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Prebiotic effects have been attributed to agave fructans through bacterial and yeast fermentations, but there are few reports on their use as raw materials of a carbon source. Kefir milk is a fermented drink with lactic acid bacteria and yeast that coexist in a symbiotic association. During fermentation, these microorganisms mainly consume lactose and produce a polymeric matrix called kefiran, which is an exopolysaccharide composed mainly of water-soluble glucogalactan, suitable for the development of bio-degradable films. Using the biomass of microorganisms and proteins together can be a sustainable and innovative source of biopolymers. In this investigation, the effects of lactose-free milk as a culture medium and the addition of other carbon sources (dextrose, fructose, galactose, lactose, inulin and fructans) in concentrations of 2, 4 and 6% w/w, coupled with initial parameters such as temperature (20, 25 and 30 °C), % of starter inoculum (2, 5 and 10% w/w) was evaluated. The method of response surface analysis was performed to determine the optimum biomass production conditions at the start of the experiment. The response surface method showed that a 2% inoculum and a temperature of 25 °C were the best parameters for fermentation. The addition of 6% w/w agave fructans in the culture medium favored the growth of biomass (75.94%) with respect to the lactose-free culture medium. An increase in fat (3.76%), ash (5.57%) and protein (7.12%) content was observed when adding agave fructans. There was an important change in the diversity of microorganisms with an absence of lactose. These compounds have the potential to be used as a carbon source in a medium culture to increase kefir granule biomass. There was an important change in the diversity of microorganisms with an absence of lactose, where the applied image digital analysis led to the identification of the morphological changes in the kefir granules through modification of the profile of such microorganisms.

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Litopenaeus vannamei, the Pacific whiteleg shrimp, is one of the most marketable species in aquaculture worldwide. However, it is susceptible to different infections causing considerable losses in production each year. Consequently, using prebiotics that promotes the proliferation of beneficial bacteria and strengthen the immune system is a current strategy for disease control. In this study, we isolated two strains of E. faecium from the gut of L. vannamei fed with agavin-supplemented diets. These isolates showed antibacterial activity against Vibrio parahaemolyticus, Vibrio harveyi and Vibrio alginolyticus, most likely due to peptidoglycan hydrolase (PGH) activity. Furthermore, we sequenced the genome of one isolate. As a result, we observed three proteins related to the production of bacteriocins, a relevant trait for selecting probiotic strains since they can inhibit the invasion of potential pathogens. Additionally, the genome annotation showed genes related to the production of essential nutrients for the host. It lacked two of the most common factors associated with virulence in Enterococcus pathogenic strains (esp and hyl). Thus, this host-probiotic-derived strain has potential application not only in shrimp health but also in alternative aquatic environments, as it is adapted to coexist within the gut shrimp microbiota, independently of the diet.

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Agavins are prebiotics and functional fiber that modulated the gut microbiota and metabolic status in obese mice. Here, we designed a placebo-controlled, double-blind, exploratory study to assess fluctuations in gastrointestinal (GI) tolerability-related symptoms to increasing doses of agavins in 38 lean and obese Mexican adults for five weeks and their impact on subjective appetite, satiety, metabolic markers, and body composition. All GI symptoms showed higher scores than placebo at almost every dose for both lean and obese groups. Flatulence caused an intense discomfort in the lean-agavins group at 7 g/day, while obese-agavins reported a mild-to-moderate effect for all five symptoms: no significant differences among 7, 10, and 12 g/day for flatulence, bloating, and diarrhea. Ratings for any GI symptom differed between 10 and 12 g/day in neither group. The inter-group comparison demonstrated a steady trend in GI symptoms scores in obese participants not seen for lean volunteers that could improve their adherence to larger trials. Only body weight after 10 g/day reduced from baseline conditions in obese-agavins, with changes in triglycerides and very-low-density lipoproteins compared to placebo at 5 g/day, and in total cholesterol for 10 g/day. Altogether, these results would help design future trials to evaluate agavins impact on obese adults.

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Highly branched neo-fructans (agavins) are natural prebiotics found in Agave plants, with a large capacity to mitigate the development of obesity and metabolic syndrome. Here, we investigated the impact of agavins intake on gut microbiota modulation and their metabolites as well as their effect on metabolic endotoxemia and low-grade inflammation in mice fed high-fat diet. Mice were fed with a standard diet (ST) and high-fat diet (HF) alone or plus an agavins supplement (HF+A) for ten weeks. Gut microbiota composition, fecal metabolite profiles, lipopolysaccharides (LPS), pro-inflammatory cytokines, and systemic effects were analyzed. Agavins intake induced substantial changes in gut microbiota composition, enriching Bacteroides, Parabacteroides, Prevotella, Allobaculum, and Akkermansia genus (LDA > 3.0). l-leucine, l-valine, uracil, thymine, and some fatty acids were identified as possible biomarkers for this prebiotic supplement. As novel findings, agavins supplementation significantly decreased LPS and pro-inflammatory (IL-1α, IL-1ß, and TNF-α; p < 0.05) cytokines levels in portal vein. In addition, lipid droplets content in the liver and adipocytes size also decreased with agavins consumption. In conclusion, agavins supplementation mitigate metabolic endotoxemia and low-grade inflammation in association with gut microbiota regulation and their metabolic products, thus inducing beneficial responses on metabolic disorders in high-fat diet-fed mice.

