Association of a 13.6-Megadalton Plasmid in Pediococcus pentosaceus with Bacteriocin Activity

Pediococcus pentosaceus FBB61 and L7230, isolated from cucumber fermentations, produced a bacteriocin, designated pediocin A, which had identical activity spectra against species of Pediococcus, Clostridium, Staphylococcus, and Streptococcus. Both strains possessed a 13.6-megadalton plasmid (pMD136). Plasmid curing experiments suggested that both bacteriocin immunity and production determinants were encoded by pMD136. Use of pediocin-producing strains in food fermentations is discussed.     

Catabolism of Serine by Pediococcus acidilactici and Pediococcus pentosaceus

The ability to produce diacetyl from pyruvate and l-serine was studied in various strains of Pediococcus pentosaceus and Pediococcus acidilactici isolated from cheese. After being incubated on both substrates, only P. pentosaceus produced significant amounts of diacetyl. This property correlated with measurable serine dehydratase activity in cell extracts. A gene encoding the serine dehydratase (dsdA) was identified in P. pentosaceus, and strains that showed no serine dehydratase activity carried mutations that rendered the gene product inactive. A functional dsdA was cloned from P. pentosaceus FAM19132 and expressed in Escherichia coli. The purified recombinant enzyme catalyzed the formation of pyruvate from l- and d-serine and was active at low pH and elevated NaCl concentrations, environmental conditions usually present in cheese. Analysis of the amino acid profiles of culture supernatants from dsdA wild-type and dsdA mutant strains of P. pentosaceus did not show differences in serine levels. In contrast, P. acidilactici degraded serine. Moreover, this species also catabolized threonine and produced alanine and α-aminobutyrate.     

Evidence for Plasmid Linkage of Raffinose Utilization and Associated alpha-Galactosidase and Sucrose Hydrolase Activity in Pediococcus pentosaceus

The ability to ferment the trisaccharide raffinose was linked with the presence of plasmid DNA in three strains of Pediococcus pentosaceus. Parental strains showed associated inducible alpha-galactosidase and sucrose hydrolase activities when grown in alpha-galactosides and sucrose, respectively. Derivative strains of PPE1.0, PPE2.0, and PPE5.0, which had lost 30-, 28-, and 23-megadalton plasmids, respectively, had no alpha-galactosidase or sucrose hydrolase activity.     

Autolytic activity and pediocin-induced lysis in Pediococcus acidilactici and Pediococcus pentosaceus strains

AIMS: To evaluate the autolytic phenotype of Pediococcus acidilactici and P. pentosaceus, the peptidoglycan hydrolases content and the effect of pediocin AcH/PA-1 and autolysins on cell lysis. METHODS AND RESULTS: The autolytic phenotype of Pediococcus strains was evaluated under starvation conditions in potassium phosphate buffer. The strains tested showed an extent of autolysis ranging between 40 and 90% after 48 h of starvation at 37 degrees C. Peptidoglycan hydrolase content was evaluated by renaturing sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) using cells of Micrococcus lysodeikticus as a target for the enzymatic activity and a major activity band migrating at about 116 kDa was detected. Additional secondary lytic bands migrating in a range of molecular weight between 45 and 110 kDa were also detected. The lytic activity, evaluated in the presence of different chemicals, was retained in 15 mM CaCl2 and in a range of pH between 5 and 9.5 but was strongly reduced in presence of 8% NaCl and in the presence of protease inhibitors. The substrate specificity of peptidoglycan hydrolases of Pediococcus strains was evaluated in renaturing SDS-PAGE incorporating cells of different bacterial species. Lytic activity was detected against cells of Lactococcus lactis subsp. lactis, L. delbrueckii subsp. bulgaricus, Lactobacillus helveticus and Listeria monocytogenes. The interaction between pediocin AcH/PA-1 and autolysis was evaluated and a relevant effect of bacteriocin in cell-induced lysis was observed. CONCLUSIONS: The autolytic phenotype is widely distributed among P. acidilactici and P. pentosaceus and the rate of autolysis is high in the majority of the analysed strains. Several autolytic bands, detected by renaturing SDS-PAGE, retained their activity against several lactic acid bacteria and L. monocytogenes. SIGNIFICANCE AND IMPACT OF THE STUDY: The characterization of the autolytic phenotype of Pediococcus acidilactici and P. pentosaceus strains should expand the knowledge of their role in fermentation processes where these species occur as primary or secondary bacterial population.     

