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.     

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     

Quality characteristics of fermented sour fish cake (Nham‐Pla)

Nham‐Pla (fermented sour fish cakes) were made from four kinds of fish, namely, striped catfish and nile tilapia from the fresh water fish and threadfin bream and barracuda from the marine fish. Sensory evaluation tests showed that Nham‐Pla made from the fresh water fish have a higher acceptability score; and score differences between catfish and nile tilapia are insignificant. However, score differences between threadfin bream and barracuda are noticeably large. Chemical analysis and Microbiological analysis have also been performed. Results indicated that the range of pH readings among a variety of samples varied from 4.50 to 5.80, lactic acid contents varied from 0.49 to 1.13% (w/w), moisture contents varied from 75.7 to 80.1% (w/w), protein contents varied from 14.08 to 14.92% (vv/w), fat content varied from 0.49 to 1.95% (w/w) and salt contents varied from 1.61 to 1.97% (w/w). Among the forty bacterial isolates identified, twenty three were identified as Leuconostoc mesenteroides, six as Lactobacillus plantarum, three as Pediococcus damnosus, three as Lactobacillus Ieichmanii, two as Lactobacillus delbmekii, two as Lactobacillus brevis and one as Lactobacillus acidophilus.     

Microbial and chemical analysis of a kvass fermentation

Kvass is a fermented cereal beverage which produced from malt, rye flour, stale rye bread, and sucrose and is consumed mainly in Eastern Europe. Moreover, it is of interest as one of the few examples of traditional, non-alcoholic cereal-based beverages. In this study, a commercial kvass sample was characterized with respect to the fermentation microflora and the concentration of microbial metabolites. Lactobacillus casei and Leuconostoc mesenteroides were present in cell counts of 7.3 × 10⁷ and 6.0 × 10⁷ cfu mL⁻¹, respectively. Saccharomyces cerevisiae was present in cell counts of 3.0 × 10⁷ cfu mL⁻¹. PCR-DGGE analysis verified that all dominant fermentation organisms were cultivated. Microbial metabolites in kvass were ethanol, lactate, and acetate. One of the kvass isolates, Ln. mesenteroides FUA 3086 harboured a putative dextransucrase gene and formed dextran and isomalto-oligosaccharides from sucrose and maltose. Fermentation of model kvass wort confirmed that all kvass isolates grew in the fermentation substrate, moreover, formation of isomaltotriose by Ln. mesenteroides FUA 3086 was observed in model kvass fermentation.     

Diversity of Lactic Acid Bacteria Isolated from Brazilian Water Buffalo Mozzarella Cheese

The water buffalo mozzarella cheese is a typical Italian cheese which has been introduced in the thriving Brazilian market in the last 10 y, with good acceptance by its consumers. Lactic acid bacteria (LAB) play an important role in the technological and sensory quality of mozzarella cheese. In this study, the aim was to evaluate the diversity of the autochthones viable LAB isolated from water buffalo mozzarella cheese under storage. Samples were collected in 3 independent trials in a dairy industry located in the southeast region of Brazil, on the 28th day of storage, at 4 ºC. The LAB were characterized by Gram staining, catalase test, capacity to assimilate citrate, and production of CO₂ from glucose. The diversity of LAB was evaluated by RAPD‐PCR (randomly amplified polymorphic DNA‐polymerase chain reaction), 16S rRNA gene sequencing, and by Vitek 2 system. Twenty LAB strains were isolated and clustered into 12 different clusters, and identified as Streptococcus thermophilus, Enterococcus faecium, Enterococcus durans, Leuconostoc mesenteroides subsp. mesenteroides, Lactobacillus fermentum, Lactobacillus casei, Lactobacillus delbrueckii subsp. bulgaricus, and Lactobacillus helveticus. Enterococcus species were dominant and citrate‐positive. Only the strains of L. mesenteroides subsp. mesenteroides and L. fermentum produced CO₂ from glucose and were citrate‐positive, while L. casei was only citrate positive. This is the first report which elucidates the LAB diversity involved in Brazilian water buffalo mozzarella cheese. Furthermore, the results show that despite the absence of natural whey cultures as starters in production, the LAB species identified are the ones typically found in mozzarella cheese.     