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[This corrects the article DOI: 10.3389/fpls.2020.00324.].

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Over 70% of Agave species, (159 of 206) are found in Mexico and are well adapted to survive under hot, arid conditions, often in marginal terrain, due to a unique combination of morphological and physiological attributes. In the pre-Columbian era agaves were also key to human adaptation to desert terrain. In contrast to other species such as cacti or resurrection plants, Agaves store carbohydrates in the form of fructan polymers rather than starch or sucrose, however, properties specific to fructans such as a strong hydration shell, the ability to be transported through phloem, variable composition throughout the Agave life-cycle and accumulation in succulent tissues and flowers suggest a potential for multiple functional roles. This mini-review summarizes current knowledge of molecular and biochemical aspects of fructan metabolism in Agave species.

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In this study the effect of agavin and inulin addition on the microstructural, textural, thermal and sensory properties of apple leathers was investigated. Agavins and inulin were added to leathers at two concentration levels (6 and 4%) individually and as a mixture. Scanning Electron Microscopy (SEM) revealed more compact and less porous matrices in the 6% concentration with respect to the control, influencing leather texture. In formulations with agavins the texture was significantly (p < 0.05) smoother than in those with inulin. No relationship was found between hardness and glass transition temperature (Tg), but there was a significant difference between treated leathers and the control. The acceptability of the product showed a direct relationship with the hardness. There were significant changes in the leathers after storage. Agavins and inulin exhibited different technological properties and considering the texturising effect of the agavins, their potential for use in the food industry is promising.

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Aguamiel is a natural sap produced by some species of agave plants, such as Agave salmiana, A. atrovirens, or A. angustifolia. It is a product with a high concentration of fructose, glucose or sucrose, although its composition may vary depending on the season in which it is produced, and may also contain agave fructans (or agavins) or fructooligosaccharides (FOS). It has been reported that FOS can be produced by enzymes that act on sucrose or inulin, transfructosylating or hydrolyzing these materials, respectively. Due to the sugar content in aguamiel, the application of an enzymatic complex produced by Aspergillus oryzae DIA MF was carried out. This complex was characterized by 1-D electrophoresis SDS-PAGE, and its transfructosylation and hydrolysis activities were determined by HPLC. In order to determine the conditions at which the concentration of FOS in this beverage increased, kinetics were carried out at different temperatures (30, 50, and 70°C) and times (0, 1, 2, 3, 4, 5, 10, and 15 h). Finally, the antioxidant and prebiotic activities were evaluated. FOS concentration in aguamiel was increased from 1.61 ± 0.08 to 31.01 ± 3.42 g/ L after 10 h reaction at 30°C applying 10% enzymatic fraction-substrate (v/v). Antioxidant activity was highly increased (34.81-116.46 mg/eq Trolox in DPPH assay and 42.65 to 298.86 mg/eq Trolox in FRAP assay) and growth of probiotic bacteria was higher in aguamiel after the enzymatic treatment. In conclusion, after the application of the enzymatic treatment, aguamiel was enriched with FOS which improved antioxidant and prebiotic properties, so it can be used as a functional food.

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Recently, agavins (branched neo-fructans) of short degree of polymerization have shown beneficial effects on the health of both healthy and overweight individuals. Therefore, the aim of the present work was to investigate the potential use of Agave angustifolia agavins on the generation of branched fructooligosacharides (a-FOS). A. angustifolia agavins were hydrolyzed using exo-, endo-inulinase, and a mixture of both (25 and 75%, respectively). Exo- and the inulinase mixture degraded quickly the agavins in relation to endo-inulinase treatment. Only endo-inulinase and the inulinase mixture generated a-FOS formation. Endo-inulinase degraded 31% of agavins, yielding approximately 20% of a-FOS after 48 h, whereas the inulinase mixture hydrolyzed 33% of agavins in just 90 min, but only yielded 10% of a-FOS. These results suggest that agave plants could be an abundant raw material for a-FOS production, which might have a huge prebiotic potential as new branched fructooligosaccharides with many applications in the alimentary and pharmaceutical industry.

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