Fermentation of calcium-fortified soymilk with Lactobacillus: effects on calcium solubility, isoflavone conversion, and production of organic acids

ABSTRACT:  The objective of this study was to enhance calcium solubility and bioavailability from calcium-fortified soymilk by fermentation with 7 strains of Lactobacillus , namely, L. acidophilus ATCC 4962, ATCC33200, ATCC 4356 , ATCC 4461 , L. casei ASCC 290, L. plantarum ASCC 276, and L. fermentum VRI-003. The parameters that were used are viability, pH, calcium solubility, organic acid, and biologically active isoflavone aglycone content. Calcium-fortified soymilk made from soy protein isolate was inoculated with these probiotic strains, incubated for 24 h at 37 °C, then stored for 14 d at 4 °C. Soluble calcium was measured using atomic absorption spectrophotometry (AA). Organic acids and bioactive isoflavone aglycones, including diadzein, genistein, and glycetein, were measured using HPLC. Viability of the strains in the fermented calcium-fortified soymilk was > 8.5 log₁₀ CFU/g after 24 h fermentation and this was maintained for 14-d storage at 4 °C. After 24 h, there was a significant increase ( P < 0.05) in soluble calcium. L. acidophilus ATCC 4962 and L. casei ASCC 290 demonstrated the highest increase with 89.3% and 87.0% soluble calcium after 24 h, respectively. The increase in calcium solubility observed was related to lowered pH associated with production of lactic and acetic acids. Fermentation significantly increased ( P < 0.05) the level of conversion of isoflavones into biologically active aglycones, including diadzein, genistein, and glycetein. Our results show that fermenting calcium-fortified soymilk with the selected probiotics can potentially enhance the calcium bioavailability of calcium-fortified soymilk due to increased calcium solubility and bioactive isoflavone aglycone enrichment.     

Bile salt deconjugation ability,bile salt hydrolase activity and cholesterol co-precipitation ability of lactobacilli strains

Eleven strains of lactobacilli were screened for their bile salt deconjugation ability, bile salt hydrolase activity (BSH) and co-precipitation of cholesterol with deconjugated bile. Bile salt deconjugation as determined by the release of cholic acid showed that more cholic acid was liberated from the deconjugation of sodium glycocholate than sodium taurocholate, and Lactobacillus acidophilus strains had higher deconjugation ability than L. casei strains. BSH activity, as quantified by the amount of taurine or glycine liberated from conjugated bile salts, indicated that substrate specificity was more towards glycine-conjugated bile compared to taurine-conjugated bile. Co-precipitation of cholesterol with cholic acid was observed from deconjugation of both conjugated bile, with more cholesterol being precipitated upon deconjugation of sodium glycocholate than upon that of sodium taurocholate. Cholesterol co-precipitation with deconjugated bile increased with decreasing pH. L. acidophilus ATCC 33200, 4356 and 4962 and L. casei ASCC 1521 showed highest deconjugation ability and BSH activity towards bile mixtures that resemble the human bile, and may be promising candidates to exert beneficial bile deconjugation activity in vivo.     

Selection and Use of Phytate-Degrading LAB to Improve Cereal-Based Products by Mineral Solubilization During Dough Fermentation

ABSTRACT:  New producers of phytate-degrading enzymes, especially lactic acid bacteria (LAB), were used to improve mineral solubilization during dough fermentation. In all, among strains from different sources by microorganisms (150 lactic acid bacteria, 36 yeasts), 38 (24%) exhibited a clear zone around the colonies by hydrolyzing hexacalcium phytate contained in solid medium. When phytase-positive strains from plate assay were tested for phytase activity in liquid medium, 6 of the strains (37%) exhibited phytate-degrading activity in at least one of the 3 different media used. Of the LAB, the highest phytase values were found for  Enterococcus faecium  A86 (0.74 U/mL) and  Lactobacillus plantarum  H5 (0.71 U/mL). Two different starter cultures obtained by combinations of phytase-positive (phy+:  L. plantarum  H5 and L3,  Leuconostoc gelidum  A16, and  E. faecium  A86) or phytase-negative (phy−:  L. gelidum  LM249,  L. plantarum  H19, and  L. plantarum  L8) selected LAB strains, were used to measure mineral concentrations of iron, zinc, and manganese during dough fermentation. Although the 2 kinds of starter showed similar acidic values, the presence of phytate-degrading LAB strains increased mineral solubilization in comparison to the starter phy−.     

