Selection Of Lactic Acid Bacteria Research Articles

Technological Performance and Selection of Lactic Acid Bacteria Isolated from Argentinian Grains as Starters for Wheat Sourdough.

The selection of lactic acid bacteria strains is interesting for the development of sourdough to obtain wheat bread with improved technological and nutritional properties. In this work, the performance of ten different LAB strains isolated from diverse cereals in wheat sourdough was evaluated. Five facultative heterofermentative (Lactobacillus pentosus ES124, Lactobacillus paralimentarius ES259, Lactobacillus plantarum ES137, Lactobacillus plantarum ATCC8014 and Lactobacillus plantarum ES147), three obligately heterofermentative (Lactobacillus brevis ES253, Lactobacillus fermentum ES142 and Lactobacillus fermentum ES148) and two homofermentative (Pediococcus acidilactici ES22 and Enterococcus faecium ES74) lactic acid bacteria strains were evaluated in ten single strain fermentations. Sugar profile, volatile compounds and proteolytic ability of sourdoughs were analyzed. The microbiological counts showed that facultative heterofermentative strains presented higher counts than homofermentative sourdoughs. Monosaccharides (glucose and fructose), maltose and sucrose, isomaltose and dextrin were detected in fermentations with homofermentative strains whilst in those with heterofermentative strains maltose/sucrose, isomaltose and dextrin were found. L. paralimentarius ES259 and L. pentosus ES124 showed the highest diversity of volatile compounds. L. plantarum ES137 and P. acidilactici ES22 were the strains with the highest proteolytic activity. The technological performance allowed us to select LAB as starters to develop breads with specific rheological properties and final quality.

Testing selectivity of bacterial and fungal culture media compared to original silage samples using next generation sequencing

Plate counts using selective culture media is still the most frequently used method for the enumeration of the different microbial groups that colonize silage, including lactic acid bacteria, yeasts and molds. Since different culture media have specific composition, they may allow the growth of specific populations. To date, no study has used next generation sequencing technology to compare the selective capacity of these different culture media although this approach could provide comprehensive insight into the relevance of using one culture medium over another. Sequencing of the 16S rDNA and ITS amplicon were performed to compare the selectivity of different culture media used in silage microbiology. Corn silage, grass-alfalfa silage and total mixed ration extracts were plated on five selective media for lactic acid bacteria, incubated under aerobic and anaerobic conditions, and on eight selective media for yeast and molds to compare their selectivity. Ensiling provided a pre-selection environment for specific microorganisms over forage and reduced the number of observed OTUs: only 12 OTUs of bacteria were observed in corn silage sampled in the center of a bunker silo, while the mean number of OTUs identified in samples taken closer to the side of the silo, influenced by higher oxygen and humidity level, increased to 79. Still, MRS and Rogosa plates had less than 12 different OTUs in the center and 24 at the side, mainly Lactobacillaceae, Acetobacteraceae, and Leuconostocaceae. Incubating the plates under anaerobic conditions was selective against Acetobacteraceae. MRS supplemented with acetic acid increased selectivity of lactic acid bacteria. When plated on culture media specific for yeast and molds, from 17 to 68 different OTUs were observed in corn silage. Mixed grass-alfalfa silage and total mixed ration samples usually had more observed OTUs and the diversity profile of the corresponding culture media was similar to that of the original samples. For yeasts and molds, Dichloran Rose Bengal Chloramphenicol Agar revealed a diversity profile close to the that of the corn silage.

Selection of Lactic Acid Bacteria Isolated from Fresh Fruits and Vegetables Based on Their Antimicrobial and Enzymatic Activities.