Production and characterization of antibacterial compounds produced by Pediococcus damnosus and Pediococcus pentosaceus

The broad-spectrum antibacterial activity exhibited by three Pediococcus strains isolated from beer was preliminarily characterized. Factors affecting the production rate of bacterial inhibitors were screened and the effects of simultaneous cultivation of Lactococcus and Pediococcus on the production of inhibitory substances were studied. The antibacterial activity against a range of Gram-negative test organisms was not affected by catalase or proteolytic enzymes and was extremely thermotolerant. Production of the inhibitors was maximal between pH 6 and pH 7. A growth medium containing unhopped end-fermented wort was beneficial for the production of inhibitors, particularly by the Pediococcus damnosus strain, and anaerobic growth conditions were preferable. The antagonistic activity against the Gram-negative test organism Salmonella infantis could be demonstrated after an incubation period of only 2 d if the Pediococcus and Lactococcus strains were incubated simultaneously as a mixed population.     

Genome Sequence of Pediococcus pentosaceus Strain IE-3

We report the 1.8-Mb genome sequence of Pediococcus pentosaceus strain IE-3, isolated from a dairy effluent sample. The whole-genome sequence of this strain will aid in comparative genomics of Pediococcus pentosaceus strains of diverse ecological origins and their biotechnological applications.     

Characterization of bacteriocin produced by Pediococcus pentosaceus from wine

A.M. STRASSER DE SAAD AND M.C. MANCA DE NADRA. 1993. Twenty strains of Pediococcus pentosaceus isolated from wine were examined for production of bacteriocins. Only two of them showed inhibitory activity, Ped. pentosaceus N4p against the indicator strains of the same species and N5p against 19 strains of the three genera of lactic acid bacteria from wine. The antimicrobial substance from N5p strains was removed by membrane (0.2 μm) filtration, destroyed by organic solvents and proteolytic enzymes. It was stable for 60 min at 100C. The bacteriocin was produced early in the growth cycle and its production was maximum after 48 h of culture in tomato juice medium at an initial pH of 6.5. The bactericidal effect was observed.     

Randomly amplified polymorphic DNA (RAPD) for discrimination of Pediococcus pentosaceus and Ped. acidilactici and rapid grouping of Pediococcus isolates

In a taxonomic study of the known Pediococcus species, together with 116 isolates from fermenting tef dough and fermented kocho using a PCR-based RAPD procedure, all the different species developed well differentiated agarose gel electrophoresis profiles. Analyses of the images with the Pearson product moment correlation coefficient (r) and upgma clustering algorithm in the GelCompar version 4·0 software gave a distinct identification scheme within and between type strains and food isolates of Pediococcus species. The procedure is simple, rapid for grouping of isolates, applicable to all species of pediococci and particularly useful for differentiating between strains of Ped. pentosaceus and Ped. acidilactici .     

Characterization of D-lactate dehydrogenase producing D-3-phenyllactic acid from Pediococcus pentosaceus

D-Lactate dehydrogenase (D-LDH) from Pediococcus pentosaceus ATCC 25745 was found to produce D-3-phenyllactic acid from phenylpyruvate. The optimum pH and temperature for enzyme activity were pH 5.5 and 45 °C. The Michaelis-Menten constant (K(m)), turnover number (k(cat)), and catalytic efficiency (k(cat)/K(m)) values for the substrate phenylpyruvate were estimated to be 1.73 mmol/L, 173 s(-1), and 100 (mmol/L)(-1) s(-1) respectively.     

