Capacity and kinetics of zearalenone adsorption by Geotrichum candidum LG-8 and its dried fragments in solution

The application of LG-8 and its dry fragments as zearalenone (ZEN) adsorbents was investigated. The study showed that Geotrichum candidum LG-8 and its fragments dried at 55°C or through lyophilization are able to adsorb around 80% of ZEN. However, besides in water and 55°C-drying conditions, SEM indicated that higher 90% of ZEN binding tended to occur when cell walls of fragments were intact with less adhesion among themselves. Notably, ZEN/LG-8 fragments complexes were quite stable, as only 1.262% and 1.969% of ZEN were released after successive pH treatments for 4 h and 5 min. The kinetic data signified that adsorption of ZEN onto LG-8 fragments followed well the pseudo-first-order kinetic model. Isotherm calculations showed Langmuir model was favourable and monolayer adsorption of ZEN occurred at functional binding sites on fragments surface. Therefore, we conclude that it can be an alternative biosorbent to treat water contained with ZEN, since LG-8 is low-cost biomass and its fragments have a considerable high biosorption capacity avoiding impacting final product quality and immunodeficient patients.

The Role of Probiotics in Improving Food Safety: Inactivation of Pathogens and Biological Toxins

Currently, many advances have been made in avoiding food contamination by numerous pathogenic and toxigenic microorganisms. Many studies have shown that different probiotics, in addition to having beneficial effects on the host's health, have a very good ability to eliminate and neutralize pathogens and their toxins in foods which leads to enhanced food safety. The present review purposes to comprehensively discuss the role of probiotics in improving food safety by inactivating pathogens (bacterial, fungal, viral, and parasite agents) and neutralizing their toxins in food products. Some recent examples in terms of the anti-microbial activities of probiotics in the body after consuming contaminated food have also been mentioned. This review shows that different probiotics have the potential to inactivate pathogens and neutralize and detoxify various biological agents in foods, as well as in the host body after consumption.

Growing conditions of Saccharomyces boulardii for the development of potentially probiotic mead: Fermentation kinetics, viable cell counts and bioactive compounds

Mead is an alcoholic beverage produced by the fermentation of a diluted honey solution by the action of yeast. Recently, research has shown the potential of S. boulardii for brewing beer and in the development of probiotic alcoholic beverages and, to date, no research has examined for mead production. The aim of this study was to evaluate the growth conditions of S. boulardii for the development of potentially probiotic mead. The findings show that initial wort soluble solids conditions of 30°Brix and initial concentration of 0.030 g/L of S. boulardii obtain potentially probiotic mead with viable yeast cells of 6.53 Log10 CFU/mL, alcohol content of 5.05%, and has the presence of total phenolics (17.72 mg GAE/100 mL) and natural antioxidants (62.79 and 1.37 µmol TE/100 mL for ABTS and FRAP methods, respectively). In conclusion, S. boulardii has a potential for the development of probiotic mead.

Impact of simulated microgravity on bioremoval of heavy-metals by Lactobacillus acidophilus ATCC 4356 from water

There are several reports about the effect of gravity removal on some characteristics of microorganisms due to possible change in surface layer thickness and adherence properties. In this study, bioremoval efficiency of Lactobacillus acidophilus ATCC 4356 from water under simulated microgravity conditions was investigated. Furthermore, pretreatment effects (untreated, NaOH, and heat pretreated) of L. acidophilus ATCC 4356 on heavy metal removal was evaluated on microgravity, as our previous research showed impact of pretreatment on adherence properties of probiotics to environmental metals. The results showed that ability of L. acidophilus for arsenic adsorption enhanced following heat-pretreatment in simulated and normal gravity. Moreover, in both conditions of simulated microgravity and normal gravity NaOH-treated L. acidophilus increased the removal of cadmium and lead. In none of the conditions, pretreatment of lactobacillus affects mercury removal. Evaluation of stability of binding of L. acidophilus-heavy metal was investigated to check irreversibility of complex formation between microorganisms and metals in simulated gastrointestinal conditions. Data showed release of heavy metals from complex in normal gravity. Obtained results of this research show the favorable potential of simulated microgravity condition to increase bioremoval capacity of L. acidophilus for heavy metals.

