Selective utilization of gluco-oligosaccharides by lactobacilli: A mechanism study revealing the impact of glycosidic linkages and degree of polymerization on their utilization

Gluco-oligosaccharides (GlcOS) are potential prebiotics that positively modulate beneficial gut commensals like lactobacilli. For the rational design of GlcOS as prebiotics or combined with lactobacilli as synbiotics, it is important to establish the structure requirements of GlcOS and specificity toward lactobacilli. Herein, the utilization of 10 GlcOS with varied degrees of polymerization (DP) and glycosidic linkages by 7 lactobacilli strains (Levilactobacillus brevis ATCC 8287, Limosilactobacillus reuteri ATCC PTA 6475, Lacticaseibacillus rhamnosus ATCC 53103, Lentilactobacillus buchneri ATCC 4005, Limosilactobacillus fermentum FUA 3589, Lactiplantibacillus plantarum WCFS1, and Lactobacillus gasseri ATCC 33323) was studied. L. brevis ATCC 8287 was the only strain that grew on α/β-(1→4/6) linked disaccharides, whereas other strains showed diverse patterns, dependent on the availability of genes encoding sugar transporters and catabolic enzymes. The effect of DP on GlcOS utilization was strain dependent. β-(1→4) Linked cello-oligosaccharides (COS) supported the growth of L. brevis ATCC 8287 and L. plantarum WCFS1, and shorter COS (DP 2–3) were preferentially utilized over longer COS (DP 4–7) (consumption ≥90% vs. 40%–60%). α-(1→4) Linked maltotriose and maltodextrin (DP 2–11) were effectively utilized by L. brevis ATCC 8287, L. reuteri ATCC 6475, and L. plantarum WCFS1, but not L. fermentum FUA 3589. Growth of L. brevis ATCC 8287 on branched isomalto-oligosaccharides (DP 2–6) suggested preferential consumption of DP 2–3, but no preference between α-(1→6) and α-(1→4) linkages. The knowledge of the structure-specific GlcOS utilization by different lactobacilli from this study helps the structural rationale of GlcOS for prebiotic development.     

Stability of microencapsulated lactic acid bacteria under acidic and bile juice conditions

The probiotic strains Lactobacillus brevis CCMA1284 and Lactobacillus plantarum CCMA0359 were microencapsulated by spray drying using different matrices – whey powder (W), whey powder with inulin (WI) and whey powder with maltodextrin (WM). Viability of the microencapsulated strains in acid and bile juices and during 90 days of storage (seven and 25 °C) was evaluated. The two strains exhibited high encapsulation efficiency (> 86%) by spray drying. The different matrices maintained L. plantarum viability above six log CFU g⁻¹ at 7 °C for 90 days, whereas similar results for L. brevis were observed only for W. The use of inulin as matrix of encapsulation did not enhance bacterial viability in the evaluated conditions. In general, the use of W and WM as matrices was effective for L. plantarum viability. However, only W was effective for L. brevis in the evaluated conditions. The spray drying technique was successfully adopted for the encapsulation of L. plantarum CCMA0359 and L. brevis CCMA1284 strains.     

Ability of Lactobacillus brevis strains to degrade food phenolic acids

The potential to degrade 15 food phenolic acids was investigated for several Lactobacillus brevis strains isolated from different sources. All the strains analysed in this study showed a similar metabolism on phenolic acids. Among the cinnamic acids assayed, only p-coumaric, ferulic and caffeic acids were metabolized by the L. brevis strains. These acids were decarboxylated to produce their corresponding vinyl derivatives. Contrarily to the results previously reported on Lactobacillus plantarum, the L. brevis strains analysed in this study were unable to subsequently reduce or metabolize these vinyl derivatives. In L. brevis, vinyl phenol, vinyl catechol, and vinyl guaiacol were the final metabolic products from p-coumaric, caffeic or ferulic acids, respectively. From the benzoic acids analysed, and similarly to L. plantarum strains, only gallic and protocatechuic acids were modified by L. brevis strains. Both acids were decarboxylated to pyrogallol and catechol, respectively. Currently, the enzymes involved in the metabolism of phenolic acids in L. brevis remain uncharacterized.     