Microbial diversity and dynamics of Pecorino di Filiano PDO,a traditional cheese of Basilicata region (Southern Italy)

The evolution of microbial populations of ‘Pecorino di Filiano’ (PF) cheese was investigated during ripening in natural cave and storeroom. 62.5% of isolates grow at 45 and 15 °C and 77.7% showed high salt concentrations tolerance. Brevibacterium linens was dominant in surface samples. Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus paracasei subsp. paracasei were more frequently isolated both surface and core samples, while Leuconostoc lactis and Leuconostoc mesenteroides subsp. mesenteroides prevailed among Leuconostoc isolates. Our results suggest the importance of the ripening environment of cheeses and how a biological ecosystem affects and produces the typical features of artisanal products.     

The probiotic,Leuconostoc mesenteroides,inhibits Listeria monocytogenes biofilm formation

Listeria monocytogenes biofilm formation renders these cells highly resistant to current sanitation methods, and probiotics may be a promising approach to the efficient inhibition of Listeria biofilms. In the present study, three Leuconostoc mesenteroides strains of lactic acid bacteria isolated from kimchi were shown to be effective probiotics for inhibiting Listeria biofilm formation. Biofilms of two L. monocytogenes serotypes, 1/2a (ATCC15313) and 4b (ATCC19115), in dual-species culture with each probiotic strain were decreased by more than 40-fold as compared with single-species Listeria biofilms; for instance, a reduction from 5.4 × 10⁶ colony forming units (CFU)/cm² L. monocytogenes ATCC19115 in single-species biofilms to 1.1 × 10⁵ CFU/cm² in dual-species biofilms. Most likely, one of the Leuconostoc strains, L. mesenteroides W51, led to the highest Listeria biofilm inhibition without affecting the growth of L. monocytogenes. The cell-free supernatant from the L. mesenteroides W51 culture containing large protein molecules (>30 kDa) also inhibited Listeria biofilms. These data indicate that Leuconostoc probiotics can be used to repress L. monocytogenes biofilm contamination on surfaces at food processing facilities.     

Analysis of the microflora in Tibetan kefir grains using denaturing gradient gel electrophoresis

The microflora of Tibetan kefir grains was investigated by culture- independent methods. Denaturing gradient gel electrophoresis (DGGE) of partially amplified 16S rRNA for bacteria and 26S rRNA for yeasts, followed by sequencing of the most intense bands, showed that the dominant microorganisms were Pseudomonas sp., Leuconostoc mesenteroides, Lactobacillus helveticus, Lactobacillus kefiranofaciens, Lactococcus lactis, Lactobacillus kefiri, Lactobacillus casei, Kazachstania unispora, Kluyveromyces marxianus, Saccharomyces cerevisiae, and Kazachstania exigua. The bacterial communities between three kinds of Tibetan kefir grains showed 78–84% similarity, and yeasts 80–92%. The microflora is held together in the matrix of fibrillar material composed largely of a water-insoluble polysaccharide.     

Influence of different yeasts on the growth of lactic acid bacteria in wine

The influence of various yeasts on the growth of lactic acid bacteria in wine was tested by inoculating Lactobacillus hilgardii, L. brevis and two strains of Leuconostoc mesenteroides into experimental wines made with twelve different yeasts of the genus Saccharomyces. Wines made from juice which had been infected with several spoilage yeasts and then fermented with a wine yeast were also tested in this way. It was found that the yeasts differed considerably in their effects on bacterial growth. In some of the experimental wines bacterial growth was delayed or failed altogether. Generally, the unfavourable influence of any yeast on bacterial growth was much reduced if the wines were left in contact with the yeast cells for some weeks after the fermentation. The significance of these results in relation to the occurrence of malo-lactic fermentation in commercial wineries is discussed.     