Effects of Pretreatments on Patulin Removal from Apple Juices Using Lactobacilli: Binding Stability in Simulated Gastrointestinal Condition and Modeling

Recently, researchers have reported the presence of patulin as a mycotoxin in commercial apple products, especially apple juices. The aim of this study was to assess adsorption of patulin from artificially contaminated apple juice using two lactic acid bacteria (LAB) strains of Lactobacillus acidophilus ATCC 4356 and Lactobacillus plantarum ATCC 8014. Furthermore, effects of five physical and chemical pretreatments on the patulin adsorption were investigated. Results demonstrated that patulin adsorption abilities of both strains increased with NaOH pretreatment but decreased after autoclaving. The NaOH-treated L. plantarum ATCC 8014 showed the best removal rate (59.74%) after 48 h of refrigerated storage, compared with the NaOH-treated L. acidophilus ATCC 4356 (52.36%). Moreover, stability of the LAB-patulin complex was assessed in simulated gastrointestinal tract conditions and a low quantity of patulin was released into the solution. The patulin adsorption process by NaOH-treated L. plantarum ATCC 8014 followed Freundlich isotherm model and pseudo-second-order kinetic model. Fourier transform infrared spectroscopy showed that polysaccharide and protein components of the L. plantarum ATCC 8014 cell wall played key roles in patulin adsorption. The major functional groups of the cell wall that were involved in adsorbing patulin included -OH/-NH, -CH₂, C=O, and C-O groups. The current results suggest that NaOH-treated L. plantarum ATCC 8014 cells include the potential to detoxify patulin-contaminated apple juices.

Characterization, mechanism of cypermethrin biosorption by Saccharomyces cerevisiae strains YS81 and HP and removal of cypermethrin from apple and cucumber juices by inactive cells

Cypermethrin is a common food contaminant and environmental pollutant that cause health threats to animals and humans. In this study, the characterization, mechanism, and application of cypermethrin removal by Saccharomyces cerevisiae were investigated. The binding of cypermethrin by the strains S. cerevisiae YS81 and HP was rapid and reached equilibrium at 2-8 h. The removal efficiency was dependent on incubation temperature and yeast concentration, whereas cypermethrin binding was not affected by pH. Heat and acid treatments enhanced the binding ability. Both strains survived in simulated digestion juices and removed cypermethrin effectively under simulated gastrointestinal conditions. Among the strains tested, the YS81 strain was the better candidate for cypermethrin concentration reduction. For the two S. cerevisiae strains, the biosorption kinetics and isotherm followed the pseudo-second-order model and Langmuir model well. The cell walls and the protoplasts were the main yeast cell components involved in cypermethrin binding. Fourier transformed infrared spectroscopy analysis revealed that -OH, -NH, -C-N, -COO^-, and -C-O played a major role in binding cypermethrin. Inactive cells effectively removed cypermethrin from apple and cucumber juices and did not affect the physico-chemical properties. Therefore, S. cerevisiae strains YS81 and HP may be used for cypermethrin reduction in food or feed.

Ultrasonic Modulation of the Technological and Functional Properties of Yeast Strains

This research was aimed at studying the effects of low intensity ultrasound (US) on some technological and functional properties of eight strains of Saccharomyces cerevisiae; namely, growth patterns (growth at 2–5% of NaCl or at 37 °C), autoaggregation and tolerance to simulated gastrointestinal conditions were evaluated. A US treatment was applied at 20% of net power (130 W) by a modulating duration (2–10 min) and pulses (2–10 s). The viable count (4.81–6.33 log CFU/mL) was not affected by US, while in terms of technological traits the effect was strain specific; in particular, for some strains a positive effect of US was found with a significant growth enhancement (growth index > 120%). The treatment was also able to increase the autoaggregation of some strains, thus suggesting that US could represent a promising way to treat and select nonconventional functional yeasts for food applications.

Microencapsulation of Saccharomyces cerevisiae into Alginate Beads: A Focus on Functional Properties of Released Cells

Five yeast strains (four wild Saccharomyces cerevisiae strains and a collection strain-S. cerevisiae var. boulardii) were encapsulated in alginate beads. Encapsulation yield was at least 60% (100% for some strains) and yeasts survived in beads for 30 days at 4 °C, although the viability was strongly affected during storage at 25 °C (3 log reduction after 7 days). The kinetic of cell release was studied under static and dynamic conditions, but the results suggest that, after 48 h, beads contained a high number of yeasts. Thus, their use is advisable as re-usable carriers of starter cultures or as a vehicle of probiotics into the gut. Finally, some functional properties (biofilm formation, hydrophobicity, auto-aggregation, survival during the transit into the gut) were evaluated on yeasts released by beads to assess if microencapsulation could negatively affect these traits. The results showed that yeasts' entrapment in beads did not affect probiotic properties.