Lactic acid bacteria (LAB) are an important source of bioactive metabolites and enzymes. LAB isolates from fresh vegetable sources were evaluated to determine their antimicrobial, enzymatic, and adhesion activities. A saline solution from the rinse of each sample was inoculated in De Man, Rogosa and Sharpe Agar (MRS Agar) for isolates recovery. Antimicrobial activity of cell-free supernatants from presumptive LAB isolates was evaluated by microtitration against Gram-positive, Gram-negative, LAB, mold, and yeast strains. Protease, lipase, amylase, citrate metabolism and adhesion activities were also evaluated. Data were grouped using cluster analysis, with 85% of similarity. A total of 76 LAB isolates were recovered, and 13 clusters were formed based on growth inhibition of the tested microorganisms. One cluster had antimicrobial activity against Gram-positive bacteria, molds and yeasts. Several LAB strains, PIM4, ELO8, PIM5 and CAL14 strongly inhibited the growth of L. monocytogenes and JAV15 and TOV9 strongly inhibited the growth of F. oxysporum. Based on enzymatic activities, 5 clusters were formed. Seven isolates hydrolyzed starch, 46 proteins, 14 lipids, and 36 metabolized citrate. LAB isolates with the best activities were molecularly identified as Leuconostoc mesenteroides, Enterococcus mundtii and Enterococcus faecium. Overall, LAB isolated from vegetables showed potential technological applications and should be further evaluated.

Biotransformation of phenolic profiles and improvement of antioxidant capacities in jujube juice by select lactic acid bacteria

The objective of this study was to investigate the effects of four commercial lactic acid bacteria (LAB), namely L. acidophilus, L. casei, L. helveticus and L. plantarum, on the phenolic profiles, antioxidant capacities and flavor profiles of jujube juices prepared from two crop varieties (Ziziphus Jujuba cv. Muzao and Hetian). Results showed that both jujube juices were excellent matrices for LAB growth with more than 11 log CFU/mL of viable counts at the end of fermentation. LAB fermentation dramatically increased total phenolic content, while decreased total flavonoid content of jujube juices. However, antioxidant capacities based on DPPH and FRAP methods were significantly improved by LAB fermentation and positively correlated with caffeic acid and rutin contents. Furthermore, a total of 74 volatile compounds were identified and increased in total content by LAB fermentation, which resulted in 22 and 19 new flavor volatiles formation in Muzao juice and Hetian juice, respectively.

ACE Inhibitory Properties and Phenolics Profile of Fermented Flours and of Baked and Digested Biscuits from Buckwheat.

The angiotensin converting enzyme (ACE) inhibitory activity and phenolics profile of fermented flours and of baked and digested buckwheat biscuits was studied. The fermentation of buckwheat flour by select lactic acid bacteria (LAB) caused a decrease in ACE inhibitory activity as compared to the non-fermented flour. The baking process significantly reduced the ACE inhibitory activity of biscuits obtained from fermented flours, whereas digestion significantly increased these properties. In non-fermented and fermented flours and buckwheat biscuits before and after in vitro digestion samples, ten phenolic acids and eight flavonoids were found. Highly significant correlations were found between sample concentration of 50% inhibition of ACE (IC50) and total phenolic compounds of fermented flour and biscuits before and after digestion for each applied LAB, thus indicating a link between phenolic compound content and ACE inhibitory activity. In the digested biscuits, the input to ACE inhibitory activity was provided by p-coumaric, sinapic, syringic, vanillic, and protocatechuic acids as well as by kaempherol, quercetin, apigenin, and orientin. Therefore, it can be concluded that cumulative action of those phenolic acids and flavonoids released after digestion is responsible, in part, for the bioaccessible ACE inhibitory activity of buckwheat biscuits.

Effects of lactic acid fermentation-based biotransformation on phenolic profiles, antioxidant capacity and flavor volatiles of apple juice

Apple juice (AJ) was fermented by six select lactic acid bacteria (LAB), namely Lactobacillus plantarum 90 (Lp90), Lactobacillus helveticus 76 (Lh76), Lactobacillus casei 37 (Lc37), Lactobacillus paracasei 01 (Lpc01), Lactobacillus acidophilus 85 (La85) and Bifidobacterium lactis 80 (Bla80). The effects of LAB fermentation on sugars and organic acids contents, phenolic profiles, antioxidant capacity and flavor volatiles of fermented AJ (FAJ) were investigated. Results showed that AJ was an excellent food matrix for LAB strains. Lh76 and Lp90 showed the highest viable counts of 12.7 log CFU/mL at the end of fermentation. Lp90, La85 and Bla80 exhibited strong malolactic conversion capacity and finally produced lactic acid more than 6.5 mg/mL. In addtion, LAB fermentation significantly (p < 0.05) decreased the total phenols and flavonoids levels. However, antioxidant activities based on DPPH and FRAP methods were enhanced during fermentation, especially for La85 which exhibited dramatical DPPH radical scavenging activity (90.05%) and FRAP (0.96 mmol Trolox/L). The improvement of antioxidant activities was suggested to be related to the increase in caffeic acid and phlorizin contents. The analysis of flavor volatiles showed that LAB fermentation resulted in formation of seven new alcohols and six new esters, and improvement of ketones and aldehydes production.

