Bioconversion Of Isoflavones Research Articles

Isoflavone aglycone-rich powder from soybean residue submerged fermentation using Lactobacillus fermentum 44197

Soybean residue contains high amounts of isoflavones and proteins with utilisation limited to animal feed and fertiliser. This study investigated isoflavone bioconversion by Lactobacillus fermentum 44197 to enhance the biological activity of fermented soybean residue to serve as a functional food ingredient. Using liquid-state fermentation, growth of L. fermentum 44197 in soybean residue substrate was similar to growth in MRS substrate. β-Glucosidase produced by L. fermentum 44197 contributed to isoflavone bioconversion from glycosides to aglycones. Submerged fermentation in substrate containing 20% soybean residue and 4% glucose at 37 °C for 24 h produced the highest isoflavone aglycones (daidzein and genistein). Fermented soybean residue was dried by drum drying and exhibited high isoflavone contents (mg/100 g db): daidzin (2.24), genistin (5.33), daidzein (28.62) and genistein (66.07) that was named isoflavone aglycone-rich powder. The powder was an excellent source of isoflavone aglycones, protein and free amino acids, exhibiting high protein solubility between pH 3 and 9 and high water absorption (4.0 g/g). Results demonstrated the potential of L. fermentum 44197 for isoflavone bioconversion of soybean residue under submerged fermentation. Isoflavone aglycone-rich powder can also be used for bioactive compound enrichment and formulation of various functional foods and health foods, especially plant-based protein products.

The dietary intervention of synbiotic preparation promotes the bioconversion of soy isoflavones to equol and its metabolic mechanism

The dietary intervention of synbiotic preparation promotes the bioconversion of soy isoflavones to equol and its metabolic mechanism

Fermentative Bioconversion of β-Glucoside Like Isoflavones is a Better Indicator of β-Glucoside Hydrolysing Capability in Probiotic Lactic Acid Bacteria (LAB) Due to the Predominant Phosphoglucosidase Activity

ABSTRACT Isoflavones provide multiple health benefits, such as the potential for prevention of cancer and osteoporosis. Isoflavones are naturally present as β-glucosides, rendering them unavailable for uptake in the human gut. In the present study, an attempt was made to understand the mechanism of β-glucoside hydrolysis by probiotic microbes. Six major probiotic-type strains were screened for β-glucosidase activity, and two annotated β-glucosidase genes were cloned and characterized from L. acidophilus. These proteins were more active on phosphorylated pNPG than on pNPG, indicating a Phosphoenolpyruvate (PEP)-dependent pathway involving phosphoglucosidase for the uptake and metabolism of β-glucosides such as isoflavones. The screening of these strains for the bioconversion of isoflavones showed above 90% isoflavone glucoside hydrolysis for four strains, with L. rhamnosus showing the highest hydrolysis. To the best of our knowledge, this is the first report comparing glucoside hydrolysis by whole bacterial cells with cell extracts and purified candidate proteins.

Microbial Community Variations and Bioconversion Improvements during Soybean-Based Fermentation by Kefir Grains.

Soybeans possess unexpected flavors and are difficult to be absorbed by the gastrointestinal tract. Kefir grain fermentation provides diverse strains and bioactive compounds, which may enhance flavor and bioaccessibility. Third-generation sequencing was applied to analyze the microbial diversity in milk and soybean kefir grains in this study. In both types of kefir grains, the most common bacterial genus was Lactobacillus, and their fungal communities were dominated by Kazachstania. Lactobacillus kefiranofaciens was the most abundant species in kefir grains, while Lactobacillus kefiri showed a higher proportion in soybean kefir grains. In addition, the quantification of free amino acids and volatile flavor compounds in soybean solution and soybean kefir have shown the increased content of glutamic acid and a decreased amount of unpleasant beany flavor compounds, demonstrating that the nutritive value and sensory properties of soybean can be improved by kefir grain fermentation. Finally, the bioconversion of isoflavones during fermentation and in vitro digestion was evaluated, suggesting that fermentation is beneficial for aglycone formation and absorption. To conclude, kefir fermentation is proposed to change the microbial structure of kefir grains, promote the nutritional value of soybean-based fermented products, and provide possible solutions for the development of soybean products.

