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Bacterial adhesion to silica sand as related to Gibbs energy variations.

Bacterial adhesion to silica sand was related to variations in system Gibbs energy DeltaG(adh). Two typical Gram-positive bacterial strains of Streptococcus mitis and Lactobacillus casei were used as the model bacteria in this research. Impacts of solution chemistry and goethite coating of silica sand on bacterial adhesion were also explored. S. mitis and L. casei had negative DeltaG(adh) with both uncoated and goethite-coated silica sand, demonstrating their adhesion potentials to these substrate. After goethite coating, DeltaG(adh) decreased (negatively increased) for both S. mitis and L. casei. In the presence of rhamnolipid biosurfactant, DeltaG(adh) increased (negatively decreased) in answer to the increase of the rhamnolipid biosurfactant concentration. Bacterial percentage adhesion to silica sand corresponded to DeltaG(adh). This study demonstrated that bacterial adhesion to substrate could be explained in terms of bacterial, substratum and intervening medium physicochemical surface properties, which can be independently determined based on contact angle measurements.

Bacterial Adhesion↗

Methotrexate analogues. 14. Synthesis of new gamma-substituted derivatives as dihydrofolate reductase inhibitors and potential anticancer agents.

The gamma-tert-butyl ester (1), gamma-hydrazide (2), gamma-n-butylamide (3), and gamma-benzylamide (4) derivatives of methotrexate (MTX) were synthesized from 4-amino-4-deoxy-N10-methylpteroic acid (APA) and the appropriate blocked L-glutamic acid precursors with the aid of the peptide bond forming reagent diethyl phosphorocyanidate. The affinity of these side chain modified products for dihydrofolate reductase (DHFR) from Lactobacillus casei and L1210 mouse leukemic cells was determined spectrophotometrically or by competitive radioligand binding assay, and their cytotoxicity was evaluated against L1210 leukemic cells in culture. The results provide continuing support for the view that the "gamma-terminal region" of the MTX side chain is an attractive site for molecular modification of this anticancer agent.

Animals↗

Competition for glucose between Candida albicans and oral bacteria grown in mixed culture in a chemostat.

The competition for glucose as a growth-limiting substrate between Candida albicans and a mixed community of oral bacteria was investigated. A chemostat was operated under glucose-limiting and glucose excess conditions at a dilution rate of 0.05/h. A mixed population of oral bacteria was established and after a steady state had been reached the chemostat was inoculated with C. albicans. Seven bacterial species Streptococcus sanguis, S. sobrinus, S. mitis, Lactobacillus casei, Veillonella dispar, Eubacterium saburreum and Fusobacterium nucleatum - were able to establish stable populations under glucose-limiting conditions. The yeast was unable to grow with the bacteria under glucose limitation. Only three bacterial species, S. sobrinus, L. casei and E. saburreum, became established under glucose-excess conditions. C. albicans was also able to become established in the glucose-excess chemostat and could grow and maintain a steady state in a mixed culture with these organisms. L. casei, S. mitis and S. sobrinus had faster glucose consumption rates than C. albicans. All the bacteria, except for E nucleatum, had maximum specific growth rates higher than C. albicans. The results suggest that glucose may act as a growth-limiting substrate for C. albicans in the establishment and growth of the yeast in a mixed community of oral bacteria.

Bacteria↗

Purification and identification of potentially bioactive peptides from enzyme-modified cheese.

Antihypertensive peptides inhibiting angiotensin I-converting enzyme have been isolated from enzymatic hydrolysates of various food materials, but no information is available on the isolation of antihypertensive peptides from enzyme-modified cheese. In this study, several bioactive peptides, mainly potential antihypertensive peptides from enzyme-modified cheese prepared by commercial and Lactobacillus casei enzymes, were purified and identified. Enzyme-modified cheese samples were prepared by combination of Neutrase (1883.0 U/ml), L. casei enzymes (amino peptidase activity 86.4 leucine aminopeptidase U/g), and Debitrase (22.0 leucine aminopeptidase U/g). The water-soluble fractions of the enzyme-modified cheeses that were prepared by different enzymes were subjected to reverse-phase HPLC on a Delta Pak C18 column. Each peak was purified on the same column using a binary gradient. One peak from the Neutrase digest, five peaks from the Neutrase-Debitrase digest, and two peaks from the Neutrase-Lactobacillus enzyme digest were purified and identified by API mass spectrometry. On the basis of their molecular masses, amino acid sequences of purified peptides were identified. beta-Casomorphin with a sequence like that of beta-casein (YPFPGPI f 60-66) was found after the Neutrase digest. All of the peptides purified from the digests with combination of Neutrase and Debitrase or Neutrase and L. casei enzymes contained active sites in their sequences. The presence of sites containing potential antihypertensive peptides suggests that the purified peptides may have antihypertensive properties. Thus, the enzyme-modified cheese process, mainly designed to produce flavor ingredients, may simultaneously produce bioactive peptides, which are considered to be of physiological importance.

