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PubMed1992

[Determining dehydrogenase activity as a method of accelerated indication of the viability of Mycobacterium tuberculosis].

A comparative effectiveness of mycobacterial dehydrogenase activity (DHA) determination was studied with the help of the following stains: methylene blue, malachite green and tetrazole derivative--triphenyl tetrazole chloride (TTC). Best result were obtained with TTC tests which allowed a reliable registration of M. tuberculosis culture viability. On the basis of indication of M. tuberculosis viability by DHA, accelerated techniques were developed to determine mycobacterial drug resistance to the main antituberculous preparations and blood bacteriostatic activity. These techniques are available for practical laboratories, economical and safe in work.

Anti-Infective Agents, Local↗

PubMed1994

Lethal photosensitisation of Staphylococcus aureus.

The purpose of this study was to determine whether toluidine blue O (TBO) could sensitise Staphylococcus aureus to killing by light from a low-power helium/neon (HeNe) laser. Suspensions of the organism were irradiated with light from a HeNe laser in the presence and absence of TBO and the survivors enumerated. A 95% reduction (9 x 10(7) cfu) in the viable count was achieved following irradiation with 0.88 J of HeNe laser light in the presence of 12.5 micrograms/ml TBO whereas no significant reductions in viability were found when suspensions were exposed to this dose of laser light in the absence of TBO. With higher doses (3.5 J) of laser light statistically significant kills (3 x 10(7) cfu) were obtained in the absence of TBO implying the presence of an endogenous photosensitiser in the organism.

Colony Count, Microbial↗

PubMed2004

Enhanced production of acetoin and butanediol in recombinant Enterobacter aerogenes carrying Vitreoscilla hemoglobin gene.

Microbial production of butanediol and acetoin has received increasing interest because of their diverse potential practical uses. Although both products are fermentative in nature, their optimal production requires a low level of oxygen. In this study, the use of a recombinant oxygen uptake system on production of these metabolites was investigated. Enterobacter aerogenes was transformed with a pUC8-based plasmid carrying the gene (vgb) encoding Vitreoscilla (bacterial)hemoglobin (VHb). The presence of vgb and production of VHb by this strain resulted in an increase in viability from 72 to 96 h in culture, but no overall increase in cell mass. Accumulation of the fermentation products acetoin and butanediol were enhanced (up to 83%) by the presence of vgb/VHb. This vgb/VHb related effect appears to be due to an increase of flux through the acetoin/butanediol pathway, but not at the expense of acid production.

Acetoin↗

PubMed2005

In-vitro analysis of APA microcapsules for oral delivery of live bacterial cells.

Oral administration of microcapsules containing live bacterial cells has potential as an alternative therapy for several diseases. This article evaluates the suitability of the alginate-poly-L-lysine-alginate (APA) microcapsules for oral delivery of live bacterial cells, in-vitro, using a dynamic simulated human gastro-intestinal (GI) model. Results showed that the APA microcapsules were morphologically stable in the simulated stomach conditions, but did not retain their structural integrity after a 3-day exposure in simulated human GI media. The microbial populations of the tested bacterial cells and the activities of the tested enzymes in the simulated human GI suspension were not substantially altered by the presence of the APA microcapsules, suggesting that there were no significant adverse effects of oral administration of the APA microcapsules on the flora of the human gastrointestinal tract. When the APA microcapsules containing Lactobacillus plantarum 80 (LP80) were challenged in the simulated gastric medium (pH = 2.0), 80.0% of the encapsulated cells remained viable after a 5-min incubation; however, the viability decreased considerably (8.3%) after 15 min and dropped to 2.6% after 30 min and lower than 0.2% after 60 min, indicating the limitations of the currently obtainable APA membrane for oral delivery of live bacteria. Further in-vivo studies are required before conclusions can be made concerning the inadequacy of APA microcapsules for oral delivery of live bacterial cells.

Administration, Oral↗

PubMed2006

Immunomodulation by SanPharma fungal metabolic products.