Associative Growth of Lactic Acid Bacteria in Cabbage Juice

Combinations of Leuconostoc mesenteroides, Lactobacillus brevis, Pediococcus cerevisiae, and Lactobacillus plantarum were grown in sterile cabbage juice broth. The effects of culture interactions were determined by lag times, generation times, pH change, and total acidity measurements. Fresh filter-sterilized cabbage juice was a better medium than autoclaved cabbage juice, or refrigerated filter-sterilized cabbage juice. The addition of NaCl (2.25%) had a minimal effect on the cultures, except for L. mesenteroides, which was inhibited. In paired association studies, L. mesenteroides was inhibited by all the other cultures, conversely, L. plantarum and L. brevis benefited from most of the culture interactions.     

Ability of lactic acid bacteria to produce N-heterocycles causing mousy off-flavour in wine

Thirty‐four strains of the genera and species representative of the wine lactic acid bacteria (LAB) were screened in an ethanolic grape juice medium for the production of mousy off‐flavour as determined by an alkaline test strip sensory method. Most Lactobacillus spp., Oenococcus oeni and Leuconostoc mesenteroides produced mousy off‐flavour, whereas Pediococcus spp. were generally incapable of detectable off‐flavour formation. To verify these results, selected LAB were tested for the ability to produce the three sensorially potent N‐heterocycles, 2‐ethyltetrahydropyridine (ETPY), 2‐acetyltetrahydropyridine (ACTPY) and 2‐acetyl‐1‐pyrroline (ACPY), which are associated with the mousy off‐flavour in wine. N‐heterocycle formation was determined by incubating a high density of bacterial cells in a chemically defined N‐heterocycle assay medium, and quantifying the ‘mousy’ compounds by gas chromatography‐mass spectrometry. Most strains produced each of the three N‐heterocycles, with the general order for this capability being Lactobacillus (heterofermentative) > Oenococcus > Pediococcus. Strains of Lactobacillus hilgardii and Lactobacillus brevis were characterised as producing the highest concentration of ACTPY (328–580 μg/L, sensory threshold in water =1.6 μg/L), whereas ACPY and ETPY were produced at a moderate concentration (< 50 and < 10 μg/L, respectively). In addition to the formation of ACPY and ACTPY, three of five strains of the commercially important wine malolactic bacterium, O. oeni, produced the highest concentration of ETPY (87–162 μg/L). Strains of the homofermentative LAB, Pediococcus sp. and Lactobacillus plantarum L11a, however, produced only a relatively low concentration of each mousy N‐heterocycle (≤ 37 μg/L), suggesting that the ability of LAB to produce mousy N‐heterocycles is linked to the pathway of sugar catabolism. The importance of selecting LAB for induction of malolactic fermentation which have limited ability to produce mousy N‐heterocycles is emphasised.     

Microbial characterization of Iranian traditional Lighvan cheese over manufacturing and ripening via culturing and PCR-DGGE analysis: identification and typing of dominant lactobacilli

This paper reports on the diversity and dynamics of the dominant microbial populations during manufacturing and ripening of Lighvan, a traditional, starter-free Iranian cheese made from raw ewe and goat’s milk as determined by culturing and PCR-DGGE. Similar dominant populations, composed of Lactococcus lactis and Lactobacillus spp. strains, were found by both techniques. However, discrepancies regarding the identity of the Lactobacillus species were encountered. Lactobacillus curvatus and Lactobacillus sakei proved to be dominant by PCR-DGGE; in contrast, Lactobacillus paraplantarum, Lactobacillus paracasei, Lactobacillus brevis and Lactobacillus plantarum were the majority cultivable organisms. RAPD typing of lactobacilli isolates showed wide genetic diversity among the species. Moreover, strain compositions change over time; L. brevis and L. paraplantarum were dominant in milk and were replaced by L. plantarum and L. paracasei strains as ripening progressed.     