Biofilm formation by potentially probiotic Saccharomyces cerevisiae strains

Four wild strains of Saccharomyces cerevisiae and the collection strain S. cerevisiae var. boulardii ATCC MYA-796 were used as test organisms to study the effect of some environmental conditions on the formation of biofilm by potentially probiotic yeasts. In a first step, the formation of biofilm was studied in four different media (YPD-Yeast Peptone Glucose; diluted YPD; 2% BP, a medium containing only bacteriological peptone; 2% GLC, a medium containing only glucose). Then, the dilution of YPD was combined with pH and temperature through a mixture design to assess the weight of the interaction of the variables; the experiments were done on S. boulardii and on S. cerevisiae strain 4. The dilution of nutrients generally determined an increased biofilm formation, whereas the effect of pH relied upon the strain. For S. cerevisiae strain 4, the highest level of sessile cells was found at pH 4-5, while S. boulardii experienced an enhanced biofilm formation at pH 6.0. Concerning temperature, the highest biofilm formation was found at 25-30 °C for both strains. The importance of this work lies in its extension of our knowledge of the effect of different environmental conditions on biofilm formation by potentially probiotic S. cerevisiae strains, as a better understanding of this trait could be an important screening tool into the selection of new multifunctional yeasts.

Adsorption of aflatoxin B1, zearalenone and ochratoxin A by microorganisms isolated from Kefir grains

A strategy to reduce the deleterious effects of mycotoxins is to use dietary supplements that contain microorganisms that bind mycotoxins and decrease their gastrointestinal absorption. Novel strains were isolated from a Kefir culture and assessed for their mycotoxin adsorption and biotransformation ability. The most active strains were identified using DNA sequencing, and the stability of microorganism/mycotoxin complexes was evaluated using buffer solutions to simulate the pH conditions in the gastrointestinal tract. Our results showed that the microorganism consortium of Kefir grains adsorbed 82 to 100% of aflatoxin B1 (AFB1), zearalenone (ZEA) and ochratoxin A (OTA) when cultivated in milk. The main strains that were capable of mycotoxin adsorption were identified as Lactobacillus kefiri, Kazachstania servazzii and Acetobacter syzygii. The strain L. kefiri KFLM3 was the most active, adsorbing 80 to 100% of the studied mycotoxins when cultivated in milk. Nonetheless, the strain K. servazzii KFGY7 retained more mycotoxin after the desorption experiments (65, 69 and 67% for AFB1, OTA and ZEA, respectively). These findings suggest that Kefir consumption may help to reduce gastrointestinal absorption of these mycotoxins and consequently reduce their toxic effects. The isolated strains may be of interest for the development of fermented dairy products for human consumption that have a new probiotic characteristic, the adsorption of mycotoxins.

A Focus on Quality and Safety Traits of Saccharomyces cerevisiae Isolated from Uva di Troia Grape Variety

The aim of this work was to study Saccharomyces cerevisiae strains isolated from vineyards of the autochthonous grape variety "Uva di Troia" located in different geographical areas of Apulian region (Southern Italy). Four hundred isolates were studied in relation to H₂ S production, β-glucosidase activity, and pigments adsorption from grape skin. Thus, 81 isolates were selected, identified through the amplification of the interdelta region, and grouped in 19 biotypes (from I to XIX). The enological performances were assessed to determine the content of residual sugars, ethanol, glycerol, and volatile acidity, after a microfermentation in Uva di Troia must for each isolate. The ability to remove ochratoxin A (OTA) was studied as an additional tool to select promising strains. A geographical-dependent technological variability was found for glycerol and volatile acidity, suggesting that the different indigenous yeasts can have a peculiar impact on the final characteristics of the corresponding wine ("Nero di Troia"). Only 2 biotypes (VI and XVII) were able to remove OTA throughout fermentation, with the highest reduction achieved by the biotype XVII (ca. 30%).