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PubMed1986

Direct measurement of femtogram amounts of DNA in cells and chloroplasts by quantitative microspectrofluorometry.

Absolute DNA amounts of individual chloroplasts were determined by measuring the fluorescence intensity of chloroplasts stained with 4',6-diamidino-2-phenylindole (DAPI) relative to that of the bacterium Pediococcus damnosus (cerevisiae) smeared on the same slide. An absolute DNA content of 7.7 X 10(15) g for a standard P. damnosus cell type was calculated by comparing the relative fluorescence values and frequency of each stage of cellular development in a culture to the average DNA content of all cell types determined by chemical methods. Chlorophyll was extracted from the chloroplasts during fixation so that chlorophyll autofluorescence was not present when DAPI fluorescence was measured. Absolute amounts of DNA could then be determined for single chloroplasts, either within cells that were individually selected from a mixed cell population or in small preparations of isolated chloroplasts. The DNA amounts of chloroplasts from mesophyll cells determined in this way were similar to the values previously determined by bulk averaging methods. Chloroplast DNA amounts from different cell types of the leaf could be measured by microspectrofluorometry, and it was found that chloroplasts from spinach epidermal cells contained about half as much DNA as chloroplasts from adjacent mesophyll cells.

Brassica↗
PubMed1996

Chemical composition of the cell wall of lactic acid bacteria and related species.

In order to examine the relationship between biological activities and the cell wall content, the murein type and the teichoic acid of the cell wall from five strains of bacteria were studied. Two of these Lactobacillus casei CRL 431 and L. acidophilus CRL 730, are used in a commercial fermented milk (BIO MILK), which is believed to be beneficial for health. The other strains, Lactococcus lactis CRL 526, Pediococcus pentosaceus CRL 923 and Propionibacterium acidipropionici CRL 1198 were included in order to compare the cell wall structures of active and inactive strains. A method was designed to confirm the amino acids of the peptidoglycan in impure substrates. Four of the studied strains, L. casei, L. acidophilus, L. lactis and P. acidipropionici, contained glycerol teichoic acids. L. casei, L. acidophilus, P. pentosaceus and L. lactis contained A4 alpha type murein, while P. acidipropionici contained A3 gamma type. The capacity of orally administered peptidoglycans of the studied strains to stimulate phagocytosis by mouse peritoneal macrophages was analyzed. Only the PG of L. casei showed this activity. No differences were observed between active and inactive strains with respect to the chemical composition of the peptidoglycan. Therefore the biological activity is unlikely to be due to the peptidoglycan structure.

Animals↗
PubMed2000

Intake, digestibility, and composition of orchardgrass and alfalfa silages treated with cellulase, inoculant, and formic acid fed to lambs.

The objectives of this study were to determine the effect of a cellulase (from Trichoderma longibrachiatum) alone or combined with a bacterial inoculant (Lactobacillus plantarum and Pediococcus cerevisiae) or formic acid on composition, intake, and digestibility of orchardgrass (Dactylis glomerata L.) and alfalfa (Medicago sativa L.) silages. Orchardgrass and alfalfa were harvested at the early heading stage and at the early bloom stage of maturity and wilted to approximately 22 and 32% DM, respectively. Forages were then ensiled in 100-L sealed barrels for at least 60 d before they were fed to lambs. Silage treated with cellulase had lower (P < .001) pH and lower (P < .001) acetic acid and NH3 N concentrations than untreated silage of both plant species and a higher (P = .004) lactic acid concentration than the control treatment of alfalfa silage. Fermentation characteristics of cellulase-treated silages, especially of alfalfa, were further enhanced by use of inoculant. Formic acid addition increased (P < .001), reducing sugar concentration of cellulase-treated orchardgrass and alfalfa silage by 90 and 154%, respectively, and decreased (P < .001) NH3 N concentration of cellulase-treated alfalfa silage by 19%. Averaged across plant species, cellulase, combined with inoculant or formic acid, resulted in 8 and 13% greater (P = .03) DMI, respectively, than the control silage. Extensive enzymatic cell-wall degradation during ensiling decreased (P = .003) NDF intake of cellulase-treated orchardgrass silage by 25% and decreased (P = .001) cellulose intake by 23%, when averaged across plant species. Addition of formic acid increased (P = .003) NDF intake of cellulase-treated orchardgrass silage by 19%. Averaged across species, cellulase application decreased (P < .05) silage NDF digestibility by 18%. Greater sugar and lower acetic acid, NH3 N, and NDF concentrations resulted in greater DMI of cellulase-treated silage than of control silage, when cellulase was combined with formic acid or inoculant.