Multilocus Hybridization Typing in Pediococcus acidilactici Strains

In previous a study we demonstrated the presence of several genomic subpopulations within a collection of Pediococcus acidilactici strains isolated from different environments, through a multilocus typing analysis taking into consideration housekeeping conserved loci and protein coding genes of the primary metabolism. In this study, representative strains of five genomic subpopulations previously described (I, II, III, V, VII) were analyzed by restriction analysis of chromosomal DNA and subsequent hybridization assays using as probes amplified fragments obtained from five housekeeping genes (16S rDNA, rpoC, ldhD, ldhL, and metS). A computer similarity and clustering analysis of hybridization data showed the subdivision of P. acidilactici strains in five distinct genotypes according to the grouping previously obtained confirming that pediocin AcH/PA-1 producer strains represent one genomic lineage within the species P. acidilactici. Received: 30 January 2001 / Accepted: 16 May 2001     

Production of L- AND D-lactate by Pediococcus pentosaceus in batch and steady-state continuous culture

The fast growth and acid production of a strain of Pediococcus pentosaceus , used as a starter culture in the production of dry sausages, was dependent on the presence of acetate. In a batch culture on a mixture of glucose and sucrose both sugars were consumed simultaneously. Similar growth rates and product yields were obtained on glucose and sucrose, d - AND l -lactate were produced via a D- and L-lactate dehydrogenase (LDH), respectively, and no racemase was present. In batch cultures about 15% of the lactic acid produced was the D-isomer, whereas in a sucrose-limited, continuous culture the fraction of D-lactic acid increased with decreasing dilution rate. The results are discussed in relation to the two LDH activities.     

Stepwise Transformation in Saccharomyces cerevisiae Yeast: Construction of Strains for Transformation and Subsequent Cytoductive Transfer of Plasmid DNA with Mitochondria

As a general transformation method in Saccharomyces cerevisiae,a "stepwise transformation method" of three steps was developed:conventional transformation of established carrier strains withplasmid DNA, subsequent effective transfer of plasmid to destinationhosts either by cytoduction or by meiosis after mating, andfinally a simple test for plasmid retention. The several auxotrophiccarrier strains constructed were readily transformable, defectivein karyogamy (kar 1), and highly susceptible to cell-wall lyticenzymes. Effective transfer of plasmid DNA from the carrierstrains to other strains by cytoduction or meiosis was confirmed,and the target transformants were obtained. The simple methodfor checking plasmid retention was based on the cytoductivetransfer of plasmid DNA to tester cells which have recessivemultiple drug resistance and kar 1 mutations. The stepwise methodshould largely extend the range of strains which can be transformedand spare time and labor. Its limitations as well as other advantagesare also discussed. ¹ The preliminary report of this paper was presented in theAnnual Meeting of the Japanese Society of Plant Physiologists,Kanazawa, April, 1984. (Received November 5, 1985; Accepted April 7, 1986)     

Plasmid transfers by conjugation and electroporation in Pediococcus acidilactici

W.J. KIM, B. RAY AND M.C. JOHNSON. 1992. Plasmid profiles of wild and mutant strains of Pediococcus acidilactici M showed that a 53.7 kb plasmid (pPR72) encodes the sucrose hydrolysis trait ( Suc +) and an 11.1 kb plasmid encodes the bacteriocin production trait ( Pap +). Neither of these plasmids encode traits involving fermentation of other carbohydrates, antibiotic resistance or resistance to bacteriocin. Broad host-range plasmids (pAMβ1 and pIP501) from Enterococcus faecalis and plasmid pPR72 from Ped. acidilactici were conjugally transferred by filter mating into two strains of Ped. acidilactici. Four plasmids, ranging in size from 4.4 to 53.7 kb, were also transferred into Ped. acidilactici strains by electroporation. Optimum transformation of the 4.4 kb plasmid, pGK12, was obtained at a DNA concentration of 1 μg/220 μl. The same amount of DNA gave lower transformation frequencies as the plasmid size increased. Results of these studies indicated that both conjugation and electroporation can be used to transfer plasmid-linked traits in Ped. acidilactici strains.     

