Probiotic and functional potential of lactic acid bacteria isolated from pulque and evaluation of their safety for food applications.

Pulque is a traditional Mexican non-distilled alcoholic beverage to which several beneficial functions are attributed, mainly associated with gastrointestinal health, which can be explained by the presence of probiotic bacteria in its microbiota. Therefore, the objective of this work was to evaluate the safety, probiotic activity, and functional characteristics of seven strains of lactic acid bacteria (LAB) isolated from pulque using the probiotic strain Lactobacillus acidophilus NCFM as control. The LAB isolates were identified by 16S rRNA sequencing and MALDI Biotyper® MS as belonging to three different Lactobacillaceae genera and species: Lactiplantibacillus plantarum, Levilactobacillus brevis and Lacticaseibacillus paracasei. Most strains showed resistance to gastric juice, intestinal juice and lysozyme (10 mg/L). In addition, all strains exhibited bile salt hydrolase (BSH) activity and antibacterial activity against the pathogenic strain Listeria monocytogenes. Additionally, cell surface characteristics of LAB were evaluated, with most strains showing good hydrophobicity, auto-aggregation, and co-aggregation towards enteropathogenic Escherichia coli and L. monocytogenes. In terms of safety, most of the strains were sensitive to the tested antibiotics and only the Lact. paracasei UTMB4 strain amplified a gene related to antibiotic resistance (mecA). The strains Lact. plantarum RVG2 and Lact. plantarum UTMB1 presented γ-hemolytic activity, and the presence of the virulence-related gene agg was identified only in UTMB1 strain. Regarding functional characterization, the tested bacteria showed good ß-galactosidase activity, antioxidant activity and cholesterol reduction Based on principal component analysis (PCA) and heat mapping, and considering the strain Lact. acidophilus NCFM as the probiotic reference, the strains Lacticaseibacillus paracasei UTMB4, Lactiplantibacillus plantarum RVG4 and Levilactobacillus brevis UTMB2 were selected as the most promising probiotic strains. The results of this study highlighted the probiotic, functional and safety traits of LAB strains isolated from pulque thus supporting the health benefits attributed to this ancestral beverage.

Combined Effect of the Potassium Dose and Plant Biofertilization by Acinetobacter calcoaceticus on the Growth, Mineral Content, Nutritional Quality, Antioxidant Activity, and Metabolomic Features of Tomatillo Fruits (Physalis ixocarpa Brot.).

An Acinetobacter calcoaceticus UTMR2 strain was evaluated in tomatillo plants (Physalis ixocarpa Brot.) using a factorial design with different potassium doses (100, 75, 50 and 0% of the recommended dose). In addition to the agronomic parameters, an analysis of the physicochemical, antioxidant, and metabolomic properties of the fruit was performed. The application of the inoculant affected several parameters of the plant (chlorophyll, weight, and contents of several mineral elements) as well as of the fruit (yield, maturity index, FRAP antioxidant capacity, and contents of protein, fiber, and fat). A multivariate analysis was performed by means of a PCA and a heatmap, indicating that the inoculant induced a strong modulating activity in tomatillo plants for the evaluated parameters, with a remarkable effect at low K doses (0 and 50%). The inoculated treatment at 75% of the K dose resulted in similar plant and fruit characteristics to the fully fertilized control. On the other hand, the biofertilized treatment with no K addition resulted in the highest values in the plant and fruit parameters. In addition, from the metabolomics analysis of the fruits at 75% of the K dose, the up-regulation of 4,4″-bis(N-feruloyl)serotonin, salvianolic acid K, and chlorogenic acid was observed, which may have a role in anti-senescence and resistance mechanisms. In conclusion, the rhizobacterial strain had a positive effect on plant growth, nutritional quality, bioactive compounds, and antioxidant activity of tomatillo fruits at reduced doses of K fertilizer, which gives support for its consideration as an effective biofertilizer strain.

Probiotic activity traits in vitro and production of antimicrobial peptides by Lactobacillaceae isolates from pulque using Lactobacillus acidophilus NCFM as control.

