides or bacteriocins.

Antibiotics, Multidrug-Resistant Bacteria, and Antibiotic Resistance Genes: Indicators of Contamination in Mangroves?

Multidrug-resistant bacteria and antibiotic resistance genes can be monitored as indicators of contamination in several environments. Mangroves are among the most productive ecosystems, and although they can be resilient to the action of climate phenomena, their equilibrium can be affected by anthropogenic activities. Regarding the presence and persistence of multidrug-resistant bacteria in mangroves, it is common to think that this ecosystem can function as a reservoir, which can disperse the antibiotic resistance capacity to human pathogens, or serve as a filter to eliminate drug-resistant genes. The possible impact of anthropogenic activities carried out near mangroves is reviewed, including wastewater treatment, food production systems, leisure, and tourism. Adverse effects of antibiotic resistance genes or multidrug-resistant bacteria, considered as emerging contaminants, have not been reported yet in mangroves. On the contrary, mangrove ecosystems can be a natural way to eliminate antibiotics, antibiotic-resistant bacteria, and even antibiotic-resistant genes from the environment. Although mangroves' role in decreasing antibiotics and antibiotic resistance genes from the environment is being proposed, the mechanisms by which these plants reduce these emerging contaminants have not been elucidated and need further studies. Additionally, further evaluation is needed on the effects of antibiotics and antibiotic-resistant bacteria in mangroves to generate an analysis of the human contribution to the degradation of this specific ecosystem as well as to define if these contaminants can be used as indicators of contamination in mangrove ecosystems.

Differential Antimicrobial Effect of Essential Oils and Their Main Components: Insights Based on the Cell Membrane and External Structure.

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.

Selection of Lactic Acid Bacteria Isolated from Fresh Fruits and Vegetables Based on Their Antimicrobial and Enzymatic Activities.

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.

Susceptibility of Multidrug-Resistant and Biofilm-Forming Uropathogens to Mexican Oregano Essential Oil.

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 (<200 mg/L CMI/CMB), and 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.

Antioxidant and Antimicrobial Activity of Mexican Oregano (Poliomintha longiflora) Essential Oil, Hydrosol and Extracts from Waste Solid Residues.

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.

Oviposition Deterrent and Larvicidal and Pupaecidal Activity of Seven Essential Oils and their Major Components against Culex quinquefasciatus Say (Diptera: Culicidae): Synergism-antagonism Effects.

The larvicidal activity of essential oils cinnamon (Cinnamomumverum J. Presl), Mexican lime (Citrusaurantifolia Swingle) cumin (Cuminumcyminum Linnaeus), clove (Syzygiumaromaticum (L.) Merr. & L.M.Perry), laurel (Laurusnobilis Linnaeus), Mexican oregano (Lippiaberlandieri Schauer) and anise (Pimpinellaanisum Linnaeus)) and their major components are tested against larvae and pupae of Culexquinquefasciatus 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 ß-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.

Improved method for qualitative screening of lipolytic bacterial strains.

Esterases and lipases are lipolytic enzymes that catalyse the hydrolysis of triacylglycerols, Determination of lipolysis on agar plates is a simple approach to determine lipase or esterase action, but visual evaluation of lipolysis is frequently difficult in practice. Therefore, the aim of this work was to improve the efficiency of lipolysis visualization in tributyrin agar (mTBA) by adding calcium and/or magnesium ions in the screening of lipolytic microbial strains. Lipolytic activity was evaluated in mTBA using the well diffusion technique, where a clear zone around the inoculated wells indicated lipid hydrolysis. Results suggest that the addition of 2.5 mM calcium and 5.0 mM magnesium was the best combination of ion addition to TBA. Lipolytic activity increased the clearing zone up to 38% more than without the addition of ions and the clear zone was clearly observed. The mTBA plate was used with culture collection microbial strains, as well as with a collection of soil microorganisms, to identify lipase producers. The addition of calcium and magnesium ions can provide an easier screening procedure for selection of lipolytic bacterial strains. •A modified tributyrin agar for screening of lipolytic bacteria was prepared by adding calcium and magnesium ions.•The modified TBA agar was tested with control bacterial strains, and, based on the results, 2.5 mM Ca and 5.0 mM Mg ions were added in the mTBA.•mTBA was validated with environmental bacterial strains for screening of lipolytic activity.