Lactose hydrolyzing enzymes in Lactobacillus acidophilus strains

Five Lactobacillus acidophilus strains were examined for lactose hydrolyzing enzymes under several growth conditions. All have both β-galactosidase (β-gal) and phospho-β-galactosidase (P-β-gal) activities. Strains W, ATCC 4356 and NCDO 1748 had different amounts of β-gal activity, but all had 100-fold or more higher than P-β-gal activity. In contrast, in strains ATCC 4962 and ATCC 19992, activities of both enzymes were similar. The β-gal synthesis in strains W, 4356 and 1748 was induced by lactose and galactose, while in strains 4962 and 19992 it appeared not to be inducible. At 45°C in the presence of lactose synthesis of only β-gal occurred in strains 4356, 1748 and W. These differences in lactose hydrolyzing enzymes between the strains could be used, along with other characteristics, for taxonomic differentiation between L. acidophilus strains. Studies with L. acidophilus W indicated that cells have maximum β-gal activity at their early stationary phase of growth and when grown in the presence of an inducer and in the absence of oxgall. Selection of strains, type of carbohydrate in growth medium, growth temperature, culture age, and the absence of oxgall during cell growth should be considered in producing L. acidophilus cultures containing high β-gal activity for use as a dietary adjunct by lactose-intolerant individuals and in the manufacture of acidophilus-fermented dairy products.     

Effect of cryoprotective agents on survival and stability of Lactobacillus acidophilus cultured in food‐grade medium

The effect of cryoprotectants on survival and stability of freeze‐dried Lactobacillus acidophilus ATCC‐4962 cultivated in food‐grade medium was evaluated. The food‐grade medium employed was more economical than the commercial de Man Rogosa and Sharpe medium and gave a higher yield of L. acidophilus ATCC‐4962. Cryoprotective agents improved significantly the cell viability. Skim milk, skim milk with malt extract and monosodium glutamate provided significantly higher viable counts, at optimum concentration of 0.3%. At higher concentration, there was a reduction in cell viability, attributed to cell shrinkage associated with osmotic pressure changes inside the cells. Lactobacillus acidophilus ATCC‐4962 was stable at 28°C until 8 weeks.     

Improving mineral availability in soymilk by dephosphorylation of phytic acid using an alkaline phytase from Bacillus amyloliquefaciens DS11

To enhance mineral availability in soymilk, the alkaline phytase from Bacillus amyloliquefaciens DS11 was applied to degrade the phytic acid in soymilk, and resulting effects on mineral profiles were assessed. Nearly 60% of phytic acid was degraded within 25 min by treatment with 0.090 unit/mg of phytate, whereas most phytic acid was removed in 125 min using 0.18 unit/mg of phytate. Compared to a control, the free calcium, magnesium, phosphorus, and iron contents significantly (p<0.05) increased by 1.9, 1.8, 4.0, and 4.0×, respectively, after 125 min of reaction using 0.18 unit/mg of phytate. Free minerals were released from the phytate complex by enzymatic dephosphorylation, resulting in enhancement of mineral availability in soymilk. Alkaline phytase DS11 has a great potential for enhancing the mineral availability in neutral pH phytate-rich foods, like soymilk.     

