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PubMed2006

Growth response and modifications of organic nitrogen compounds in pure and mixed cultures of lactic acid bacteria from wine.

The interactions between the proteolytic X2L strain of Oenococcus oeni and the non-proteolytic 12p strain of Pediococcus pentosaceus were assayed. The characteristics of cell growth, protein degradation, and amino acid production of both strains were determined in pure and mixed cultures. O. oeni showed poor cell growth and greater ability in the release of amino acids to the extracellular medium, whereas P. pentosaceus showed a higher yield in cell production with a decrease in the amino acid concentration in the medium. P. pentosaceus especially consumed essential amino acids for growth, and O. oeni released several of the essential amino acids important for growth of P. pentosaceus. In the mixed culture, mutualism was observed. The higher activity of the proteolytic system of O. oeni in mixed culture produced an increase in cell growth and in the amount of essential amino acids released. These findings provide new knowledge about the metabolic interactions between lactic acid bacteria isolated from wine when proteins are degraded in mixed bacterial populations.

Amino Acids↗
PubMed2001

Behavior of variable V3 region from 16S rDNA of lactic acid bacteria in denaturing gradient gel electrophoresis.

Separation of amplified V3 region from 16S rDNA by denaturing gradient gel electrophoresis (DGGE) was tested as a tool for differentiation of lactic acid bacteria commonly isolated from food. Variable V3 regions of 21 reference strains and 34 wild strains referred to species belonging to the genera Pediococcus, Enterococcus, Lactococcus, Lactobacillus, Leuconostoc, Weissella, and Streptococcus were analyzed. DGGE profiles obtained were species-specific for most of the cultures tested. Moreover, it was possible to group the remaining LAB reference strains according to the migration of their 16S V3 region in the denaturing gel. The results are discussed with reference to their potential in the analysis of LAB communities in food, besides shedding light on taxonomic aspects.

DNA, Bacterial↗
PubMed2001

Characterization, production, and purification of carnocin H, a bacteriocin produced by Carnobacterium 377.

Carnocin H, a bacteriocin produced by a Carnobacterium sp., inhibited lactic acid bacteria, clostridia, enterococci, and some Staphylococcus aureus strains. Some strains of Listeria and Pediococcus were also sensitive to carnocin H. The bacteriocin was produced during the late stationary growth phase. Carnocin H was purified by cation exchange chromatography and reverse phase chromatography. Amino acid sequence and composition indicate that carnocin H is a novel bacteriocin belonging to the class II bacteriocins. The bacteriocin consists of approximately 75 amino acid residues with a highly cationic N-terminal containing six succeeding lysines. Activity, as measured by agar diffusion zones, was reduced at increased pH values, levels of indicator bacteria, NaCl, agar, and soy oil.

Amino Acid Sequence↗
PubMed1998

Conservation of the major cold shock protein in lactic acid bacteria.

Primers designed from consensus regions of the major cold shock gene of different bacterial species were used in PCR amplification of Lactic Acid Bacteria (LAB). An appropriately-sized PCR product was obtained from Lactococcus lactis subsp. lactis LL43-1 and MG1363; Lactococcus lactis subsp. cremoris LC10-1, LC11-1, and LC12-1; Streptococcus thermophilus ST1-1; Enterococcus faecalis EF1-1; Lactobacillus acidophilus LA1-1; Lactobacillus helveticus LH1-1; Pediococcus pentosaceus PP1-1; and Bifidobacterium animalis BA1-1. The PCR products were cloned and sequenced. The deduced amino acid sequences displayed high sequence similarity with the major cold shock proteins of Escherichia coli and Bacillus subtilis and the human Y-box factor. The amino acid residues of the cold shock domain implicated in nucleic acid binding in several unrelated species were also highly conserved in the LAB strains. It is possible, therefore, that this protein in LAB may also act as a transcriptional enhancer to other cold shock genes and/or act as an RNA chaperone unwinding tightly folded RNA molecules.

Amino Acid Sequence↗
PubMed2004

Characterization of mesentericin ST99, a bacteriocin produced by Leuconostoc mesenteroides subsp. dextranicum ST99 isolated from boza.

