Pediococcus Parvulus Research Articles

Distribution of Native Lactic Acid Bacteria in Wineries of Queretaro, Mexico and Their Resistance to Wine-Like Conditions.

Native lactic acid bacteria (LAB) are capable of growing during winemaking, thereby strongly affecting wine quality. The species of LAB present in musts, wines during malolactic fermentation (MLF), and barrels/filters were investigated in wineries from the emerging wine region of Queretaro, México using multiplex PCR and culture. The resistance to wine-like conditions (WLC): ethanol (10, 12, and 13%), SO2 (30 mg⋅l-1), and low pH (3.5) of native LAB strains was also studied. Five species were detected within 61 samples obtained: Oenococcus oeni, Lactobacillus plantarum, Pediococcus parvulus, Lactobacillus hilgardi, and Lactobacillus brevis. Four species (excepting L. brevis) were found in must; O. oeni and P. parvulus were ubiquitous in wine and L. plantarum and L. brevis were mainly present at the initial stage of MLF, while L. hilgardii was mostly detected at the advanced stage. Furthermore, some species detected in barrel/filter, prove them to be hazardous reservoirs. From 822 LAB isolates, only 119 resisted WLC with 10% ethanol; the number of strains able to grow in WLC with 13% ethanol decreased approximately by 50%, O. oeni being the most versatile species with 65% of resistant isolates, while Lactobacillus spp. and P. parvulus were the most strongly affected, especially those recovered from barrel/filter, with less than 10% of resistant isolates. This study evidences the presence of local strains able to be used as starter cultures, and also enabled the assessment of the risks derived from the presence of spoilage LAB strains resistant to WLC.

Characterization of macrophage-activating lactic acid bacteria isolated from Mukeunji.

Lactic acid bacteria (LAB) were reported to comprise the majority of the bacterial population in mukeunji, a long-fermented kimchi. This current study investigated the probiotic abilities of LAB isolated from mukeunji. Forty bacterial strains from mukeunji were identified by SDS-PAGE gel patterns, which were further tested for acid and bile tolerance. An assessment of the immuneboosting effects of these strains in RAW264.7 cells was also carried out by measurement of secreted proinflammatory cytokines. Heat-killed LAB were also tested for their contribution to cytokine production because certain LAB are not durable in the digestive tract. Immune-boosting strains were further characterized by SDS-PAGE of whole-cell protein and 16S rRNA gene sequencing, resulting in the identification of Lactobacillus plantarum, L. sakei, Weissella cibaria, and Pediococcus parvulus. These data and the fact that mukeunji is highly consumed in Korea, together, highlight the need of detailed epidemiological and animal feeding studies.

Impact of pulsed-electric field and high-voltage electrical discharges on red wine microbial stabilization and quality characteristics.

In this study, pulsed-electric fields (PEF) and high-voltage electrical discharges (HVED) are proposed as new techniques for the microbial stabilization of red wines before bottling. The efficiency of the treatment was then evaluated. PEF and HVED-treatments have been applied to wine for the inactivation of Oenococcus oeni CRBO 9304, O.oeni CRBO 0608, Pediococcus parvulus CRBO 2.6 and Brettanomyces bruxellensis CB28. Different treatment times (1, 2, 4, 6, 8 and 10ms) were used at 20kVcm(-1) for the PEF treatments and at 40kV for the HVED treatments, which correspond to applied energies from 80 to 800 kJl(-1) . The effects of the treatments on the microbial inactivation rate and on various characteristics of red wines (phenolic composition, chromatic characteristics and physico-chemical parameters) were measured. The application of PEF or HVED treatments on red wine allowed the inactivation of alteration yeasts (B.bruxellensis CB28) and bacteria (O.oeni CRBO 9304, O.oeni CRBO 0608 and P.parvulus CRBO 2.6). The electric discharges at 40 kV were less effective than the PEF even after 10ms of treatments. Indeed, 4ms of PEF treatment at 20kVcm(-1) were sufficient to inactivate all micro-organisms present in the wines. Also, the use of PEF had no negative impact on the composition of wines compared to the HVED treatments. Contrary to PEF, the phenolics compounds were degraded after the HVED treatment and the physico-chemical composition of wine were modified with HVED. PEF technology seems to be an interesting alternative to stabilize microbiologically wines before bottling and without modifying their composition. This process offers many advantages for winemakers: no chemical inputs, low energy consumption (320kJl(-1) ), fast (treatment time of 4ms) and athermal (ΔT≈10°C).