Amino Acid Sequence↗

Application of antimicrobial-producing lactic acid bacteria to control pathogens in ready-to-use vegetables.

Five psychrotrophic strains of lactic acid bacteria (Lactobacillus casei, Lact. plantarum and Pediococcus spp.) were isolated from 22 samples of commercial salads. These strains were shown to inhibit Aeromonas hydrophila, Listeria monocytogenes, Salmonella typhimurium and Staphylococcus aureus on MRS agar, in salads and in juice prepared from vegetable salads. Lactobacillus casei IMPCLC34 was most effective in reducing total mesophilic bacteria and the coliform group; Aer. hydrophila, Salm. typhimurium and Staph. aureus disappeared after 6 d of storage, while the counts for L. monocytogenes remained constant. The potential application of antimicrobial-producing lactic acid bacteria as biopreservatives of ready-to-use vegetables is suggested.

Antibiosis↗

Effect of Tween 80 on incubation period of Lactobacillus casei assay of serum folate.

Contamination of folic acid assay medium with oleate led to a lag phase when Lactobacillus casei cultures were grown on folic acid but not when whole serum provided the folate source. This led to high assay values when using 20-hour incubation periods but satisfactory results were obtained after 48 hours' incubation. The addition of Tween 80 to the medium eliminated the lag phase and the assay results were consistent after 13, 24, and 48 hours' incubation.

Biological Assay↗

Salivary pH-rise activities in caries-free and caries-active naval recruits.

Kleinberg (1967) (Archs oral Biol. 12, 1457-1473) has observed that the incubation of a salivary sediment/supernatant mixture with a low concentration of glucose produces a pH drop followed by a pH rise. As this pH-rise effect could elevate oral pH in vivo, the degree of such activity could be directly related to caries resistance. The pH-rise of paraffin-stimulated whole saliva samples from 54 caries-free and 54 caries-active male naval recruits was compared in two assays. The first, conducted with sediment/supernatant/2.8 mM glucose mixtures, showed no significant differences for mean pH versus time profiles for 26 caries-free and 26 caries-active subjects. Concomitant assays, in which 3.33 mM arginine and water replaced the supernatants in the assay mixtures, showed slightly higher mean pH/time profiles, with higher minima for the caries-free subjects. These profile differences were statistically significant for the arginine-containing mixtures, a result attributed to different microbial distributions for the caries-free and caries-active sediments. The second assays were conducted on saliva supernatants from 28 caries-free and 28 caries-active subjects, employing a strain of Lactobacillus casei in place of salivary sediment in the assay system. No statistically significant differences were evident between the mean pH/time profiles for the two groups of subjects, although a significant positive correlation was observed between pH minimum and bicarbonate content of the samples. Thus no relationship of salivary pH-rise activity and caries experience were found.

Arginine↗

Aortic graft infection by Lactobacillus casei: a case report.

A 65-year-old man with an abdominal aortic endoprosthesis presented with fever without other symptoms. Investigations revealed Lactobacillus casei bacteraemia. The Lactobacillus graft infection was at first successfully treated by antibiotic therapy. However, during follow-up a relapse occurred, and after surgical replacement of the graft the patient was cured. At surgery an aortoenteric fistula was found as source of the infection.

Aged↗

Experimental production of elevated serum folate in dogs with intestinal blind loops. II. Nature of bacterially produced folate coenzymes in blind loop fluid.

Jejunal and ileal blind loops were constructed in separate groups of dogs and the folate coenzymes present in these loops were investigated. Although only those dogs with high blind loops had appreciably elevated folate levels active for Lactobacillus casei but not Streptococcus faecalis, every blind loop appeared to contain four folate compounds--5-formyltetrahydrofolic acid, 5-methyltetrahydrofolic acid, tetrahydrofolic acid and a compound tentatively identified as 5-formyltetrahydrofolic triglutamate. Why increased levels of 5-methyltetrahydrofolate alone are present in the serum of dogs with a high blind loop is discussed.

Animals↗

[Colonization of the digestive tract by defined lactoflora in gnotobiotic and conventional lambs].