Microbial Diversity of Type I Sourdoughs Prepared and Back‐Slopped with Wholemeal and Refined Soft (Triticum aestivum) Wheat Flours

The fermentation of type I sourdough was studied for 20 d with daily back‐slopping under laboratory and artisan bakery conditions using 1 wholemeal and 2 refined soft wheat (Triticum aestivum) flours. The sourdough bacterial and yeast diversity and dynamics were investigated by plate counting and a combination of culture‐dependent and culture‐independent PCR‐DGGE approach. The pH, total titrable acidity, and concentration of key organic acids (phytic, lactic, and acetic) were measured. Three flours differed for both chemical and rheological properties. A microbial succession was observed, with the atypical sourdough species detected at day 0 (i.e. Lactococcus lactis and Leuconostoc holzapfelii/citreum group for bacteria and Candida silvae and Wickerhamomyces anomalus for yeasts) being progressively replaced by taxa more adapted to the sourdough ecosystem (Lactobacillus brevis, Lactobacillus alimentarius/paralimentarius, Saccharomyces cerevisiae). In mature sourdoughs, a notably different species composition was observed. As sourdoughs propagated with the same flour at laboratory and artisan bakery level were compared, the influence of both the substrate and the propagation environment on microbial diversity was assumed.     

Effect of Germination and Fermentation on in vitro Starch and Protein Digestibility of Pearl Millet

Germination of pearl millet grain for 24 hr significantly improved its in vitro starch and protein digestibility. Fermentation of pearl millet sprouts by mixed culture combinations of yeasts and bacteria (Saccharomyces diastaticus and Lactobacillus brevis; Saccharomyces diastaticus and Lactobacillus fermentum; Saccharomyces cerevisiae and Lactobacillus brevis; and Saccharomyces cerevisiae and Lactobacillus fermentum) resulted in a significant increase in protein and starch digestibility. The pearl millet sprouts fermented with mixed culture containing S. diastaticus and L. brevis had the highest in vitro starch digestibility, while the sprouts fermented with the culture containing 5. cerevisiae and L. fermentum had the highest in vitro protein digestibility.     

Isolation and identification of exopolysaccharide producer lactic acid bacteria from Turkish yogurt

Lactic acid bacteria (LAB) were isolated from traditional yogurt samples and genotypic characterization of these isolates revealed the presence of 21 distinct LAB strains belonging to Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus, Leuconostoc mesenteroides, and Lactobacillus plantarum as new LAB strains. Determination of the exopolysaccharide (EPS) production characteristics of the selected strains of each species revealed that all strains possessed at least one gene required for both homopolymeric‐ and heteropolymeric‐type EPS production. Structural analysis of the EPSs showed that L. delbrueckii subsp. bulgaricus Y39 and S. thermophilus Y102 produced heteropolymeric EPS containing glucose and galactose, whereas Leuc. mesenteroides Y35 and L. plantarum Y36 produced homopolymeric glucan‐type EPS. The level of EPS production in these strains was found to be in a similar range. These strains with EPS production characteristics are good candidates for future studies as new LAB for yogurt production.

Practical applications

Recent trends in yogurt production technology have led to an increased use of ropy starter cultures in yogurt production due to the technological roles of exopolysacharides (EPS) produced by these cultures. The main role of EPS in yogurt production is to improve the textural properties of yogurt as an in situ produced natural polymer. In addition to the yogurt starter cultures, use of adjunct cultures during production of yogurt is also of special interest to enhance the technological and nutritional characteristics of yogurt. Therefore, in this study, potential yogurt starter and adjunct cultures from traditional yogurt samples with EPS production characteristics were isolated. From these isolates, Lactobacillus delbrueckii subsp. bulgaricus Y39 and Streptococcus thermophilus Y102 produced heteropolymeric EPS containing glucose and galactose, whereas Leuconostoc mesenteroides Y35 and Lactobacillus plantarum Y36 produced homopolymeric glucan.     