LACTIC ACID BACTERIA FLORA OF KONYA KUFLU CHEESE: A TRADITIONAL CHEESE FROM KONYA PROVINCE IN TURKEY

The aim of this study was to characterize the lactic acid bacteria flora of mature Konya Kuflu cheese. Konya Kuflu cheese is a traditional blue cheese which is produced from raw milk without starter culture addition and mould growth occurs in uncontrolled conditions during its ripening. Lactic acid bacteria (LAB) isolated from 9 mature Konya Kuflu cheese samples were investigated using a combination of conventional biochemical tests, API test kits, and molecular approaches. For some isolates, different results were obtained according to the identification technique. The overall LAB profile of Konya Kuflu cheese samples revealed that Lactobacillus brevis, Lactobacillus paracasei/Lactobacillus casei, Lactobacillus plantarum, Enterococcus faecium, and Enterococcus faecalis are the predominant species. In addition, 1 Pediococcus parvulus and 1 Enterococcus durans were also identified.

Phenotypic and genotypic identification of lactic acid bacteria isolated from traditional pickles of the Çubuk region in Turkey.

A total of 152 lactic acid bacteria (LAB) were isolated from pickles produced in the Ankara-Çubuk region. These isolates were clustered into eight groups on the basis of their phenotypic characteristics including cell morphology, CO2 production from glucose, growth at 10 and 45 °C, growth in 6.5 % NaCl, and growth at pH 9.6. API 50 CH carbohydrate fermentation test, 16S ribosomal RNA (rRNA) sequence analysis, and sodium dodecyl sulfate-acrylamide gel electrophoresis (SDS-PAGE) whole-cell protein profile analysis were also performed for precise identification of the isolates at the species level. Molecular identification revealed that the most prevalent LAB species involved in pickle fermentation were Pediococcus ethanolidurans (46 isolates, 30.3 %), Lactobacillus brevis (37 isolates, 24.3 %), Lactobacillus plantarum (37 isolates, 24.3 %), and Lactobacillus buchneri (15 isolates, 9.9 %). Other LAB were found in minor frequencies such as Pediococcus parvulus (8 isolates, 5.3 %), Lactobacillus namurensis (6 isolates, 3.9 %), Lactobacillus diolivorans (1 isolate, 0.7 %), Lactobacillus parabrevis (1 isolate, 0.7 %), and Enterococcus casseliflavus (1 isolate, 0.7 %). When results of phenotypic and genotypic identification methods were compared, differences in the species distribution of LAB associated with pickles were defined between the API and the 16S rRNA sequencing. The API 50 CHL test coincided with the 16S rRNA results in 71 out of the 152 tested isolates, indicating that API gave unreliable identification results. A clear correlation could not be found between the results of whole-cell SDS profiles and 16S rRNA sequencing. Therefore, molecular characterization by 16S rRNA sequencing was considered to be the most reliable method for identifying isolates. The results presented in this work provide insight in to the LAB population associated with traditional Çubuk pickles and constitute a LAB strain resource for further studies involving the development of starter cultures.