Lactic acid bacteria isolated from Boza, a cereal-fermented beverage from Belogratchik, Bulgaria, were screened for the production of bacteriocins. With the first screening, 13 of the 52 isolates inhibited the growth of Listeria innocua and Lactobacillus plantarum. The cell-free supernatant of one of these strains, classified as Leuconostoc mesenteroides subsp. dextranicum ST99, inhibited the growth of Bacillus subtilis, Enterococcus faecalis, several Lactobacillus spp., Lactococcus lactis subsp. cremoris, Listeria innocua, Listeria monocytogenes, Pediococcus pentosaceus, Staphylococcus aureus and Streptococcus thermophilus. Clostridium spp., Carnobacterium spp., L. mesenteroides and Gram-negative bacteria were not inhibited. Maximum antimicrobial activity, i.e. 6,400 arbitrary units (AU)/ml, was recorded in MRS broth after 24 h at 30 degrees C. Incubation in the presence of protease IV and pronase E resulted in loss of antimicrobial activity, confirming that growth inhibition was caused by a bacteriocin, designated here as mesentericin ST99. No loss in activity was recorded after treatment with alpha-amylase, SDS, Tween 20, Tween 80, urea, Triton X-100, N-laurylsarcosin, EDTA and phenylmethylsulfonylfluoride. Mesentericin ST99 remained active after 30 min at 121 degrees C and after 2 h of incubation at pH 2 to 12. Metabolically active cells of L. innocua treated with mesentericin ST99 did not undergo lysis. Mesentericin ST99 did not adhere to the cell surface of strain ST99. Precipitation with ammonium sulfate (70% saturation), followed by Sep-Pack C18 chromatography and reverse-phase HPLC on a C18 Nucleosil column yielded one antimicrobial peptide.

Anti-Bacterial Agents↗
PubMed2006

Biofilm formation in an ice cream plant.

The sites of biofilm formation in an ice cream plant were investigated by sampling both the production line and the environment. Experiments were carried out twice within a 20-day period. First, stainless steel coupons were fixed to surfaces adjacent to food contact surfaces, the floor drains and the doormat. They were taken for the analysis of biofilm at three different production stages. Then, biofilm forming bacteria were enumerated and also presence of Listeria monocytogenes was monitored. Biofilm forming isolates were selected on the basis of colony morphology and Gram's reaction; Gram negative cocci and rod, Gram positive cocci and spore forming isolates were identified. Most of the biofilm formations were seen on the conveyor belt of a packaging machine 8 h after the beginning of the production, 6.5 x 10(3) cfu cm(-2). Most of the Gram negative bacteria identified belong to Enterobacteriaceae family such as Proteus, Enterobacter, Citrobacter, Shigella, Escherichia, Edwardsiella. The other Gram negative microflora included Aeromonas, Plesiomonas, Moraxella, Pseudomonas or Alcaligenes spp. were also isolated. Gram positive microflora of the ice cream plant included Staphyloccus, Bacillus, Listeria and lactic acid bacteria such as Streptococcus, Leuconostoc or Pediococcus spp. The results from this study highlighted the problems of spread of pathogens like Listeria and Shigella and spoilage bacteria. In the development of cleaning and disinfection procedures in ice cream plants, an awareness of these biofilm-forming bacteria is essential for the ice cream plants.

Biofilms↗
PubMed2006

Methylglyoxal bypass identified as source of chiral contamination in l(+) and d(-)-lactate fermentations by recombinant Escherichia coli.

Two new strains of Escherichia coli B were engineered for the production of lactate with no detectable chiral impurity. All chiral impurities were eliminated by deleting the synthase gene (msgA) that converts dihydroxyacetone-phosphate to methylglyoxal, a precursor for both L: (+)- and D: (-)-lactate. Strain TG113 contains only native genes and produced optically pure D: (-)-lactate. Strain TG108 contains the ldhL gene from Pediococcus acidilactici and produced only L: (+)-lactate. In mineral salts medium containing 1 mM betaine, both strains produced over 115 g (1.3 mol) lactate from 12% (w/v) glucose, >95% theoretical yield.

Biotechnology↗
PubMed2003

Two distinct pathways for the formation of hydroxy FA from linoleic acid by lactic acid bacteria.