Animal Feed↗
PubMed2000

Enzyme, bacterial inoculant, and formic acid effects on silage composition of orchardgrass and alfalfa.

We evaluated the effects of cellulase (from Trichoderma longibrachiatum) application rates on neutral detergent fiber (NDF) concentration and fermentation products of orchardgrass (Dactylis glomerata L.) and alfalfa (Medicago sativa L.) silages harvested with decreasing dry matter (DM) digestibility. Additionally, the impacts of inoculant (Lactobacillus plantarum and Pediococcus cerevisiae), pectinase (from Aspergillus niger), or formic acid on silage composition were studied. Forages wilted to a DM content of about 320 g/kg were ensiled in laboratory silos for 60 d. Cellulase, combined with inoculant, was applied at 2, 10, and 20 ml/kg of herbage (at least 2500 IU/ml). Cellulase at 10 ml/kg was also applied alone or in combination with pectinase and inoculant or formic acid. The NDF concentration of orchardgrass silage decreased with increasing cellulase up to 20 ml/kg, at which NDF content was decreased by 30%. The NDF concentration of alfalfa silage decreased with increasing cellulase application up to 10 ml/kg, at which NDF content was decreased by 13%. Immature plants were more responsive to cellulase treatment than mature plants. Cellulase at 2 ml/kg combined with inoculant improved fermentation characteristics of the silages but generally, there was no effect on silage fermentation by higher cellulase applications, resulting in an accumulation of sugar. The improved fermentation of orchardgrass treated with cellulase and inoculant was mostly related to the effect of inoculant, whereas cellulase alone improved fermentation characteristics of alfalfa silage and this effect was enhanced by addition of inoculant. Decreased NDF and increased sugar concentrations did not improve the in vitro DM digestibility of cellulase-treated silages.

Aspergillus niger↗
PubMed1993

Fate of Listeria monocytogenes and pediococcal starter cultures during the manufacture of chicken summer sausage.

Two formulations of chicken summer sausages [100% hand deboned chicken meat (HDCM) and 85% HDCM and 15% chicken hearts (HDCM-CH)] were prepared with a nonpediocin-producing (PED-) Pediococcus acidilactici starter culture and inoculated with 10(4) or 10(7) cfu of a five-strain mixture of Listeria monocytogenes/g of batter. Sausages were fermented to pH 5.0 (11 h), cooked to an internal temperature of 66.5 C, cold-showered, and stored at 4 C (60 days) and 30 C (7 days). For both formulations and inoculation levels, L. monocytogenes populations decreased 1.3 to 1.8 log10 cfu/g by the end of fermentation. No L. monocytogenes organisms were recovered from sausages (by enrichment) following the cook and shower or storage at 4 or 30 C. In contrast, P. acidilactici increased .7 to 1.2 log10 cfu/g during fermentation, and < 10(2) cfu/g remained after the cook and shower and storage at 4 and 30 C. In a second set of experiments, sausages (HDCM) were prepared with a PED- or a pediocin-producing (PED+) P. acidilactici starter culture and challenged with the L. monocytogenes mixture (10(7) cfu/g). The PED- culture reduced numbers of L. monocytogenes 1.2 log10 cfu/g during fermentation, whereas L. monocytogenes numbers declined 2.6 log10 cfu/g in the presence of the PED+ culture. Although acid production by both starter cultures was equivalent, greater inhibition of L. monocytogenes by the PED+ compared with the PED- starter culture was attributed to in situ production of pediocin. Pediococcal starter cultures and proper cooking eliminated L. monocytogenes from sausages and established that PED+ cultures provide an additional hurdle against poultry-related listeriosis.

Animals↗
PubMed1999

Effect of diacetyl on controlling Escherichia coli O157:H7 and Salmonella Typhimurium in the presence of starter culture in a laboratory medium and during meat fermentation.