Unpasteurised commercial boza as a source of microbial diversity

Boza is a cereal-based fermented beverage widely consumed in many countries of the Balkans. The aim of this study was to investigate the microbiota of three Bulgarian boza samples through a combination of culture-dependent and -independent methods with the long-term objective of formulating a multi-strain starter culture specifically destined for the manufacture of new cereal-based drinks. The isolation campaign for lactic acid bacteria (LAB) allowed the identification of Lactobacillus parabuchneri, Lactobacillus fermentum, Lactobacillus coryniformis, Lactobacillus buchneri, Pediococcus parvulus and members of the Lactobacillus casei group. Concerning yeasts, the following isolates were identified: Pichia fermentans, Pichia norvegensis, Pichia guilliermondii (synonym Meyerozyma guilliermondii) and Torulaspora spp. A high intra-species diversity was revealed by Randomly Amplified Polymorphic DNA (RAPD) analysis. In parallel, microbial DNA was directly extracted from the three boza samples, and portions of the rrn operons were analysed through Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE). The molecular fingerprinting partially confirmed the results of culturing. Among LAB, the species Weissella confusa, Weissella oryzae, Leuconostoc citreum, Lactococcus lactis, Pediococcus parvulus and Pediococcus ethanolidurans were detected together with members of the Lb. casei group. Among the yeasts, the species P. fermentans, M. guilliermondii, Galactomyces geotrichum and Geotrichum fragrans were found. The overall results confirmed boza as having a rich and heterogeneous biodiversity both in terms of species and genetically diverse strains, thus encouraging its exploitation for the isolation and future technological characterisation of cultures to be selected for the manufacture of innovative cereal-based drinks.

Inventory of lactic acid bacteria populations in red wine varieties from Appellation of Origin Méntrida

A study of bacterial populations present during spontaneous malolactic fermentation of wines of different grape varieties (Tempranillo, Merlot, Syrah, Cabernet Sauvignon and Garnacha) at six wineries of the Appellation of Origin Mentrida has been carried out using culture-dependent and culture-independent methods. A total of 1,082 isolates were genetically characterised by randomly amplified polymorphic DNA-PCR displaying 147 genotypes, 97 of which were clusters including two or more isolates (major clusters). Identification of representative isolates from each, using 16S-ARDRA, species-specific PCR or 16S gene sequencing showed presence of Oenococcus oeni (76.71 % of the isolates), Enterococcus faecium (11.92 %) and Pediococcus parvulus (10.44 %) as predominant species. The presence of coincident genotypes of these species, especially of O. oeni, at different wineries suggests their adaptation to the conditions of elaboration used in the wineries and to the characteristics of the wines from this Appellation of Origin. Combination of these results with those obtained using an independent-culture method, such as the polymerase chain reaction–denaturing gradient gel electrophoresis (PCR–DGGE), confirmed the predominance of O. oeni that was the only species detected from both methods. Acetobacter sp. and Enterobacteriaceae family were also detected by PCR–DGGE, being the diversity of species lower when this method was used. This research has provided detailed information about the composition of the bacterial community present in wine of different grape varieties, showing for the first time the presence of the species E. faecium, P. parvulus, Lactobacillusbrevis, Lactobacillusacidophilus and Acetobacter sp. in wines of this region, some of them considered as potential spoilage bacteria.

Biodegradation of ochratoxin A by Pediococcus parvulus isolated from Douro wines

Lactic acid bacteria (LAB) are a promising solution to reduce exposure to dietary mycotoxins because of the unique mycotoxin decontaminating characteristic of some LAB. Ochratoxin A (OTA) is one of the most prominent mycotoxins found in agricultural commodities. The present work reports on the ability of Pediococcus parvulus strains that were isolated from Douro wines that spontaneously underwent malolactic fermentation to detoxify OTA. These strains were identified and characterised using a polyphasic approach that employed both phenotypic and genotypic methods. When cultivated on OTA-supplemented MRS media, OTA was biodegraded into OTα by certain P. parvulus strains. The presence of OTα was confirmed using LC–MS/MS. The conversion of OTA into OTα indicates that the OTA amide bond was hydrolysed by a putative peptidase. The rate of OTA biodegradation was found to be dependent on the inoculum size and on the incubation temperature. Adsorption assays with dead P. parvulus cells showed that approximately 1.3%±1.0 of the OTA was adsorbed onto cells wall, which excludes this mechanism in the elimination of OTA by strains that degrades OTA. Under optimum conditions, 50% and 90% of OTA were degraded in 6 and 19h, respectively. Other LAB strains that belonged to different species were tested but did not degrade OTA. OTA biodegradation by P. parvulus UTAD 473 was observed in grape must. Because some P. parvulus strains have relevant probiotic properties, the strains that were identified could be particularly relevant to food and feed applications to counteract the toxic effects of OTA.

