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Abstract Grape seed extract from (Vitis vinifera) (VGSE) is an excellent source of various polyphenols that exhibit highly potent antioxidant and disease prevention properties. Although numerous biological activities, with potential for improving human health, have been reported for VGSE, there is a lack of data relating to the health benefits of VGSE on DNA damage, protein damage, labile iron activity, and enzyme inhibitory effects. This investigation demonstrated, for the first time, that VGSE inhibits DNA and BSA damage and labile iron activity in-vitro. Moreover, VGSE also inhibited in-vitro activities of AChE, tyrosinase, and α-amylase. VGSE treatment significantly reduced viability of MCF-7, Hep-G2, Caco-2, and Huh-7 cells after 48-h treatments. The results obtained provide additional support for the purported health benefits of VGSE and reinforce its potential in disease prevention and therapy, especially in relation to cancer.

Copyright of Alexandria Journal of Food Science & Technology is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Alexandria Journal of Food Science & Technology is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Yeast feed additives present a natural approach for mitigating ruminal greenhouse gases (GHG) in an environmentally sustainable manner. This study aimed to isolate yeast strains from ruminal fluids capable of reducing GHG from Aflatoxin (AFB1) contaminated diets. Two isolates of Pichia manchuria (FFNLYFC1 and FFNLYFC2) were isolated and identified from the ruminal contents of dairy Zaraibi goats. An in vitro gas production assay was conducted to evaluate the impact of the yeast supplementations on a basal diet contaminated with AFB1 or not. The treatments were control (-AFB1; basal diet without supplements), control with AFB1 contamination (+ AFB1; basal diet containing 20 ppb AFB1), and yeast-supplemented diets (basal diet supplemented with Saccharomyces cerevisiae, and three treatments of P. manchuria [FFNLYFC1, FFNLYFC2, and their mixture at 1:1 ratio (Mix)]. High biological components were detected in abundance of both FFNLYFC1, FFNLYFC2 filtrates (e.g., diisooctyl phthalate). The Mix and FFNLYFC2 of P. manchuria reduced (P < 0.05) methane by 23.5 and 20.8%, respectively, while only Mix inhibited carbon dioxide by 44% compared to the + AFB1 diet. All yeast diets improved (P < 0.05) ammonia concentration, total protozoal and Entodinium spp. counts compared to + AFB1 diet. The Mix exhibited higher (P < 0.05) values of ruminal degraded cellulose, total short-chain fatty acids, acetate and propionate compared to the individual isolates diets. The results suggest synergistic interactions among P. manshurica isolates, leading to enhanced ruminal fermentation and reduced GHG emissions while alleviating the adverse effects of AFB1. Therefore, we recommended the Mix of P. Manchuria as a novel feed additive to ruminant diets., (© 2024. The Author(s).)

This study was undertaken to evaluate the effect of yoghurt supplementation with rice and wheat brans or dietary fibers on serum lipid profile, liver, and heart functionalities, and hepatopathological aspects of the liver of hypercholesterolemic rats. 48 male rats were divided into 8 groups. Group 1 was kept as negative control and fed with a standard diet, and groups 2 to 6 were fed a hypercholesterolemia-induced diet supplemented with brans or dietary fibers of both grains. G2 received yoghurt without supplementation. The experiment lasted for 4 weeks. Results revealed that hypercholesterolemic rats administrated yoghurt supplemented with brans or dietary fibers reduced serum glucose from 113.9 ± 2.72 to 85.5 ± 4.94 in the serum of animals that received dietary fibers of rice and wheat, respectively. In addition, lipids profile and liver antioxidant status were improved. In addition, liver and heart functionalities and liver histopathological architecture were all improved depending on the type of administrated brans or fibers added to yoghurt. The inclusion of 0.5% of rice or wheat brans could be recommended to be added to yoghurt. PRACTICAL APPLICATIONS: Yoghurt is the most famous fermented milk in the world. Supplementation of yoghurt with rice and wheat brans or dietary fibers increased its nutritional value. We proved that this new product contributes to reducing serum glucose, improving lipids profile, and enhancing liver and heart functions in hypercholesterolemic rats. This study confirmed the suitability to add a thesis type of brans or dietary fibers as bioactive ingredients to yoghurt and increased the varieties of functional foods., (© 2022 Wiley Periodicals LLC.)