Bioaccessibility of anti-AGEs activity, antioxidant capacity and phenolics from water biscuits prepared from fermented buckwheat flours

The bioaccessible anti-AGEs activity of buckwheat biscuits (BB) was studied in bovine serum albumin/glucose model and its relationship to the bioaccessible antioxidant/reducing capacity measured by ABTS test and FRAP assay, and bioaccessible total phenolic compounds was addressed. The BB were baked from common buckwheat flours after liquid-state fermentation (LSF) by select lactic acid bacteria (LAB) and fungi Rhizopus oligosporus 2740. The LAB and fungi-dependent variation in AGEs inhibition by BB extracts was noted. A high bioaccessible anti-AGEs activity, antioxidant/reducing capacity and TPC from BB was found after digestion in vitro of BB. The positive correlation noted between the anti-AGEs bioaccessibility indexes, antioxidant/reducing bioaccessibility indexes and total phenolic compounds bioaccessibility indexes indicated for the contribution of the bioaccessible phenolic antioxidants to the inhibitory activity of buckwheat biscuits against AGEs formation.

Isolation and selection of technologically important lactic acid bacteria and yeast from fermented potato

SummaryThis study focused on the isolation, identification and selection of lactic acid bacteria (LAB) and yeasts with important technological properties from fermented potato. A total of three LAB and two yeasts (Weissella sp. strain IMAU50209, Pediococcus pentosaceus strain W2SR04, Pediococcus sp. NBRC 107186 strain, Pichia sp. strain AQGWD7 and Saccharomyces cerevisiae strain YJM1592) were isolated and identified by molecular methods. Weissella sp. strain IMAU50209 showed good acidification and proteolytic ability. More so, it generated more volatile compounds and recorded the highest exopolysaccharide content (824.44 ± 4.19 mg L−1). Saccharomyces cerevisiae strain YJM1592 recorded high gas retention value (VR) 1740.00 ± 86.27 mL and produced beneficial volatile compounds, as compared to Pichia sp. strain AQGWD7. Therefore, Weissella sp. strain IMAU50209 and Saccharomyces cerevisiae strain YJM1592 could enhance gluten‐free potato bread quality.

Application of unsupervised clustering algorithm and heat-map analysis for selection of lactic acid bacteria isolated from dairy samples based on desired probiotic properties

Phenotypic and genotypic characterization of candidate probiotic strains are indispensable steps to the nourishments utilization. Hence, in this study, sixty-three lactic acid bacteria (LAB) isolates of traditional dairy origin already distinguished using pyrosequence-based 16S-rRNA profiling were characterized for their probiotic properties. The unsupervised clustering algorithm and heat-map analysis efficiency for selection of candidate probiotic strains by oppressing their phenotypic characteristics were tested. Results demonstrated that YP9, YP8, TP15, and ShP1 isolates show highest acid and bile tolerance, and Cell surface hydrophobicity. Moreover, CP3, CP12, TP15, TP16, TP17, ShP1, YP8, YP9, and CuP3 showed the highest BSH activity. Interestingly, the inhibitory effects of YP8, ShP1, and YP9 against Yersinia, Listeria, and Yersinia, respectively, were confirmed. Clustering and heat-map analysis effectively selected and distinguished nine Lactobacillus isolates (YP8, YP9, CP3, TP15-17, ShP1, CP12, and CuP3) as candidate probiotic strains. This study opens a new avenue on the selection and characterization of new isolates of bacteria based on their probiotics properties for future application in functional foods.