OBJECTIVE: In the present study, a series of fungal metabolite products from SanPharma (Dohren, Germany) were tested for effects on human peripheral blood leukocytes in vitro using standard immunologic methods. BACKGROUND: Therapeutic strategies used in German biological medicine often include treatment (oral, nasal, rectal, topical, or injection) with fungal or bacterial products, also known as "isopathic remedies," of which some are limited to metabolic products, whereas others include microbial cell lysates and cell wall fragments as well. The SanPharma products are based on metabolites, and do not contain microbial cell wall compounds. METHODS: Activation of natural killer (NK) cells was evaluated by cell surface immunostaining using CD3, CD56, CD69, and CD25 monoclonal antibodies. Production of interferon-gamma was evaluated by enzyme-linked immunoabsorbent assay (ELISA) on supernatants collected after 5 days' culture of peripheral blood mononuclear cells (PBMC). Direct mitogenic effect was assessed using the lipophilic membrane dye PHK26 (Sigma-Aldrich, St. Louis, MO) in a fluorescence-based proliferation assay, in which fluorescence intensity is reduced upon cell divisions. Cell viability upon exposure to fungal metabolites was assessed using propidium iodide staining and flow cytometry. RESULTS: All fungal metabolite products specifically induced the expression of the CD69 marker on human CD3-negative, CD56-positive NK cells, but not CD3-positive T cells, in vitro, as shown by the induction of the CD69 marker on up to 50% of NK cells after 18 hours' culture with metabolites. Only one of the five metabolite products, Roqueforti, induced cyclooxygenase-2 (COX-2), indicating that nuclear factor-kappaB (NFkappaB)-mediated signaling may not have been involved in the NK activation by the other four products. The Notatum product reduced baseline levels of COX-2, indicating an anti-inflammatory effect. No evidence of toxic or mitogenic effects was found. CONCLUSIONS: The fungal metabolite products from SanPharma specifically activate human NK cells in vitro.

Antigens, CD↗

PubMed2005

Effect of the lactoperoxidase system against three major causal agents of disease in mangoes.

The antibacterial activity of the lactoperoxidase system (LPS) on the growth of Xanthomonas campestris, the causal agent of bacterial black spot in mangoes, Botryodiplodia theobromae, the causal agent of stem-end rot disease in mangoes, and Colletotrichum gloeosporioides, the causal agent of anthracnose disease in mangoes, was determined during culture at 30 degrees C and at several pH values (4.5, 5.5, and 6.5). When the results of using the LPS were compared with those from control cultures without the LPS reagents, the growth of the three microorganisms was totally inhibited in all of the conditions tested. Viability tests enumerating cultivable cells of X. campestris showed that the LPS had a bactericidal effect, whatever the pH value. This effect is faster at pH 5.5, corroborating the results reported in the literature (optimal pH for the LPS efficiency). Further, we proved that hydrogen peroxide alone had little inhibition effect on the growth of the microorganisms studied. This compound is essentially used to convert thiocyanate into hypothiocyanate during the lactoperoxidase reaction. The potential of the LPS for the postharvest treatment of the fruits for controlling microbial diseases was thus demonstrated. Nevertheless, further studies are needed on fresh fruits before envisaging any application.

Anti-Bacterial Agents↗

PubMed1976

A bacterial RNA polymerase mutant that renders lambda growth independent of the N and cro functions at 42 degrees C.

We describe a bacterial RNA polymerase mutation, rif 501, which confers rifampicin resistance and thermosensitivity to E. coli K 12. The purified RNA polymerase enzyme from rif 501 bacteria shows increased heatsensitivity in vitro at 51 degrees C. However, in vivo, at 42 degrees C the non-permissive temperature, mutant bacteria continue to grow and to synthesize RNA for 90 min. On a lawn of the mutant bacteria, at 40-41 degrees C, phage lambda forms clear plaques (LycA phenotype); this is probably due to an enhancement of cro function; we surmise that at 42 degrees C the transcription originating from the pR (but not from the pL) promoter on the lamdba genome becomes N-independent and less sensitive to the absence of the cro product. We discuss the possibility that both the N and cro proteins of phage lambda interact directly with the bacterial RNA polymerase. These observations indicate that the loss of viability of the rif 501 mutant at the restrictive temperature is not a consequence of an immediate inactivation of RNA polymerase; rather we feel it is due to a modification of the activity of RNA polymerase, leading to a disruption of the cellular regulation.

Coliphages↗

PubMed1978

Plasma-membrane lipid composition and ethanol tolerance in Saccharomyces cerevisiae.

Populations of cells suspended anaerobically in buffered (pH 4.5) M ethanol remained viable to a greater extent when their plasma membranes were enriched in linoleyl rather than oleyl residues irrespective of the nature of the sterol enrichment. However, populations with membranes enriched in ergosterol or stigmasterol and linoleyl residues were more resistant to ethanol than populations enriched in campesterol or cholesterol and linoleyl residues. Populations enriched in ergosterol and cetoleic acid lost viability at about the same rate as those enriched in oleyl residues, while populations grown in the presence of this sterol and palmitoleic acid were more resistant to ethanol. Suspending cells in buffered ethanol for up to 24 h did not lower the ethanol concentration.

Anaerobiosis↗

PubMed1999

Feasibility of using food-grade additives to control the growth of Clostridium perfringens.