Microbiological and Chemical Properties of Siahmazgi Cheese, an Iranian Artisanal Cheese: Isolation and Identification of Dominant Lactic Acid Bacteria

In this study, the chemical and microbiological properties of Siahmazgi cheese, an Iranian artisanal cheese made of unheated ewe and goat milk without addition of starter culture, were evaluated. The pH of the samples ranged from 4.76 to 5.18. The average numbers of total viable count and lactic acid bacteria (LAB) in cheese samples were 3.7 × 106 and 6.9 × 106 cfu/g, respectively. Coliforms and Enterobacteriaceae were absent in all the samples. A total of 125 LAB isolates were selected according to their Gram-positive and catalase-negative characteristics, out of which 23 strains were cocci and 102 were lactobacilli. Identification of the selected isolates was done through biochemical tests and 16s rDNA sequencing. Isolated strains were identified as Lactobacillus plantarum group (41.6%), Lactobacillus brevis (39.2), Lactobacillus parabuchneri (0.8%), Enterococcus faecium (13.6%), Enterococcus durans (3.2%) and Pediococcus parvulus (1.6%). The results of this study showed the microbiological diversity of traditional Siahmazgi cheese. Practical Applications Exploring the microbiological diversity of traditional dairy products is required for selection of appropriate strains to manufacture the products with consistent quality and original taste on industrial scale.

Evaluation of lactic acid bacterial strains of boza for their exopolysaccharide and enzyme production as a potential adjunct culture

Boza is a non-alcoholic beverage obtained from fermented cereals. Thirteen lactic acid bacteria (LAB), previously isolated from boza were identified and evaluated to determine the various technological properties for selecting appropriate strains as adjunct culture in boza. Each isolate was checked for purity, Gram-stained and tested for the catalase and oxidase activity and then subjected to identification by polymerase chain reaction (PCR) with partial 16S rRNA gene sequencing. The tests for carbohydrate fermentation and enzyme profiles were carried out with the API 50 CHL and API ZYM galleries, respectively. Exopolysaccharide (EPS) production of strains was determined by Fourier transform infrared spectroscopy (FT-IR) and quantified by the phenol sulphuric acid method. To our best knowledge, this is the first study reporting on Lactococcus garvieae (E32), Pediococcus parvulus (E42) and Streptococcus macedonicus (A15) in boza. All strains, except S. macedonicus (A15) produced EPS. Leuconostoc citreum (E55) and Lactococcus lactis (A47) were the highest EPS producing strains, yielding 2.39±0.49 and 1.98±0.23g/L of EPS, respectively. Lactobacillus paracasei (D41), Lactobacillus plantarum (B2), Lactococcus lactis (F39) and among low-EPS producing strains Lactobacillus coryniformis (C55), L. paracasei (E8), and P. parvulus (E42) were evaluated to be promising candidates as potential adjunct culture in boza. The variety of enzyme production was also concern. Lc. garvieae (E32) was found to produce the largest variety of enzymes among the strains. FT-IR spectroscopy can be used for the assessment of EPS production by microorganisms reliably and accurately.