Quantitative structure-activity relationship of molecules constituent of different essential oils with antimycobacterial activity against Mycobacterium tuberculosis and Mycobacterium bovis.

BACKGROUND: Essential oils and their constituents are commonly known for their antibacterial, antifungal and antiparasitic activity, and there are also reports on the antimycobacterial properties, but more experimental data are needed for the description of the mechanism of action or structural (and molecular) properties related to the antimicrobial activity. METHODS: Twenty-five constituents of essential oils were evaluated against Mycobacterium tuberculosis H37Rv and Mycobacterium bovis AN5 by the Alamar Blue technique. Twenty compounds were modeled using in silico techniques descriptor generation and subsequent QSAR model building using genetic algorithms. The p-cymene, menthol, carvacrol and thymol were studied at the quantum mechanical level through the mapping of HOMO and LUMO orbitals. The cytotoxic activity against macrophages (J774A) was also evaluated for these four compounds using the Alamar Blue technique. RESULTS: All compounds tested showed to be active antimicrobials against M. tuberculosis. Carvacrol and thymol were the most active terpenes, with MIC values of 2.02 and 0.78 µg/mL respectively. Cinnamaldehyde and cinnamic acid were the most active phenylpropanes with MIC values of 3.12 and 8.16 µg/mL respectively. The QSAR models included the octanol-water partition (LogP) ratio as the molecular property that contributes the most to the antimycobacterial activity and the phenolic group (nArOH) as the major structural element. CONCLUSIONS: The description of the molecular properties and the structural characteristics responsible for antimycobacterial activity of the compounds tested, were used for the development of mathematical models that describe structure-activity relationship. The identification of molecular and structural descriptors provide insight into the mechanisms of action of the active molecules, and all this information can be used for the design of new structures that could be synthetized as potential new antimycobacterial agents.

Epidemiologic investigation of tuberculosis in a Mexican population from Chihuahua State, Mexico: a pilot study.

Tuberculosis (TB) and its co-morbid conditions have become a burden on global health economies. It is well understood that susceptibility of the host to TB infection/disease is influenced by both genetic and environmental factors and their interactions. The aims of this pilot case-control study are to characterize the sociodemographic and environmental factors related to active TB disease (TB/case) and latent TB infection (LTBI/control) status, and to identify risk factors associated with progression from LTBI to TB. We recruited 75 cases with TB (mean age=46.3y; females=41%) and 75 controls with LTBI (mean age=39.0y; females=37%), from the Mestizo population of Cuidad Juárez, Mexico. In addition to the determination of case/control status, information on environmental variables was collected (e.g., socioeconomic status, smoking, alcohol consumption, substance abuse, nutritional status, household demographics, medical histories and presence of type 2 diabetes [T2DM]). The data were analyzed to identify the environmental correlates of TB and LTBI using univariate and multivariate statistical approaches. Following multivariate logistic regression analysis, TB was associated with poor nutrition, T2DM, family history of TB, and non-Chihuahua state of birth. These preliminary findings have relevance to TB control at the Mexico-United States border, and contribute to our future genetic study of TB in Mexicans.