Diacetyl is a flavor compound that possesses antimicrobial activity and is found in several dairy products. The effect of diacetyl on controlling the growth of two foodborne pathogens, Escherichia coli O157:H7 and Salmonella Typhimurium, when grown with Pediococcus acidilactici as a meat starter culture was evaluated in a laboratory medium and during salami fermentation. Diacetyl (50 ppm) added to each mixed culture system strongly inhibited the growth of E. coli O157:H7 and Salmonella Typhimurium in the laboratory medium (brain heart infusion, 2.3% of NaCl, 0.75% of dextrose) (P < 0.05). During meat fermentation, the growth of E. coli O157:H7 and Salmonella Typhimurium was inhibited significantly by addition of diacetyl (300 ppm) (P < 0.05) after 24 h fermentation. However, the acid production and growth of P. acidilactici were not affected by the addition of diacetyl (P > 0.05). After 24 h meat fermentation, about a 1.0-log CFU/g difference occurred in numbers of each foodborne pathogen mixed with P. acidilactici (P < 0.05) with and without 300 ppm diacetyl. Diacetyl and the acid produced by the meat starter culture reduced the growth of the two foodborne pathogens during salami fermentation. These results suggest that diacetyl can be used as a food ingredient during meat fermentation to control E. coli O157:H7 and Salmonella Typhimurium without harmful effects on the growth and acid production of P. acidilactici.

Animals↗
PubMed2000

Stimulation of starter culture for further reduction of foodborne pathogens during salami fermentation.

This study was conducted to determine if stimulated meat starter culture (MSC; Pediococcus acidilactici) would further control Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus during salami fermentation. Manganese ion (0.005% of MnSO4) was used as a stimulator for the growth and acid production of MSC. After 24-h salami fermentation, nonstimulated MSC and stimulated MSC reduced E. coli O157:H7 levels by 1.3 and 2.3 log10 units, respectively. Nonstimulated MSC reduced L. monocytogenes levels by 1.2 log10 units, whereas the stimulated MSC achieved a 2.2-log10 reduction after 24-h fermentation. In the case of S. aureus, nonstimulated MSC and stimulated MSC reduced S. aureus levels by 1.3 and 2.3 log10 units after 24-h fermentation, respectively. Stimulated MSC by MnSO4 reduced those foodborne pathogens more effectively compared with nonstimulated MSC (P < 0.05).

Animals↗
PubMed2003

Isolation, selection, and characterization of lactic acid bacteria for a competitive exclusion product to reduce shedding of Escherichia coli O157:H7 in cattle.

Lactic acid bacteria (LAB) were selected on the basis of characteristics indicating that they would be good candidates for a competitive exclusion product (CEP) that would inhibit Escherichia coli O157:H7 in the intestinal tract of live cattle. Fecal samples from cattle that were culture negative for E. coli O157:H7 were collected. LAB were isolated from cattle feces by repeated plating on deMan Rogosa Sharpe agar and lactobacillus selection agar. Six hundred eighty-six pure colonies were isolated, and an agar spot test was used to test each isolate for its inhibition of a four-strain mixture of E. coli O157:H7. Three hundred fifty-five isolates (52%) showed significant inhibition. Seventy-five isolates showing maximum inhibition were screened for acid and bile tolerance. Most isolates were tolerant of acid at pH levels of 2, 4, 5, and 7 and at bile levels of 0.05, 0.15, and 0.3% (oxgall) and were subsequently identified with the API system. Lactobacillus acidophilus, Lactobacillus fermentum, Lactobacillus delbreukii, Lactobacillus salivarius, Lactobacillus brevis, Lactobacillus cellobiosus, Leuconostoc spp., and Pediococcus acidilactici were the most commonly identified LAB. Nineteen strains were further tested for antibiotic resistance and inhibition of E. coli O157:H7 in manure and rumen fluid. Four of these 19 strains showed susceptibility to all of the antibiotics, 13 significantly reduced E. coli counts in manure, and 15 significantly reduced E. coli counts in rumen fluid (P < 0.05) during at least one of the sampling periods. One of the strains, M35, was selected as the best candidate for a CEP. A 16S rRNA sequence analysis of M35 revealed its close homology to Lactobacillus crispatus. The CEP developed will be used in cattle-feeding trials.

