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PubMed1969

Aerobic and facultative microflora of fresh and spoiled refrigerated dough products.

The microbial flora of fresh, unsterile, dough products held at refrigeration temperatures was compared with the microbial flora of the same products that had spoiled spontaneously. Various methods based on selective media were used to determine molds, yeasts, and bacteria present. Except for two special cases in which a yeast and Penicillium roqueforti induced spoilage, all of the samples deteriorated because of bacterial growth. A total of 1,132 bacterial isolates was subjected to further classification. In the spoiled products, 92% of the isolates belonged to the Lactobacillaceae. More than one-half of these (53%) belonged to the genus Lactobacillus, and an additional 36% were in the genus Leuconostoc. In the genus Leuconostoc almost all of the strains (94%) were L. mesenteroides. The third most common genus present was Streptococcus, represented by 3% of the total isolates. A preliminary taxonomic study of the microflora of refrigerated dough products revealed none of the isolates to be indicators of fecal contamination and none to be forms known to produce toxins. The highest counts encountered in the moist, fresh products were up to 200 million lactic acid bacteria per g in buttermilk biscuits, with a psychrophilic count as high as 4.8 million. In the spoiled samples, the highest total counts were 820 million in buttermilk biscuits. Mold counts were no higher than 1,800, except in the sample ruined by P. roqueforti where the count was 130,000 mold colonies.

Bacteria↗
PubMed1972

Occurrence and properties of lactic dehydrogenases of fermentative mycoplasmas.

Eight fermentative mycoplasmas differing in genome size, deoxyribonucleic acid (DNA) base composition, or sterol dependence were examined for lactic dehydrogenase composition by spectrophotometric assay and polyacrylamide gel electrophoresis. Three completely different patterns of lactic dehydrogenase composition were found. (i) A nicotinamide adenine dinucleotide (NAD)-dependent l(+)-lactic dehydrogenase was found in Mycoplasma pneumoniae, M. gallisepticum, M. mycoides var. mycoides, mycoplasma UM 30847, M. neurolyticum, and Acholeplasma axanthum. Electrophoresis of cell-free extracts of each of these mycoplasmas produced, with the exception of M. mycoides var. mycoides and UM 30847, single, different enzyme bands. M. mycoides var. mycoides and UM 30847 were similar and formed multiple bands of enzyme activity. We were unable to establish whether these multiple bands were due to lactic dehydrogenase isoenzymes or artifacts. (ii) An NAD-dependent d(-)-lactic dehydrogenase which could not be reversed to oxidize lactate was found in M. fermentans. (iii) A. laidlawii A possessed an NAD-independent d(-)-lactic dehydrogenase capable of reducing dichlorophenol-indophenol, and an NAD-dependent l(+)-lactic dehydrogenase which is specifically activated by fructose-1,6-diphosphate. Heretofore, this enzyme regulatory mechanism was known to occur only among the Lactobacillaceae. No yeast-type lactic dehydrogenase activity was found in any of the mycoplasmas examined. The stereoisomer of lactic acid accumulated during growth correlated perfectly with the type of NAD-dependent lactic dehydrogenase found in each mycoplasma. The types of lactic dehydrogenase activity found in these mycoplasmas were not related to genome size, DNA base composition, or sterol dependence.

Cell-Free System↗
PubMed1965

Oxidative Metabolism in Pediococcus pentosaceus III. Glucose Dehydrogenase System.

Lee, Chin K. (North Carolina State of the University of North Carolina, Raleigh), and Walter J. Dobrogosz. Oxidative metabolism in Pediococcus pentosaceus. III. Glucose dehydrogenase system. J. Bacteriol. 90:653-660. 1965.-A method was developed for the purification of glucose dehydrogenase from Pediococcus pentosaceus Az-25-5. The procedures included treatments with protamine sulfate, ammonium sulfate, and heat in addition to acid precipitation, calcium phosphate adsorption and elution, and diethylaminoethyl-Sephadex column chromatography. The final preparation thus obtained was purified 255-fold and exhibited both similarities and dissimilarities to the same enzyme isolated from other sources. The enzyme is absolutely specific for nicotinamide adenine dinucleotide phosphate (NADP) as a cofactor, and oxidizes only glucose or its analogue 2-deoxyglucose via the following reversible reaction: beta-d-glucose + NADP right harpoon over left harpoon d-glucono-delta-lactone + NADPH(2) + H(+). K(m) values were 2.3 x 10(-2) for glucose and 2 x 10(-4) for NADP. Monovalent cations were required for stability of the enzyme and stimulated activity. The pH optimum was 7.0, and the equilibrium constant was determined to be 13.4 x 10(-7) at pH 6.4. Among the Lactobacillaceae, glucose dehydrogenase activity was found to be essentially limited to members of the genus Pediococcus. Studies on the enzymatic composition of P. pentosaceus viewed in conjunction with other available data led to the conclusion that this enzyme is not involved to any significant extent in the energy metabolism of this organism.