Peniophora lycii phytase is stabile and degrades phytate and solubilises minerals in vitro during simulation of gastrointestinal digestion in the pig

BACKGROUND: Microbial phytases (EC 3.1.3) are widely used in diets for monogastric animals to hydrolyse phytate present in the feed and thereby increase phosphorus and mineral availability. Previous work has shown that phytate solubility is strongly affected by calcium in the feed and by pH in the gastrointestinal (GI) tract, which may have an effect on phytase efficacy. An in vitro model simulating the GI tract of pigs was used to study the survival of Peniophora lycii phytase and the effect of the phytase on phytate degradation, inositol phosphate formation and mineral solubilisation during in vitro digestion of a 30:70 soybean meal/maize meal blend with different calcium levels. RESULTS: The phytase retained 76 and 80% of its initial activity throughout the gastric in vitro digestion. Total phytate hydrolysis by P. lycii phytase was in the same range at total calcium levels of 1.2 and 6.2 mg g^?1 dry matter (DM), despite very large differences in phytate solubility at these calcium levels. However, at 11.2 and 21.2 mg Ca g^?1 DM, phytate hydrolysis was significantly lower. The amount of soluble mineral was generally increased by P. lycii phytase. CONCLUSION: Stability of P. lycii phytase during gastric digestion was not found to be critical for phytate hydrolysis. Furthermore, original phytate solubility was not an absolute requirement for phytate degradation; phytate solubility seemed to be in a steady state, allowing insoluble phytate to solubilise as soluble phytate was degraded. This is new and interesting knowledge that adds to the current understanding of phytate–phytase interaction. Copyright © 2007 Society of Chemical Industry     

α-Galactosidase and proteolytic activities of selected probiotic and dairy cultures in fermented soymilk

The metabolic activities of Lactobacillus acidophilus (LAFTI^® L10 and La4962) Bifidobacterium (lactis LAFTI^® B94 and longum Bl536), Lactobacillus casei (LAFTI^® L26 and Lc279), Lactobacillus delbrueckii ssp. bulgaricus Lb1466 and Streptococuss thermophilus St1342 were assessed in soymilk. Strains were initially analyzed for α-galactosidase activity and organic acid production in MRS broth at 37 °C. Consequently, soymilk was fermented with each strain and cell growth, production of organic acid, metabolism of oligosaccharides and proteolytic and ACE-inhibitory activities were assessed during 48 h of incubation at 42 °C. All strains exhibited variable α-galactosidase activity, with Bifidobacterium lactis B94 showing the highest activity. The oligosaccharide metabolism depended on α-galactosidase activity. B. lactis B94, S. thermophilus St1342 and L. acidophilus La4962 reduced raffinose substantially by 77.4%, 64.5% and 55.9%, respectively. All strains reached the desired therapeutic level of 10⁸ cfu/ml in soymilk after 48 h at 42 °C. The hydrolysis of protein in soymilk likely depended on strain (P < 0.0001) and time (P < 0.0001). The strains also released bioactive peptides with ACE-inhibitory activities between 17% and 43%.     

Synergy effects by combination with lactic acid bacteria and frutooligosaccharides on the cell growth and antimicrobial activity

The aim of this study was to identify probiotic possibility of lactic acid bacteria (LAB) from mustard leaf kimchi and investigate synergy effects of combination with LAB and fructooligosaccharide (FOS) on antimicrobial activity. Lactobacillus acidophilus GK20, L. paracasei GK74, and L. plantarum GK81 have high survival ratio under gastric and intestinal fluids and were resistant to ampicillin, streptomycin, or tetracycline. The pH of LAB gradually decreased but the titratable acidity increased owing to organic acids production. Especially, L. acidophilus GK20 and L. paracasei GK74 produced hydrogen peroxide and bacteriocin. When LAB was co-cultured with Listeria monocytogenes or Staphylococcus aureus in broth without FOS, the inhibition ratio of L. monocytogenes and S. aureus by L. acidophilus GK20 was 36 and 57%, but L. paracasei GK74 showed higher inhibitory effect against L. monocytogenes than S. aureus. Meanwhile, the cell growth, culture pH, titratable acidity, and bacteriocin activity of L. acidophilus GK20 and L. paracasei GK74 were significantly (p<0.05) increased in MRS with FOS than without prebiotic. In conclusion, L. acidophilus GK20 and L. paracasei GK74 could be potentially used as novel probiotic strains, moreover, the combination between L. acidophilus GK20 or L. paracasei GK74 and FOS has great potential as a synbiotic.     