A Comparison of Growth of Individual Meat Bacteria on the Lean and Fatty Tissue of Beef, Pork and Lamb

Growth of Hafnia alvei, Serratia liquefaciens, Lactobacillus plantarum, Lactobacillus curvatus and Leuconostoc mesenteroides on inoculated lean and fat tissue of beef, pork and lamb was investigated. Increases in H. alvei, S. liquefaciens and L. plantarum counts on refrigerated beef and pork fat usually were greater (P<0.05) than on comparable lean samples. On dark-firm-dry (DFD) beef, these differences in counts between lean and fat samples were smaller or disappeared. Increases in L. mesenteroides and L. curvatus counts on fat were either smaller than or did not differ from those on lean samples. Sour, buttermilk-like off-odors were the most common defect on stored samples.     

Effects of Germination and Pure Culture Fermentation by Yeasts and Lactobacilli on Phytic Acid and Polyphenol Content of Pearl Millet

Germination of pearl millet at 30°C for 24 hr reduced phytic acid significantly (P<0.05) which, on fermentation with mixed pure cultures of Saccharomyces diastaticus, Saccharomyces cerevisiae, Lactobacillus brevis, and Lactobacillus fermentum at 30°C for 72 hr, was eliminated or reduced to negligible levels in fermented sprouts. Concentration of polyphenols did not change on germination. The fermentation of sprouts by combinations of S. cerevisiae with L. brevis and S. cerevisiae and L. fermentum did not change polyphenol whereas S. diastaticus with L. brevis (SdLb) increased and S. diastaticus with L. fermentum combinations decreased the polyphenol in the sprouts.     

Anti‐inflammatory and cytotoxic effects of ginseng extract bioconverted by Leuconostoc mesenteroides KCCM 12010P isolated from kimchi

A bioconversion technique using microorganisms has been applied to ginseng to increase content of bioactive ginsenoside and biofunctionality such as anticancer, anti‐obesity and antioxidant activities. The objective of this study was to screen lactic acid bacteria for bioconversion of ginsenosides and to evaluate anti‐inflammatory and cytotoxic effects of bioconverted ginseng extract. Strains isolated from kimchi were screened for their β‐glucosidase activities using esculin agar. Selected strain was identified based on 16S rRNA sequencing and carbohydrate fermentation. During ginseng fermentation, viable cell number and pH were determined. Bioconverted ginsenosides were analysed by HPLC. Anti‐inflammatory effects were evaluated using RAW 264.7 cells, and cytotoxic effects were determined by MTT assay. Among 166 isolates screened, Leuconostoc mesenteroides was selected for ginseng bioconversion, as it showed a higher β‐glucosidase activity and viable cell number than any of the other tested strains. After fermentation for 2 days, viable cell number was 8.8 log CFU mL^?1 and final pH was 4.8. Ginsenoside Rb₂ was bioconverted into ginsenoside Rg₃ (Rb₂ → Rd → Rg₃) by L. mesenteroides. The nitric oxide contents of 2‐day‐fermented extract decreased by as much as 25%, compared to a non‐fermented extract. The cell viabilities of HepG2, HT‐29, HeLa and LoVo treated with fermented ginseng extract also decreased by 49.7%, 20.2%, 21.0% and 8.7%, respectively, compared to those of control cells treated with non‐fermented extract. Ginseng extract bioconverted by L. mesenteroides showed anti‐inflammatory and anticancer effects. Therefore, bioconverted ginseng extract might have applications in the pharmaceutical and/or functional food industry.     

Effects of several starter cultures on the anti-mold activity and sensory attributes of a traditional flat bread (Sangak) from Iran

Effects of 8 different sourdoughs and their replacement levels at 10, 20, and 30%(w/w) on the volume (of dough), crust hardness, organoleptic, and anti-mold properties of Iranian sangak bread were investigated. Saccharomyces cerevisiae, Lactobacillus plantarum, Lactobacillus acidophilus, and Leuconostoc mesenteroides were selected for the preparation of sourdough samples. The highest dough volume was achieved when sourdough (those having S. cerevisiae) was used at 30%. The highest taste scores were found with the bread sample using the above-mentioned starters at 30% sourdough replacement level. Considering the chewing, appearance, and overall quality of the new products, most of the samples maintained the favorite sensory aspects of sangak bread. Use of lactic acid bacteria and yeast strains as part of the sourdough formulation (followed by the use of sourdough in the dough formulation) resulted in improved crust properties and greater anti-mold activities.     