Characterization and Technological Properties of Lactic Acid Bacteria in the Production of “Sorghurt,” a Cereal-Based Product

A total of 57 predominant LAB strains isolated from cassava and maize grains fermentation processes for fufu and ogi were identified using phenotypic and genomic fingerprinting methods such as rep-PCR and ARDRA. They were divided into facultatively heterofermentative rods (26.3%), obligately heterofermentative rods (31.6%), and tetrad forming homofermentative cocci (42.1%). Selected strains were further identified by sequencing the 16S rDNA gene. Technological studies such as acidification, hydrogen peroxide production, starch hydrolysis, enzymatic activities, degradation of oligosaccharides, and in vitro adherence properties were carried out. Lactobacillus plantarum strains demonstrated better and rapid acid production capability, followed by the Pediococcus strains, while L. fermentum strains exhibited slower acid production. Hydrogen peroxide production was observed among the LAB groups. The test strains utilized the indigestible sugars raffinose and stachyose. Only L. pentosus demonstrated high amylase activity comparable to that of L. amylovorus DSM 20531. Lactobacillus plantarum and L. fermentum strains showed high β-glucosidase activity. Six strains were selected as starter cultures. The strains were tolerant to acidic pH levels and bile salt. The yoghurt-like “sorghurt” produced using the selected starter cultures had a final pH of less than pH 4.0, and a viable count of less than 5.5 Log₁₀cfu/mL at the end of a 24 h fermentation period. The samples were generally acceptable to the taste panelists. The starter organisms demonstrated varying degree of adherence to HT29 MTX cell line. Therefore, employing functionally defined LAB strains may be one practical approach for incorporating health-promoting features into appropriate food products suitable for targeted population.     

Characteristics of lactic acid bacteria isolated from forage crops and their effects on silage fermentation

Enterococcus faecalis CA 6, E faecium CA 10, E casseliflavus CA 13, Weissella paramesenteroides CA 14, Leuconostoc pseudomesenteroides CA 17, Pediococcus pentosaceus CA 21, P acidilactici CA 25 and Lactobacilus plantarum CA 28 isolated from forage crops were characterised and their effects on silage fermentation were studied. Strains CA 6, CA 10 and CA 13 grew only at relatively high pH (above 5.0), while strains CA 21, CA 25 and CA 28 were able to grow at pH values below 4.0. Strain CA 25 grew at 50 °C, but the others did not grow at above 45 °C. These strains were used as inoculants for perennial ryegrass silage ensiled at 25 or 45 °C. At 25 °C all strains significantly (P < 0.01) reduced the pH value and butyric acid content and greatly increased the lactic acid content compared with the control, particularly strains CA 21, CA 25 and CA 28. At 45 °C strain CA 25 markedly improved the fermentation quality of silage, but the others did not. These silages had a lower lactic acid content and a higher proportion of L (+)‐ to total lactic acid than equivalent silages kept at 25 °C. The results confirmed that at 25 °C P pentosaceus CA 21, P acidilactici CA 25 and L plantarum CA 28 were the most effective, whereas at 45 °C only P acidilactici CA 25 had a beneficial effect on silage fermentation quality. © 2000 Society of Chemical Industry     

Dialysis Pure-Culture Process for Lactic-Acid Fermentation of Vegetables

Blanched and brined cucumbers and green beans were fermented with pure cultures of lactic acid bacteria by use of a dialyzer with microporous membrane separating the continuously circulated vegetable brines and cultures. Dialysis fermentations were conducted separately with Lactobacillus brevis, L. plantarum and Pediococcus cerevisiae; L. brevis performed the most satisfactorily. Maximal populations of all three species were lo-100 times higher in the dialysis cultures than when cultivated directly in blanched cucumber brines. Five lots of the vegetables were fermented consecutively for 8 wk with the same culture of L. brevis. Addition of calcium acetate as a pH buffer increased cell populations, extended cell viability, and increased fermentation rates.     