Effect of prebiotics on viability and growth characteristics of probiotics in soymilk

BACKGROUND: Soy products have attracted much attention lately as carriers for probiotics. This study was aimed at enhancing the growth of probiotics in soymilk via supplementation with prebiotics. RESULTS: Lactobacillus sp. FTDC 2113, Lactobacillus acidophilus FTDC 8033, Lactobacillus acidophilus ATCC 4356, Lactobacillus casei ATCC 393, Bifidobacterium FTDC 8943 and Bifidobacterium longum FTDC 8643 were evaluated for their viability and growth characteristics in prebiotic‐supplemented soymilk. In the presence of fructooligosaccharides (FOS), inulin, mannitol, maltodextrin and pectin, all strains showed viability exceeding 7 log₁₀ colony‐forming units mL^?1 after 24 h. Their growth was significantly (P < 0.05) increased on supplementation with maltodextrin, pectin, mannitol and FOS. Additionally, supplementation with FOS, mannitol and maltodextrin increased (P < 0.05) the production of lactic acid. Supplementation with FOS and maltodextrin also increased the α‐galactosidase activity of probiotics, leading to enhanced hydrolysis and utilisation of soy oligosaccharides. Finally, prebiotic supplementation enhanced the utilisation of simpler sugars such as fructose and glucose in soymilk. CONCLUSION: Supplementation with prebiotics enhances the potential of soymilk as a carrier for probiotics. Copyright © 2009 Society of Chemical Industry     

Functional Properties of Lactic Acid Bacteria Isolated from Romanian Fermented Vegetables

A total of 139 lactic acid bacterium (LAB) strains isolated from Romanian traditionally fermented vegetables were screened for the ability to produce exopolysaccharides and for their antagonistic activity against a set of nine LAB strains, three Bacillus strains, and four Gram-negative bacteria. Eighty-five of the tested strains showed a variable antimicrobial activity against Listeria monocytogenes ATCC 1911, 35 of the strains showed a limited inhibition zone against Escherichia coli ATCC25922, and 26 strains against Salmonella enterica ATCC 14024, while 19 strains showed inhibition against one or all three Bacillus strains used as indicators. None of the tested strains showed an antimicrobial activity against Staphylococcus aureus ATCC 25923. Several strains showed antibacterial activity against more than one indicator strain. For instance, Lactobacillus plantarum 307, Lactobacillus brevis 308, and Lactobacillus plantarum/pentosus 358 were active against five of the indicator strains used, while other 23 LAB were active against three indicator strains. In the case of two strains, namely Leuconostoc citreum 344 and Lactobacillus brevis 183, the activity was maintained after neutralizing the pH of the cell-free supernatant likely due to the production of bacteriocins. The gel permeation chromatography-based screening revealed seven EPS-producing LAB strains. Two of the positive strains, namely Leuconostoc citreum 177 and Leuconostoc citreum 52, have been shown to produce large amounts of EPS, of about 20 g/L. All isolated EPS have a high molecular mass, of above 1400 KDa, and a monomer composition dominated by the presence of glucose.     

Monitoring the stepwise phytate degradation in the upper gastrointestinal tract of pigs