Immunomodulatory function and in vivo properties of Pediococcus pentosaceus OZF, a promising probiotic strain

Some of the important properties of probiotics are the ability to survive during gastrointestinal transit and to modulate the immune functions. The objectives of the reported study were to assess in vivo gastrointestinal survival of orally administered Pediococcus pentosaceus OZF using an animal model BALB/c mice, and to examine its effects on the immune response. Following oral administration to mice, the ability of Pediococcus pentosaceus OZF to pass and survive through the mouse gastrointestinal system was investigated by analyzing the recovery of the strain in fecal samples. Microbiological and polymerase chain reaction (PCR) methods proved that the strain OZF could overcome specific conditions in the gastrointestinal tract of mice and reach the intestine alive after ingestion. To observe the effect of oral administration on immune response, IL-6, IL-12 and IFN-γ were measured by ELISA, and the strain OZF was found to cause increases in IL-6 synthesis in regularly fed mice. However, stimulation was carried out with various concentrations of bacterial ssDNA and heat killed cells of Pediococcus pentosaceus OZF. The heat killed cells of the strain OZF were shown to produce IFN-γ independently from IL-12. On the other hand, a significant difference between control and experimental group was noticed when lipopolysaccharide, a TLR4 (toll like receptor) ligand, was used. Overall, Pediococcus pentosaceus OZF may be a valuable probiotic strain for therapeutic uses. Nevertheless, further studies on the mechanisms of immunomodulatory effect will allow for better clarification of the immune functions of this strain.     

Storage of Escherichia coli Strains Containing Plasmid DNA in Liquid Nitrogen

The stability of plasmids and lysogenic bacteriophage in 16 strains of Escherichia coli was studied following storage in liquid nitrogen for periods up to 2 years. A comparison was made with cultures which had undergone lyophilization. Plasmid loss was detected by plating on selective media containing antibiotics to which resistance was conferred by plasmid DNA. Loss of plasmid DNA was not evident following storage in liquid nitrogen or lyophilization.     

Aspartate aminotransferase of Pediococcus cerevisiae.

A five-step procedure is described for preparing highly purified aspartate aminotransferase (L-aspartate: 2-oxoglutarate aminotransferase, EC.2.6.1.1) from cell-freee enzyme extracts of Pediococcus cerevisiae. An overall purification of 130-fold was achieved. Some of P. cerevisiae aspartate aminotransferase properties were studied, i.s. pH optimum (7.8--8.0), optimum of temperature (37 degrees), Michaelis constans for 4 enzyme substrates and substrate specificity of enzyme. The enzyme is very thermolabile. During purification the enzyme was stabilizated by 2-oxoglutarate. The highly purified preparation was stored in the solution containing ammonium sulphate. The obtained aspartate aminotransferase preparation was free of alanine and aromatic amino acids aminotransferase activites and did not reveal malate dehydrogenase activity.     

Purification and partial characterization of a tripeptidase from Pediococcus pentosaceus K9.2.