Previously, it was demonstrated that the combination of sucrose laurate (SL) ethylenediaminetetraacetate (E) and butylated hydroxyl anisole (B) (SLEB) was an effective antimicrobial agent against both gram-negative (aerobes) and gram-positive (facultative anaerobes) foodborne bacteria. This investigation examines the sensitivity of Clostridium perfringens to SLEB relative to: (1) the minimum inhibitory concentration (MIC) of SLEB required to inhibit the growth of C. perfringens and (2) the antibacterial effectiveness of different combination ratios of SLEB in fluid thioglycollate medium (FTM). Results indicated that the MIC of SLEB (1:1:1, v/v/v) against C. perfringens on tryptose sulfite cycloserine (TSC) agar was > 150 ppm at 37 degrees C. However, in FTM, a SLEB (1:1:1, v/v/v) concentration of > 100 ppm inhibited C. perfringens during an incubation (anaerobic) period of 196 h at 37 degrees C. The sensitivity of C. perfringens to different combination ratios was also investigated in FTM. The results showed that, when the concentrations of SL and E were held at 75 ppm in the SLEB combination, and the concentration of B increased from 0 to 75 ppm, C. perfringens growth increased initially during the first 24 h of incubation (37 degrees C) but remained constant during the next 48 h. Similarly, when concentrations of SL and E were held constant at 150 ppm in the SLEB combination and the B ratio increased from 50 to 150 ppm in FTM, C. perfringens viability decreased in all of the treated samples during 72-h incubation at 37 degrees C. The results indicated that SLEB was an effective inhibitor of C. perfringens growth activities, and the ratios of the components of SLEB can be adjusted to meet specific preservation needs.

Butylated Hydroxyanisole↗

PubMed1999

Saccharomyces cerevisiae viability is strongly dependant on rehydration kinetics and the temperature of dried cells.

The effects of rehydration kinetics and temperature on the viability of Saccharomyces cerevisiae dehydrated by drying were studied. During rehydration, a water activity range of 0.117-0.455 must be crossed slowly in order to maintain cell viability. If this range is crossed rapidly, cell viability can be preserved if rehydration takes place at 50 degrees C. Several hypotheses have been proposed to explain previous results. One hypothesis, which relates cell mortality after rapid rehydration to water flow through the membrane in phase transition, is the more plausible and requires further investigation.

Colony Count, Microbial↗

PubMed1996

Kill kinetics of antimicrobial agents against Helicobacter pylori.

We evaluated the activity of clarithromycin, 14-OH clarithromycin, amoxycillin, bismuth, metronidazole and ciprofloxacin against six strains of Helicobacter pylori to determine if there were differences in response to these antimicrobial agents during growth in vitro. Clarithromycin and its 14-hydroxy-metabolite exhibited an early bactericidal activity with at least a 3 log10 reduction after 2-8 incubation. Exposure to bismuth, ciprofloxacin and metronidazole resulted in a > 3 log reduction by 24 h with the greatest decrease in viability occurring between 8 and 24 h. The viable count of three strains was reduced by a 1-2 log10 after 24 h exposure to amoxycillin and by a > 3 log10 after 48 h.

Amoxicillin↗

PubMed1990

[The effect of silicon on the growth of Staphylococcus aureus].

Various studies on the effect of silicon on the development of chronic inflammatory diseases of the mucous membrane such as chronic sinusitis have been carried on for the past twenty years. Staphylococcus aureus is usually detected frequently in chronic sinusitis. In this study, proliferation of Staphylococcus aureus in various culture fluids with Si concentrations ranging from 10 to 410 ppm was observed through 16 hours by means of the measurement of optical density, protein concentration and viability count. As the result of this observation, higher concentration of Si in the culture fluid showed a remarkable growth accelerating effect on Staphylococcus aureus compared with normal culture fluid containing about 10 ppm of Si. High Si concentration in mucous membrane tissue was considered to help the growth of bacteria in the sinus.

Colony Count, Microbial↗

PubMedDate not supplied

[Granulated preparations of azotobacter in a clay-mineral base].

Interaction of Azotobacter chroococcum 20 cells with clay minerals increased their viability at supraoptimal temperatures. Therefore, clay minerals were used to develop granular bacterial preparations with high viable cell counts and stable compositions during long-term storage. The titers of viable bacteria in the preparations remained 60-70% of the initial level after 12-month storage.

Aluminum Silicates↗

PubMed1997

Screening of antiadherent activity on Streptococcus sobrinus culture.