The degradation and formation of inositol phosphates as affected by microbial phytase and gastrointestinal enzyme activities during the passage of phytate through the stomach and small intestine were studied in two experiments with four barrows and three collection periods. The degradation and formation of inositol phosphates were measured at the duodenal and ileal sites using Cr‐NDR, TiO₂ and Co‐EDTA as indigestible markers. In experiment 1, the effect of graded doses of Aspergillus niger phytase (0, 150 and 900 FTU Natuphos^® kg^?1), added to a maize–soybean meal‐based diet with very low intrinsic phytase activity on the degradation of phytate and the formation of inositol phosphates during digestion in the stomach and small intestine was investigated. In experiment 2, three different mixtures of inositol phosphates, produced by Aspergillus niger phytase, containing mainly high, intermediate and low phosphorylated inositol phosphates, were added to the same maize–soybean meal‐based diet as used in experiment I. The fate of the inositol phosphates during digestion in the stomach and small intestine was studied. Experiment 1 showed that the extent of phytate degradation was dependent of the graded dietary phytase activities. At high phytase activity (900 FTU kg^?1 of diet), strong phytate degradation occurred and the once hydrolysed phytate was rapidly dephosphorylated to lower inositol phosphates (mainly inositol di‐ and triphosphates). Intermediate inositol phosphates, such as inositol tetraphosphates, were quantitatively unimportant in duodenal and ileal digesta. At a phytase activity of 150 FTU kg^?1 of diet, a broader spectrum of intermediate inositol phosphates was determined, which was probably due to a slower breakdown of phytate. Experiment 2 showed as a predominant result that lower inositol phosphates such InsP₄ and InsP₃ were degraded, whereas InsP₂ accumulated in the duodenal and ileal digesta. No substantial disappearance of phytate from the stomach and small intestine was found when high concentrations of soluble phytate were added to the diet, which indicates that no substantial phytate absorption occurs in the upper part of the pig gut. Copyright © 2005 Society of Chemical Industry     

Survival,growth characteristics and bioactive potential of Lactobacillus acidophilus in a soy‐based cream cheese

BACKGROUND: Soy‐based products have received much attention lately as dairy replacers and carriers for probiotics, without the cholesterol and lactose intolerance factors. We have previously developed a soy cream cheese product and would like to evaluate its suitability as a carrier for probiotic microorganisms. Soy cream cheese is commercially uncommon, while a probiotic soy cream cheese is yet to be available in the market. RESULTS: Five strains of probiotics were screened for their α‐galactosidase activity. Lactobacillus acidophilus FTCC 0291 showed the highest α‐galactosidase‐specific activity and was incorporated into soy cream cheese for a storage study of 20 days at 25 and 4 °C. L. acidophilus FTCC 0291 in soy cream cheese at both storage temperatures maintained a viability exceeding 10⁷ CFU g^?1 over storage. Oligosaccharide and reducing sugar analyses indicated that L. acidophilus FTCC 0291 was capable of utilizing the existing reducing sugars in soymilk and concurrently hydrolyzing the oligosaccharides into simpler sugars for growth. L. acidophilus FTCC 0291 also produced organic acids, leading to decreased pH. Under low pH and high organic acid concentration, the growth of total aerobes and anaerobes was significantly (P < 0.05) suppressed compared to the control. The hydrolysis of protein in soymilk produced essential growth factors such as peptides and amino acids that may have promoted the growth of L. acidophilus FTCC 0291 and the release of bioactive peptides with in vitro angiotensin I‐converting enzyme inhibitory activity. CONCLUSION: This study showed that soy cream cheese could be used as a carrier for probiotic bacteria, with potential antihypertensive property. Copyright © 2009 Society of Chemical Industry     

Supplementation of alkaline phytase (Ds11) in whole-wheat bread reduces phytate content and improves mineral solubility

Abstract: In this study, alkaline phytase was added to whole‐wheat bread and the phytate content and mineral profiles were compared to commercially available acidic phytase. At neutral pH, some phytate (approximately 20%) was degraded by endogenous phytase in wheat flour, while 40% of phytate was hydrolyzed by alkaline phytase DS11 and a 35% reduction was observed with acidic phytase. Most of the enzymatic activity occurred during the proofing stage, and the rate of reaction depended on pH. DS11 phytase effectively degraded the phytate level within a 30 min treatment at pH 7; however, at least 60 min was needed with acidic phytase to achieve the same hydrolysis level. Mineral profiles were also dramatically affected by the phytate reduction. The biggest increase was observed in Fe²⁺ by the phytase treatment. The Fe²⁺ content increased 10‐fold at pH 7 and 8‐fold at pH 5 with alkaline phytase DS11. Alkaline phytase DS11 was shown to be effective at phytate reduction in whole‐wheat bread preparation. Additionally, phytate degradation enhanced the mineral availability of bread.     