Selection of Lactic Acid Bacteria Isolated from Thai Traditional Fermented Foods to use as Starter Cultures Based on Antioxidant Activity and no Histidine Production

Four strains of lactic acid bacteria (LAB), isolated from various Thai traditional fermented foods, were investigated on free radical scavenging activity of 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2-Azino-bis-3-ethylbenzothiazoline-6-sulfonic Acid (ABTS). Antioxidant activity by all isolated LAB in intracellular cell free ex- tracts (ICFE) was higher than in intact cells. The LAB strains FF and FB, isolated from fermented foods (fish and sliced beef), their (ICFE) showed the highest radical- scavenging activity for DPPH and ABTS at 65% and 60%, respectively for the former strain. The detection of amino acid decarboxylase of LAB were investigated by growing on decarboxylase medium and quantitatively evaluated by confirmation of amine forming capacity using an HPLC procedure. In this work, all tested LAB strains were tyramine producer; however, the weakest strain was FF followed by strain FB. In contrast, all of them did not produce histamine. Based on 16S rRNA genes, strain FF was identified as Lactobacillus fermentum, while strain FB was Lactobacillus plantarum. Both are potential starter cultures for producing fermented meat sausages.

Bioaccessibility of D-chiro-inositol from water biscuits formulated from buckwheat flours fermented by lactic acid bacteria and fungi

In this study, the bioaccessibility of D-chiro-inositol (DCI) from water biscuits formulated from raw and roasted buckwheat flours originating from common buckwheat after liquid-state fermentation (LSF) by select lactic acid bacteria (LAB) and fungi Rhizopus oligosporus 2740 was studied. The LAB-dependent variation in DCI content in fermented buckwheat flours was noted. LSF by L. salivarius AWH and R. oligosporus 2740 significantly enhanced the DCI content, whereas most of the applied LAB reduced DCI in the fermented flours. Baking at 220 °C for 30 min significantly enhanced the DCI level; however, no correlation was found between the DCI content in fermented flours and the biscuits prepared from them. The potential bioaccessibility of DCI from water biscuits was low. It can be concluded that, by applying select LAB and R. oligosporus 2740 for LSF, the heat treatment and physical structure of biscuits were mainly responsible for the potential bioaccessibility of DCI.

Selection of lactic acid bacteria for exopolysaccharide production

An important source of natural alternative to commercial additives that are commonly extracted from plants and animals is the exopolysaccharide (EPS) produced by lactic acid bacteria (LAB). A screening for EPS production by Lactobacillus delbrueckii, Lactobacillus rhamnosus NBRC 3425 and Weisella paramesenteroides was conducted to identify which among these three LAB would produce the highest yield of EPS. The test organisms were grown in a Semi-defined Medium (SDM) of Sanchez et al (2006) with some modifications. EPS production was confirmed by the formation of precipitate after mixing the broth medium with 95% absolute ethanol. Results of total sugar analysis by phenol-sulfuric acid assay revealed that estimated EPS yield of L. rhamnosus NBRC 3425 was significantly higher at p&lt;0.05 than those of W. paramesenteroides and L. delbrueckii ssp. lactis with values of 0.1355g/L, 0.0652g/L and 0.0544g/L, respectively even though their viable count did not differ significantly from each other. Correspondingly, the pH of L. rhamnosus NBRC 3425 media was also significantly higher (pH 4.03) than L. delbrueckii (pH 3.60) and W. paramesenteroides (pH 3.83).

Isolation and Partial Characterization of Lactic Acid Bacteria from the Gut Microbiota of Marine Fishes for Potential Application as Probiotics in Aquaculture.

With the increase of antimicrobial resistances due to the widespread use of antibiotics, the search of new probiotics to control aquaculture diseases has a growing public interest. The aim of this study was to isolate bacteria with antimicrobial effect from the gut of marine healthy fishes and select lactic acid bacteria (LAB) as potential probiotics, being strains considered as generally regarded as safe (GRAS) by the European Food Safety Agency (EFSA). Of a total of 45 Gram-positive strains with antimicrobial activity found in a screening of the gut microbiota of 13 marine fishes, nine were identified as LAB by 16S rRNA gene sequencing. LAB strains (five Lactococcus lactis subsp. lactis, two Enterococcus spp., one Lactobacillus plantarum, and one Leuconostoc mesenteroides subsp. mesenteroides) also showed a broad-spectrum antibacterial activity against aquaculture pathogens such as Vibrio harveyi, V. splendidus, and Photobacterium damselae and survived in experimental gastrointestinal conditions when grown in culture media modified with different values of pH and bile salts. These results showed the potential of LAB obtained from the indigenous microbiota of wild marine fishes for use as probiotics in aquaculture.