Isoflavone Metabolism by Lactic Acid Bacteria and Its Application in the Development of Fermented Soy Food with Beneficial Effects on Human Health.

Isoflavones are phenolic compounds (considered as phytoestrogens) with estrogenic and antioxidant function, which are highly beneficial for human health, especially in the aged population. However, isoflavones in foods are not bioavailable and, therefore, have low biological activity. Additionally, their transformation into bioactive compounds by microorganisms is necessary to obtain bioavailable isoflavones with beneficial effects on human health. Many lactic acid bacteria (LAB) can transform the methylated and glycosylated forms of isoflavones naturally present in foods into more bioavailable aglycones, such as daidzein, genistein and glycitein. In addition, certain LAB strains are capable of transforming isoflavone aglycones into compounds with a greater biological activity, such as dihydrodaidzein (DHD), O-desmethylangolensin (O-DMA), dihydrogenistein (DHG) and 6-hydroxy-O-desmethylangolensin (6-OH-O-DMA). Moreover, Lactococcus garviae 20-92 is able to produce equol. Another strategy in the bioconversion of isoflavones is the heterologous expression of genes from Slackia isoflavoniconvertens DSM22006, which have allowed the production of DHD, DHG, equol and 5-hydroxy-equol in high concentrations by engineered LAB strains. Accordingly, the consequences of isoflavone metabolism by LAB and its application in the development of foods enriched in bioactive isoflavones, as well as health benefits attributed to their consumption, will be addressed in this work.

Effects of enzyme-assisted extraction on the profile and bioaccessibility of isoflavones from soybean flour

The effects of enzymatic extraction strategies on extractability, bioconversion, and bioaccessibility of biologically active isoflavone aglycones, total phenolic content, and antioxidant activity of aqueous extracts from full-fat soy flour were evaluated. Protease, tannase, and cellulase enzymes were used individually or in combination. Except for the protease treatment, all enzymatic treatments increased the extraction of biologically active isoflavones (daidzein and genistein) compared with the control. The use of a mixture of protease, tannase, and cellulase resulted in increased extractability and/or bioconversion of aglycones from soy flour, indicating a synergistic effect amongst the enzymes. Daidzein and genistein concentrations increased from 29.0 to 158.2 μg/g and from 27.0 to 156.5 μg/g (compared to the control), respectively. Furthermore, enzymatic extraction followed by in vitro gastrointestinal digestion significantly increased the bioaccessibility of isoflavone aglycones, total phenolic content (by 22–45%), and antioxidant activity (by 15–22%) of the extracts. These results demonstrate that enzyme selection is an efficient strategy to maximize the extraction, bioconversion, and bioaccessibility of bioactive isoflavones from soy flour, which could contribute to health benefits associated with the consumption of soy-rich products.