Effect of the lactic acid bacteria on the control of listerial activity and shelf life of smoked salmon scraps

The potential protective activity of lactic acid bacteria (LAB) from cold smoked salmon scraps was evaluated towards Listeria monocytogenes. Seventy‐three LAB strains were isolated and identified by biomolecular methods; Lactobacillus curvatus and Lactobacillus sakei prevailed. Three of the strains tested, identified as L. sakei, profile O, had a significant inhibitory activity against L. monocytogenes ATCC 19115 and clones DUP‐1042 and DUP‐18596. The evolution of microbial populations and chemical parameters were determined at time intervals to verify the shelf life. Listeria monocytogenes was isolated in half the packages also exceeding the legal limit. The shelf life of scraps was set at 30 days. Clonal characterisation of L. monocytogenes was performed by ribotyping. DUP‐1042, one of the human pathogen clones, was the most represented pattern. The results suggest further studies aimed at the selection of autochthonous nonspoilage LAB strains as bioprotective agents for cold smoked salmon.     

Microbial safety and probiotic potential of packaged yogurt products in Pakistan

Yogurt is a health food with notable market production and demand. Because of this, we conducted a study on prominent commercial brands of yogurts in Pakistan for microbial content and the probiotic potential of the contained lactic acid bacteria (LAB), in the context of their label claims. All contained viable LAB, but the numbers (cfu g⁻¹) varied considerably. Three of the products made explicit probiotic claims, but LAB from these displayed no probiotic attributes per WHO-FAO guidelines. The yogurt starter and nonstarter Lactobacillus strains had no gelatinase or hemolytic activity and exhibited significant antibacterial activity against some human pathogens. One brand with a probiotic claim contained an L. acidophilus strain that showed cholesterol assimilation activity in vitro. Some potential human pathogens that were hemolytic and resistance to β-lactam antibiotics were also detected in the products. The findings demonstrate a need for better quality control and regulation to ensure safety and efficacy of yogurt products.     

Effect of Lactic Acid Bacteria Fermentation on Rosmarinic Acid and Antioxidant Properties of in vitro Shoot Culture of Orthosiphon aristatus as a Model Study

In vitro shoot culture of Orthosiphon aristatus was selected as a model system for lactic acid bacteria (LAB) fermentation study. This in vitro plant was subjected to different types of LAB fermentations (Lactobacillus plantarum ATCC 8014 and Lactobacillus acidophilus NCFM) for a different time periods of 24, 48, and 72 h at 37^oC. The LAB fermentations consisted of solid state fermentations in a climatic incubator and liquid state of fermentations in a DCU fermenter system. The aim was to determine the effect of fermentation on antioxidant properties of the in vitro plant extract. Results indicate that all types of LAB fermentation decreased the level of rosmarinic acid and total phenolic compounds; however, a slight increase in total flavonoids and flavonols was observed in solid state fermentations samples. The highest reduction was obtained in the sample of liquid state fermentation inoculated with L. plantarum for a period of 72 h. The loss in rosmarinic acid and phenolics was concomitant with a loss of total antioxidant activity (DPPH, TEAC, and SOD-like activity). HPLC result confirmed that the longer fermentation was the greater reduction phenolic acids content was found. These results indicate LAB fermentation caused a decrease on antioxidant properties of in vitro shoot culture of Orthosiphon aristatus.     