Selection of lactic acid bacteria as a probiotic and evaluated its performance on gnotobiotic catfish Clarias sp.

&lt;p class="JudulBabdenganNomor"&gt;ABSTRACT&lt;/p&gt;&lt;p class="JudulBabdenganNomor"&gt; &lt;/p&gt;&lt;p&gt;This study aimed to select lactic acid bacteria (LAB) as a potential probiotic that producing anti‒microbial compounds in order to treat motile aeromonads septicemia diseases caused by &lt;em&gt;Aeromonas hydrophila&lt;/em&gt; on catfish &lt;em&gt;Clarias&lt;/em&gt; sp. and evaluated its performance on gnotobiotic catfish. The &lt;em&gt;in vitro&lt;/em&gt; assay was done to select several LAB isolates based on antagonistic activity against pathogenic bacteria. The selected isolate was tested &lt;em&gt;in vivo&lt;/em&gt; to observe their ability to improve growth performances of catfish. The study was conducted with five treatments consists of K‒ (normal catfish without addition probiotic, without challenge test), K+ (normal catfish without addition of probiotic, with challenge test), Np (normal catfish with addition of probiotic and challenge test), G (gnoto catfish without addition of probiotic, with challenge test), and Gp (gnoto catfish with addition of probiotic and challenge test). The results showed that the addition of &lt;em&gt;Pediococcus pentosaceus&lt;/em&gt; E2211 as selected probiotic could increase survival rate, specific growth rate, and immune response towards infection of &lt;em&gt;A. hydrophila&lt;/em&gt;. The best survival rate after challenge test was obtained in Np and Gp treatments (88.46%), followed by G treatment (65.38%), while the K+ was only 53.84%. The conclusion of this study was &lt;em&gt;P. pentosaceus&lt;/em&gt; E2211 potentially used as a probiotic candidate for normal and gnotobiotic catfish. The presence of normal microflora with &lt;em&gt;P. pentosaceus&lt;/em&gt; E2211 in Np treatment showed the best probiotic performance with daily growth rate 3.28%, feed conversion ratio 1.79, and total intestinal bacteria reached 10&lt;sup&gt;8&lt;/sup&gt; CFU/mL significantly different from other treatments (P&amp;lt;0.05).&lt;/p&gt;&lt;p&gt;Keywords: &lt;em&gt;Aeromonas hydrophila,&lt;/em&gt; catfish, LAB, probiotic, screening&lt;/p&gt;&lt;p&gt; &lt;/p&gt;&lt;p&gt; &lt;/p&gt;&lt;p align="center"&gt;&lt;strong&gt;ABSTRAK&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Tujuan penelitian ini adalah menyeleksi bakteri asam laktat (BAL) sebagai probiotik potensial penghasil senyawa antimikrob guna menanggulangi penyakit &lt;em&gt;motile aeromonad septicemia&lt;/em&gt; akibat &lt;em&gt;Aeromonas hydrophila&lt;/em&gt; pada ikan lele &lt;em&gt;Clarias &lt;/em&gt;sp. dan evaluasi kinerjanya pada ikan lele gnotobiotik. Pengujian &lt;em&gt;in vitro &lt;/em&gt;dilakukan untuk menyeleksi beberapa isolat BAL sebagai kandidat probiotik berdasarkan aktivitas antagonis terhadap bakteri patogen. Isolat terpilih kemudian diuji &lt;em&gt;in vivo&lt;/em&gt; untuk mengetahui kemampuannya dalam meningkatkan performa tumbuh ikan lele.&lt;em&gt; &lt;/em&gt;Penelitian ini menggunakan rancangan acak lengkap dengan lima perlakuan, yaitu: K‒ (lele normal tanpa probiotik dan tanpa tanpa diuji tantang), K+ (lele normal tanpa probiotik dan diuji tantang), Np (lele normal diberi probiotik dan diuji tantang), G (lele gnoto tanpa probiotik dan diuji tantang), dan Gp (lele gnoto diberi probiotik dan diuji tantang). Hasil penelitian menunjukkan pemberian probiotik terpilih BAL &lt;em&gt;Pediococcus&lt;/em&gt;&lt;em&gt; pentosaceus&lt;/em&gt; E2211 mampu meningkatkan sintasan, laju pertumbuhan, dan respons imun ikan lele terhadap infeksi &lt;em&gt;A. hydrophila&lt;/em&gt;. Sintasan terbaik pascauji tantang diperoleh pada perlakuan Np dan Gp yaitu sebesar 88,46%, diikuti perlakuan G sebesar 65,38%, sementara pada K+ hanya mencapai 53,84%. Kesimpulan dari penelitian ini ialah isolat BAL terpilih &lt;em&gt;P. pentosaceus &lt;/em&gt;E2211 berpotensi sebagai kandidat probiotik untuk ikan lele normal dan lele gnotobiotik &lt;em&gt;Clarias &lt;/em&gt;sp. Keberadaan mikroflora normal yang berasosiasi dengan &lt;em&gt;P. pentosaceus &lt;/em&gt;E2211 pada perlakuan Np menunjukkan kinerja probiotik terbaik dengan nilai laju pertubuhan harian 3,28%, rasio konversi pakan 1,79 dan total bakteri usus mencapai 10&lt;sup&gt;8&lt;/sup&gt; CFU/mL yang berbeda signifikan dibanding perlakuan lainnya (P&amp;lt;0,05).&lt;/p&gt;&lt;p&gt;Kata kunci: &lt;em&gt;A. hydrophila,&lt;/em&gt; BAL, ikan lele, probiotik, seleksi&lt;/p&gt;&lt;p&gt; &lt;/p&gt;