Although arid land honey is outstanding for its conventional uses in food and medicine, there is an absence of data regarding its health benefits from the perspective of enzyme inhibitory effects that are affirmed by the current study. For the first time, this investigation demonstrates that different types of honey exert inhibitory effects on the activities of angiotensin, tyrosinase, xanthine oxidase, -α -amylase, acetylcholinesterase, and lipase, in addition to the inhibition of bovine serum albumin damage. The present study also provides a comparison with perceived healthy honey from non-arid areas. The results indicated huge contrasts among honey samples through all assessed parameters. Results also demonstrated that at least one type of honey from arid land contained a higher inhibition effect when compared with honey from other regions. Therefore, a possible application of arid land honey and its active compounds can be the utilization as a therapeutic agent against several diseases., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

It is well-documented that iron deficiency leads to anemia, which is the utmost critical problem of nutrition worldwide. Inulin, indigestible polysaccharides, or prebiotic agents may act as vehicles to enhance the iron bioavailability through the formation of the polysaccharide-iron complex. The present study was undertaken to evaluate the therapeutic effects of yogurt fortified with iron and supplemented by long- or short-chain inulin on the growth status, blood parameters, antioxidant capacity, and liver function enzymes in anemic rats. Five animal groups were assigned as the control (G1), which were fed a standard diet and there were four anemic groups, in which haemolytic anemia was induced by phenylhydrazine. The anemic rats were divided into 4 groups according to the regime of feeding as G2: control anemic group fed low-iron diet while the remaining anemic groups were fed yogurt fortified with Fe 2 (SO 4 ) 3 without inulin (G3) or with either long- (G4) or short-chain (G5) inulin. The results showed that the animals subjected to treatment G4 had the highest ( P ≤ 0.05) weight gain and organ coefficient compared with other anemic groups (G2, G3, and G5). Among the anemic groups, the animals that belonged to G4 showed a significant restorative effect by returning the hemoglobin and hematocrit levels and the red blood cell count to the normal control liver. Also, the liver iron content, enzymatic activities, and antioxidant capacities improved in the animals subjected to G4 and G5 treatment groups. The histological structures of the liver tissues of the animals that belonged to G4 and G5 were extremely close to that of the normal control liver. Long-chain inulin-containing yogurt exhibited the best effects in terms of iron supplementation, bioavailability, and antioxidant activities. This formula might be a potential new iron supplement and a good functional food candidate., Competing Interests: The authors declare that they have no conflicts of interest., (This journal is © The Royal Society of Chemistry.)

This study aimed to develop a novel nontoxic, biocompatible, biodegradable, and cost-efficient matrix for the encapsulation of antimicrobial component (nisin) to be used as bio-preservative agent in cheddar cheese. Nisin A loaded beads were prepared from alginate at 0.5%, 1% and 2%; and hi-maize resistant starch at 0.5 or 1%. Beads were characterized by microscopic examination and transmission electron microscopy. Molecular structures were investigated by FTIR, and particle size distributions were measured. The Entrapment efficiency (EE) was measured microbiologically by agar diffusion. The encapsulated nisin showed similar inhibition activities in all developed formulas with an inhibition zone of 15 ± 2 mm. The FTIR analysis confirmed the compatibility of the nisin with sodium alginate and starch. The formulas composed of 1% Alginate and 0.5% Non-Gelatinized Starch had the highest encapsulation efficiency among other formulas (33%). Moreover, that formula allowed the protection and gradual release of the encapsulated nisin during a long-term storage for up to two months. Application in cheddar cheese proved the inhibition of encapsulated nisin on the growth of C. tyrobutyricum at the large-scale production. In conclusion, the alginate (Alg)/non-gelatinized resistant starch formula is suitable for the protection and controlled release of nisin in food applications., (Copyright © 2019. Published by Elsevier B.V.)