Immunomodulation of human macrophages and myeloid cells by 2-substituted (1–3)-β-d-glucan from P. parvulus 2.6

β-glucans produced by eukaryotic cells and by microorganisms are known to modulate immune responses by affecting macrophage activation. Here, we have investigated the effect of purified 2-substituted (1–3)-β-d-glucan, produced by either Pediococcus parvulus 2.6 or Lactococcus lactis NZ9000[pNGTF], on the effector functions of human PMA-differentiated THP-1 cells and M1 pro-inflammatory monocyte-derived macrophages. The results reveal that this kind of β-D-glucan activates macrophages and has an anti-inflammatory effect.

Salt-Reduced Takanazuke Produced with an Isolated Starter Strain

To reduce the amount of salt added during the production of takanazuke, two isolated bacterial strains, B17-4 (Lactobacillus (para) plantarum) and C120-3 (Pediococcus parvulus), were used as starter strains. Takanazuke with bacterial starter was incubated with 2% (w/w) NaCl, and 6% (w/w) NaCl was added to takanazuke without starter as a control. Takanazuke was incubated at the average monthly temperatures in the Aso region (10.8 – 25.0°C). pH decreased to 4.3 with strain B17-4 and 4.2 with strain C120-3 after 12 days, while it decreased gradually to 4.2 without a starter strain after 40 days. Strain B17-4 produced less lactate and assimilated less reducing sugar than strain C120-3, which seemed to depend on the production of extracellular polysaccharide by strain B17-4. In takanazuke with starter strains and 2% (w/w) NaCl, both B17-4 and C120-3 were dominant in culture during the 181-day study.

Protective effect of microbial immunostimulants and antiviral plants against WSSV in Litopenaeus vannamei cultured under laboratory conditions

Abstract The effect of a mixture of antiviral plants (Echinacea purpurea and Uncaria tomentosa) and microbial immunostimulants (Pediococcus parvulus and Candida parapsilosis) on growth performance, survival, white spot syndrome virus (WSSV) prevalence, and immune response of L. vannamei was evaluated under laboratory conditions. Powdered plants (PP) were included in the commercial feed pellet at 0.0, 1.0, 2.0, and 4.0 g kg feed− 1 and microbial immunostimulants (MI) were included at 0.0, 2.1, 4.2, and 8.4 mg kg feed− 1. A bioassay was conducted for 21 days. Feed supplemented with PP and MI did not influence survival and shrimp growth. However, the prevalence of WSSV in shrimp with low viral load decreased from 100% in the control group to 0% in animals fed with the PP and MI mixture. Additives increased significantly the phenoloxidase activity but not hemocyte and superoxide anion amount. The PP and MI mixture, added to feed, has the potential to be used prophylactically as an antiviral against WSSV in cultured shrimp.

Xylooligosaccharides from Hardwood and Cereal Xylans Produced by a Thermostable Xylanase as Carbon Sources for Lactobacillus brevis and Bifidobacterium adolescentis

To compare xylans from forestry with agricultural origins, hardwood xylan (birch) and cereal arabinoxylan (rye) were hydrolyzed using two variants of the xylanase RmXyn10A, full-length enzyme and catalytic module only, from Rhodothermus marinus . Cultivations of four selected bacterial species, using the xylooligosaccharide (XOS) containing hydrolysates as carbon source, showed selective growth of Lactobacillus brevis DSMZ 1264 and Bifidobacterium adolescentis ATCC 15703. Both strains were confirmed to utilize the XOS fraction (DP 2-5), whereas putative arabinoxylooligosaccharides from the rye arabinoxylan hydrolysate were utilized by only B. adolescentis. Escherichia coli did not grow, despite its capability to grow on the monosaccharides arabinose and xylose. It was also shown that Pediococcus parvulus strain 2.6 utilized neither xylose nor XOS for growth. In summary, RmXyn10A or its catalytic module proved suitable for high-temperature hydrolysis of hardwood xylan and cereal arabinoxylan, producing XOS that could qualify as prebiotics for use in functional food products.