Animals↗
PubMed2003

Inhibition of nonproteolytic Clostridium botulinum with lactic acid bacteria and their bacteriocins at refrigeration temperatures.

Nonproteolytic Clostridium botulinum (strains 17B, Beluga, and 202F) was found to be inhibited by Lactobacillus, Lactococcus, Streptococcus, and Pediococcus species in tests by the spot-on-the-lawn simultaneous-antagonism method at 10, 15, and 25 degrees C. C. botulinum 17B was the most resistant strain. Inhibition zone size increased with decreasing incubation temperature. Six strains of Lactobacillus acidophilus and seven strains of bifidobacteria failed to produce an inhibition zone on buffered reinforced clostridium Prussian blue agar seeded with spores of any of the selected C. botulinum strains. C. botulinum 17B was sensitive to 50 to 100 IU of nisin per ml and to 10 to 20 AU of pediocin A per ml.

Bacteriocins↗
PubMed2005

Assessment of the effects of Nurmi-type cultures and a defined probiotic preparation on a Salmonella typhimurium 29E challenge in vivo.

The effects of treatment with an undefined commercial Nurmi-type culture (NTC), cultured cecal contents, and a dual-strain probiotic, containing Enterococcus faecalis and Pediococcus pentosaceus, on Salmonella Typhimurium colonization were evaluated in a specific-pathogen-free bird model. Two sets of trials were performed, and each study was arranged as a randomized complete block design with three treatments. Treatments consisted of (i) control, (ii) commercial NTC, and (iii) cultured cecal contents in the first set of trials and (i) control, (ii) defined probiotic, and (iii) cultured cecal contents in the second set. On day 1, birds were administered 1.2 x 10(7) CFU of the appropriate treatment by oral gavage. On day 3, all birds were challenged with 1 x 10(6) CFU of Salmonella Typhimurium 29E (nalidixic acid resistant). Chicks were asphyxiated with argon gas on day 10, and ceca were aseptically removed. Salmonella Typhimurium counts (CFU per milliliter of cecal contents) were determined on brilliant green agar containing 30 mg of nalidixic acid per liter, and CFU counts were log transformed prior to analysis. Cecal pH and volatile fatty acid concentrations were also determined. Data were analyzed by one-way analysis of variance, and means were compared by Tukey's pairwise analysis. Commercial NTC and cultured cecal contents treatments resulted in a significant decrease (P < or = 0.05) in Salmonella Typhimurium 29E colonization, with the NTC offering a higher level of protection. In the second set of trials, the defined probiotic tended to reduce colonization by Salmonella Typhimurium (P = 0.07), while chicks treated with cultured cecal contents displayed a significant decrease (P = 0.03) when compared to the negative control. No significant change was observed in cecal pH or in acetate and propionate concentrations; however, a significant increase in butyrate concentrations in both the cultured cecal contents and defined probiotic treatment groups was observed when compared to the control birds. These observations suggest that defined cultures are less effective Salmonella control agents than are preparations generated from the complete cecal microflora.

Administration, Oral↗
PubMedDate not supplied

Lactic acid bacteria in the quality improvement and depreciation of wine.