The underutilized Kenyan variety of Dolichos lablab bean seeds serve as a good source of natural antioxidants, which can probably be effective in reducing the risk of occurrence of several diseases. This study was undertaken for the first time to address the limited knowledge regarding the antioxidant activities of lablab beans. Moreover, their DNA damage inhibitory activity, bovine serum albumin (BSA) damage inhibitory activity, and the inhibition of acetylcholinesterase and porcine α-amylase were also investigated. The antioxidant capacity of Dolichos lablab bean seeds extracted with methanol, water or methanol/water combination was evaluated by the ferric-reducing antioxidant power (FRAP) assay, free radical-scavenging activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitric oxide (NO) radical-scavenging assay, and 2,20-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Results reported in the present study indicate that water, methanol and water/methanol extracts of lablab bean flour exhibited good antioxidant activity by effectively scavenging various free radicals, such as DPPH, NO, and ABTS radicals. The extracts also exhibited protective effects against DNA and BSA damage and inhibitory effects on porcine α-amylase. Findings of this study suggest that extracts from the lablab bean flour would have potential application in food supplements, and pharmaceutical and cosmetic industries.

This study was undertaken to develop new probiotic products based on liquid maple sap or its concentrate. Sap and concentrate, with or without inulin (2%) were inoculated with Bifidobacterium lactis Bb12 and Lactobacillus rhamnosus GG valio at initial counts of 10⁷-10⁸ CFU/ml. Viability was assessed over four weeks of storage at 4 °C and under in vitro simulated gastrointestinal conditions using dynamic gastrointestinal model known as TIM-1. Viability was maintained throughout the storage period at the same order of 10⁷ to 10⁸ CFU/ml. Inulin significantly enhanced the survivability during passage through the gastrointestinal tract simulator. The developed products could be an excellent alternative for delivering probiotics, especially for individuals suffering from lactose intolerance to dairy products., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Aims: To evaluate the survival of Pediococcus acidilactici UL5 and its ability to produce pediocin PA-1 during transit in an artificial gastrointestinal tract (GIT). To investigate the physicochemical and biological stability of purified pediocin PA-1 under GIT conditions., Methods and Results: Skim milk culture of Ped. acidilactici UL5 was fed to a dynamic gastrointestinal (GI) model known as TIM-1, comprising four compartments connected by computer-controlled peristaltic valves and simulating the human stomach, duodenum, jejunum and ileum. This strain tolerated a pH of 2·7 in the gastric compartment, while lower pH reduced its viability. Bile salts in the duodenal compartment brought a further 4-log reduction after 180 min of digestion, while high viable counts (up to 5 × 10(7) CFU ml(-1) fermented milk) of Ped. acidilactici were found in both the jejunal and ileal compartments. Pediococcus acidilactici recovered from all four compartments was able to produce pediocin at the same level as unstressed cells. The activity of the purified pediocin in the gastric compartment was slightly reduced after 90 min of gastric digestion, while no detectable activity was found in the duodenal, jejunal and ileal compartments during 5 h of digestion. HPLC analysis showed partial degradation of the pediocin peptide in the duodenal compartment and massive breakdown in the jejunal and ileal compartments., Conclusions: Pediococcus acidilactici UL5 showed high resistance to GIT conditions, and its ability to produce pediocin was not affected, suggesting its potential as a probiotic candidate. The physicochemical and biological stability of pediocin was significantly poor under GIT conditions., Significance and Impact of the Study: Pediococcus acidilactici UL5 appears to be a potential probiotic candidate because its capacity to produce pediocin PA-1 is not affected by the GI conditions as well as the strain shows an acceptable survival rate. Meanwhile, purified pediocin PA-1 losses activity during GIT transit; microcapsules could be used to deliver it to the target site., (© 2009 The Authors. Journal compilation © 2009 The Society for Applied Microbiology.)