Selection of biosurfactan/bioemulsifier-producing bacteria from hydrocarbon-contaminated soil

Petroleum-derived hydrocarbons are among the most persistent soil contaminants, and some hydrocarbon-degrading microorganisms can produce biosurfactants to increase bioavailability and degradation. The aim of this work was to identify biosurfactant-producing bacterial strains isolated from hydrocarbon-contaminated sites, and to evaluate their biosurfactant properties. The drop-collapse method and minimal agar added with a layer of combustoleo were used for screening, and positive strains were grown in liquid medium, and surface tension and emulsification index were determined in cell-free supernantant and cell suspension. A total of 324 bacterial strains were tested, and 17 were positive for the drop-collapse and hydrocarbon-layer agar methods. Most of the strains were Pseudomonas, except for three strains (Acinetobacter, Bacillus, Rhodococcus). Surface tension was similar in cell-free and cell suspension measurements, with values in the range of 58 to 26 (mN/m), and all formed stable emulsions with motor oil (76-93 percent E24). Considering the variety of molecular structures among microbial biosurfactants, they have different chemical properties that can be exploited commercially, for applications as diverse as bioremediation or degradable detergents.

Phenotypic and genotypic characteristics of Lactococcus lactis strains isolated from different ecosystems.

Lactococcus lactis is the lactic acid bacteria most used in the manufacture of dairy products because of its fast lactose fermentation and flavor production. In this study, L. lactis strains isolated from different sources and previously characterized and evaluated for their capability to produce flavor were compared with respect to their phenotypic and genotypic characteristics. The variability of phenotypes and genotypes in the L. lactis strains were influenced by the source of isolation. In general, strains that shared the same genotype presented different phenotypes, and only some genotypes were clearly related to the source of isolation. On the other hand, phenotypic characteristics such as coagulant activity and utilization of lactose, glucose, and arginine were closely related to the ecosystem of origin. Coagulant activity and lactose utilization, phenotypic characteristics that are of utmost importance for efficient flavor production by starters in the manufacture of dairy products, were better for strains isolated from raw milk dairy products than for those isolated from vegetables.

Selection of biosurfactan/bioemulsifier-producing bacteria from hydrocarbon-contaminated soil.

Petroleum-derived hydrocarbons are among the most persistent soil contaminants, and some hydrocarbon-degrading microorganisms can produce biosurfactants to increase bioavailability and degradation. The aim of this work was to identify biosurfactant-producing bacterial strains isolated from hydrocarbon-contaminated sites, and to evaluate their biosurfactant properties. The drop-collapse method and minimal agar added with a layer of combustoleo were used for screening, and positive strains were grown in liquid medium, and surface tension and emulsification index were determined in cell-free supernantant and cell suspension. A total of 324 bacterial strains were tested, and 17 were positive for the drop-collapse and hydrocarbon-layer agar methods. Most of the strains were Pseudomonas, except for three strains (Acinetobacter, Bacillus, Rhodococcus). Surface tension was similar in cell-free and cell suspension measurements, with values in the range of 58 to 26 (mN/m), and all formed stable emulsions with motor oil (76-93% E24). Considering the variety of molecular structures among microbial biosurfactants, they have different chemical properties that can be exploited commercially, for applications as diverse as bioremediation or degradable detergents.

Apego al tratamiento farmacológico en pacientes con diagnóstico de diabetes mellitus tipo 2 / Pharmacological therapy compliance in diabetes

Objetivos. Establecer la frecuencia de apego al tratamiento farmacológico en pacientes diabéticos tipo 2, relacionarla con el control metabólico e identificar factores que influyen para el no apego. Material y métodos. Estudio transversal comparativo, efectuado en 150 pacientes con diabetes mellitus tipo 2 de la unidad de medicina familiar No. 33 del Instituto Mexicano del Seguro Social de Chihuahua, Chih., México, hecho entre 1997 y 1998. Se midió el apego con cuenta de tabletas en su domicilio. El control metabólico se midió con hemoglobina glucosilada. Un cuestionario investigó factores relacionados. Se utilizó estadística descriptiva, t de Student y razón de momios. Resultados. El apego correspondió a 54.2 por ciento. Los factores asociados al no apego fueron la escolaridad primaria y la falta de información sobre la enfermedad (p<0.05) Conclusiones. El apego fue bajo; los factores relacionados con la falta del mismo son modificables con educación. El texto completo en inglés de este artículo está disponible en: http://www.insp.mx/salud/index.html