The winemaking process includes two main steps: lactic acid bacteria are responsible for the malolactic fermentation which follows the alcoholic fermentation by yeasts. Both types of microorganisms are present on grapes and on cellar equipment. Yeasts are better adapted to growth in grape must than lactic acid bacteria, so the alcoholic fermentation starts quickly. In must, up to ten lactic acid bacteria species can be identified. They belong to the Lactobacillus, Pediococcus, Leuconostoc and Oenococcus genera. Throughout alcoholic fermentation, a natural selection occurs and finally the dominant species is O. oeni, due to interactions between yeasts and bacteria and between bacteria themselves. After bacterial growth, when the population is over 10(6) CFU/ml, malolactic transformation is the obvious change in wine composition. However, many other substrates can be metabolized. Some like remaining sugars and citric acid are always assimilated by lactic acid bacteria, thus providing them with energy and carbon. Other substrates such as some amino acids may be used following pathways restricted to strains carrying the adequate enzymes. Some strains can also produce exopolysaccharides. All these transformations greatly influence the sensory and hygienic quality of wine. Malic acid transformation is encouraged because it induces deacidification. Diacetyl produced from citric acid is also helpful to some extent. Sensory analyses show that many other reactions change the aromas and make malolactic fermentation beneficial, but they are as yet unknown. On the contrary, an excess of acetic acid, the synthesis of glucane, biogenic amines and precursors of ethylcarbamate are undesirable. Fortunately, lactic acid bacteria normally multiply in dry wines; moreover some of these activities are not widespread. Moreover, the most striking trait of wine lactic acid bacteria is their capacity to adapt to a hostile environment. The mechanisms for this are not yet completely elucidated. Molecular biology has provided some explanations for the behaviour and the metabolism of bacteria in wine. New tools are now available to detect the presence of desirable and undesirable strains. Even if much remains unknown, winemakers and oenologists can nowadays better control the process. By acting upon the diverse microflora and grape musts, they are more able to produce healthy and pleasant wines.

Carbohydrate Sequence↗
PubMedDate not supplied

[Biological deacidification of wines using lactic-acid bacteria and yeasts].

Based on a study of 200 lactic-acid bacteria monocultures and 30 associating lactic bacteria and yeasts cultures, a stable association was created formed by Leuconostoc oenos, Pediococcus pentosaceus and Saccharomyces cerevisiae yeasts, intended for the biological deacidification of wine. Physiology of microorganisms and their effect on the wine chemical composition was studied. By means of selective association, high quality fine wines were produced from the high-acid wines.

Food Microbiology↗
PubMed2003

Bacteriological evaluation of dog and cat diets that claim to contain probiotics.

Nineteen commercial pet foods claiming to contain probiotics were evaluated. Selective bacterial culture was performed to identify organisms that were claimed to be present. Twelve diets claimed only to contain specific bacterial fermentation products, which does not necessarily indicate that live growth would be expected, but these products also included the term "probiotic" somewhere on the package, suggesting that live, beneficial organisms were present. No products contained all of the listed organisms, while 1 or more of the listed contents were isolated from 10 out of 19 products (53%). Eleven products contained additional, related organisms including Pediococcus spp, which was isolated from 4 products. No relevant growth was present in 5 (26%) products. Average bacterial growth ranged from 0 to 1.8 x 10(5) CFU/g. Overall, the actual contents of the diets were not accurately represented by the label descriptions.

Animal Feed↗
PubMed2005

[Partial sequence homology of FtsZ in phylogenetics analysis of lactic acid bacteria].

FtsZ is a structurally conserved protein, which is universal among the prokaryotes. It plays a key role in prokaryote cell division. A partial fragment of the ftsZ gene about 800bp in length was amplified and sequenced and a partial FtsZ protein phylogenetic tree for the lactic acid bacteria was constructed. By comparing the FtsZ phylogenetic tree with the 16S rDNA tree, it was shown that the two trees were similar in topology. Both trees revealed that Pediococcus spp. were closely related with L. casei group of Lactobacillus spp. , but less related with other lactic acid cocci such as Enterococcus and Streptococcus. The results also showed that the discriminative power of FtsZ was higher than that of 16S rDNA for either inter-species or inter-genus and could be a very useful tool in species identification of lactic acid bacteria.

Bacterial Proteins↗
PubMed1975

Transport and metabolism of folates by bacteria.