265 BERBERINE AMELIORATES OVARIECTOMY-INDUCED ANXIETY-LIKE BEHAVIORS BY ENRICHMENT IN EQUOL GENERATING GUT MICROBIOTA

Background Decline in circulating ovarian hormone levels is associated with increment in anxiety and alteration in intestinal microbiota. As a kind of gut microbiota modulator, berberine (BBR) has shown efficacy in treating diseases such as menopausal osteoporosis and type 2 diabetes through regulating bacteria. However, the effects of BBR on ovariectomy-induced anxiety are still unclear and whether or not gut microbiota modifies the possible effect of BBR remain to be fully elucidated. Aim To demonstrate that BBR is able to alleviate anxiety through modulating intestinal microbiota under estrogen-deficient conditions. Methods Female specific pathogen-free (SPF) SD rats were ovariectomized (OVX) or shamoperated (sham). BBR (100mg/kg) or control vehicle was administered via oral gavage every day for four weeks. Open field test (OFT) and elevated plus maze test (EPM) were used to detect the anxiety-like behaviors. Moreover, the 16S rRNA sequencing and liquid chromatography/mass spectrometry (LC/MS) analysis were utilized to validate the changes in intestinal microbes and microbiota isoflavone metabolites, respectively. The concentration of serum estradiol (E2) was measured using ELISA. Further, female germ-free (GF) SD rats were operated and treated with BBR or vehicle under sterile conditions. Fecal microbiota transplantation (FMT) was conducted using fecal samples from SPF rats to colonize GF-OVX rats. Results Compared with SPF-sham rats, OFT and EPM showed increased anxiety in SPFOVX rats, and BBR treatment significantly ameliorated anxiety-like behaviors compared with SPF-OVX rats. The serum level of isoflavone metabolite equol and the ratio of equol to daidzein were decreased by ovariectomy and elevated by BBR treatment. Furthermore, BBR treatment altered the microbiota diversity and taxa richness of the gut microbiome. The alpha diversity revealed a significant reduction in richness and diversity after BBR administration compared with SPF-OVX group. The beta diversity showed dissimilarity in composition among each group. At the genus level, BBR-treated rats harbored a higher abundance of beneficial gut microbes, such as Bacteroides, Bifidobacterium, Lactobacillus, and Akkermansia, among which many species are involved in isoflavone bioconversion (Fig.1). Notably, estrogen deficiency in GF rats also resulted in anxiety-like behaviors, however gavage feeding of BBR to GF-OVX rats had no significant effects on behavior improvement and equol metabolism. FMT of SPF-BBR rats to GF-OVX rats improved anxiety-like behaviors and increased the serum concentration of isoflavone metabolite equol (Fig.2). Conclusions Gut microbiota is critical in BBR treatment of ovariectomy-aggravated anxiety, indicating a promising therapeutic strategy for postmenopausal anxiety. Download : Download high-res image (316KB) Download : Download full-size image Fig. 1 . BBR ameliorates the anxiety-like behaviors and gut dysbiosis of SPF-OVX rats. (A) Elevated plus-maze test results. (B) Open field test results. (C) Ovarian hormone levels. (D) Isoflavone levels. (E) α-diversity indices. (F) β-diversity measured by PCoA. (G) LEfSe analysis from phylum to genus. Data are expressed as the mean ± SEM. *P Download : Download high-res image (217KB) Download : Download full-size image Fig. 2 . GF condition eliminates the anti-anxiety effects of BBR, while fecal microbes from SPF-BBR rats ameliorates anxiety of GF-OVX rats. (A) Elevated plus-maze test results of GF rats. (B) Open field test results of GF rats. (C) Ovarian hormone levels of GF rats. (D) Isoflavone levels of GF rats. (E) Elevated plus-maze test results of FMT rats. (F) Open field test results of FMT rats. (G) Ovarian hormone levels of FMT rats. (H) Isoflavone levels of FMT rats. Data are expressed as the mean ± SEM. *P

Bioconversion and bioaccessibility of isoflavones from sogurt during in vitro digestion

This study investigated the bioconversion and bioaccessibility of soy isoflavones produced in sogurt fermented with S. thermophilus and L. bulgaricus during in vitro digestion. The highest survivability of S. thermophilus (6.49 log cfu/mL) and L. bulgaricus (6.48 log cfu/mL) was in oral phase. In gastric phase, the total aglycones of sogurt (26.73 g/L) increased up to 20 times than control (1.21 g/L), with a significant increase in daidzein (17.05 g/L) and genistein (9.68 g/L). Addition of 8U of β-glucosidase into soymilk significantly increased the conversion of isoflavone in ENTII (daidzein: 0.46 g/L; genistein: 0.18 g/L) than in ENTI (daidzein: 0.33 g/L; genistein: 0.20 g/L). The particle size analysis and confocal micrographs of digesta also suggest the size of fat and protein in gastric phase to be smaller than in intestinal phase. The results indicate the prospective to develop soy-based fermented products capable of releasing high isoflavone in the digestive system.