Oral administration of live exopolysaccharide-producing Pediococcus parvulus, but not purified exopolysaccharide, suppressed Enterobacteriaceae without affecting bacterial diversity in ceca of mice.

Growing evidence indicates that the gut microbiota could have an important role in the development of diet- and lifestyle-induced diseases. It has been shown that modulation of the gut microbiota by means of probiotics and prebiotics could improve host health. An oat-based product fermented by the exopolysaccharide (EPS)-producing organism Pediococcus parvulus 2.6 has been reported to have a bifidogenic effect. To find out whether the effect could be attributed to the EPS or the bacterium, mice were fed a diet supplemented with 2% purified EPS or 10(8) CFU/g of live P. parvulus 2.6 for 6 weeks. Both supplementations altered the gut microbiota composition but in different directions. Purified EPS not only significantly lowered the microbial diversity (P < 0.001) but decreased the bifidobacterial population (P = 0.01). In contrast, the live EPS-producing bacterium P. parvulus 2.6 antagonized Enterobacteriaceae without disturbing the homeostasis of the cecal microbiota.

English

This study examined the effect of probiotic lactic acid bacteria (LAB) and yeast on growth and survival of tilapias,&nbsp;Oreochromis niloticus&nbsp;and&nbsp;Oreochromis&nbsp;sp. LAB and yeast were included in the diet. Microorganisms were identified at molecular level. The first bioassay (120 days, weight = 0.18 &plusmn; 0.03 g) was done with&nbsp;Oreochromis&nbsp;sp. with a control group, and animals fed with the probiotics (5 &times; 104, 1 &times; 106&nbsp;and 1 &times; 107&nbsp;CFU/g feed). The second bioassay lasted for 92 days with juveniles of&nbsp;Oreochromis&nbsp;sp. (weight 4.09 &plusmn; 0.99 g) and&nbsp;O. niloticus&nbsp;(weight 6.12 &plusmn; 0.86 g) and consisted of a control group and animals fed with probiotics (5 &times; 104&nbsp;CFU/g) daily, every 10 days, and during the first 10 days only. LAB belonged to&nbsp;Pediococcus parvulus&nbsp;and yeast to&nbsp;Candida parapsilosis. In the first bioassay, no significant differences were found in survival and weight of&nbsp;Oreochromis&nbsp;sp. In the second bioassay, no significant differences were found in survival, but, in growth, fish fed with probiotics every 10 days (O. niloticus) and fish fed with probiotics daily and every 10 days&nbsp;(Oreochromis&nbsp;sp.) grew significantly better than the control group. The results indicated that LAB and yeast can be used as a feed additive every 10 days to reduce costs of commercial cultures. &nbsp; Key words:&nbsp;Oreochromis niloticus, tilapia, probiotics, lactic acid bacteria, yeast.

Putrescine production from different amino acid precursors by lactic acid bacteria from wine and cider

The aim of this work was to study the production of biogenic amines and particularly putrescine in lactic acid bacteria (LAB) related to wine and cider. We applied an analytical protocol that involves the use of PCR and TLC techniques to determine the production of putrescine from different precursors. Moreover, we also studied the ability of the Lactobacillus and Pediococcus tested to produce histamine and tyramine. The results showed that the majority of the Lactobacillus brevis analyzed harbour both AgDI and tdc genes and are tyramine and putrescine producers. Conversely, among the other LAB tested, only one Lactobacillus hilgardii and one Pediococcus pentosaceus produced putrescine. The AgDI gene was also detected in two other LAB (Lactobacillus mali and Pediococcus parvulus), but no putrescine production was observed. Finally, hdc gene and histamine production were found in strains (L. hilgardii 5211, isolated from wine, and Lactobacillus casei 18, isolated from cider) that were not putrescine producers.

