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Staphylococcus haemolyticus contains two D-glutamic acid biosynthetic activities, a glutamate racemase and a D-amino acid transaminase.

Two D-glutamic acid biosynthetic activities, glutamate racemase and D-amino acid transaminase, have been described previously for bacteria. To date, no bacterial species has been reported to possess both activities. Genetic complementation studies using Escherichia coli WM335, a D-glutamic acid auxotroph, and cloned chromosomal DNA fragments from Staphylococcus haemolyticus revealed two distinct DNA fragments containing open reading frames which, when present, allowed growth on medium without exogenous D-glutamic acid. Amino acid sequences of the two open reading frames derived from the DNA nucleotide sequences indicated extensive identity with the amino acid sequence of Pediococcus pentosaceous glutamate racemase in one case and with that of the D-amino acid transaminase of Bacillus spp. in the second case. Enzymatic assays of lysates of E. coli WM335 strains containing either the cloned staphylococcal racemase or transminase verified the identities of these activities. Subsequent DNA hybridization experiments indicated that Staphylococcus aureus, in addition to S. haemolyticus, contained homologous chromosomal DNA for each of these genes. These data suggest that S. haemolyticus, and probably S. aureus, contains genes for two D-glutamic acid biosynthetic activities, a glutamate racemase (dga gene) and a D-amino acid transaminase (dat gene).

Amino Acid Isomerases↗

Characterization of the genes encoding D-amino acid transaminase and glutamate racemase, two D-glutamate biosynthetic enzymes of Bacillus sphaericus ATCC 10208.

In Bacillus sphaericus and other Bacillus spp., D-amino acid transaminase has been considered solely responsible for biosynthesis of D-glutamate, an essential component of cell wall peptidoglycan, in contrast to the glutamate racemase employed by many other bacteria. We report here the cloning of the dat gene encoding D-amino acid transaminase and the glr gene encoding a glutamate racemase from B. sphaericus ATCC 10208. The glr gene encodes a 28. 8-kDa protein with 40 to 50% sequence identity to the glutamate racemases of Lactobacillus, Pediococcus, and Staphylococcus species. The dat gene encodes a 31.4-kDa peptide with 67% primary sequence homology to the D-amino acid transaminase of the thermophilic Bacillus sp. strain YM1.

Amino Acid Isomerases↗

REVERSAL OF d-CYCLOSERINE INHIBITION OF BACTERIAL GROWTH BY ALANINE.

Zygmunt, Walter A. (Mead Johnson & Co., Evansville, Ind.). Reversal of d-cycloserine inhibition of bacterial growth by alanine. J. Bacteriol. 84:154-156. 1962.-Reversal of the antibacterial activity of d-4-amino-3-isoxazolidone by alanine in bacterial cultures actively growing on chemically defined media was compared in cultures requiring exogenous alanine and those capable of its synthesis. dl-Alanine was the most effective reversal agent in Pediococcus cerevisiae, an alanine-requiring organism, and d-alanine was effective in Escherichia coli and Staphylococcus aureus, organisms synthesizing alanine. With all three cultures, l-alanine was the least effective reversal agent.

Journal Article↗

Group Q streptococci. II. Nutritional characteristics and growth relationship to thymine, folate, and folinate.

The vitamin requirements of the group Q streptococci (Streptococcus avium) and the established enterococcal species (S. faecalis and S. faecium) paralleled one another, although S. avium did not characteristically require riboflavine or pyridoxal. S. avium was further differentiated in that it required thymine for growth initiation whether or not folate was present. Folate was stimulatory in the presence of sub-optimal concentrations of thymine, as well as during the early growth period with optimal thymine concentrations. Folinate completely replaced the thymine requirement, and the S. avium strains required significantly higher concentrations than did Pediococcus cerevisiae 8081. The requirement pattern for folate and related compounds was compared, and marked differences were observed in the requirements of S. faecalis, S. faecium, S. avium, and P. cerevisiae.

Enterococcus faecalis↗

Vancomycin-resistant gram-positive bacteria isolated from human sources.

Recent reports of infections with vancomycin-resistant gram-positive bacteria prompted us to study vancomycin-resistant isolates from human sources to characterize the types of bacteria displaying this phenotype. Thirty-six vancomycin-resistant gram-positive isolates, 14 from clinical specimens and 22 from stool samples, were identified. These isolates were tentatively identified as Lactobacillus spp. (25 strains), Leuconostoc spp. (6 strains), and Pediococcus spp. (3 strains) on the basis of morphology and physiological tests. Two isolates of indeterminate morphology could not be unambiguously assigned to a genus. Four isolates of vancomycin-resistant lactobacilli from normally sterile body sites were considered to be clinically significant. Vancomycin-resistant gram-positive bacteria may represent an emerging class of nosocomial pathogens. Better methods for distinguishing the various genera in the clinical microbiology laboratory are needed.