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.     

Probiotic properties of lactic acid bacteria isolated from Mukeunji, a long-term ripened kimchi

Lactic acid bacteria (LAB) isolated from mukeunji was screened for characterization of beneficial properties required as probiotics. Among the isolates from mukeunji, 5 LAB strains were selected due to their high levels of tolerance to simulated gastric fluid. These strains were identified by using SDS-PAGE of whole cell protein pattern and 16S rDNA sequencing. Subsequently, it was found that 2 isolates, Lactobacillus brevis C1 and Lactobacillus plantarum G4 among the 5 isolates were highly resistant to bile cytotoxicity in terms of survival rate, 162.2 and 114.3%, respectively. According to the results of in vitro adhesion assay, Lb. brevis C1, Lb. plantarum G4, and Lactobacillus sakei N1 had higher numbers of adhesion to Caco-2 epithelium cells than that of Lactobacillus rhamnosus GG, a well known probiotic. None of the isolates produced a carcinogenic enzyme, β-glucuronidase. In addition, Lb. brevis C1 and Lb. plantarum G4 exhibited high levels of DPPH scavenging capacity. These results suggest that 2 isolates from mukeunji, Lb. brevis C1 and Lb. plantarum G4 may have potential for food products as probiotics because they showed high levels of bile acid tolerance and probiotic properties.     

Screening and Characterization of Lactobacillus sp. from the Water of Cassava’s Fermentation for Selection as Probiotics

The present study aimed to evaluate selected probiotic properties of Lactobacilli isolated from the water of submerged cassava fermentation. Following Lactobacilli isolation, isolates were screened for their antimicrobial activity. Acid and bile tolerances, bile salt hydrolase (Bsh) activity spectrum were assessed. Among the 113 isolates obtained, 16 showed a broad antimicrobial activity spectrum against the indicator microorganisms. From these 16, 12 were found acid and bile resistant. They hydrolyzed glycoconjugated or tauroconjugated bile salts. From the four bile Bsh genes screened, only Bsh-Lp1 was found in five isolates. They identified as Lactobacillus paraplantarum, Lactobacillus paracasei, Lactobacillus brevis, and Lactobacillus plantarum. Based on the principal component analysis, L. paracasei 62L, L. plantarum 85L and 86L were selected as the most promising strains. These results suggest that water from submerged cassava fermentation can be a source of Lactobacilli with high probiotic potential.     

Genetic screening of lactic acid bacteria of oenological origin for bacteriocin-encoding genes

A total of 330 lactic acid bacteria isolated from South African red wines during alcoholic and malolactic fermentations and 9 commercial malolactic bacteria starter cultures were screened for antimicrobial activity. Of the entire screened isolates, 26 strains, belonging to the species Lactobacillus plantarum, Lactobacillus paracasei, Lactobacillus hilgardii and Oenococcus oeni, showed activity towards various wine-related and non-wine-related indicator strains. A PCR-based screening revealed the presence of the plantaricin encoding genes plnA, plnEF, plnJ and plnK in five selected Lb. plantarum strains. Furthermore, a co-culture experiment with Lb. plantarum and Enterococcus faecalis was performed. A complete inhibition of cell growth of Ent. faecalis was observed within 72 h. Four putative bacteriocin-encoding genes in the genome of O. oeni were identified and sequenced.     