Journal Article↗
PubMed1965

Numerical survey of some bacterial taxa.

Focht, D. D. (Iowa State University, Ames), and W. R. Lockhart. Numerical survey of some bacterial taxa. J. Bacteriol. 90:1314-1319. 1965.-A numerical analysis was made of 77 properties of each of 43 bacterial strains, representing 25 genera from 8 families in the orders Eubacteriales and Pseudomonadales. Four major groups were found, related to one another at approximately the same level of similarity: (1) a large cluster containing the subgroups (1a) Athiorhodaceae-Spirillaceae, (1b) Xanthomonas, and (1c) "inactive" Micrococcaceae-Achromobacteraceae; (2) a cluster containing the "active" Micrococcaceae and Lactobacillaceae; (3) the enterobacteria; and (4) Aeromonas. There was a sharp distinction between the branches of groups 1a, 1c, and 2. The composition of groups was essentially the same whether or not fermentation of carbohydrates (28 characters) was included in the analysis. Several individual strains, notably, Bacillus subtilis, Leuconostoc mesenteroides, Pseudomonas aeruginosa, and Erwinia amylovora, were related to none of the groups, and others (two species of Proteus, Flavobacterium devorans, and Lactobacillus casei) showed only minimal quantitative relationships with their groups. These results suggest that there may be significant variation in levels of similarity within microbial groups presently accorded equivalent taxonomic rank, and that some present distinctions among taxa, particularly at the generic level, cannot be confirmed on the basis of overall similarity.

Bacteria↗
PubMed1999

[Probiotics and their therapeutic properties].

Probiotics are specific products of microorganisms, and by being biologically active positively act on stabilizing the bacteriological flora of the gastrointestinal tract. They are live or lyophilized bacterial cultures, especially those derived from lactic fermentation (Lactobacillacea and Streptococcacea). The first to use the term probiotics were Lilly and Stillwell in 1965 when referring to substances produced by protozoa, which in turn stimulated the growth of other organisms. Probiotics are devoid of side affects and do not cause accumulation of toxic substances in the body. They are administered for therapeutic, prophylactic and nutritional purposes both in humans and in animals. Interest into probiotics has been spurred on by the growing abundance of civilization disorders such as neoplasms, atherosclerosis, heart disease, hypertension and HIV infection. Probiotics are potentially capable of annihilating these disorders. Starter cultures are pure mixed bacterial, fungal or mold cultures which by transformation of their metabolism faciliate favourable changes in apperance, aroma, consistency, and durability of foodstuffs. Contemporary knowledge concerning probiotics and their action is derived from many years of tradition in consumption of fermented milk products and the documentation of much research into strains of lactic bacteria, their harmless action on health and overall beneficial effect.

Animals↗
PubMed2000

Class II antimicrobial peptides from lactic acid bacteria.

Strains of lactic acid bacteria (LAB) produce a wide variety of antibacterial peptides. More than fifty of these so-called peptide bacteriocins have been isolated in the last few years. They contain 20-60 amino acids, and are cationic and hydrophobic in nature. Several of these bacteriocins consist of two complementary peptides. The peptide bacteriocins of LAB are inhibitory at concentrations in the nanomolar range, and cause membrane permeabilization and leakage of intracellular components in sensitive cells. The inhibitory spectrum is limited to gram-positive bacteria, and in many cases to bacteria closely related to the producing strain. Among the target organisms are food spoilage bacteria and pathogens such as Listeria, so that many of these antimicrobial peptides could have a potential as food preservatives as well as in medical applications.

Amino Acid Sequence↗
PubMed2002

Characterization of a hydrogen-producing granular sludge.

This study demonstrated that hydrogen-producing acidogenic sludge could agglutinate into granules in a well-mixed reactor treating a synthetic sucrose-containing wastewater at 26 degrees C, pH 5.5, with 6 h of hydraulic retention. A typical matured granule is 1.6 mm in diameter, 1.038 g/mL in density, 11% in ash content, and over 50 m/h in settling velocity. Treating a solution containing 12.15 g/L of sucrose at a volumetric loading rate of 48.6 g/(L x d), the reactor containing 20 g/L of granular sludge degraded 97% of sucrose. Effluent comprised 46% acetate and 49% butyrate and the methane-free biogas comprised 63% hydrogen, 35% carbon dioxide, and 2% nitrogen. Hydrogen production rate was 13.0 L/(L x d), and the yield was 0.28 L/g-sucrose. The granule had multiple cracks on the surface and comprised two morphological types of bacteria: fusiform bacilli and a spore-forming bacterium. Phylogenetic analysis showed that 69.1% of the clones were affiliated with four Clostridium species in the family Clostridiaceae, and 13.5% with Sporolactobacillus racemicus in the Bacillus/Staphylococcus group.