Adult↗

Clinical and microbiologic characteristics of pediococci.

Over a 43-month period, 23 separate isolates of nonenterococcal alpha- and nonhemolytic streptococci were reported by our clinical microbiology laboratory to be resistant to vancomycin. This constituted 0.32% of nonenterococcal alpha- and nonhemolytic streptococci reported and 4.4% of such streptococci upon which susceptibility testing was performed. Of 13 isolates which were available for further study, all were highly resistant to vancomycin (MIC greater than or equal to 1,024 micrograms/ml), but none were actually streptococci. Three were clearly gram-positive rods by Gram stain and were found to be homofermentative lactobacilli. Two strains with elongated gram-positive cocci from colonies on agar showed small gram-positive rods when grown in thioglycolate broth and were physiologically identified as Lactobacillus confusus. Two isolates with lenticular gram-positive cocci appeared to be Leuconostoc mesenteroides subsp. mesenteroides. Six gram-positive isolates with round cells from growth on agar and from broth were arranged in tetrads in broth and closely resembled Pediococcus acidilactici. Twelve additional strains of pediococci that were not of human origin were also found to be highly resistant to vancomycin. These findings confirm published reports of clinical isolation of organisms resembling pediococci and suggest that clinically isolated, vancomycin-resistant bacteria which superficially resemble streptococci are probably other lactic acid bacteria.

Drug Resistance, Microbial↗

Identification of vancomycin-resistant lactic bacteria isolated from humans.

By using cell morphology, arginine dihydrolase, and gas production in de Man, Sharp, Rogosa broth, 122 isolates of vancomycin-resistant lactic bacteria from humans were assigned to five profiles, allowing us to distinguish Pediococcus, homofermentative and heterofermentative Lactobacillus, and Leuconostoc species. The absence of L-(+)-lactic acid, as detected spectrophotometrically, was confirmatory for Leuconostoc species. API 50 CHL panels were useful for the identification of Lactobacillus species.

Drug Resistance, Microbial↗

Identification of Enterococcus species and phenotypically similar Lactococcus and Vagococcus species by reverse checkerboard hybridization to chaperonin 60 gene sequences.

Data from four recent studies (S. H. Goh et al., J. Clin. Microbiol. 36:2164-2166, 1998; S. H. Goh et al., J. Clin. Microbiol. 34:818-823, 1996; S. H. Goh et al., J. Clin. Microbiol. 35:3116-3121, 1997; A. Y. C. Kwok et al., Int. J. Syst. Bacteriol. 49:1181-1192, 1999) suggest that an approximately 600-bp region of the chaperonin 60 (Cpn60) gene, amplified by PCR with a single pair of degenerate primers, has utility as a potentially universal target for bacterial identification (ID). This Cpn60 gene ID method correctly identified isolates representative of numerous staphylococcal species and Streptococcus iniae, a human and animal pathogen. We report herein that this method enabled us to distinguish clearly between 17 Enterococcus species (Enterococcus asini, Enterococcus rattus, Enterococcus dispar, Enterococcus gallinarum, Enterococcus hirae, Enterococcus durans, Enterococcus cecorum, Enterococcus faecalis, Enterococcus mundtii, Enterococcus casseliflavus, Enterococcus faecium, Enterococcus malodoratus, Enterococcus raffinosus, Enterococcus avium, Enterococcus pseudoavium, Enterococcus new sp. strain Facklam, and Enterococcus saccharolyticus), and Vagococcus fluvialis, Lactococcus lactis, and Lactococcus garvieae. From 123 blind-tested samples, only two discrepancies were observed between the Facklam and Collins phenotyping method (R. R. Facklam and M. D. Collins, J. Clin. Microbiol. 27:731-734, 1989) and the Cpn60 ID method. In each case, the discrepancies were resolved in favor of the Cpn60 ID method. The species distributions of the 123 blind-tested isolates were Enterococcus new sp. strain Facklam (ATCC 700913), 3; E. asini, 1; E. rattus, 4; E. dispar, 2; E. gallinarum, 20; E. hirae, 9; E. durans, 9; E. faecalis, 12; E. mundtii, 3; E. casseliflavus, 8; E. faecium, 25; E. malodoratus, 3; E. raffinosus, 8; E. avium, 4; E. pseudoavium, 1; an unknown Enterococcus clinical isolate, sp. strain R871; Vagococcus fluvialis, 4; Lactococcus garvieae, 3; Lactococcus lactis, 3; Leuconostoc sp., 1; and Pediococcus sp., 1. The Cpn60 gene ID method, coupled with reverse checkerboard hybridization, is an effective method for the identification of Enterococcus and related organisms.

