RESUMO
Probiotic-containing foods are among the most appreciated functional foods; however, probiotic-based dairy products cannot be consumed by people who are lactose intolerant, allergic to milk, or vegetarian or vegan individuals. Thus, new non-dairy matrices have been tested for probiotics delivery. This study evaluated the growth and viability of Limosilactobacillus fermentum ATCC 23271 and Lacticaseibacillus rhamnosus ATCC 9595 in Pitanga juice (Eugenia uniflora L.). The effects of the fermentation on the antioxidant and anti-infective properties of the juice were also analyzed. The E. uniflora juice allowed lactobacilli growth without supplementation, reaching rates around 8.4 Log CFU/mL and producing organic acids (pH values < 4) after 72 h of fermentation. The strain remained viable after 35 days of refrigerated storage. Fermentation by these bacteria increases the antioxidant capacity of the juice. The central composite rotational design was employed to evaluate the effects of bacterial inoculum and pulp concentration on growth and organic acids production by L. fermentum ATCC 23271. The strain was viable and produced organic acids in all tested combinations. L. fermentum-fermented juice and its cell-free supernatant significantly increased the survival of Tenebrio molitor larvae infected by enteroaggregative Escherichia coli 042. The results obtained in this study provide more insights into the potential of Pitanga juice to develop a functional non-dairy probiotic beverage with antioxidant and anti-infective properties.
Assuntos
Antioxidantes , Eugenia , Fermentação , Limosilactobacillus fermentum , Probióticos , Antioxidantes/farmacologia , Antioxidantes/metabolismo , Limosilactobacillus fermentum/metabolismo , Limosilactobacillus fermentum/crescimento & desenvolvimento , Limosilactobacillus fermentum/fisiologia , Limosilactobacillus fermentum/efeitos dos fármacos , Probióticos/farmacologia , Eugenia/química , Anti-Infecciosos/farmacologia , Sucos de Frutas e Vegetais/microbiologia , Sucos de Frutas e Vegetais/análise , Lacticaseibacillus rhamnosus/metabolismo , Lacticaseibacillus rhamnosus/crescimento & desenvolvimento , Lacticaseibacillus rhamnosus/efeitos dos fármacos , Viabilidade Microbiana/efeitos dos fármacosRESUMO
Presence of bacterial contaminants at levels > 107 colony forming units per milliliter (CFU/mL) during ethanol production processes reduces the alcoholic fermentation yield by 30%. Antibiotics are currently used to control contamination, but their residues may be detected in yeast extract, restricting this by-product trade to several countries. Thus, the objective of this study was to assess antimicrobial activity of the natural compounds hops extract, 4-hydroxybenzoic acid, nisin Z, and lysozyme against Lactobacillus fermentum, Leuconostoc mesenteroides, and Saccharomyces cerevisiae, aiming development of a formula. Minimum Inhibitory Concentration of each antimicrobial was determined for bacteria and subsequently, nisin (30 mg/L) and hops extract (5 mg/L) were tested together, showing inhibitory effects combining doses of each antimicrobial that were equivalent to an eightfold reduction of their original Minimum Inhibitory Concentrations (3.75 and 0.625 mg/L, respectively), resulting in a FICIndex of 0.25. Thereon, a formula containing both compounds was developed and tested in fermentation assays, promoting reductions on bacterial population and no severe interferences in yeast viability or population even at extreme doses. Therefore, these compounds have great potential to successfully substitute conventional antibiotics in the ethanol industry.
Assuntos
Anti-Infecciosos/farmacologia , Etanol/metabolismo , Fermentação/fisiologia , Humulus/química , Extratos Vegetais/farmacologia , Antibacterianos/farmacologia , Microbiologia Industrial , Lactobacillales/efeitos dos fármacos , Limosilactobacillus fermentum/efeitos dos fármacos , Leuconostoc mesenteroides/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Muramidase/farmacologia , Nisina/análogos & derivados , Nisina/farmacologia , Parabenos/farmacologia , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharum/químicaRESUMO
The stability of microorganisms along the time is important for allowing their industrial use as starter agents, improving fermentation processes. This study aimed to evaluate the survival and maintenance of the cell viability of the lactic acid bacteria Lactobacillus fermentum IAL 4541 and the yeast Wickerhamomyces anomalus IAL 4533, both isolated from wheat sourdough, after lyophilisation with different cryoprotectant and storage at room temperature along a year. Treatments involved adding control solution (S1â¯=â¯0.1% peptone water), and four cryoprotectant solutions S2 (10% sucrose), S3 (5% trehalose), S4 (10% skim milk powder) and S5 (10% skim milk powder plus 5% sodium glutamate) to the microbial cells previously of freeze drying processing. To verify the effect of lyophilisation on the number of microbial cells recovered, microbiological analyses were performed and cell viability was calculated before and after lyophilisation and regularly during a storage period of 365â¯days at room temperature. Viability after freeze-drying was influenced by the cryoprotectant agent employed, as well the microbial stability conferred along the storage. Differences on the microorganism response to some protectors were observed between the lactic acid bacteria and the yeast evaluated. W. anomalus was more affected by absence of cryoprotectant (S1) during freeze drying processing, but this microorganism was more stable than L. fermentum along the storage without the presence of protectant agents. For L. fermentum, S5 was the best protectant, allowing the recovering of 100% of the bacterial cells after lyophilisation and 87% of cell viability was observed after one year storage, followed by S4 (96 and 74%, respectively). S4 and S5 were the best protectant to W. anomalus (viability >80% after 1â¯year), but no increase in the yeast cell viability was conferred by addition of glutamate (S5) to skim milk. After 1â¯year of storage, trehalose was much more effective on protection of the yeast than bacteria (72% and 7% of viability, respectively). S2 was the less protectant agent among the tested, and their effectiveness was higher in L. fermentum (allowing 14% of cell recovering up to 120â¯days of storage) if compared to W. anomalus (25% of viability until 90â¯days of storage). Our results demonstrate that freeze-drying is a realistic technology for the stability and maintenance of the potential sourdough starter L. fermentum and W. anomalus for long time; however, the choice of cryoprotectant will influence the process effectiveness.