Alcohols↗
PubMed2002

Characterization of electrostatic binding sites of extracellular polymers by linear programming analysis of titration data.

Electrostatic binding sites of extracellular polymeric substances (EPS) were characterized from titration data using linear programming analysis. Test results for three synthetic solutions of given solutes comprising amino, carboxyl, and phenolic groups indicated that this method was able to identify the electrostatic binding sites. For the six sites with pK(a) between 3 and 10, the estimated pK(a) deviated 0.11 +/- 0.09 from the theoretical values, and the estimated concentrations deviated 3.0% +/- 0.9% from the actual concentrations. Two EPS samples were then extracted from a hydrogen-producing sludge (HPS) and a sulfate-reducing biofilm (SRB). Analysis of charge excess data in titration from pH 3 to 11 indicated that the EPS of HPS comprised of five electrostatic binding sites with pK(a) ranging from 3 to 11. The pK(a) values of these binding sites and the possible corresponding functional groups were pK(a) 4.8 (carboxyl), pK(a) 6.0 (carboxyl/phosphoric), pK(a) 7.0 (phosphoric), pK(a) 9.8 (amine/phenolic), and pK(a) 11.0 (hydroxyl). EPS of the SRB comprised five of similar binding sites (with corresponding pK(a) values of 4.4, 6.0, 7.4, 9.4, and 11.0), plus one extra site at pK(a) 8.2, which was likely corresponding to the sulfhydryl group. The total electrostatic binding site concentration of EPS extracted from HPS were 10.88 mmol/g-EPS, of which the highest concentration was from the site of pK(a) 11.0. The corresponding values for the EPS extracted from SRB were 16.44 mmol/g-EPS and pK(a) 4.4. The total concentrations of electrostatic binding sites found in this study were 20- to 30-fold of those reported for bacterial cell surface, implying that EPS might be more crucial in biosorption of metals than bacterial cell surface in wastewater treatment and in bioremediation.

Bacteria↗
PubMed2005

Growth of Leuconostoc mesenteroides NRRL-B523 in an alkaline medium: suboptimal pH growth inhibition of a lactic acid bacterium.

Bacterial profile modification (BPM), a form of tertiary oil recovery, diverts water from the water-flooded high-permeability zone into the oil-bearing low-permeability zone. During field use, exopolymer-producing bacteria plug the high-permeability zone only in the immediate vicinity of the injection point (the near-well bore region). For effective BPM the plug must penetrate far into the formation. Slowing the specific growth rate, lengthening the lag phase, and slowing the polymerization rate are techniques that can prolong the onset of biopolymer gelation and extend the depth of the biological plug. In batch experiments, the growth of Leuconostoc mesenteroides NRRL-B523 was inhibited by the synergistic effects of high substrate loading and an alkaline pH. Exponential growth was delayed up to 190 h. It was observed that cell division was significantly retarded until the medium pH, reduced by the acid byproducts of fermentation, reached a critical value of 6.79 +/- 0.06. A mathematical model was developed to describe the relationship between specific growth rate, lag time, and medium pH.

Bioreactors↗
PubMed1979

Dextran biosynthesis and dextransucrase production by continuous culture of Leuconostoc mesenteroides.

Leuconostoc mesenteroides NRRL B-512(F) was grown in continuous culture under conditions of energy-limited growth. The extracellular enzyme dextransucrase (sucrose: 1,6-alpha-D-glucan 6-alpha-glucosyltransferase EC 2.4.1.5), was not detected in glucose- or maltose-limited cultures. Under conditions of sucrose-limited growth, the enzyme activity of the cell-free culture supernatant increased with increasing dilution rate only after the critical concentration of enzyme inducer (sucrose) in the chemostat had been achieved. The appearance of fructose in the effluent of the sucrose-limited chemostat at higher dilution rates indicated that sucrose was being diverted to dextran biosynthesis. The competition between bacteria and extracellular enzyme for the common substrate sucrose represents an inefficiency in the system of enzyme production. Dextransucrase was isolated from the cell-free culture supernatant by ammonium sulfate precipitation and DEAE-cellulose chromatography. The enzyme preparation exhibited both dextran biosynthetic activity and an invertase-like activity. The biosynthetic efficiency was increased by decreasing the temperature from 30 to 10 degrees C. The enzyme was irreversibly denatured by prolonged incubation in the absence of Ca2+.

Dextrans↗
PubMed2006

Dysbacteriosis in silver-stained cervical smears of Dutch-Moroccan immigrants: HPV infection and preneoplasia.