Bacterial Typing Techniques↗

Lactobacillus plantarum gene clusters encoding putative cell-surface protein complexes for carbohydrate utilization are conserved in specific gram-positive bacteria.

BACKGROUND: Genomes of gram-positive bacteria encode many putative cell-surface proteins, of which the majority has no known function. From the rapidly increasing number of available genome sequences it has become apparent that many cell-surface proteins are conserved, and frequently encoded in gene clusters or operons, suggesting common functions, and interactions of multiple components. RESULTS: A novel gene cluster encoding exclusively cell-surface proteins was identified, which is conserved in a subgroup of gram-positive bacteria. Each gene cluster generally has one copy of four new gene families called cscA, cscB, cscC and cscD. Clusters encoding these cell-surface proteins were found only in complete genomes of Lactobacillus plantarum, Lactobacillus sakei, Enterococcus faecalis, Listeria innocua, Listeria monocytogenes, Lactococcus lactis ssp lactis and Bacillus cereus and in incomplete genomes of L. lactis ssp cremoris, Lactobacillus casei, Enterococcus faecium, Pediococcus pentosaceus, Lactobacillius brevis, Oenococcus oeni, Leuconostoc mesenteroides, and Bacillus thuringiensis. These genes are neither present in the genomes of streptococci, staphylococci and clostridia, nor in the Lactobacillus acidophilus group, suggesting a niche-specific distribution, possibly relating to association with plants. All encoded proteins have a signal peptide for secretion by the Sec-dependent pathway, while some have cell-surface anchors, novel WxL domains, and putative domains for sugar binding and degradation. Transcriptome analysis in L. plantarum shows that the cscA-D genes are co-expressed, supporting their operon organization. Many gene clusters are significantly up-regulated in a glucose-grown, ccpA-mutant derivative of L. plantarum, suggesting catabolite control. This is supported by the presence of predicted CRE-sites upstream or inside the up-regulated cscA-D gene clusters. CONCLUSION: We propose that the CscA, CscB, CscC and CscD proteins form cell-surface protein complexes and play a role in carbon source acquisition. Primary occurrence in plant-associated gram-positive bacteria suggests a possible role in degradation and utilization of plant oligo- or poly-saccharides.

Antigens, Surface↗

Monitoring the lactic acid bacterial diversity during shochu fermentation by PCR-denaturing gradient gel electrophoresis.

The presence of lactic acid bacteria (LAB) during shochu fermentation was monitored by PCR-denaturing gradient gel electrophoresis (DGGE) and by bacteriological culturing. No LAB were detected from fermented mashes by PCR-DGGE using a universal bacterial PCR primer set. However, PCR-DGGE using a new primer specific for the 16S rDNA of Lactococcus, Streptococcus, Tetragenococcus, Enterococcus, and Vagococcus and two primers specific for the 16S rDNA of Lactobacillus, Pediococcus, Leuconostoc, and Weissella revealed that Enterococcus faecium, Lactobacillus casei, Lactobacillus fermentum, Lactobacillus nagelii, Lactobacillus plantarum, Lactococcus lactis, Leuconostoc citreum, Leuconostoc mesenteroides, and Weissella cibaria inhabited in shochu mashes. It was also found that the LAB community composition during shochu fermentation changed after the main ingredient and water were added during the fermentation process. Therefore, we confirmed that PCR-DGGE using all three primers specific for groups of LAB together was well suited to the study of the LAB diversity in shochu mashes. The results of DGGE profiles were similar to the results of bacteriological culturing. In conclusion, LAB are present during shochu fermentation but not dominant.

Bacteria, Aerobic↗

A novel lantibiotic, nukacin ISK-1, of Staphylococcus warneri ISK-1: cloning of the structural gene and identification of the structure.