Citrulline production by lactic acid bacteria in Chinese rice wine

Ethyl carbamate (EC) is a carcinogenic compound derived from the spontaneous reaction of ethanol with urea or citrulline in Chinese rice wine. Polymerase chain reaction–denaturing gradient gel electrophoresis showed that five species, Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus brevis, Lactococcus lactis and Lactobacillus coryniformis were the most abundant bacteria in the Chinese rice wine production process. Five strains belonging to these species can degrade arginine primarily in the exponential growth phase and accumulate citrulline in MRS‐Arg medium. In addition, an L. brevis strain was shown to be capable of assimilating citrulline, indicating the potential of this strain suggesting a potential route to reduce citrulline content and ethyl carbamate formation in Chinese rice wine fermentation. Copyright © 2018 The Institute of Brewing & Distilling     

Diversity and probiotic potentials of lactic acid bacteria isolated from gilaburu,a traditional Turkish fermented European cranberrybush (Viburnum opulus L.) fruit drink

The aim of the present study was to characterize lactic acid bacteria (LAB) strains isolated from traditional fermented gilaburu fruit juice and their probiotic potential. The LAB counts of the fermented gilaburu fruit juice were in the range of 3.92–8.30 log cfu/g. Total of 332 isolates belonging to Lactobacillus and Leuconostoc species were characterized from traditional fermented gilaburu juice by genotypic methods. It was also determined that the major LAB strains belong to Lactobacillus plantarum (173 isolates), Lactobacillus casei (52 isolates) and Lactobacillus brevis (24 isolates), while Lactobacillus buchneri, Lactobacillus parabuchneri, Lactobacillus pantheris, Leuconostoc pseudomesenteroides and Lactobacillus harbinensis were the least in isolated LAB strains. In terms of the probiotic potentials, Lb. plantarum strains were able to grow at pH 2.5, but 3 of Lb. casei strains, one of each Lb. brevis and Lb. buchneri strains could not grow at the same pH. All selected LAB stains were resistant to bile salt at ≤ 0.3% concentration. While all the LAB species grew at 15 °C, two Lactobacillus hordei strains could also grow at 45 °C. The highest cell hydrophobicity degrees were for Lb. casei (G20a) and Lb. plantarum (G19e) as 87.5 and 86.0%, respectively. Listeria monocytogenes and Bacillus cereus were the most sensitive bacteria against the selected LAB strains, while Escherichia coli and Staphylococcus aureus were the most resistant. Again all the isolated LAB species were resistant to three antibiotics; kanamycin, streptomycin and vancomycin. Characterization and probiotic potentials of the LAB isolated from fermented gilaburu (Viburnum opulus) juice were studied first time, and further research needs to be done on their behaviors in similar food formulations as a probiotic.     

Microbial Sour Doughs Influence Acidification Properties and Breadmaking Potential of Wheat Dough

Breads from sour doughs were started with Lactobacillis plantarum (L-73, or B-39) or Lactobacillus brevis (L-62)-, and incorporated at 10, 17.5, or 25%. Lactic and acetic acid production depended on bacterial starter and yeast. Started doughs had longer mixing time, stability, more softening with time; lower resistance to extension; shorter fermentation, less stability, and greater oven rise. Breads had greater volume, lower density, softer crumb and higher slice height. Interactive effects between inoculum and microbial composition of starter were reflected in sensory scores. Adequate sour dough inoculum was lower for heterofermentative strains (10%, L-62) than for homofermentative strains (17.5%, B-39; 25%, L-73), due to deleterious effects on rheological properties.     

Regulation of acetic acid production by homo-and heterofermentative lactobacilli in whole-wheat sour-doughs