Twenty-three of 86 strains of lactic acid bacteria transformed linoleic acid into hydroxy FA. Two distinct conversion pathways were in operation. Two strains of Lactobacillus acidophilus and a strain of Pediococcus pentosaceus produced 13(S)-hydroxy-9-octadecenoic acid 113(S)-OH 18:11 and 10,13dihydroxyoctadecanoic acid (10,13-OH 18:0) as main and minor products, respectively, whereas 13 strains, including L. casei subsp. casei, L. paracasei subsp. paracasei, L. rhamnosus, L. lactis subsp. cremoris, and Streptococcus salivarius subsp. thermophilus produced 10-hydroxy-12-octadecenoic acid (10-OH 18:1). Seven strains of L. plantarum converted linoleic acid to 10-hydroxyoctadecanoic acid (10-OH 18:0) through 10-OH 18:1. Linoleic acid at 2 g/L was converted by L. acidophilus IFO13951T to 1.3 g of 13(S)-OH 18:1 and 0.09 g of 10,13-OH 18:0 in 7 d. Lactobacillus paracasei subsp. paracasei JCM 1111 produced 10-OH 18:1 in 91% yield, and L. plantarum JCM 8341, 10-OH 18:0 in 59% yield from linoleic acid (2 g/L) under optimal conditions. To our knowledge, this is the first report on the production of 13(S)-OH 18:1 by lactic acid bacteria other than ruminal bacteria, and of 10,13-OH 18:0 by any bacteria.

Fatty Acids↗
PubMed1992

Identification and characterization of two bacteriocin-producing strains of Lactococcus lactis isolated from vegetables.

Isolated from mixed salad and fermented carrots, 123 strains of lactic acid bacteria were screened for bacteriocin production. Two strains, D53 and 23, identified as Lactococcus lactis by DNA-DNA hybridizations, produced heat stable bacteriocins which were resistant to trypsin and pepsin, but were inactivated by alpha-chymotrypsin and proteinase K. The bacteriocins were active from pH 2 to 9 and inhibited species of Listeria, Lactobacillus, Lactococcus, Pediococcus, Leuconostoc, Carnobacterium, Bacillus and Staphylococcus. Strain D53 produced bacteriocin at pH values of 4.5-8.0 and from 10 to 37 degrees C.

Anti-Bacterial Agents↗
PubMed1993

Detection, identification and characterization of bacteriocin-producing lactic acid bacteria from retail food products.

Forty bacteriocin-producing (Bac+) lactic acid bacteria (LAB) were isolated from food samples purchased from retail supermarkets and local farms. Of the 40 Bac+ isolates, 18 were isolated from 85 food samples by enrichment (21% isolation rate) whereas eight were obtained from 63 samples by direct plating (13% isolation rate). By direct plating, Bac+ LAB were detected at levels up to 2.4 x 10(5) cfu/g in ready-to-eat meats. The Bac+ isolates were identified by carbohydrate fermentation patterns, SDS-PAGE protein patterns, and other biochemical characteristics; SDS-PAGE proved invaluable in identifying strains that could not be identified by other means. Differential inhibitory spectra against indicator microorganisms assisted in the identification of 19 unique Bac+ isolates. Bac+ LAB included Enterococcus faecalis, Lactobacillus curvatus, Lb. delbrueckii, Lb. plantarum, Lactococcus lactis, and Pediococcus acidilactici. Lb. curvatus (four strains) and Lc. lactis (nine strains) were the only isolates inhibitory to foodborne pathogens including Listeria monocytogenes, Bacillus cereus, Clostridium perfringens and Staphylococcus aureus. Some Lc. lactis isolates inhibited as many as nine Gram-positive genera. Lb. curvatus FS47 and FS65 grew to high cell densities and produced bacteriocin at 6 degrees C; however, Lc. lactis FS56 produced greater levels of bacteriocin at lower cell densities. The high incidence of Bac+ LAB detected in retail foods indicates that the public is consuming a wide variety of Bac+ LAB that occur as natural contaminants. These data suggest a greater role for bacteriocins as biopreservatives in food.

Animals↗
PubMed1994

Influence of pH, salt and nitrite on the heme-dependent catalase activity of lactic acid bacteria.