Soy fermentation by orally isolated putative probiotic Streptococcus salivarius for healthy oral

Aim: Consumption of aglycones-rich fermented soy has been positively associated with the recuperation of systemic inflammation. As oral conditions have an impact on overall health and diseases, the reestablishment of bacteria particularly by indigenous oral probiotic is believed to be able to reverse oral inflammation by antagonize oral pathogen and thus maintaining good oral health. Streptococcus salivarius can be combined with bioactive isoflavone aglycones to further improve oral healthiness. This study aimed to explore decent advantages by indigenous source of Streptococcus isolated from healthy periodontal to ferment soy while maintaining probiotic properties before delivering in product targeting oral health. Materials and Methods: Putative probiotic properties of isolated strains were explored through antibiotic susceptibility ensuring safe strain consumption. S. salivarius from Taylor’s University Culture Collection (TUCC) 1254 was selected for probiotic properties evaluation, in comparison with the type strain. Both strains were evaluated for fermentation ability in soy through growth, β-glucosidase assay, and isoflavone bioconversion. Results: The antagonistic ability of S. salivarius TUCC 1254 was better under anaerobic than microaerobic condition; the strain also showed higher colonizing ability to epithelial tissue than the tooth surface resemblance. The strain showed vast cell growth accompanied by organic acid production and higher β-glucosidase enzyme to bioconvert isoflavone glucosides to bioactive aglycones that could reduce oral inflammation than K12. Soy improved auto-aggregation ability of S. salivarius, which could promote biofilm formation and thus could achieve enhanced oral pathogen-eradicating intention. Conclusion: This study suggested that indigenous bacteria could serve as a better source of oral probiotics and coupling with fermented soy bioactive isoflavone aglycones, become a deliverable platform for improving oral health.

Deglycosylation patterns of isoflavones in soybean extracts inoculated with two enzymatically different strains of lactobacillus species

Microorganism selection is critical to deglycosylation in soybean fermentation for producing beneficial phytochemicals. This study investigated isoflavone bioconversion in soybean extract inoculated with Lactobacillus plantarum K2-12 and Lactobacillus curvatus JD0-31 exhibiting different enzyme activities. L. plantarum showed higher esterase (C4), esterase (C8), β-galactosidase, α-glucosidase, β-glucosidase, and N-acetyl-β-glucosaminase activities. We found that isoflavone bioconversion was distinguished into isoflavone backbone structure types. Malonyl- and acetyl- types of isoflavones except for malonyl daidzin were not significantly differed their contents between lactobacilli. Deglycosylating severity was observed in malonyl genistin in both lactobacilli, resulting mass production of genistein. On the other hand, daidzein glycosides were dependable to lactobacilli, in which L. plantarum efficiently degraded malonyl daidzin and daidzin in fast time. Glycitein was most degradable among the three aglycones by fermentation. These results suggest that efficient control of isoflavone deglycosylation by Lactobacillus species should be controlled to the inoculation period and select target isoflavones.

Optimization of lactic acid fermentation conditions for fermented tofu whey beverage with high-isoflavone aglycones

Four lactic acid bacteria strains (Lactobacillus paracasei, Leuconostoc mesenteroides, Lactobacillus rhamnosus GG and Lactobacillus plantarum), possessing β-glucosidase enzyme activity, were investigated for tofu whey fermentation based on the capacity of bioconversion of isoflavones. The results suggested that the mixture of L. rhamnosus GG and L. paracasei had great potential for efficient enrichment of bioactive isoflavone aglycones and the percentage composition (daidzein, genistein) increased from 4.6 to 93.78% after fermentation of tofu whey. At the same time, the viable cell counts of the mixture of L. rhamnosus GG and L. paracasei increased to 9.13 log10 CFU/mL while pH value dropped to 4.48 and titratable acidity was 0.28%. Headspace solid-phase microextraction method followed by gas chromatography-mass spectrometry analysis indicated that the odor compounds, particularly the aldehydes and alcohols, were metabolized to trace or undetected levels after fermentation. This research provided not only a new way to develop a functional probiotic beverage enriched in isoflavone aglycones, but also provided a potentially valuable new use for soy whey protein.