The efficiency of sour-dough as a possible preservative agent of microbial spoilage of bread depends on its acetic acid content. As a secondary metabolite of sugar fermentation by lactic acid bacteria, acetic acid may be promoted in the presence of O₂ or H⁺ acceptors. This paper studies the influence of O₂ and high fructose content products (pure sugar, invert sugar, fructose syrup) addition on acetic acid production by hetero- (Lactobacillus brevis 25a, B-21, L-62;L. sanfrancisco L-99) and homofermentative (L. plantarum B-39) lactobacilli in whole-wheat sour-doughs [280 and 250 dough yield (DY)]. The pH and total titratable acidity (TTA) of sour-doughs after 44 h fermentation varied with DY and strain. As expected, the addition of O₂ promoted greater increases in TTA with heterofermentative lactobacilli (15–42%) than withL. plantarum (15%). Fructose addition was only effective for heterofermentative strains, but the overall effects were smaller than those observed for oxygenation. The ability of lactobacilli to produce acetic acid in sour-doughs without treatment varied from 0.16 g/100 g flour at 44 h (B-39, 280, 350 DY) to 0.47–0.65% (L-62, 280, 350 DY). The production of acetic acid was positively promoted by all treatments. Oxygenation was again the most effective way of inducing acetic acid production; increases ranged from 54% (B-21) to 269% (L-99, 350 DY). The addition of H⁺ acceptors had variable effects. Pure fructose resulted, in general, in greater increases than invert sugar of fructose syrup. The main effects were detected forL. brevis 25a (280 DY) B-21 (350 DY) andL sanfrancisco L-99 (350 DY) with increases ranging from 92 to 123%. The highest levels of acetic acid (1.02–1.04%) corresponded to sour-doughs (44 h, 35° C shaking 150 rpm) started with L-62 (280, 350 DY) or L-99 (350 DY).

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Beeinflussung der Essigsäurebildung durch homo- und heterofermentative Laktobacillen in Weizenvollkornsauerteigen

Zusammenfassung Die Haltbarkeit von Sauerteig-Brot gegen mikrobiologische Verderbnis beruht auf seinem Säuregehalt. Als sekundäres Stoffwechselprodukt der Zuckergärung durch Milchsäurebakterien, kann die Essigsäure-Bildung von Sauerstoff- oder Wasserstoffacceptoren gefördert werden. Diese Veröffentlichung befaßt sich mit dem Einfluß von Sauerstoff und Produkten mit hohem Fructosegehalt (Rohrzucker, Invertzucker, Fructose-Sirup) auf die Essigsäure-Bildung durch hetero- (Lactobacillus brevis B-21, 25a, L-62;L. sanfrancisco L-99) und homofermentative (L. plantarum B-39) Laktobacillen in Weizenvollkornsauerteigen (TA 280 und 350). ph-Wert und Säuregrad von Sauerteigen nach 44-stündiger Gärung waren verschieden je nach TA und Stamm. Wie erwartet, verursachte die Zugabe von Sauerstoff eine größere Zunahme des Säuregrades mit heterofermentativen Laktobacillen (15–42%) als mitL. plantarum (15). Fructose-Zugabe war nur wirksam für die heterofermentativen Stämme, aber die allgemeinen Wirkungen waren kleiner als die bei der Behandlung mit Sauerstoff beobachteten. Die Fähigkeit von Laktobazillen, ohne Behandlung in Sauerteigen Essígsäure zu bilden, schwankte zwischen 0.16 g/100 g Mehl (B-39, 280, 350 TA) und 0.47–0.65% (L-62, 280, 350 TA). Die Bildung von Essigsäure wurde durch alle Behandlungen gefördert. Die Behandlung mit Sauerstoff war wieder die effizienteste zur Förderung der Essigsäurebildung; der Anstieg schwankte zwischen 54% (B-21) und 269% (L-99, 350 TA). Die Zugabe von Wasserstoffacceptoren hatte verschiedene Effekte. Reine Fructose ergab im allgemeinen größere Anstiege als Invertzucker oder Fructose Sirup. Die Haupteffekte wurden beiL. brevis 25a (280 TA), B-21 (350 TA) undL. sanfrancisco L-99 (350 TA) mit Anstiegen von 92% bis 123% nachgewiesen. Die mit L-62 (280, 350 TA) oder L-99 (350 TA) hergestellten Sauerteige (44 h, 35 °C, 150 rpm schütteln) ergaben die höchste Gehalte an Essigsäure (1.02–1.04%).