Staphylococcus warneri ISK-1, which we had previously reported as Pediococcus sp. ISK-1, produces a novel bacteriocin, nukacin ISK-1. Edman degradation of the chemically reduced nukacin ISK-1 produced a sequence of 27 amino acids, 7 of which were unidentified. Using single-specific-primer-PCR product as a probe, a 3.6-kb HindIII fragment containing the nukacin ISK-1 structural gene (nukA) was cloned and sequenced. The deduced amino acid sequence of nukacin ISK-1 had 57 amino acids, including a 30-amino acid leader region. The propeptide sequence showed significant similarity to those of lacticin-481 type lantibiotics. In the region upstream of nukA, a part of a long open reading frame (ORF), designated as nukM, encoding a putative modification enzyme was oriented in the opposite direction. In the region downstream of nukA, ORF1 was found in which the sequence of the putative translational product was similar to various response regulatory proteins.

Amino Acid Sequence↗

Characterization of a phage resistance plasmid, pLKS, of silage-making Lactobacillus plantarum NGRI0101.

Phage contamination has resulted in abnormal fermentation in silage. We isolated a phage-resistant strain, Lactobacillus plantarum NGRI0101 from silage. The strain carried two plasmids, pLKL (6.8 kb) and pLKS (2.0 kb). By curing and retransformation of the plasmids, we clarified that pLKS has phage resistant activity, characterized as no adsorption inhibition. pLKS has 2,025 bp and three orfs, orfl23, orf132, and orf918. The predicted amino acid sequence of the orf918 product showed high similarity to those of Rep proteins of Pediococcus halophilus plasmid pUCL287 and Lactobacillus acidophilus plasmid pLA103. The replication origin (ori) was upstream from orf918. There was no gene similar to typical phage resistant genes encoded by known plasmids. The phage resistance of L. plantarum NGRI0101 may possibly be due to a plasmid-encoded abortive infection.

Amino Acid Sequence↗

Nutritional quality of lactic fermented bitter gourd and fenugreek leaves.

Pediococcus pentosaceus was selected from isolates obtained from the naturally fermenting bitter gourd and fenugreek leaves based on its high titre and broad spectrum of inhibitory activity against spoilage organisms. This strain was then employed for fermentation of bitter gourd and fenugreek which resulted in a more acceptable product having enhanced fat, pyridoxine and ascorbic acid levels. It was of interest to note that vitamin B12 was formed in the fenugreek as a result of the fermentation.

Developing Countries↗

The effect of Lactobacillus buchneri and other additives on the fermentation and aerobic stability of barley silage.

Whole-plant barley (39.4% dry matter) was treated with various chemical and biological additives to assess their effects on silage fermentation and aerobic stability. Treatments were untreated forage, forage treated with several amounts of Lactobacillus buchneri and enzymes (L. buchneri at 1 x 10(5), 5 x 10(5), and 1 x 10(6) cfu/g of fresh forage), forage treated with an inoculant containing (Lactobacillus plantarum, Pediococcus pentosaceus, Propionibacterium freudenreichii, and enzymes), or forage treated with a buffered propionic acid-based additive (0.2% of fresh weight). Sixty-nine d after ensiling, silages treated with L. buchneri and enzymes had lower pH, but had higher concentrations of acetic and propionic acids and higher concentrations of ethanol when compared with untreated silage. Silage treated with the multistrain inoculant containing L. plantarum had lower pH and higher concentrations of lactic acid, but lower concentrations of ammonia-N, neutral detergent fiber, and acid detergent fiber than did untreated silage. The addition of the buffered propionic acid additive resulted in silage with higher concentrations of lactic and acetic acid compared with untreated silage. Numbers of yeasts in all silages were low at silo opening (less than 3.0 log cfu/g) and were numerically the lowest in silages treated with L. buchneri but only treatment with the intermediate and high level of L. buchneri improved the aerobic stability of silage. Because of the altered fermentation pattern, inoculation with L. buchneri, when applied at equal to or more than 5 x 10(5) cfu/g, and enzymes improved the aerobic stability of barley silage.

Acetic Acid↗

Use of an alpha-galactosidase gene as a food-grade selection marker for Streptococcus thermophilus.

The alpha-galactosidase gene (aga) of Lactococcus raffinolactis ATCC 43920 was previously shown to be an efficient food-grade selection marker in Lactococcus lactis and Pediococcus acidilactici but not in Streptococcus thermophilus. In this study, we demonstrated that the alpha-galactosidase of L. raffinolactis is thermolabile and inoperative at 42 degrees C, the optimal growth temperature of S. thermophilus. An in vitro assay indicated that the activity of this alpha-galactosidase at 42 degrees C was only 3% of that at 30 degrees C, whereas the enzyme retained 23% of its activity at 37 degrees C. Transformation of Strep. thermophilus RD733 with the shuttle-vector pNZ123 bearing the aga gene of L. raffinolactis (pRAF301) generated transformants that were stable and able to grow on melibiose and raffinose at 37 degrees C or below. The transformed cells possessed 6-fold more alpha-galactosidase activity after growth on melibiose than cells grown on lactose. Slot-blot analyses of aga mRNA indicated that repression by lactose occurred at the transcriptional level. The presence of pRAF301 did not interfere with the lactic acid production when the transformed cells of Strep. thermophilus were grown at the optimal temperature in milk. Using the recombinant plasmid pRAF301, which carries a chloramphenicol resistance gene in addition to aga, we showed that both markers were equally efficient at differentiating transformed from nontransformed cells. The aga gene of L. raffinolactis can be used as a highly efficient selection marker in Strep. thermophilus.