Cold-smoked salmon treated with divergicin M35-producing Carnobacterium divergens M35, C. divergens ATCC 35677 (a non-producer of bacteriocin), purified divergicin M35 or supernatants of C. divergens M35 culture in snow crab hepatopancreas (SCH) medium or MRS broth was challenged with Listeria monocytogenes (up to 10(3) CFU/g). Samples were stored at 4 degrees C for up to four weeks. L. monocytogenes, total bacterial and lactic acid bacterial counts were determined along with changes in total volatile base nitrogen (TVBN) and biogenic amine production as well as texture, color and odor. A 2.6 log CFU/g reduction in L. monocytogenes was obtained for up to 10 days of storage in samples treated with C. divergens M35. Purified divergicin M35 (50 microg/g), SCH supernatant or MRS supernatant brought reductions of 1 log CFU/g at the beginning of storage. However, the anti-listerial activity of the supernatants lasted for 15 days compared to 3 days for purified divergicin M35. Color and texture were affected little in samples containing C. divergens M35 compared to un-inoculated samples. TVBN and biogenic amine production, particularly tyramine, remained below the maximum acceptable level in fish appreciation. These results clearly show the potential of C. divergens M35 culture as well as divergicin M35 bio-ingredient for application to the inactivation of L. monocytogenes in ready-to-eat seafood.

The anti-listerial effect of pediocin PA-1 and its producing strain, Pediococcus acidilactici UL5, was investigated in vivo using an ICR mouse model. The effect of intra-gastric administration of a single dose of P. acidilactici UL5 (4 x 10(10) CFU/animal) on the propagation of Listeria monocytogenes LSD348 in intestine, liver and spleen was negligible. P. acidilactici UL5 did not appear competitive with the mouse intestinal flora and was not detectable in fecal samples collected two days after administration. However, double-agar-layer activity assay showed the ability of P. acidilactici UL5 colonies recovered from fecal samples one day after administration to produce pediocin PA-1 and inhibit L. monocytogenes. Moreover, repeated doses (250 microg/day for three consecutive days) of purified pediocin PA-1 provided up to 2-log reductions in fecal listerial counts compared to the infected control group and slowed pathogen translocation into the liver and spleen, leading to the disappearance of L. monocytogenes infection in these two organs within six days. Neither P. acidilactici UL5 nor ingested purified pediocin PA-1 had any negative effect on feed intake or body weight development. Pediocin PA-1 did not affect the composition of the mouse intestinal flora, suggesting a potential advantage over other inhibitory agents as a prophylactic measure against L. monocytogenes.

This study was undertaken to genetically identify and phenotypically characterize 14 bifidobacteria isolated from 20 breast-fed newborns. These isolates showed 98%-99% similarity to Bifidobacterium thermacidophilum subsp. suis based on 16S rDNA. Further analysis by pulsed-field gel electrophoresis of chromosomal DNA digested with XbaI revealed 4 distinct restriction patterns. The predominant pattern, shared by 8 (57%) isolates, produced a macro-restriction profile with about 13 large fragments ranging in size from >242.5 to 23.1 kb, whereas the other 6 displayed 3 distinct restriction profiles all characterized by more micro- than macro-restriction, with fragments ranging in size from 97 to 9.4 kb. Phenotypic characteristics, including carbohydrate fermentation profile, maximal growth temperature, and antibiotic susceptibility, varied widely even among strains showing the same restriction profile. The presence of B. thermacidophilum in stools of newborn infants may indicate the potential of these bacteria for aiding the development of the intestinal ecosystem.

Variants resistant to nisin A (vA), nisin Z (vZ), pediocin PA-1 (vP), divergicin M35 (vD) and to bacteriocin-like compounds produced by Bifidobacterium thermophilum subsp. infantis RBL67 (vB) were developed from Listeria monocytogenes LSD530. Lactic acid production, specific growth rate, potassium ion efflux, susceptibility to 13 antibiotics, cell-envelope fatty acid composition and bacteriocin cross-resistance were evaluated. Lactic acid production decreased to 75% or less of that by strain LSD530 for vP, vD and vB and to 20% or less for vA and vZ. Specific growth rates also decreased for all five variants. Acquired resistance to nisin A or Z increased resistance to pediocin and divergicin while vD showed increased resistance to nisin Z but decreased resistance to nisin A and vP exhibited increased resistance to nisin Z, pediocin and divergicin but decreased resistance to nisin A. Acquired bacteriocin resistance generally decreased antibiotic sensitivity, particularly to ampicillin, chloramphenicol, erythromycin and tetracycline. Palmitic acid (C(16:0)) in the cell wall fraction of all variants was significantly higher than in strain LSD530, accounting for 18%, 43%, 32%, 26%, 53% and 44% of the total fatty acids for LSD530, vP, vD, vB, vA, and vZ, respectively. The relationship between the acquisition of bacteriocin resistance, cross-resistance and pathogenicity of Listeria monocytogenes should be studied.