Lysozyme resistance of the ropy strain Pediococcus parvulus IOEB 8801 is correlated with beta-glucan accumulation around the cell

Lactic acid bacteria (LAB) are often exploited to carry out malolactic fermentation in wine. However, a few specific LAB strains and, more precisely, some Pediococcus parvulus strains synthesize a β-glucan, which can be deleterious to wine quality as it confers a ropy texture to the wine that can no longer be commercialized. Although molecular methods exist to detect these unwanted microorganisms, ropy Pediococcus still remain difficult to remove from wine, because of their natural resistance to traditional wine stabilizing treatments. In this work, we show that ropy P. parvulus are resistant to lysozyme. We clearly demonstrate that this resistance may be ascribed to the presence of the β-glucan that forms around the cell a protective barrier against anti-bacteria agents. Moreover, this resistance increases during bacterial growth. We show that using lysozyme with β-glucanase can strongly improve the treatment against ropy strains, in model media as well as red and white wine based media. This work not only brings potential solutions to the wine industry, but also opens interesting perspectives for studying β-glucan producing bacteria which are widespread in the food industry.

Characterization of lactic acid bacteria from naturally-fermented Manzanilla Aloreña green table olives

Manzanilla Aloreña (or Aloreña) table olives are naturally fermented traditional green olives with a denomination of protection (DOP). The aim of this study was to search for lactic acid bacteria (LAB) with technological properties of interest for possible inclusion in a starter or protective culture preparation or also as probiotics. A collection of 144 LAB obtained from Aloreña green table olives naturally-fermented by four small-medium enterprises (SMEs) from Málaga (Spain), including lactobacilli (81.94%), leuconostocs (10.42%) and pediococci (7.64%) were studied. REP-PCR clustering and further identification of strains by sequencing of phes and rpo genes revealed that all lactobacilli from the different SMEs were Lactobacillus pentosus. Pediococci were identified as Pediococcus parvulus (SME1) and leuconostocs as Leuconostoc pseudomesenteroides (SME1 and SME4). Genotyping revealed that strains were not clonally related and exhibited a considerable degree of genomic diversity specially for lactobacilli and also for leuconostocs. Some strains exhibit useful technological properties such as production of antimicrobial substances active against pathogenic bacteria such as Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Streptococcus mutans and Salmonella enterica, utilization of raffinose and stachyose, production of bile salt hydrolase, phytase and haeme-dependent catalase activities, growth at 10 °C and in the presence of 6.5% NaCl, good acidifying capacity and also resistance to freezing. However, none of the isolates showed protease or amylase activity, and also did not exhibit biogenic amine production from histidine, ornithine, cysteine or tyrosine. On the basis of data obtained, selected strains with potential traits were tested for their survival at low pH and their tolerance to bile salts, and the survival capacity demonstrated by some of the analysed strains are encouraging to further study their potential as probiotics.

Comparative analysis of production and purification of homo- and hetero-polysaccharides produced by lactic acid bacteria

Lactic acid bacteria (LAB) produce homopolysaccharides (HoPS) and heteropolysaccharides (HePS) with potential functional properties. In this work, we have performed a comparative analysis of production and purification trials of these biopolymers from bacterial culture supernatants. LAB strains belonging to four different genera, both natural as well as recombinant, were used as model systems for the production of HoPS and HePS. Two well characterized strains carrying the gft gene were used for β-glucan production, Pediococcus parvulus 2.6 (P. parvulus 2.6) isolated from cider, and the recombinant strain Lactococcus lactis NZ9000[pGTF] (L. lactis NZ9000[pGTF]). In addition, another cider isolate, Lactobacillus suebicus CUPV225 (L. suebicus CUPV225), and Leuconostoc mesenteroides RTF10 (L. mesenteroides RTF10), isolated from meat products were included in the study. Chemical analysis of the EPS revealed that L. mesenteroides produces a dextran, L. suebicus a complex heteropolysaccharide, and the β-glucan producing-strains the expected 2-substituted (1,3)-β-glucan.