Growth characteristics of agrowaste‐immobilised lactobacilli in soymilk during refrigerated storage

We aimed at evaluating agricultural wastes as solid supports for the immobilisation of lactobacilli in a liquid media, namely soymilk. Lactobacillus acidophilus FTDC 1331, L. acidophilus FTDC 2631, L. acidophilus FTDC 2333, L. acidophilus FTDC 1733 and L. bulgaricus FTCC 0411 were immobilised on solid supports produced from durian (Durio zibethinus), cempedak (Artocarpus champeden) and mangosteen (Garcinia mangostana). The immobilised cells were inoculated into soymilk and stored at 4 °C over 168 h. Soymilk inoculated with non‐immobilised cells was used as the control. Immobilised cells showed higher survivability over 168 h compared to the control, accompanied by higher reduction of simple sugars and oligosaccharides in soymilk. Higher growth and higher utilisation of substrates also led to the higher production of lactic and acetic acids, which lowered the pH in soymilk compared to the control. Our results illustrated that agrowastes could be used as immobilisers to enhance the growth of lactobacilli in a liquid medium.     

The degradation of phytate by microbial and wheat phytases is dependent on the phytate matrix and the phytase origin

BACKGROUND: Phytases increase utilization of phytate phosphorus in feed. Since wheat is rich in endogenous phytase activity it was examined whether wheat phytases could improve phytate degradation compared to microbial phytases. Moreover, it was investigated whether enzymatic degradation of phytate is influenced by the matrix surrounding it. Phytate degradation was defined as the decrease in the sum of InsP₆ + InsP₅. RESULTS: Endogenous wheat phytase effectively degraded wheat InsP₆ + InsP₅ at pH 4 and pH 5, while this was not true for a recombinant wheat phytase or phytase extracted from wheat bran. Only microbial phytases were able to degrade InsP₆ + InsP₅ in the entire pH range from 3 to 5, which is relevant for feed applications. A microbial phytase was efficient towards InsP₆ + InsP₅ in different phytate samples, whereas the ability to degrade InsP₆ + InsP₅ in the different phytate samples ranged from 12% to 70% for the recombinant wheat phytase. CONCLUSION: Wheat phytase appeared to have an interesting potential. However, the wheat phytases studied could not improve phytate degradation compared to microbial phytases. The ability to degrade phytate in different phytate samples varied greatly for some phytases, indicating that phytase efficacy may be affected by the phytate matrix. Copyright © 2011 Society of Chemical Industry     

Detoxification of cancerogenic compounds by lactic acid bacteria strains

ABSTRACT

Carcinogens in food are an important issue that threat people’s health right now. Lactic acid bacteria (LAB) strains as well-known probiotics have shown numerous perspectives in being used as a good food additive to confront cancerogenic compounds in recent years. Some LAB strains can remove cancerogenic compounds from medium environment via direct physical binding and avoid re-pollution of poisonous secondary metabolites which are generated from degradation of cancerogenic compounds. This article presents a whole overview of the physical-binding of LAB strains to such common cancerogenic compounds existed in food and feed environments as mycotoxins, polycyclic aromatic hydrocarbons (PAHs), heterocyclic amines (HAs) and pthalic acid esters (PAEs).In most cases, summaries of these published researches show that the binding of LAB strains to cancerogenic compounds is a physical process. Binding sites generally take place in cell wall, and peptidoglycan from LAB cells is the chief binding site. The adsorption of lactic acid bacteria to cancerogenic compounds is strain-specific. Specially, the strains from the two genera Lactobacillus and Bifidobacterium show a better potential in binding cancerogenic compounds. Moreover, we firstly used molecular dynamic computer model as a highly potential tool to simulate the binding behavior of peptidoglycan from Lactobacillus acidophilus to DBP, one of pthalic acid esters with genetic toxicity. It was seen that the theoretical data were quite consistent with the experimental results in terms of the ability of this bacterium to bind DBP. Also, the toxicity reduction of cancerogenic compounds by LAB strains could be achieved either in gastrointestinal model or animal tests and clinical researches as well. In conclusion, carefully selected LAB strains should be a good solution as one of safety strategies to reduce potential risk of cancerogenic compounds from food-based products.