The effects of acid, oxgall, and H(2)O(2) on susceptibilities to antibiotics and nisin were examined for 13 strains of bifidobacteria. Susceptibilities to ampicillin, cloxacillin, penicillin, vancomycin, kanamycin, neomycin, paramomycin, streptomycin, chloramphenicol, erythromycin, tetracycline, and nisin A were assayed by a microdilution broth method. Acid-, oxgall- and H(2)O(2)-stressed variants were produced and assayed. Exposure to a pH of 2.0 for 60 min reduced susceptibilities to cloxacillin and nisin A but increased susceptibilities to ampicillin, vancomycin, aminoglycosides, chloramphenicol, and erythromycin in a strain-dependent manner. Exposure to oxgall (0.3%) for 90 min increased susceptibilities to cell wall-directed antibiotics and aminoglycosides but increased resistances to tetracycline and nisin A. Oxidative stress increased the susceptibilities of 70% of the strains to ampicillin and chloramphenicol, of 50% of the strains to cloxacillin and tetracycline, and of 40% of the strains to erythromycin but did not affect susceptibilities to vancomycin, kanamycin, and nisin A. This study shows that exposure of bifidobacteria to stressful conditions resembling those in the gastrointestinal tract may substantially modify their susceptibilities to antibiotics and may thus affect their probiotic capacities, especially when they are used for the management of intestinal infections and antibiotic-associated diarrhea.

Three bacteriocin-producing bifidobacterial isolates from newborns were identified as Bifidobacterium thermacidophilum (two strains) and B. thermophilum (one strain). This study was undertaken to evaluate the ability of these strains to compete with food-borne Listeria monocytogenes for adhesion and invasion sites on Caco-2 and HT-29 cells. The bifidobacteria adhered at levels ranging from 4% to 10% of the CFU added, but none of the bifidobacteria were able to invade cells. The abilities of Listeria to adhere to and to invade cells varied widely depending on the strain tested. Three groups of Listeria were identified based on invasiveness: weakly invasive, moderately invasive, and highly invasive strains. One strain from each group was tested in competition with bifidobacteria. B. thermacidophilum RBL70 was the most effective in blocking invasion of Listeria, and the decreases in invasion ranged from 38% to 90%. For all three bifidobacterial strains, contact between the cell monolayer and the bifidobacteria for 1 h before exposure to Listeria increased the degree of inhibition. Finally, visualization of competition for adhesion sites on cells by fluorescent in situ hybridization suggested that the two bacteria tended to adhere in close proximity.

An immuno-culture method has been developed by combination of specific monoclonal antibodies and plate culture to allow detection of viable bifidobacteria. Cell wall proteins were selected as surface antigen to produce antibodies against bifidobacteria. The cell wall proteins were extracted and purified from six ATCC strains of bifidobacteria grown in MRS broth using an anaerobic system. To compare the profile of the protein extracts, all the protein solutions obtained were analyzed by SDS-PAGE. Similar bands corresponding to the major proteins of each species of bifidobacteria were observed. The proteins were tested for their immunogenicity in Balb/c mice after immunization and subsequent analysis using ELISA procedures. High immune responses were generated in mice immunized by proteins from Bifidobacterium bifidum and Bifidobacterium longum. Monoclonal antibodies were produced against B. longum and tested for their specificity, sensitivity and cross reactivity with other bifidobacteria species. All the hybridoma cells selected produced anti-B. longum antibodies cross-reacting with native and purified proteins from five other bifidobacteria species. An epitope supported by a cross-reacting protein of 58 kDa shared by bifidobacteria was revealed by western blot. This was confirmed by immune-transmission electron microscopy observations which showed the specific interaction of these antibodies with bifidobacterial cell wall proteins. Also, the antibody obtained was found to be specific for the genus Bifidobacterium and sensitive, allowing the detection of at least 10(5) target cells/ml. An immuno-culture detection approach was then developed using the selected anti-B. longum antibodies. This method was shown to be very efficient for the detection of viable cells of bifidobacteria suggesting the possibility of its use to quantify these bacteria in various food matrices.