Transport of labeled folic acid (PteGlu), pteroylpolyglutamates (PteGlu3-5), 5-methyl-tetrahydrofolate (5-methyl-H4PteGlu), and methotrexate in late-log phase cells of Lactobacillus casei was active, and subject to inhibition by unlabeled pteroylmonoglutamates, pteroylpolyglutamates, and iodoacetate, but not glutamate or glutamate dipeptides. Pteroylpolyglutamates were transported without prior hydrolysis and shared a common uptake system with pteroylmonoglutamates. The affinity and maximum velocity of PteGlun uptake decreased with increasing glutamate chin length (Km:PteGlu1, 0.03 mum; PteGlu3, 0.32 mum; PteGlu4, 1.9 mum; PteGlu5, 3.7 mum) and comparisons with growth response curves suggested that polyglutamates were more effectively utilized by L. casei, once transported, than monoglutamate. No concentration of 5-methyl-H4PteGlu3-8 inside the cells was observed. The major folate metabolites found in L. casei preloaded with high levels of [3H]PteGlu (0.5 mum) were 10-formyl-H4PteGlu2 and 10-formyl-PteGlu. Both compounds were released, the monoglutamate more rapidly. Pteroyltriglutamate formation appeared to be a rate-limiting step in intracellular metabolism. No 10-formyl-Pte-Glu was found in iodoacetate-treated cells and efflux was inhibited. Cells preloaded with low levels of [3H]PteGlu (7 nm) metabolized the vitamin to polyglutamate forms, the major derivatives being H4PteGlun. First order exit rates of labeled folate from preloaded L. casei indicated an inhibition of PteGlu uptake with time. Exit rates dropped from 0.05 min-1 to greater than 0.002 min-1 as intracellular folate was metabolized from monoglutamate to polyglutamate derivatives (n larger than or equal to 3). In the latter case, materials lost by efflux were breakdown products and no folate of glutamate chain length greater than two was released. Pediococcus cerevisiae actively transported 5-methyl-H4PteGlu but did not take up to 5-methyl-H4PTeGlu3-8. No active accumulation of 5-methyl-H4PteGlu was observed in Streptococcus faecalis.

Azides↗
PubMedDate not supplied

Forms of human milk folacin and variation patterns.

The pattern of folacin in 180 human milk samples collected from 16 women was studied before and after pteroylglutamic hydroxylase (conjugase) treatment. The differential response of Lactobacillus casei versus Streptococcus faecalis distinguishes N-5-methyltetrahydrofolate from other forms. Growth of Pediococcus cerevisiae differentiates the reduced monoglutamates, other than the N-5-methylated derivative, from oxidized folacins. Mean folacin activity with L. casei was 85.3 ng/ml. Prior to conjugase treatment of samples, mean activity was 46.9 ng/ml with this organism. The responses of S. faecalis and P. cerevisiae were 48% and 7.6%, respectively, of the total L. casei active folacins. The total L. casei active folacins increased from 76.5 ng/ml at 6 weeks of lactation to 97.1 ng/ml at 12 weeks of lactation. Increases were also observed with time of day: from morning (65.7 ng/ml), to afternoon (80.0 ng/ml), and to evening (114.7 ng/ml). Hindmilk had greater total L. casei activity (100.0 ng/ml) than foremilk (73.8 ng/ml). Although folacins active for S. faecalis and P. cerevisiae were not affected by duration of lactation, increases in folacin activity with time of day and from fore- to hindmilk were observed using both of these organisms. Values for the folacin content of human milk are therefore dependent on sampling procedures. Pteroylpolyglutamates of greater than or equal to 3 glutamic acid residues and N-5-methyltetrahydrofolate are the predominant forms of human milk folacin based on differential growth responses of L. casei, S. faecalis, and P. cerevisiae to these forms.

Bacteriological Techniques↗
PubMed1987

[Taxonomic study of epiphyte lactic bacteria in grapes in Galicia].

A taxonomic analysis of the malolactic microflora present in nine grape samples from different zones of Galicia, was carried out. Nineteen strains were isolated and identified as Lactobacillus plantarum (42%), L. brevis (10.6%), L. casei (5.25%), L. hilgardii (5.25%), Streptococcus cremoris (5.25%), Leuconostoc lactis (5.25%), L. oenos (10.6%), and Pediococcus acidilactici (15.8%).

Fruit↗
PubMed1987

[Influence of vancomycin by venous route on salivary and fecal aerobic floras].

An IV vancomycin treatment induces a reduction of Gram positive cocci (Staphylococcus, Enterococcus) of the aerobic salivary and fecal flora. Some of these strains persisted during and after treatment, but remained susceptible to vancomycin. Others isolated Gram positive cocci were resistant to vancomycin before and after treatment. They were identified as Pediococcus sp., and Leuconostoc sp. There is a reduction of the number of Gram positive cocci, without increase of Gram negative rods, Lactobacillus, or Candida which are always resistant to vancomycin.

Acinetobacter↗