WASTES OF AGROINDUSTRY AN ALTERNATIVE TO DEVELOP BIOPREPARATES WITH PROBIOTIC CAPACITY

&lt;p&gt;The objective of this study was to obtain and characterize three candidate microbial cultures for veterinary probiotics, developed in different substrates on agro-industry wastes. A selection of lactic acid bacteria (Lactobacillus acidophilus, L. bulgaricus, Streptoccus thermophillus) and yeasts of Kluyveromyces fragilis (L-4 UCLV) were used to develop probiotic preparations. The substrates chosen were: molasses (as a source of carbohydrates) and soy milk, whey, torula yeast and orange vinasse (as a source of protein) to obtain a high number of microorganisms and levels of organic acids. The substrates under study were composed of: T1, molasses and soy milk. T2, buttermilk more torula yeast and molasses. T3, orange vinasse and molasses. All the variables were incubated for 24 at 37 ° C. Dry matter, crude and true protein, ether extract, ash, viability and microbial concentration were determined in all treatments (T1, T2 and T3). At the time of incubation, the pH values of all the treatments were lower than 4.22 and at 24 hours it was reduced to 3.86. The values of the dry material and ether extract were higher (P&amp;lt;0.05) in T1; the crude and true protein was higher (P&amp;lt;0.05) in T2; whereas, ash was higher (P&amp;lt;0.05) in T3. But for all the variables the microbial concentration and the viability was higher than 93% and 7.7x107 cfu/mL respectively. The results of the present study showed that byproducts such as: molasses, soy milk, whey, milk yeast and orange vinasse are suitable substrates to develop microorganisms with probiotic capacity and obtain an acceptable probiotic for veterinary use.&lt;/p&gt;

Antimicrobial activity of preparations after combined cultivation of lactic acid bacteria and yeast strains.