The objective of this work was to determine in vitro probiotic activity traits of 11 lactic acid bacteria (LAB) strains isolated from pulque obtained from three different locations in the Mexican states of Oaxaca and Puebla using the probiotic strain Lactobacillus acidophilus NCFM as a positive control, and to detect their production of antimicrobial peptides, including bacteriocins and peptidoglycan hydrolases (PGH). The LAB isolates were identified by sequencing of their 16S rRNA as belonging to four different genera of the Lactobacillaceae family: Lactiplantibacillus, Levilactobacillus, Lacticaseibacillus and Liquorilactobacillus, corresponding to the species plantarum, brevis, paracasei and ghanensis, respectively. Most of the strains showed resistance to high acidity (pH 2) and bile salts (0.5%), with survival rates up to 87 and 92%, respectively. In addition, most of the strains presented good antimicrobial activity against the foodborne pathogens Listeria monocytogenes, ECEC and Salmonella Typhi. The strain Liquorilactobacillus ghanensis RVG6, newly reported in pulque, presented an outstanding overall performance on the probiotic activity tests. In terms of their probiotic activity traits assessed in this work, the strains compared positively with the control L. acidophilus NCFM, which is a very-well documented probiotic strain. For the antimicrobial peptide studies, four strains presented bacteriocin-like mediated antibiosis and six had significant PGH activity, with two strains presenting outstanding overall antimicrobial peptide production: Lacticaseibacillus paracasei RVG3 and Levilactobacillus brevis UTMB2. The probiotic performance of the isolates was mainly dependent on strain specificity. The results obtained in this work can foster the revalorization of pulque as a functional natural product.

Biocontrol of Alternaria alternata and Fusarium oxysporum by Trichoderma asperelloides and Bacillus paralicheniformis in tomato plants.

The objective of this work was to evaluate the effectiveness of the putative biocontrol agents (PBA) Bacillus paralicheniformis and Trichoderma asperelloides in vitro and in vivo to control two of the most important tomato plant diseases: vascular wilt (Fusarium oxysporum) and early blight (Alternaria alternata). The assessment of the in vitro interactions between the PBA and the phytopathogenic fungi was performed by dual confrontation assays. The biocontrol effectiveness of the individual and combined PBA treatments towards individual phytopathogen inoculations was evaluated in tomato plants. T. asperelloides was able to exert an outstanding mycoparasitic effect on both phytopathogenic fungi in the in vitro tests by hyphal strangulation and penetration. In addition, the individual PBA treatments were effective in the biocontrol of A. alternata and F. oxysporum in tomato plants reducing the plant disease severity in more than 53.8 and 66.7% for each of the pathogens, respectively. On the other hand, the combined use of the tested strains showed similar effectiveness in the biocontrol of A. alternata, but no synergism was observed. In addition, it was concluded that B. paralicheniformis protected the plants from the attack of A. alternata through the induction of the systemic resistance of the plant. This study demonstrated the effectiveness of the individual and combined use of the strains tested for the biocontrol of A. alternata and F. oxysporum in tomato plants.

Productivity and Antioxidant Activity of Wild, Reconstituted, and Hybrid Strains of the Pink Oyster Mushroom, Pleurotus djamor (Agaricomycetes), from Mexico.

The genus Pleurotus is the third most commonly produced edible fungi in the world. In addition, species of genus Pleurotus have functional properties such as anticancer, antiviral, antimicrobial, anti-inflammatory, and antioxidant activities, which are mainly attributed to phenolic compounds. For these reasons, this study evaluated the productivity and antioxidant activity (AA) of 2 wild strains (white and pink), 2 reconstituted strains (called "BB" and "RR"), and 4 hybrid strains (H1, H2, H3, and H4) of P. djamor from monokaryotic components (neohaplonts). The results showed that the white wild-type strain and the reconstituted strains exhibited the best production potential, expressed as biological efficiency and mycelial growth rate. The carpophores of hybrid strains H1 and H3 had the greatest AA, as evaluated with DPPH radical scavenging and reducing power assays, respectively. The H3 strain had the highest total phenol (TP) content. Pearson correlations led us to conclude that the mycelial growth rate has a regular inverse correlation with TP and a regular direct correlation with AA of methanolic extracts from carpophores and myce-lia. This is, to our knowledge, the first report in the literature about the effect of Pleurotus strain hybridization through a chemical de-dikaryotization process on TP content.