Characterization and Distribution of Lactic Acid Bacteria from Traditional Cocoa Bean Fermentations in Bahia

Bacteria of the families Lactobacilaceae and Streptococcaceae were isolated from cocoa beans fermented by the traditional method used in the State of Bahia (Brazil). During the first 48 hr of the process these bacteria were better established than the yeasts. This observation differs from those reported by other researchers working in other countries. Identification studies showed eight homolactic species: Lactobacillus plantarum, Lactobacillus casei, Lactobacillus delbrueckii, Lactobacillus acidophilus, Lactobacillus lactis, Pediococcus cerevisiae, Pediococcus acidilactici, Streptococcus lactis and two heterolactic species: Leuconostoc mesenteroides and Lactobacillus brevis. L. plantarum was found better distributed and the thermophile L. delbrueckii was found to constitute 26% of the population at 16 hr.     

Contribution of Lactobacillus plantarum and Leuconostoc mesenteroides subsp. mesenteroides to Atypical Odors of Beef Strip Loins

Sterile beef strip loin tissue was inoculated with Lactobacillus plantarum or Leuconostoc mesenteroides subsp. mesenteroides, placed in sterile sample bottles which were purged with CO₂, and stored up to 28 days at 3°C. Volatile compounds detected in the headspace of these samples included acetone, toluene, acetic acid, ethyl acetate, a C₇ hydrocarbon, and trichloromethane. The profile of volatiles in packaged sterile loin tissue stored for up to 28 days was similar. However, the inoculated samples spoiled (soured) at a faster rate.     

Analysis of volatile compounds produced by different species of lactobacilli in rye sourdough using multiple headspace extraction

Profiles of volatile organic compound (VOC) produced by nine individual lactic acid bacteria (LAB) during rye sourdough fermentation were compared by automated SPME and GC/MS‐Tof. The dough samples were inoculated with individual strains, placed inside the headspace vials and incubated during next 24 h. The production or loss of VOC‐s was followed by adsorbing volatiles onto 85‐m Car/PDMS fibre in every 4 h. Volatile profiles differed among LAB species and divided LAB into two main groups – hetero‐ and homofermentative. Hetrofermentative LAB (Lactobacillus brevis; Leuconostoc citreum; Lactobacillus vaginalis, Lactobacillus panis) showed high production of acetic acid, CO₂, ethanol, ethylacetate, producing also hexyl acetate, ethyl hexanoate and isopentyl acetate. Whereas homofermentative LAB species (Lactobacillus helveticus; Lactobacillus casei; Lactobacillus sakei; Lactobacillus curvatus) produced a considerable amount of 2,3‐butanedione. Production of l ‐leucine methyl ester was unique for Lb. sakei, Lb. casei and Lb. curvatus strains. Lb. helveticus was the only LAB that produced benzaldehyde.     

Quality attributes and firming kinetics of partially baked frozen wholewheat bread with sourdough

Partially baked frozen (PBF) process prolongs bread shelf life, but diminishes its volume and crumb texture. Therefore, we investigated the possibility of using sourdough for the quality improvement in PBF wholewheat bread. Sourdough was fermented with either Lactobacillus plantarum, Lb. brevis or Leuconostoc mesenteroides mixed with yeast Candida humilis and added at 7.5, 15, 22.5 or 30% on bread dough basis. The choice of sourdough starter significantly affected bread acidity characteristics, flavour, specific volume, shape and crumb firmness. The sourdough amount and acetic acid content of bread inversely correlated to flavour score, specific volume, shape and crumb softness. The overall quality of PBF wholewheat bread was most efficiently improved after adding Lb. plantarum sourdough at 15–22.5%, resulting in retarded firming rate (74–94%) and improved specific volume (25–28%) in comparison with PBF bread without sourdough. Such sourdough has lactic to acetic acid higher than previously recommended for traditional sourbreads.