Novel process of hydration, followed by incubation and thermal processing, for high isoflavone bioconversion in soybeans

The potentially bioavailable aglyconic isoflavone content of soybeans was increased by a process based on the controlled hydration of whole beans, followed by an incubation step and cooking. For developing the process, the effects of three operation variables: temperature, intermittent soaking and incubation time on the isoflavone profile of the processed soybeans were assessed. By hydrating the whole beans under controlled conditions (54 °C; 15 rpm for a rotating soaking basket) and holding the beans for an appropriate incubation time, it was possible to substantially increase the total aglycone content from (μmol·10−2·g−1) ~5 in the raw, to ~95 in the processed soybean. A conventional thermal treatment (1 kg⋅cm−2, 5 min), necessary to attain the nutritional and sensory characteristics, produced additional hydrolysis of glucosides, accounting for extra 14% of total aglycone yield. The entire process avoided the need to grind the bean and permitted an overall 21.8-fold increase (per-mole basis) conversion of all forms of isoflavone glucosides to aglycones, particularly to the (S)-equol precursor, daidzein, and with minimal back-diffusion or leaching to the outside medium.

Strategic ultrasound-induced stress response of lactic acid bacteria on enhancement of β-glucosidase activity for bioconversion of isoflavones in soymilk

The purpose of the study is to develop the new methodology of strategic ultrasound treatment on lactic acid bacteria (LAB) to induce stress response for the enhancement of β-glucosidase activity that can be used for the biotransformation of glucosides into aglycones isoflavones in soymilk. Among the five LAB tested, Lactobacillus acidophilus BCRC 10695 showed the best ability to release β-glucosidase for further ultrasonic stimulation to induce proper stress response. With ultrasound (20 kHz, amplitude at 20%) to irradiate on L. acidophilus BCRC 10695 at stationary phase of growth for 2 min and 24 h of re-incubation, the β-glucosidase activity was enhanced to 3.91 U/ml, which was 1.82 times of that without ultrasound treatment. Using the ultrasound-treated L. acidophilus BCRC 10695 to ferment soymilk, the fraction of aglycones in total isoflavones in soymilk was effectively increased from 21.8% initially to 97.9% in 24 h. The strategic ultrasound treatment on L. acidophilus BCRC 10695 demonstrated promotion of β-glucosidase activity, and this methodology had the potential to be applied in the production of functional soymilk by adding probiotics LAB to increase the bioactive isoflavones and nutritional values for human health.

Bacterial communities and metabolic activity of faecal cultures from equol producer and non-producer menopausal women under treatment with soy isoflavones

BackgroundIsoflavones are polyphenols with estrogenic activity found mainly in soy and soy-derived products that need to be metabolised in the intestine by the gut bacteria to be fully active. There is little knowledge about isoflavone bioconversion and equol production in the human intestine. In this work, we developed an in vitro anaerobic culture model based on faecal slurries to assess the impact of isoflavone supplementation on the overall intestinal bacterial composition changes and associated metabolic transformations.ResultsIn the faecal anaerobic batch cultures of this study bioconversion of isoflavones into equol was possible, suggesting the presence of viable equol-producing bacterial taxa within the faeces of menopausal women with an equol producer phenotype. The application of high-throughput DNA sequencing of 16S rRNA gene amplicons revealed the composition of the faecal cultures to be modified by the addition of isoflavones, with enrichment of some bacterial gut members associated with the metabolism of phenolics and/or equol production, such as Collinsella, Faecalibacterium and members of the Clostridium clusters IV and XIVa. In addition, the concentration of short-chain fatty acids (SCFAs) detected in the isoflavone-containing faecal cultures was higher in those inoculated with faecal slurries from equol-producing women.ConclusionsThis study constitutes the first step in the development of a faecal culturing system with isoflavones that would further allow the selection and isolation of intestinal bacterial types able to metabolize these compounds and produce equol in vitro. Although limited by the low number of faecal cultures analysed and the inter-individual bacterial diversity, the in vitro results obtained in this work tend to indicate that soy isoflavones might provide an alternative energy source for the increase of equol-producing taxa and enhancement of SCFAs production. SCFAs and equol are both considered pivotal bacterial metabolites in the triggering of intestinal health-related beneficial effects.