The effect of Lactobacillus casei 249/89 on the colonization of the intestinal tract and selected indicators of the metabolic profile of gnotobiotic and conventional lambs from the viewpoint of its possible utilization in the prevention of diarrhoeal syndrome of bacterial etiology in young animals has been studied. Five gnotobiotic and three conventional lambs were used in these studies. The lambs were slaughtered at 3, 6, 10, 15 and 21 days of age. The population of L. casei colonizing the intestinal epithelium was at the age dynamics on average higher in gnotobiotic lambs compared with lactobacilli in conventional lambs (Fig. 1). The significant difference (p < 0.001) was noted at the age of 3 days (gnotobiotic lambs = 3.40 log 10/cm2 and conventional lambs = 1.08 log 10/cm2). Also the counts of lactobacilli colonizing individual sections of the intestine (Fig. 2) was on average higher in gnotobiots with significant differences in jejunum and colon (p < 0.05). In both groups, the highest number of lactobacilli was observed on the intestinal epithelium in lower sections of the digestive tract. In gnotobiots, the population of L. casei colonizing the duodenum was highest at the age of 3 days (3.49 log 10/cm2), in jejunum (3.74 log 10/cm2) and in ileum 4.37 log 10/cm2) at the age of 6 days and in the colon (4.7 log 10/cm2) at the age of 15 days (Fig. 3). In conventional lambs, the population of lactobacilli colonizing individual sections of the intestinum was increasing with age (Fig. 4). The number of L. casei in the intestinal content of gnotobiotic lambs was on average higher than that in conventional animals but the differences were not significant. In both groups, the highest number of lactobacilli was noted at the age of 10 days (gnotobiotic lambs = 5.9 log 10/ml; the conventional lambs = 4.6 log 10/ml). From the viewpoint of individual sections of the intestine, the population of L. casei in the intestinal content of gnotobiotic lambs was higher than the lactobacilli count in conventional animals with significant difference in jejunum (p < 0.01). In gnotobiots, the highest lactobacilli count was in the colon (6.17 log 10/ml); in conventional lambs in the ileum (4.71 log 10/ml).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

[Action of salicylates on the disappearance of bacteria (Lactobacillus casei) phagocytized by polymorphonuclear cells].

This is a study of the modifications caused by acetylsalicylic acid and CuII (aspirinate)4 in the speed with which phagocytized bacteria disappear from polymorphonuclears (PMN) of the peritoneal exudate of guinea pigs. Acetylsalicylic acid inhibits the normal processes that cause the disappearance of the phagocytized bacteria; CuII (aspirinate)4, on the contrary, at low concentration (5 10(-6)) and during the first 45 minutes, causes an evident increase in the speed of disappearance of bacteria from PMN.

Animals↗

Effect of age, amount of inoculum and inoculation medium composition on lactic acid production from glucose by Lactobacillus casei subsp. rhamnosus.

Effect of composition of the medium used for the inoculum cultivation, of the age and amount of the inoculum was investigated using a 3-L glass fermentor with a working volume of 1 L. The highest productivity of the culture was obtained when using a 20% (V/V) 1-d inoculum grown in the MRS medium. Yields of lactic acid were 88-97%, while the L(+)-isomer represented about 80% of the total product.

Bacteriological Techniques↗

Cloning, sequence analysis, and expression of Lactobacillus casei phage PL-1 lysis genes.

The genes encoding the host cell wall-lytic proteins were searched in the genome DNA of phage PL-1 active against Lactobacillus casei ATCC 27092 by comparing the amino acid sequences with those of others using a computer software of the DDBJ data base. The gene regions found were cloned into E. coli by inserting PCR-amplified DNA fragments into the EcoRI site of pUC 19, and the nucleotide sequences were determined. One of the ORFs (hol) consisted of 270 bp encoding 90 amino acids. The hol product (holin) possessed a putative secretion signal, two putative transmembrane helices, and a highly charged C-terminus. Another ORF (lys) consisted of 1050 bp encoding an N-acetylmuramoyl-L-alanine amidase of 350 amino acids. The gene lys was expressed in E. coli using pCALn expression vector, and the purified gene product hydrolysed the amide linkage in the peptidoglycans of L. casei. The amino acid sequence of PL-1 amidase showed a high homology to those of Lactococcus lactis phage rlt and Listeria monocytogenes phage A511. It was suggested that the N-terminal region was involved in enzyme activity and the C-terminal region in binding the enzyme to the cell wall substrate, respectively.

Amidohydrolases↗

In situ and non-invasive detection of specific bacterial species in oral biofilms using fluorescently labeled monoclonal antibodies.