Assuntos
Crioprotetores/farmacologia , Liofilização/métodos , Limosilactobacillus fermentum/efeitos dos fármacos , Limosilactobacillus fermentum/crescimento & desenvolvimento , Viabilidade Microbiana , Saccharomyces/efeitos dos fármacos , Saccharomyces/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Crioprotetores/química , Lactobacillales/efeitos dos fármacos , Lactobacillales/crescimento & desenvolvimento , Glutamato de Sódio , Sacarose , Temperatura , Fatores de Tempo , TrealoseRESUMO
The objective of this study was to evaluate the probiotic properties of Lactobacillus casei and Lactobacillus fermentum strains, as well as to select novel and safe strains for future development of functional fermented products. The in vitro auto-aggregation, co-aggregation, hydrophobicity, ß-galactosidase production, survival to gastrointestinal tract (GIT), and antibiotic susceptibility were evaluated. The selected strains were additionally tested by the presence of genes encoding adhesion, aggregation and colonization, virulence factors, antibiotic resistance, and biogenic amine production, followed by the evaluation of acidifying kinetic parameters in milk, and survival of the strains under simulated GIT conditions during refrigerated storage of fermented milk. Most strains of both species showed high auto-aggregation; some strains showed co-aggregation ability with other lactic acid bacteria (LAB) and/or pathogens, and both species showed low hydrophobicity values. Seven L. casei and six L. fermentum strains produced ß-galactosidase enzymes, and ten strains survived well the simulation of the GIT stressful conditions evaluated in vitro. All strains were resistant to vancomycin, and almost all the strains were resistant to kanamycin. L. casei SJRP38 and L. fermentum SJRP43 were distinguished among the other LAB strains by their higher probiotic potential. L. fermentum SJRP43 presented fewer genes related to virulence factors and antibiotic resistance and needed more time to reach the maximum acidification rate (Vmax). The other kinetic parameters were similar. Both strains survived well (> 8 log10 CFU/mL) to the GIT-simulated conditions when incorporated in fermented milk. Therefore, these strains presented promising properties for further applications in fermented functional products.
Assuntos
Queijo/microbiologia , Trato Gastrointestinal/microbiologia , Lacticaseibacillus casei/isolamento & purificação , Limosilactobacillus fermentum/isolamento & purificação , Viabilidade Microbiana , Probióticos/farmacologia , Animais , Antibacterianos/farmacologia , Fermentação , Interações Hidrofóbicas e Hidrofílicas , Cinética , Lacticaseibacillus casei/efeitos dos fármacos , Lacticaseibacillus casei/fisiologia , Limosilactobacillus fermentum/efeitos dos fármacos , Limosilactobacillus fermentum/fisiologia , Leite/microbiologia , Probióticos/efeitos adversos , beta-Galactosidase/metabolismoRESUMO
Bacterial adhesion onto hydroxyapatite is known to depend on the surface properties of both the biomaterial and the bacterial strain, but less is known about the influence of the composition of the aqueous medium. Here, the adhesion of Streptococcus mutans and 3 different Lactobacilli on powdered hydroxyapatite was shown to change with Ca2+ concentration. The effect depends on the surface properties of each strain. Adhesion of Lactobacillus fermentum and salivarius (and of Streptococcus mutans at low Ca2+) was enhanced with increasing Ca2+ concentration. Lactobacillus casei was efficiently removed by adhesion on hydroxyapatite, even without Ca2+ addition, and the effect of this ion was only marginal. The results are interpreted in terms of Ca2+-mediated adhesion, and relative to the hydrophobic properties of each strain and the electrical properties of the bacterial and solid surfaces (electrophoretic mobility).