The vaginal/cervical smears of a group of Moroccan immigrants were used to compare vaginal dysbacteriosis (i.e., a bacterial population change with a decrease in lactobacilli and an increase of coccoid bacteria in vaginal/cervical smears) with Dutch women. From our archives, 779 smears from Moroccan immigrants were compared with 1,060 smears of age-matched Dutch women. For bacterial flora, Jones-Marres silver stains were used to define four groups. Koilocytosis and cervical intraepithelial neoplasia (CIN) were also recorded. The bacterial vaginal flora of Moroccan immigrants and Dutch women was different. The Moroccan women had a lower dysbacteriosis than Dutch women (3% vs. 24%). Koilocytosis and CIN were less frequent in the immigrant population. The possible synergy of a disturbed vaginal flora with human papillomavirus (HPV), HIV, or cervical preneoplasia indicates that vaginal hygiene and a normal flora may have positive effects on the uterine cervix.

Case-Control Studies↗
PubMed2006

Dysbacteriosis and squamous (pre)neoplasia of immigrants and Dutch women as established in population-based cervical screening.

We examined the statistical relationships between dysbacteriosis and (pre)neoplasia related to age and ethnicity from the cervical screening of almost half a million smears. Data from 445,080 smears were coded according to KOPAC (the Dutch national cervical smear coding system) with nine grades. Prevalence per 100,000 smears and relative risks (RR) were calculated for dysbacteriosis and for squamous abnormalities. Patients were stratified by their probable country of origin. Dutch women had an RR of 0.92 for dysbacteriosis. Surinamese women had the highest RR for dysbacteriosis (RR = 2.36) and Moroccan women had the lowest (RR = 1.00). The same trends were seen for the risks of squamous abnormalities. The data for Turkish women follow the patterns of those for Surinamese women. The RR of dysbacteriosis is highest at 50 yr (1.28) and lowest at 35 yr (0.86). When dysbacteriotic and non-dysbacteriotic smears were compared, dysbacteriosis was observed more frequently in smears with squamous abnormalities (4.1% vs. 2.2%). Dysbacteriosis may warrant more intensive cytological surveillance and changes in lifestyle.

Adult↗
PubMed2006

Microscopic diagnosis of dysbacteriosis in stained vaginal smears in clinical practice.

Dysbacteriosis is a microscopical diagnosis. In women with dysbacteriosis, an overgrowth of coccoid bacteria and almost a complete absence of lactobacilli are observed in the (stained) vaginal smear. The aim of this study was to determine the accuracy of this microscopic diagnosis in clinical practice. The analysis concerned 342 consecutive cases in which the microscopy of the stained smears was performed by general practitioners trained in diagnosing dysbacteriosis. These smears were sent to the pathologist for confirmation of the microscopical diagnosis of the clinician. The cytological diagnoses of the pathologist, sometimes performed on restained slides when the quality of the staining was substandard, were considered as the "gold standard." In 92 of the 342 cases, dysbacteriosis was unequivocally established by the pathologist. Sensitivity and specificity of the microscopical diagnoses of the clinicians were 40% and 85%, respectively. There were 37 false-positive and 54 false-negative diagnoses of dysbacteriosis rendered by the clinicians. The most frequent reason for a false-negative diagnosis was an excess of lactobacilli in the smear. This study shows that even in stained smears it is difficult for clinicians to render a correct evaluation of the status of the vaginal flora.

Adult↗
PubMed1985

Effect of iron on neonatal gut flora during the first three months of life.

To study the effect of milk supplemented with iron on neonatal gut flora, faecal specimens of ten infants receiving breast milk, six receiving a cow-milk preparation supplemented with iron (5 mg/l) and seven receiving the same product without iron supplement (iron concentration less than 0.5 mg/l) were examined during the first 12 weeks of life. In breast-fed infants bifidobacteria was predominant, counts of Escherichia coli were low, and other bacteria were rarely present. Infants receiving fortified cow-milk preparation had high counts of Escherichia coli, counts and isolation frequency of bifidobacteria were low and other bacteria were frequently isolated. In those on unfortified cow-milk preparation isolation frequency of Escherichia coli, bifidobacteria and bacteroides was comparable with that in breast-fed infants; however, counts of Escherichia coli were high. It is concluded that the faecal flora of infants fed unfortified cow-milk preparation acquires characteristics of that found in breast-fed infants.

Animals↗
PubMed2002

Isolation of Carnobacterium piscicola from human pus--case report.

Carnobacterium piscicola was first described in 1984. These bacteria are often isolated from fish afflicted with bacterial infections. To date, there has been no reported isolation of this bacterium from human specimens. We report here the isolation of C. piscicola from the pus following traumatic amputation of the right hand in the wrist of a 35-year-old man. The traumatic amputation occurred with an industrial water sawmill. The identity of the human strain was determined biochemically, by 16S rDNA sequence similarity and by fatty-acid methyl-ester profile from bacterial cell.

Adult↗