Aims: Divergicin M35 is a new class IIa bacteriocin produced by Carnobacterium divergicin M35. The bactericidal activity of this antimicrobial peptide was tested against a set of 11 strains of Listeria monocytogenes isolated from food., Methods and Results: The minimal inhibitory concentration (MIC) was determined by the microdilution method. The strains tested displayed a different level of sensitivity to divergicin M35. L. monocytogenes LSD530, referred to as DivS strain, was the most sensitive and appeared to be inhibited by concentration of divergicin M35 below 0.13 microg ml(-1). The mutant resistant to divergicin M35, called DivM, was obtained from L. monocytogenes LSD530 (DivS) by gradually increasing the amounts of divergicin M35 until 1.3 microg ml(-1). Notably, DivM was stable after 50 generations. DivS parental strain was inhibited by a concentration of 4 microg ml(-1). L. monocytogenes LSD530 was shown to be resistant to divergicin M35 at 1.3 microg ml(-1). Remarkably, in the presence of divalent cations such as Ca(2+), Mg(2+) and Mn(2+), the lethality caused by divergicin M35 was reduced by 0.48, 0.54 and 0.63 log CFU per ml (after 18 h at 30 degrees C), respectively. The total DNA profiles of DivS and DivM were similar. DivS and DivM showed variable sensitivity to antibiotics. The two-dimensional (2-D) electrophoresis of cell wall proteins did not show any significant difference between DivS and DivM strains but their fatty acid composition showed a significant difference in C(16:0) content., Conclusions: Resistance to divergicin M35 is likely ascribed to modification in cell wall fatty acid composition rather than protein modification., Significance and Impact of the Study: This study provides original results contributing to understanding of the resistance of L. monocytogenes to divergicin M35, a new class IIa bacteriocin.

The objective of this study was to evaluate the effect of capsular and ropy exopolysaccharide (EPS)-producing strains of Lactococcus lactis ssp. cremoris on textural and microstructural attributes during ripening of 50%-reduced-fat Cheddar cheese. Cheeses were manufactured with added capsule- or ropy-forming strains individually or in combination. For comparison, reduced-fat cheese with or without lecithin added at 0.2% (wt/vol) to cheese milk and full-fat cheeses were made using EPS-nonproducing starter, and all cheeses were ripened at 7 degrees C for 6 mo. Exopolysaccharide-producing strains increased cheese moisture retention by 3.6 to 4.8% and cheese yield by 0.28 to 1.19 kg/100 kg compared with control cheese, whereas lecithin-containing cheese retained 1.4% higher moisture and had 0.37 kg/100 kg higher yield over the control cheese. Texture profile analyses for 0-d-old cheeses revealed that cheeses with EPS-producing strains had less firm, springy, and cohesive texture but were more brittle than control cheeses. However, these effects became less pronounced after 6 mo of ripening. Using transmission electron microscopy, fresh and aged cheeses with added EPS-producing strains showed a less compact protein matrix through which larger whey pockets were dispersed compared with control cheese. The numerical analysis of transmission electron microscopy images showed that the area in the cheese matrix occupied by protein was smaller in cheeses with added EPS-producing strains than in control cheese. On the other hand, lecithin had little impact on both cheese texture and microstructure; after 6 mo, cheese containing lecithin showed a texture profile very close to that of control reduced-fat cheese. The protein-occupied area in the cheese matrix did not appear to be significantly affected by lecithin addition. Exopolysaccharide-producing strains could contribute to the modification of cheese texture and microstructure and thus modify the functional properties of reduced-fat Cheddar cheese.