A screening of commercial starter cultures used for the production of dry sausage showed a maximum heme-dependent catalase activity in the range of 60 mumol/l hematin for Lactobacillus sake, Lactobacillus plantarum, Lactobacillus pentosus and Pediococcus acidilactici. Pseudocatalase activity was not detected. In standard dry sausage production, 2-3% (w/w) nitrite salt (0.6% sodium nitrite per 100 g NaCl) is normally added, which corresponds to 4-6% salt in the water phase. In vitro experiments with L. sake and L. plantarum have shown that such a high concentration of salt caused a significant reduction of catalase activity and bacterial growth. In the case of P. acidilactici, the catalase activity remained constant at a salt concentration up to 6% (w/w); at 7% (w/w) the activity decreased sharply. The pH also affected the catalase activity, which remained constant up to pH 5.1 and decreased dramatically at lower values. The effect of nitrite has also been investigated. L. pentosus and P. acidilactici were not affected by the addition of 160 ppm nitrite (NO2-); L. plantarum, on the other hand, showed a significantly reduced catalase activity. In practice, optimum fermentation characteristics combined with an optimum catalase activity which are not inhibited by salt concentrations higher than 6% (w/v) and a residual nitrite content of about 160 ppm (w/v), are of the utmost importance in screening and selection of lactic acid bacteria for starter cultures.

Catalase↗
PubMed1988

Molecular taxonomy and phylogenetic position of lactic acid bacteria.

Lactic acid bacteria, important in food technology, are Gram-positive organisms exhibiting a DNA G + C content of less than 50 mol%. Phylogenetically they are members of the Clostridium-Bacillus subdivision of Gram-positive eubacteria. Lactobacillus and streptococci together with related facultatively anaerobic taxa evolved as individual lines of descent about 1.5-2 billion years ago when the earth passed from an anaerobic to an aerobic environment. In contrast to the traditional, morphology-based classification, the genus Lactobacillus is intermixed with strains of Pediococcus and Leuconostoc. Similarly, the physiology-based clustering of lactobacilli into Thermo-, Strepto- and Betabacterium does not agree with their phylogenetic relationships. On the other hand, the phenotypically defined genus Streptococcus is not a phylogenetic coherent genus but its members fall into at least 3 moderately related genera, i.e. Streptococcus, Lactococcus and Enterococcus. The genus Bifidobacterium, frequently grouped with the lactobacilli, is the most ancient group of the second, the Actinomycetes subdivision of the Gram-positive eubacteria. In addition, propionibacteria, microbacteria and brevibacteria belong to this subdivision but the latter organisms appear as offshoots of non-lactic acid bacteria.

Bacteria↗
PubMed1995

Genetic organization of a small cryptic plasmid of Helicobacter pylori.

A 2.9-kb cryptic plasmid of Helicobacter pylori (Hp), pHel1, was isolated and the complete nucleotide (nt) sequence was determined. An open reading frame (ORF1) was identified encoding a putative polypeptide of 63,709 Da, the existence and correct size of which was confirmed by T7 promoter expression analysis. The ORF1 sequence showed strong amino-acid sequence identity to a recently identified putative ORF1 protein of a cryptic Hp plasmid, pHPM180, and significant homologies to putative Rep proteins of Campylobacter coli (RepB) and Pediococcus halophilus (RepA), and was therefore designated RepA. A functional role of RepA in replication of pHel1 was demonstrated by the fact that only pHel1 plasmid derivatives with an intact repA gene were able to autonomously replicate in Hp. Upstream of repA, a 22-bp sequence was recognized which was tandemly repeated four and a half times, a feature typical for many replication origins (ori) and commonly termed a DNA iteron. Analysis of the repA upstream region by primer extension identified a transcription start point for the repA mRNA, but did not correspond to known consensus promoter sequences. Southern hybridizations using pHel1 as a probe under stringent conditions revealed that homologous sequences to pHel1 were present in nearly all plasmid-carrying Hp strains, but not in a plasmid-carrying Helicobacter felis strain, suggesting that this type of replicon is predominantly found in the Hp species.

Amino Acid Sequence↗
PubMed2005

Use of hydrolysates from Atlantic cod (Gadus morhua L.) viscera as a complex nitrogen source for lactic acid bacteria.