The mutans group of streptococci is considered to play a key role in the etiology of dental caries. We have evaluated the ability of different substances to prevent dental plaque formation without affecting Streptococcus sobrinus viability. Viable organisms were detected as CFU/mL in agar plates and bacterial adherence was assessed by dry weight. We studied 23 compounds and we demonstrated that phenyl salicylate, phenylmercuric nitrate and potassium iodate are more effective to inhibit adhesion without showing antibacterial activity.

Anti-Infective Agents, Local↗

PubMedDate not supplied

[Symbiosis in survival of microorganisms in hyperhaline water reservours].

Differently directed effects from autochthonous algae and bacteria on allochthonous microflora in hyperosmotic conditions were revealed and analyzed. Living halophilic microorganisms increase survival time of enterobacteria. Cellular extracts from halophils decrease storage time of allochthonous bacteria in a highly mineralized medium. Allochthonous bacteria in hyperosmotic conditions are able to suppress viability of autochthonous halophilic microflora. Symbiotic interactions between autochthonous and allochthonous microorganisms, defined by correlation of protective and antagonistic effects, regulate survival of microorganisms in hyperhaline water reservours and can be used for the assessment of their ecological and sanitary-and-hygienic states.

Chlorophyta↗

PubMedDate not supplied

Engineered bioretention for removal of nitrate from stormwater runoff.

A bioretention unit is a simple, plant- and soil-based, low-impact treatment and infiltration facility for treating stormwater runoff in developed areas. Nitrate, however, is not attenuated in conventional bioretention facilities. Thus, this study systematically evaluated a reengineered concept of bioretention for nitrate removal via microbial denitrification, which incorporates a continuously submerged anoxic zone with an overdrain. Experimental studies were performed in four phases. In the first two phases, column studies demonstrated that, overall, newspaper is the best solid-phase electron-donor substrate for denitrification out of the set studied (alfalfa, leaf mulch compost, newspaper, sawdust, wheat straw, wood chips, and elemental sulfur) based on superior nitrate removal and effluent water quality. The nitrate loading and hydraulic loading studies in the second phase provided design information. In the third phase, system viability after 30- and 84-day dormant periods was evaluated in column studies, demonstrating that newspaper-supported biological denitrification should be effective under conditions of intermittent loadings. Finally, in the fourth phase, pilot-scale bioretention studies demonstrated the effectiveness of the proposed design, showing nitrate plus nitrite mass removals of up to 80%. These results indicate that engineered bioretention for the removal of nitrogen from stormwater runoff has the potential for successful application as an urban stormwater treatment practice.

Biodegradation, Environmental↗

PubMed1994

Role of intestinal mucus in transepithelial passage of bacteria across the intact ileum in vitro.

BACKGROUND: Although gastrointestinal mucus is one of a number of putative host defense mechanisms that protect the gut barrier against microbial translocation, little experimental data are available to show its role in this process. The present study sought to determine the role of mucus depletion on the transepithelial passage of bacteria across viable segments of rat ileum mounted in Ussing chambers in vitro. METHODS: Intestinal mucus was depleted in 12 rats after injection with pilocarpine (160 mg/kg intraperitoneally) 45 minutes before intestinal harvest. The mucosal surfaces of the perfused gut segments mounted in the Ussing chamber were exposed to 5 x 10(9) CFU/ml Escherichia coli C-25. Viability was monitored by continuous measurements of the potential difference generated by the membranes. The electrical characteristics were unaltered by pilocarpine pretreatment or exposure to bacteria. RESULTS: Bacterial passage occurred in 100% of pilocarpine membranes as compared with 33.3% in controls (p < 0.05). Pilocarpine-treated membranes resulted in 19.9 +/- 7.5 mg of retrievable mucus as compared with 28.8 +/- 7.2 mg in controls (p < 0.05). Light and transmission electron microscopy revealed an intact epithelial surface in all membranes. There was a marked decrease in mucus on the surface of pilocarpine-treated membranes. CONCLUSIONS: Intestinal mucus secretion is a critical factor in the barrier function of the gut, and its depletion results in a dramatic increase in bacterial passage across the intact rat ileum.

Animals↗

PubMed1990

Recovery of exponentially growing cultures of Klebsiella pneumoniae NCIB 418 after heat shocks.

Exponentially growing cultures of Klebsiella pneumoniae were subjected to heat shocks in the superoptimal and supermaximal temperature ranges for growth on glucose in a defined mineral salts medium. Transitory changes in the specific growth rate constant during recovery were evident. The response was heat shock temperature and exposure time dependent. Cell viability determinations, based on colony counts, indicated complete recovery from heat treatments at superoptimal temperatures. In contrast, at supermaximal temperatures, discrepancies in colony counts on different agars were observed. The kinetic response of the specific growth rate constant after a heat shock at supermaximal temperatures is explained by segregation within the bacterial population.

Colony Count, Microbial↗