Noninvasive in situ detection of suspected cariogenic bacterial species within dental biofilms could facilitate monitoring of the dynamic change of oral microbial flora and assist in the assessment of the treatment efficacy of therapeutic agents. In this study, we explore the possibility to use three well-characterized monoclonal antibodies (MAbs) against Streptococcus mutans, Actinomyces naeslundii, and Lactobacillus casei to identify these three important members of the oral microbial community in the complex environment of oral biofilms. These MAbs, which were conjugated to different fluorescent labels and visualized with confocal laser scanning microscopy (CLSM), proved to be an useful tool to identify the three species of interest (S. mutans, A. naeslundii, and L. casei) under various experimental conditions including in vitro and in vivo derived oral biofilms. Manifold addition of the MAbs on consecutive days did not alter the biofilm structure thus allowing monitoring of the same biofilm over extended time periods. Using this MAb-based method the effect of sucrose challenge on the biofilm composition and the distribution of S. mutans, A. naeslundii, and L. casei were examined. S. mutans was found to be the predominant species under the various biofilm conditions tested. These studies indicate that MAbs based bacterial detection with CLSM is a versatile tool which permits new insights into the ecology of oral biofilm development.

Actinomyces↗

Enterococcus faecalis induces inflammatory bowel disease in interleukin-10 knockout mice.

Germ-free interleukin-10 knockout (IL-10 KO) mice developed inflammatory bowel disease (IBD) after they were colonized with a pure culture of Enterococcus faecalis. E. faecalis not only induced IBD (primarily in colon and rectum) but rectal dysplasia and adenocarcinoma was also found in the IL-10 KO mice. Conventional (complex-intestinal flora) IL-10 KO mice developed IBD within 10 to 15 weeks of age and showed more pathology in the cecum (typhlitis) than we observed with E. faecalis-induced IBD in gnotobiotic IL-10 KO mice. Conversely, neither germ-free IL-10 mice nor IL-10 KO mice colonized as adults, with a pure culture of Candida albicans, Escherichia coli, Lactobacillus casei, L. reuteri, L. acidophilus, a Bifidobacterium sp., Lactococcus lactis, or a Bacillus sp. developed IBD during the 25- to 30-week study. E. faecalis is a common intestinal microbe of man and animals that can trigger IBD, dysplasia, and carcinoma in a genetically susceptible murine host.

Animals↗

Antagonistic activity of Lactobacillus casei strain shirota against gastrointestinal Listeria monocytogenes infection in rats.

In the present study, the effect of ingested viable Lactobacillus casei Shirota strain YIT9029 on oral infection with the enteric pathogen Listeria monocytogenes in Wistar rats was investigated. Rats were orally infected with 10(9) viable L. monocytogenes. Starting 3 days before the infection, rats received a daily dosage of 10(9) viable L. casei. It was shown that supplementation of L. casei significantly reduced the numbers of L. monocytogenes in stomach, caecum, faeces, spleen and liver, 2 days after L. monocytogenes infection. The number of L. monocytogenes in the mesenteric lymph nodes was not affected by the ingestion of L. casei. In comparison with control animals, the levels of the liver-specific alanine aminotransferase were lower in L. casei-fed rats. Histological analysis of spleen and liver revealed no differences between the experimental and control animals. In a parallel study with orally L. monocytogenes infected rats, it was shown that L. casei was able to increase cellular immunity significantly as determined with the delayed-type hypersensitivity response against heat-killed L. monocytogenes. In conclusion, in the present study it was shown that orally administered L. casei is able to enhance host resistance against oral L. monocytogenes infection. In the gastrointestinal tract, as well as in the spleen and liver, L. monocytogenes numbers were reduced. Furthermore, it is concluded that the enhancement of this anti-Listeria activity might be, at least partly, due to increased cell-mediated immunity.

Alanine Transaminase↗

Subunit composition of the H+-ATPase complex from anaerobic bacterium Lactobacillus casei.

The H+-ATPase complex has been isolated from the membranes of the anaerobic bacterium Lactobacillus casei by two independent methods. 1. The crossed-immunoelectrophoresis of the 14C-labelled ATPase complex against antibodies to a highly purified soluble ATPase has been used. The subunit composition of the complex has been established by autoradiography. The soluble part of L. casei ATPase, in contrast to coupling factor F1-ATPases of aerobic bacteria, chloroplasts and mitochondria which include two kinds of large subunit (alpha and beta), consists of one kind of large subunit with a molecular mass of 43 kDa. Moreover, a minor polypeptide of 25 kDa has been found in the soluble ATPase. Factor F0 of L. casei ATPase complex consists of a 16-kDa subunit and two subunits with molecular masses less than 14 kDa. 2. A dicyclohexylcarbodiimide-sensitive ATPase complex has been isolated from L. casei membranes by treating them with a mixture of octyl glucoside and sodium cholate. The complex, purified by centrifugation on a sucrose density gradient, contains the main subunits with molecular masses of 43 kDa, 25 kDa and 16 kDa and a dicyclohexylcarbodiimide-binding subunit with a molecular mass less than 14 kDa.

Adenosine Triphosphatases↗