Use of antimicrobials in both human and animal populations over the past several decades has led to the emergence of multidrug-resistant bacteria populations that are resistant to many commercially available drugs. For example, acquired resistance to first-line antimicrobial agents increasingly complicates the management of extra-intestinal infections due to Escherichia coli, which are a major source of illness and death. The continued development of new classes of natural antimicrobial agents, possessing antibacterial activity, has become of increasing importance for medicine and veterinary. So, selection of lactic acid bacteria and yeast strains for their combined cultivation with the aim of increasing of the activity is topical. It was shown that during combined cultivation of the lactic acid bacteria with probiotic properties and yeast strains, antimicrobial activity depends on the genus and species to which the strain of lactic acid bacteria and yeast belongs. They inhibited the growth of multidrug-resistant bacteria with better efficiency. Increasing of the antimicrobial activity can be explained by the synergetic effect of products of cultures metabolism and by interaction between lactic acid bacteria cells with the cell wall of yeasts. Our data showed perspectives of combined cultivation of yeast and lactic acid bacteria for creation of a new class of antimicrobial preparations with high antibacterial activity and broad spectrum of action. Preparation can be recommended for treatment of animals.

Transformation of plant isoflavones into bioactive isoflavones by lactic acid bacteria and bifidobacteria

Isoflavones are usually found in nature in their glycosilated or methylated forms, and should be hydrolysed to become bioavailable and physiologically active. The deglycosylation of isoflavone C-glycosides and O-glycosides and the demethylase activity were studied in a selection of lactic acid bacteria (LAB) and bifidobacteria by assessing the degree of transformation of the pure precursor compounds, daidzin, genistin, puerarin, formononetin and biochanin A into daidzein or genistein. Only one Bifidobacterium strain and two Enterococcus strains hydrolysed the C-glycosidic bond of puerarin, while deglycosylation of O-glycosides daidzin and genistin was observed in all the tested strains. Demethylation of biochanin A and formononetin was observed in the most of LAB and bifidobacteria. Besides, the subsequent metabolites dihydrodaidzein and dihydrogenistein where produced by many of the strains via daidzein and genistein. In this work, we show the potential of LAB and bifidobacteria as part of functional foods because of their ability to transform plant isoflavones into their bioactive forms.

Selection of Lactic Acid Bacteria for the Optimized Production of Sheep’s Milk Yogurt with a High Conjugated Linoleic Acid Content

Thirty-five different lactic acid bacteria (LAB) strains were screened for their conjugated linoleic acid (CLA) isomers (C18:2 cis-9, trans-11 and C18:2 trans-10, cis-12) producing ability from linoleic acid (LA) in sheep’s milk. Preliminary experiments revealed that Lactobacillus delbrüeckii ssp. bulgaricus 2230 and Streptococcus thermophilus St 360 among the screened strains had the highest CLA-producing ability. This two strains were assayed in an 11-run fractional factorial design to investigate the effect of four variables included glucose, powdered sheep milk, LA and inoculum ratio on CLA production in a sheep’s milk yogurt. The optimum conditions for producing the highest levels of CLA (42.86%) were obtained by adding 10.00 mg/mL of glucose, 30.00 mg/mL of powdered sheep milk, 0.90 mg/mL of LA and a 1:2 (St:Lb) ratio of bacterial strains in the inoculum. This CLA-rich sheep’s milk yogurt could be an important supplementary food source for increasing the CLA in the human diet.

Fermentation-based biotransformation of bioactive phenolics and volatile compounds from cashew apple juice by select lactic acid bacteria

Select lactic acid bacteria (LAB); Lactobacillus plantarum, L. casei and L. acidophilus were targeted for enhancing bioactives and flavor volatiles of cashew apple juice (CAJ) that is an underutilized byproduct from cashew nut processing in Tropical countries. Results indicated the vitamin C and phenolic metabolites such as condensed tannin can be increased at certain stages such as at 12 h over the 48 h fermentation period. Whereas antioxidant activity based on DPPH and ABTS radical scavenging activity generally decreased from initial unfermented stage range of (75%–95%) to consistently in the 50% range by 48 h of fermentation and this follows the decrease in viable counts. The fermentation process increased the condensed tannin contents in CAJ whereas hydrolysable tannins decreased. In this study the changes in flavor volatile types were also analyzed over the course of CAJ fermentation. The results indicated that LAB changed the flavor profiles of fermented CAJ and overall the fruity odor decreased, but the whiskey and acid odor increased. These results provide the foundation to further target the functional benefits of LAB-induced fermented CAJ for further human, animal, and plant health applications.