Bioconversion of Isoflavones into Bioactive Equol: State of the Art.

Soy isoflavones, an important class of phytoestrogens, are suggested to be responsible for a number of biological activities associated with health benefits, including defense against various chronic diseases, including breast and prostate cancer, cardiovascular disorders, and osteoporosis, and they may alleviate the symptoms of menopause. However, current researches (including patents) have shown that the clinical efficacy of these phenolic compounds is related to the ability of an individual to biotransform isoflavones into equol, which is a metabolite of daidzein formed exclusively by the intestinal microbiota. This biologically active metabolite presents greater effects than other isoflavones; however, only about 30-50 % of people have a microbiota that is able to produce equol from dietary daidzein. Concern has recently grown about applications to improve the production of this metabolite. This paper summarizes the metabolism of equol, its production, and clinical implications.

Soymilk residue (okara) as a natural immobilization carrier for Lactobacillus plantarum cells enhances soymilk fermentation, glucosidic isoflavone bioconversion, and cell survival under simulated gastric and intestinal conditions.

Cell immobilization is an alternative to microencapsulation for the maintenance of cells in a liquid medium. However, artificial immobilization carriers are expensive and pose a high safety risk. Okara, a food-grade byproduct from soymilk production, is rich in prebiotics. Lactobacilli could provide health enhancing effects to the host. This study aimed to evaluate the potential of okara as a natural immobilizer for L. plantarum 70810 cells. The study also aimed to evaluate the effects of okara-immobilized L. plantarum 70810 cells (IL) on soymilk fermentation, glucosidic isoflavone bioconversion, and cell resistance to simulated gastric and intestinal stresses. Scanning electron microscopy (SEM) was used to show cells adherence to the surface of okara. Lactic acid, acetic acid and isoflavone analyses in unfermented and fermented soymilk were performed by HPLC with UV detection. Viability and growth kinetics of immobilized and free L. plantarum 70810 cells (FL) were followed during soymilk fermentation. Moreover, changes in pH, titrable acidity and viscosity were measured by conventional methods. For in vitro testing of simulated gastrointestinal resistance, fermented soymilk was inoculated with FL or IL and an aliquot incubated into acidic MRS broth which was conveniently prepared to simulate gastric, pancreatic juices and bile salts. Survival to simulated gastric and intestinal stresses was evaluated by plate count of colony forming units on MRS agar. SEM revealed that the lactobacilli cells attached and bound to the surface of okara. Compared with FL, IL exhibited a significantly higher specific growth rate, shorter lag phase of growth, higher productions of lactic and acetic acids, a faster decrease in pH and increase in titrable acidity, and a higher soymilk viscosity. Similarly, IL in soymilk showed higher productions of daizein and genistein compared with the control. Compared with FL, IL showed reinforced resistance to simulatedgastric and intestinal stresses in vitro that included low pH, low pH plus pepsin, pancreatin, and bile salt. Our results indicate that okara is a new potential immobilization carrier to enhance the growth and glucosidic isoflavone bioconversion activities of L. plantarum in soymilk and improve cell survivability following simulated gastric and intestinal conditions.

Aglycone Isoflavones and Exopolysaccharides Produced by Lactobacillus acidophilus in Fermented Soybean Paste.

Bioconversion of aglycone-formed isoflavones from glycoside-formed isoflavones by commercial lactic acid bacteria in fermented soybean paste was evaluated. Enterococcus faecium KCTC 13410 showed the most resistant capacity and Lactobacillus acidophilus KCTC 3925 had a sensitive susceptibility at a high NaCl concentration (13.2%) in fermented soybean paste. Among the 5 strains tested, Lac. acidophilus KCTC 3925 showed the highest relative ratio of aglycone-formed isoflavones to total isoflavones in fermented soybean paste. Production of exopolysaccarides (EPS) by lactic acid bacteria was compared using de Man, Rogosa, and Sharpe medium containing 1% sucrose at 37°C for 48 h. Among the 5 lactic acid bacteria, Lac. acidophilus KCTC 3925 and Lactobacillus rhamnosus KCTC 3929 were investigated to produce EPS. Based on the results concerning growing susceptibility and conversion of aglycone-formed isoflavones/EPS production, it is anticipated that Lac. acidophilus KCTC 3925 may be used for preparation of Cheonggukjang, which contains relative low NaCl content.