     

Bacterial community dynamics,lactic acid bacteria species diversity and metabolite kinetics of traditional Romanian vegetable fermentations

BACKGROUND: Artisanal vegetable fermentations are very popular in Eastern European countries. Fresh vegetables undergo a spontaneous fermentation in the presence of salt, which is mainly carried out by lactic acid bacteria (LAB). RESULTS: Culture‐dependent and culture‐independent analyses of end‐samples of various spontaneous vegetable fermentations carried out in houses of the Chiodju region (central Romania) revealed Lactobacillus plantarum and Lactobacillus brevis as the most frequently isolated LAB species. Leuconostoc mesenteroides and Leuconostoc citreum were also found. Furthermore, the community dynamics of spontaneous cauliflower and mixed‐vegetable (green tomatoes, carrots and cauliflower) fermentations revealed three steps: an initial phase characterised by the presence of Enterobacteriaceae and a wide LAB species diversity, encompassing Weissella species; a second phase from day 3 onwards wherein L. citreum and Lb. brevis occurred; and a final phase characterised by the prevalence of Lb. brevis and Lb. plantarum. Metabolite target analysis revealed that glucose and fructose were mostly depleted at the end of fermentation. The main products of carbohydrate metabolism were lactic acid, acetic acid, ethanol and small amounts of mannitol, indicating heterolactate fermentation. CONCLUSION: Given their prevalence at the end of vegetable fermentations, Lb. brevis and Lb. plantarum appear to be good candidate starter cultures for controlled vegetable fermentation processes. © 2012 Society of Chemical Industry     

Development of fermented instant Chinese noodle using Lactobacillus plantarum

A new-type of instant Chinese noodle was developed with the application of lactic acid fermentation by lactobacilli. Since the pH value of the noodle sheets is alkaline with kansui (around 8.5), alkaline tolerance is required for the lactobacilli to ferment noodle sheets. The screening of the lactobacilli strains suitable for the fermentation was conducted using 46 strains from 12 species (including subspecies) of lactobacilli. Several strains of Lactobacillus pentosus and Lactobacillus plantarum were found to be fermenters. Among these, L. plantarum NRIC 0380, that showed the highest fermentation rate and favorable modification of noodle, was selected as the best strain, and was employed for the pilot scale manufacture of instant Chinese noodle. During fermentation, L. plantarum NRIC 0380 produced lactic acid to about 11 g/kg noodle sheet after 24 h with a concomitant pH decrease from an initial of about 7.9 down to 3.9. Sensory test after rehydration with boiled water revealed that the fermented instant Chinese noodle sheets at pH 7.5 had increased hardness, elasticity and light sour taste.     

Diversity and screening of lactic acid bacteria in la-baicai made by Korean-Chinese in northeastern China

This study investigated the lactic acid bacteria (LAB) population in la-baicai (spicy cabbage), a traditional fermented food made by the Korean-Chinese community in northeastern China and screened for functional LAB. LAB diversity was analyzed using denaturing gradient gel electrophoresis (DGGE), and 81 LAB strains were isolated and identified based on 16S rDNA sequencing analysis. Polymerase chain reaction DGGE detected 21 LAB species, belonging to the genera Lactobacillus (Lb.), Leuconostoc (Leu.), Pediococcus and Weissella, in 45 la-baicai samples. Lb. plantarum and Lb. sakei were considered to be dominant in the bacterial community. Among 81 LAB isolated by traditional pure culture methods were Lb. plantarum (25 strains), Lb. brevis (two strains), Lb. casei, (four strains), Lb. pentosus (three strains), Enterococcus faecium (45 strains), and E. durans (two strains). The tolerances of these LAB were investigated. Six LAB with high salt (NaCl)-tolerance were screened from the isolates, and 16% (w/v) was the highest salt-tolerance reached. Among the isolates, strain N1, identified as Lb. pentosus, survived well in a simulated digestive environment. Traditional fermented la-baicai from northeastern China is a rich LAB resource. Further study is needed and would be worthwhile to advance the benefits of these LAB.