Natural antioxidant extracts as food preservatives.

The food industry is becoming more specialized and processing methods are continuously being developed to meet consumer needs. Consumers demand products that are safe and preferably free of synthetic additives. These additives are associated with health effects, in most cases without reasonable justification. Consequently, consumers are looking for clearly labelled products that guarantee the absence of synthetic additives. This has led to the need to search for natural additives, which the food industry claims arenatural antioxidant preservatives. The sources of natural antioxidants can be extremely varied, because practically all plants contain antioxidants that allow them to protect themselves from solar radiation and pests, as well as to regulate the production of chemical energy. However, the best alternatives for the food industry are fruits and spices, because they are already foods themselves. This article will describe fruits and spices considered as important sources of phenolic antioxidants. The main medicinal properties are related to phenolic compounds and their uses as additives, depending on their chemical structure.

Effect of crude plant extracts from some Oaxacan flora on two deleterious fungal phytopathogens and extract compatibility with a biofertilizer strain.

The antimicrobial activity of 12 plant extracts was tested against the phytopathogens Alternaria alternata and Fusarium solani. In addition, the compatibility of the extracts toward Bacillus liqueniformis, a biofertilizer and a non-target microorganism, was assessed. Plants tested belong to the Euphorbiaceae, Asteraceae, Crassulaceae, Rubiaceae, Convolvulaceae, Verbenaceae, Orchidaceae, Nyctaginaceae, Boraginaceae, and Tiliaceae families and were collected in the State of Oaxaca. The antifungal activity of the plant extracts (50-100 mg/mL) against A. alternata and F. solani, was determined by measuring the mycelium radial growth and obtaining the minimum inhibitory concentration (MIC) of fungal growth. In addition, with the aim of finding plant extracts which are compatible with a B. licheniformis biofertilizer strain and to test the non-toxic nature of the treatments, the toxicity of the extracts toward this strain was evaluated using the agar diffusion method. Azoxystrobin (12 µg) and chloramphenicol (30 µg) were used as positive controls for the pathogens and for the non-target bacteria, respectively. Plant extracts inhibited fungal growth in the ranges of 0.76-56.17% against F. solani and 2.02-69.07% against A. alternata. The extracts of Acalypha subviscida, Ipomoea murucoides, Tournefortia densiflora and Lantana achyranthifolia showed MIC values between 5.77-12.5 mg/mL for at least one of the fungal species. The best treatment, Adenophyllum aurantium, exhibited a maximum inhibition for both F. solani (56.17%, MIC = 7.78 mg/mL) and A. alternata (68.64% MIC = 7.78 mg/mL), and resulted innocuous toward B. licheniformis. Therefore, this plant has an outstanding potential for the agroecological control of fungal phytopathogens in industrial crops.

The Artisanal Production of Pulque, a Traditional Beverage of the Mexican Highlands.

Pulque is a traditional fermented alcoholic, acidic, viscous drink of the Mexican central highlands. Its production from the "aguamiel" (sap) of agave plants dates back ~1,500 years and continues to be made by artisanal methods. However, the variability of pulque's quality and its instability hamper its widespread distribution and consumption. Microbiological surveys of pulque from three ranches revealed tremendous variability in the types and quantity of the indigenous microbiota. The population of lactic acid bacteria ranged from 6 × 10(7) to 2 × 10(11) CFU/mL. This variability might be attributed to the conditions on the ranches where the pulque was made. In an attempt to identify these sources of variability, the microbial populations of aguamiel and pulque from a single agave plant were determined. Surprisingly, the population size of the "unfermented" aguamiel and the pulque converged by the end of 3 weeks. The potential use of bacteriocinogenic LAB and known starter cultures to improve pulque properties are discussed.