A tripeptidase was purified from the cytoplasm of Pediococcus pentosaceus K9.2 by anion-exchange chromatography, gel filtration chromatography, and high-performance liquid chromatography. The molecular mass of the enzyme was estimated by gel filtration at 100,000 Da. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified peptidase showed one protein band of 45,000 Da. Optimal enzyme activity was obtained at pH 7.0 and at 50 degrees C. The peptidase hydrolyzed all tripeptides tested. Cleavage was not observed with dipeptides, oligopeptides, or amino acid-p-nitroanilide derivatives. Strong inhibition of activity was caused by EDTA, 1,10-phenanthroline, dithiothreitol, and beta-mercaptoethanol, whereas phenylmethylsulfonyl fluoride and sulfur-reactive reagents had no effect on peptidase activity. Mg2+, Mn2+, and Ca2+ stimulated the hydrolyzing activity of the enzyme. The 20 N-terminal amino acids of the tripeptidase from P. pentosaceus had 84% identity with those from the corresponding N-terminal region of the tripeptidase from Lactococcus lactis subsp. cremoris Wg2.     

Evaluation of in vitro Probiotic Potential of Pediococcus pentosaceus OZF Isolated from Human Breast Milk

This study was conducted to evaluate the probiotic properties of Pediococcus pentosaceus OZF isolated from human breast milk. The results obtained so far suggest that the strain is resistant to low pH, bile salt, pepsin and pancreatin, so it could survive while passing through the upper part of the gastrointestinal tract and reveal its potential probiotic action on host organism. The strain was non-pathogenic (γ-hemolytic), produced anti-Listerial bacteriocin, exhibited a strong autoaggregating phenotype (85.71%) and demonstrated 6.26 and 12.99% coaggregation with Salmonella enterica serotype Typhimurium SL 1344 and Escherichia coli LMG 3083 (ETEC), respectively. The degree of adhesion of Ped. pentosaceus OZF to the human Caco-2 cell line was investigated and when compared to the adhesion of pathogenic strains tested, it was shown to inhibit the growth of human enterotoxigenic E. coli LMG 3083 (ETEC) and of Salm. Typhimurium SL 1344. Ped. pentosaceus OZF seems to adhere to human intestinal cells via mechanisms that involve different combinations of carbohydrate and lipid factors on the bacteria and eukaryotic cell surface. The percentage of adhesion to n-hexadecane was 34% showing that the surface was rather hydrophilic. Higher affinity displayed by Ped. pentosaceus OZF for chloroform demonstrates the basic property of a cell, which may be due to the presence of carboxylic groups on the cell surface.     

Overproduction of glutamate racemase of Pediococcus pentosaceus in Escherichia coli clone cells and its purification

We previously isolated a 6.0-kb DNA fragment that specifies glutamate racemase activity from the chromosomal DNA of Pediococcus pentosaceus by digestion with HindIII (N. Nakajima, K. Tanizawa, H. Tanaka, and K. Soda, 1986), Agric. Biol. Chem. 50, 2823-2830). We digested it further with EcoRI to obtain a fragment of 1.8 kb, which was blunt-ended and ligated into the SmaI site of vector plasmid pKK223-3. The recombinant plasmid showed a high glutamate racemase activity upon transformation of Escherichia coli W3110 cells with it; the plasmid was named pICR223. Glutamate racemase was overproduced in the clone cells and occurred in inclusion bodies in the cells. The enzyme was solubilized with 6 M urea, renatured by dialysis to remove urea, and purified to homogeneity with an overall yield of about 70% after a single DEAE-cellulose column chromatography. The amount of enzyme produced by the clone cells corresponded to about 38% of the total insoluble protein.     

Sugar and organic acid metabolism in mixed cultures of Pediococcus pentosaceus and Leuconostoc oenos isolated from wine

Pediococcus pentosaceus 12p and Leuconostoc oenos X₂L isolated from Argentinian wine were examined for growth and changes in the concentrations of glucose, fructose, sucrose and mannitol and malic, citric, acetic and lactic acids in pure and mixed cultures. In mixed cultures a mutualistic growth response and a change in the balance of end-products of sugar and organic acid metabolism were observed. The production of mannitol and acetic acid was lower while D(-) and L(+) lactic acids were detected in higher levels than in pure cultures. Malic and citric acids were metabolized simultaneously, but the amount of citric acid consumed was lower than in pure culture of Leuc. oenos.