Hydrolysates of cod viscera were tested as an alternative to commonly used complex nitrogen sources (peptones and/or extracts) for the type strains of the lactic acid bacteria Lactococcus lactis, Lactobacillus acidophilus, Lactobacillus helveticus, Lactobacillus casei, Lactobacillus sakei and Pediococcus pentosaceus. Comparative studies with MRS-like media containing different nitrogen sources showed that all the fish hydrolysates performed equally well or better than commercial extracts/peptones for all selected lactic acid bacteria.

Animals↗
PubMed2005

Yeast and lactic acid flora of tej, an indigenous Ethiopian honey wine: variations within and between production units.

A total of 200 samples of tej, an indigenous Ethiopian honey wine, were collected from ten production units at different production times. The samples were analysed for their microbial flora. Mean counts of aerobic mesophilic bacteria and aerobic spores for the different production units were <3 log cfu/ml. Coliforms and other members of Enterobacteriaceae were below detectable levels basically due to the low pH of the samples (<4.0). Yeasts were among the dominant micro-organisms in all samples with mean counts of 6 log cfu/ml for all production units. Over 25% of the yeast isolates belonged to Saccharomyces cerevisiae followed by Kluyvermyces bulgaricus (16%), Debaromyces phaffi (14%) and K. veronae (10%). Yeast counts showed significant variation within samples of a production unit (CV>10%) and difference in counts among all samples was also significant (P<0.01). The lactic acid bacteria had counts of 6 log cfu/ml with a significant variation within samples of a production unit (CV>10%) or among all samples (P<0.01). In most production units, the heterolactics had higher counts than the homolactics. The lactic flora consisted of Lactobacillus, Streptococcus, Leuconostoc and Pediococcus species. The lactobacilli were, however, the most frequently encountered groups. In most of the samples, the lactic flora was dominated by two (49.5%) or three (46%) groups of lactic acid bacteria.

Colony Count, Microbial↗
PubMed2006

Survival of Escherichia coli O157:H7 in dry fermented sausages containing micro-encapsulated probiotic lactic acid bacteria.

Escherichia coli O157:H7 is capable of surviving the rigorous processing steps during the manufacture of dry fermented sausages. The effect of adding two probiotic organisms, Lactobacillus reuteri and Bifidobacterium longum as co-cultures with the meat starter cultures Pediococcus pentosaceus and Staphylococcus carnosus on the viability of E. coli O157:H7 in dry fermented sausages was studied. A 5 strain cocktail of E. coli O157:H7 was added at 7.4 log cfu/g to the sausage batter and challenged with either or both Lb. reuteri or B. longum before or after they were micro-encapsulated. Sausages were fermented at < or = 26 degrees C and 88% relative humidity (RH) followed by drying at 75% RH and 13 degrees C for 25 d. The pH, water activity (aw), protein, moisture, and numbers of all inoculated organisms were monitored during processing. The pH and aw decreased from 5.7 and 0.98 to 4.9 and 0.88 at the end of fermentation and drying, respectively. These processes reduced E. coli O157:H7 by 1.0 and 0.7 log cfu/g at the end of fermentation and drying, respectively. Unencapsulated Lb. reuteri with or without B. longum reduced E. coli O157:H7 by 3.0 log cfu/g and B. longum caused a 1.9 log cfu/g reduction. While micro-encapsulation increased survival of Lb. reuteri and B. longum, it reduced their inhibitory action against E. coli O157:H7.

Animals↗
PubMed2004

Tannase activity by lactic acid bacteria isolated from grape must and wine.

We examined a range of oenological lactic acid bacteria species and reference strains for their potential to degrade tannins. Bacterial tannase activity was checked by a spectrophotometric and a visual reading method. None of the strains belonging to the oenological species of the genus Lactobacillus, Leuconostoc, Oenococcus or Pediococcus were tannase producers, with the exception of Lactobacillus plantarum. All the L. plantarum strains analyzed were positive for tannase activity and their identities were reconfirmed by L. plantarum PCR-specific assay or by sequencing the 16S rDNA. Tannase activity could be considered an important criterion for the selection of malolactic starter cultures since it might confer advantages in the winemaking process by reducing astringency and haze in wine.

Base Sequence↗