Carnobacterium divergens M35, isolated from a commercial sample of frozen smoked mussels, produces a new bacteriocin, divergicin M35, a class IIa bacteriocin. Divergicin M35 is sensitive to pronase-E, alpha-chymotrypsin and proteinase K, but not to trypsin and withstands thermal treatments up to 121 degrees C for 30 min. Divergicin M35 was extracted from the culture supernatant of C. divergens M35 using an SP-Sepharose cation-exchange column, desalted and purified on a C18 Sep-Pack column and further purified by reverse phase-high pressure liquid chromatography. This procedure allowed the recovery of 10% of the bacteriocin present in the culture supernatant with purity higher than 99%. Divergicin M35 had a molecular mass of 4518.75 Da as determined by mass spectrometry, a pI value of 8.3 and positive net charge (+3). The amino acid sequence of divergicin M35 was found to consist of 43 amino acid with four cysteine residues (Cys10, 15, 25, 43) and showed 80.5% homology with divercin V41 (80.5%) and 80.0% with bavaricin MN. Divergicin M35 showed powerful antilisterial activity, especially against Listeria monocytogenes and was also active against carnobacteria but not against strains of Lactococcus, Lactobacillus, Enterococcus, Bifidobacteria and Escherichia. Divergicin M35 production began in late exponential phase and reached a maximum activity of 65,000 AU/ml in early stationary phase. Initial broth pH, Tween 80 and acetate did not affect C. divergens M35 growth or divergicin production. This bacteriocin may be a potential tool for inhibiting L. monocytogenes in seafood products that do not usually undergo an adequate heat treatment.

A 1 day turbidometric microplate bioassay (TMB) was developed for the rapid, accurate and precise quantification of lactic acid bacteria (LAB) bacteriocins (nisin Z and pediocin PA-1). Parameters such as the concentration of the indicator strains and the incubation time were optimized for each bacteriocin. A high correlation coefficient (r(2)=0.992+/-0.004) was obtained for the exponential regression in the nisin Z concentration range of 20-120 ng/ml with 1 x 10(7) CFU indicator strain (Pediococcus acidilactici UL5) and an incubation time of 3 h. Using these parameters, the detection limit was estimated at 80 ng/ml (3.2 IU/ml), compared to 300 ng/ml for the agar diffusion assay (ADA). High precision (<7%) and accuracy (10%) were obtained for all nisin Z concentrations tested. Similar results were obtained with pediocin PA-1 with r(2)=0.993+/-0.005, a precision (8.2%) and an accuracy lower than 15%.

Aims: This study aimed to characterize new isolates of human bifidobacteria, evaluate some of their probiotic potential and to screen these isolates for their effectiveness at inhibiting Listeria monocytogenes in vitro., Methods and Results: Thirty-four Bifidobacterium isolates from infant faeces were identified by fructose-6-phosphate phosphoketolase and PCR. Six isolates, coded RBL67, RBL68, RBL69, RBL70, RBL85 and RBL86, showed higher antagonistic activity against L. monocytogenes. Neutralized culture supernatants of these strains did not inhibit L. monocytogenes when tested by agar diffusion method. However, the concentration of supernatant by speed-vac resulted in the formation of an inhibitory effect with supernatants from strains RBL67, RBL68 and RBL70. This effect was shown to be related to heat-stable proteinaceous compound(s) which were resistant to heating at 100 degrees C for 5 min but not to pronase-E, proteinase-K or trypsin. The extraction of the inhibitory compounds by methanol-acetone extraction procedure indicated that four strains (RBL67, RBL68, RBL69 and RBL70) were mostly soluble in acetone. However, strain RBL85 produced inhibitory substances that were soluble in methanol., Conclusion: Infant bifidobacterial isolates produce heat-stable proteinaceous compounds active against L. monocytogenes., Significance and Impact of the Study: Production of antibacterial substances by bifidobacteria would improve intestinal bacterial ecology and inhibit intestinal pathogens.