Contents and bioconversion of β-glycoside isoflavones to aglycones in the processing conditions of soybean tempeh

Abstract: The objective of this work was to evaluate the effect of the processing conditions of soybean tempeh on the contents of β-glycoside isoflavones and on their bioconversion into aglycones. Different times of soaking (6, 12, and 18 hours), cooking (15, 30, and 45 minutes), and fermentation (18, 24, and 30 hours) with Rhizopus oligosporus at 37°C were evaluated for tempeh preparation. Grains from the cultivar 'BRS 267' were used, and the experiment was carried out according to a central composite design (23). The response functions comprised the contents of genistin, malonyldaidzin, malonylgenistin, daidzein, and genistein, quantified by ultraperformance liquid chromatography (UPLC). Soaking, cooking, and fermentation times change the content, profile, and distribution of the different forms of isoflavones in tempeh. The highest bioconversion of glycoside isoflavones into aglycones occurred in 6-hour soaked soybean grains, whose cotyledons were cooked for 15 minutes and subjected to 18-hour fermentation.

Enrichment of two isoflavone aglycones in black soymilk by Rhizopus oligosporus NTU 5 in a plastic composite support bioreactor.

A plastic composite support (PCS) bioreactor was implemented to evaluate the effects on isoflavone deglycosylation in black soymilk fermented by Rhizopus oligosporus NTU 5. Evaluation for the optimal PCS for mycelia immobilisation was conducted, which led to the significant results that the most mycelium weight (0.237 g per PCS, P < 0.05) is held by an S-type PCS; therefore, it was selected for black soymilk fermentation. It was found that the PCS fermentation system without pH control exhibits better efficiency of isoflavone bioconversion (daidzin to daidzein, and genistin to genistein) than the one with pH control at pH 6.5. As for the long-run fermentation, those without pH control indeed accelerate the isoflavone bioconversion by continuously releasing β-glucosidase into soymilk. Deglycosylation can be completed in 8 to 24 h and sustained for at least 34 days as 26 batches. The non-pH-control fermentation system also exhibits the highest total phenolic content (ranged from 0.147 to 0.340 mg GAE mL(-1) sample) when compared to the pH-controlled and suspended ones. Meanwhile, the black soymilk from the 22nd batch with 8 h fermentation demonstrated the highest DPPH radical scavenging effect (54.7%). A repeated-batch PCS fermentation system was established to accelerate the deglycosylation rate of isoflavone in black soymilk. © 2015 Society of Chemical Industry.

Effect of electroporation on bioconversion of isoflavones and probiotic properties of parents and subsequent passages of Bifidobacterium longum.

This study aimed to evaluate the effects of electroporation on growth, bioconversion of isoflavones, and probiotic properties of parent organisms and subsequent passages of Bifidobacterium longum FTDC 8643. Electroporation with the strength of electric field at 7.5kVcm(-1) for 3.5ms was applied on B. longum FTDC 8643. The viability of B. longum FTDC 8643 increased significantly upon treatment with electroporation. Such treatment also enhanced the intracellular and extracellular β-glucosidase activity, leading to enhanced production of bioactive isoflavone aglycones in mannitol-soymilk (P < 0.05). In addition, these treated cells also exhibited better tolerance toward acidic (pH2 and pH3) and intestinal bile salt condition compared to the control (P < 0.05). The electroporated cell also possessed better adhesion ability and antimicrobial activity (P < 0.05). However, all these positive effects were only prevalent in the parent cells and were not observed in their subsequent passages of electroporated cells. Our results suggested that electroporation could enhance the bioactive and probiotic potentials of parent cells of B. longum FTDC 8643 and could be used in the production of probiotic foods with enhanced bioactivity.