Selection of lactic acid bacteria producing bacteriocin

Lactic acid bacteria were isolated from 10 samples of the traditionally fermented foods (5 samples of Vietnamese fermented pork roll and 5 samples of the salted field cabbage) and 5 samples of fresh cow milks collected from households in Vietnam. 22 strains of lactic acid bacteria were isolated for inhibition to Lactobacillus plantarum JCM 1149. Of these, only 2 strains including DC1.8 and NC1.2 have rod shape, the others have coccus shape. 7 strains showing higher antibacterial activity were selected for checking spectrum of antibacteria with indicator bacteria consistting of Bacillus subtilis ATCC 6633, Enterococcus faecium JCM 5804 and Staphylococcus aureus TLU. By which, 3 strains including NC3.5 (from Vietnamese fermented pork roll), DC1.8 (from salted field cabbage) and MC3.19 (from fresh cow milk) were selected because of their higher antibacterial ability. However, the antibacterial activity of the lactic acid bacteria can be based on their disposable compounds and some other antibacterial compounds produced during their growth (such as lactic acid, H2O2, bacteriocins, etc.). For seeking lactic acid bacteria with capability of producing bacteriocins, antibacterial compounds with protein nature, 3 above strains were checked sensitiveness to proteases (including protease K, papain, α – chymotrypsin and trypsin). Because bacteriocins are proteinaceous antibacterial compounds, so their antibacterial activity will be reduced if proteases are added. The result showed DC1.8 and MC3.19 were capable of producing bacteriocin during culture process. They were identified as Lactobacillus acidophilus and Lactococcus lactis and classified, respectively, based on analysis chemical characterisitcs by standard API 50 CHL kit and phylogeny relationship by 16s rRNA sequences.&#x0D; Các chủng vi khuẩn lactic được phân lập từ 10 mẫu thực phẩm lên men truyền thống (5 mẫu nem chua, 5 mẫu dưa cải bẹ muối) và 5 mẫu sữa bò tươi được thu thập từ các hộ gia đình ở Việt Nam. 22 chủng vi khuẩn lactic đã được phân lập với tiêu chí có khả năng kháng lại vi khuẩn kiểm định Lactobacillus plantarum JCM 1149. Trong số đó, 2 chủng DC1.8 và NC1.2 có tế bào hình que, các chủng còn lại có tế bào hình cầu. 7 chủng thể hiện hoạt tính kháng khuẩn cao được lựa chọn để xác định phổ kháng khuẩn rộng hơn với ba loài vi khuẩn kiểm định Bacillus subtilis ATCC 6633, Enterococcus faecium JCM 5804 và Staphylococcus aureus TLU. Từ đó lựa chọn được 3 chủng có hoạt tính kháng khuẩn cao hơn hẳn. Các chủng này gồm NC3.5 phân lập từ nem chua, DC1.8 phân lập từ dưa cải bẹ muối và MC3.19 phân lập từ sữa bò tươi. Tuy nhiên, hoạt tính kháng khuẩn của vi khuẩn lactic bao gồm những hợp chất nội tại có trong nó và cả những hợp chất được sinh ra trong quá trình phát triển của nó (như axit lactic, H2O2, bacteriocin, …). Với định hướng tìm chủng vi khuẩn lactic có khả năng sinh bacteriocin, chất kháng khuẩn có bản chất protein, 3 chủng trên được kiểm tra độ nhạy cảm với các protease (gồm protease K, papain, α – chymotrypsin và trypsin). Do bacteriocin là chất kháng khuẩn có bản chất protein nên hoạt tính kháng khuẩn của chúng sẽ bị giảm nếu protease được bổ xung vào. Kết quả lựa chọn được chủng DC1.8 và MC3.19 có khả năng sinh bacteriocin. Hai chủng này được phân loại đến loài nhờ vào phân tích đặc điểm sinh hóa bằng kit API 50 CHL và mối quan hệ di truyền thông qua trình tự gen 16s rRNA. Kết quả phân loại đã xác định chủng DC1.8 thuộc loài Lactobacillus acidophilus và chủng MC3.19 thuộc loài Lactococcus lactis.