Dairy Products↗

The metabolism of folinic acid (leucovorin) following oral and parenteral administration.

Serum and urinary distributions of following oral and parenteral administration of leucovorin (3-15 mg) were examined in normal adult volunteers microbiologically using lactobacillus casei, Streptococcus faecalis and Pediococcus cerevisiae as test organisms. By the parenteral route, nearly one-third of the folate in the serum and urine was in the form of folinic acid and the remainder as 5-methyltetrahydrofolic acid. Almost all the folate in serum and urine was in the form of 5-methyltetrahydrofolic acid after oral administration. Peak serum folate was observed 3 hr after oral administration, later than that seen after parenteral administration (30 min). Elevation of serum folate was achieved by the increase of the methyl form of folate following repeated administration of leucovorin orally and parenterally. As the form of folate actually rescuing normal cells in a high-dose methotrexate regimen was thought to be methyl, use of the oral route as a principal means of administration of leucovorin in a rescue program was looked into.

Administration, Oral↗

Characterization and antimicrobial spectrum of bifidocin B, a bacteriocin produced by Bifidobacterium bifidum NCFB 1454.

Five stains of Bifidobacterium bifidum (ATCC 11863 and 29591, and NCFB 1453, 1454, 1455) were examined for production of bacteriocins in MRS broth with 0.05% cysteine. Only strain NCFB 1454 excreted a bacteriocin into the broth: it was designated bifidocin B. Bifidocin B was sensitive to several proteolytic enzymes (protease IV, pronase E, protease XVII, proteinase K, trypsin, alpha-chymotrypsin, papain, and pepsin), but was resistant to catalase, peroxidase, lipase, lysozyme, cellulase, ribonuclease A, and amylases. It was also resistant to organic solvents such as ethyl alcohol, acetone, hexane, chloroform, methanol, and ether, and to heating at 90 degrees C for 15, 30, and 60 min or at 121 degrees C for 15 min. Bifidocin B remained active after storage at -20 or -7 degrees C for 3 months and retained biological activity after exposure to pH values of 2 to 10. Bifidocin B was active against some food-borne pathogens and food spoilage bacteria such as Listeria, Enterococcus, Bacillus, Lactobacillus, Leuconostoc, and Pediococcus species but was not active against the other gram-positive and gram-negative bacteria tested. Bifidocin B was produced during exponential phase, reaching a maximum activity of 3,200 AU/ml at early stationary phase. Bifidocin B had a molecular mass of about 3.3 kDa as analyzed by Tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Bacteria↗

Aspects of microbiological and chemical quality of turmus, lupin seeds debittered by soaking in water.

Eleven species of spherical lactic acid bacteria (LAB) belonging to the genera Leuconostoc, Lactococcus, Enterococcus and Pediococcus were the predominant microorganisms in 40 samples of turmus, ready-to-eat lupin seeds debittered by boiling and soaking in water. The average counts of the LAB in the 20 winter samples and the 20 summer samples were 7.4 and 8.7 log CFU/g, respectively. The averages of the Enterobacteriaceae counts were 5.1 and 6.6 log CFU/g, respectively, and the 11 species isolated belonged to the genera Enterobacter, Citrobacter, Escherichia and Klebsiella. The average yeast counts in winter and summer samples were 3 and 3.2 log CFU/g, respectively, and the 5 species isolated were in the genera Saccharomyces, Cryptococcus, Rhodotorula and Candida. Although Salmonella was not isolated from any sample and the Staphylococcus aureus count in all samples was < 1 log CFU/g, microbial hazards could be associated with the high Enterobacteriaceae counts and the presence of Escherichia coli. Total alkaloid concentration in 30% of the samples examined was higher than 0.02%, thus making the seeds a potential chemical hazard. Boiling the turmus directly before consumption and discarding the seeds with a bitter taste may help in avoiding some of the microbial and chemical hazards which could be associated with turmus consumption.

Alkaloids↗