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PubMedDate not supplied

[Cultivation of microorganisms in micro-volumes of culture media].

Studies on the cultivation of aerobic microorganisms in microdrops of growth medium, immobilized in a layer of highly dispersed disconnector (Aerosil), were carried out. The dispersion of the growth medium and its immobilization in a layer of Aerosil was found to produce no influence on the morphological, cultural and biochemical properties of Serratia marcescens cells, determined both immediately after treatment with the field and some time after storage of the treated suspensions. On the contrary, the duration of the action of ferromagnetic bodies produced essential influence on the viability of the microorganisms in dispersed growth medium and on the accumulation of cells in the course of subsequent cultivation. The development of cells grown in the microdrops of the nutriuent medium was similar to that of cells grown in submerged cultivation, following the S-shaped curve. With the increase of the seed dose a drop in the initial growth rate occurred and the accumulation of microbial cells increased by the end of the process. The greatest increase of biomass was observed with minimal seed doses. With a rise in the concentration of amino nitrogen in the growth medium the yield of cells increased only till this concentration reached 320 mg%. Under these conditions the specific growth rate also increased. The accumulation of cells was greater and occurred earlier when microorganisms were cultivated in immobilized state in powder.

Bacteriological Techniques↗

PubMed1986

[Development and survival of Yersinia enterocolitica in pasteurized milk and ice cream].

Studied were the laboratory development and survival of Yersinia enterocolitica organisms in pasteurized milk and ice-cream that had been contaminated with varying amounts of microbial cells. The milk was kept at 4 degrees, 9 degrees, and 21 degrees C for 120 days, and the ice-cream--at--18 degrees and --23 degrees C for 8 months. Yersinia development and survival were found to be dependent on temperature as well as on the numbers and activity of microflora. When milk was kept at temperatures below 10 degrees C the organisms retained viability for more than 120 days, while at room temperature (20 degrees--22 degrees C) they remained active for up to 30-60 days. The presence of coliform bacteria inhibited the development of Yersinia, its replication and survival rates being reduced. These were dependent in ice-cream on the amount of viable cells in the initial raw material. When contamination was at 10-15 cells per cu. cm Yersinia organisms remained viable up to the 45th day, and at 100 cells per cu. cm--up to the 90th day. At 1000 cells/cu. cm and more viable cells could be found up to the eighth month, their count over a 6-month period being reduced from 84.2 up to 98.5 per cent.

Animals↗

PubMed1997

Biocompatibility of silver-modified polyester for antimicrobial protection of prosthetic valves.

BACKGROUND AND AIMS OF THE STUDY: The biocompatibility of a silver-coated polyethylene terephthlate (PET, polyester) fabric for the inhibition of prosthetic valve endocarditis (PVE) associated with mechanical heart valves (MHVs) was assessed. The infrequency of PVE is outweighed by mortality rates commonly exceeding 50%. These high mortality rates have been attributed to the poor effect of antibiotic therapy on colonized valves and infected myocardial tissue. Silver has been used as an antimicrobial for centuries due to its general effectiveness and relative lack of toxicity. Our previous work has shown PET polyester fabric coated with metallic silver by an ion beam-assisted deposition (IBAD) process to: (i) be effective in vitro in the inhibition of microbial attachment and colonization; (ii) be tightly adherent and low leaching; and (iii) promote tissue ingrowth and the organization of tissue pannus in a short-duration (five weeks) sheep mitral mechanical heart valve model. METHODS: This paper addresses additional biocompatibility assessment consisting of a cell compatibility assay in which serum extracts of silver-coated fabric were exposed to fibroblasts for 48 hours, after which cell viability and function were measured. The amount of silver in the extract was measured using elemental analysis techniques. RESULTS: No signs of toxicity were seen in the cells until the extract concentration reached 1200 p.p.m. Ten-week duration mechanical valve replacement studies in sheep with uncoated or coated polyester sewing cuffs showed comparable tissue ingrowth and mature pannus with a suggestion of a thinner pannus on the silver-coated fabric. Additional antimicrobial testing confirmed the effectiveness of this coating in inhibiting colonization of polyester fabric. CONCLUSIONS: These current results, together with the earlier data, suggest that IBAD silver coating on polyester facilitates healing and may provide protection against PVE.

Animals↗

PubMed1988

A microbial culture system for use in remote field environments.

Field studies of human flora carried out in remote environments are often compromised by problems associated with media, equipment or cargo limitations. For the International Biomedical Expedition to Antarctica an anaerobic culture system was developed based on sealed vials, pre-reduced anaerobically sterilized media, antibiotic selective media and compact processing equipment. The system proved simple to use in a harsh environment and gave results comparable with standard plate and roll-tube techniques. No problems with dehydration, contamination or oxidation were encountered. Furthermore, the system preserved viability of primary isolates for up to 6 months of storage.

Anaerobiosis↗

PubMedDate not supplied

[Viability and virulence of Francisella tularensis subsp. Holarctica in water ecosystems (experimental study)].

Under conditions of artificial water biocenosis a virulent strain of F. tularensis could be detected in fresh water shrimps and mollusks for about a month, in Conepoda for up to 20 days and in Chydorus sphaericus for up to 7 days from the moment of the aquaria water contamination. In silt F. tularensis could be detected for a longer period (up to 2 months). Daphnia, Oligochaeta and C. sphaericus appeared to be unfavorable environment for this microorganism. The virulence level of F. tularensis microbial cells decreased in paralell with prolongation of their stay in water biocenosis. The presence of water biota favours F. tularensis preservation in water reservoirs for a longer time.

Animals↗

PubMed1974

Genetic analysis of two spored asci produced by the spo 3 mutant of Saccharomyces.

Ascospores present in two-spored asci formed by sop3-1 diploids at a semipermissive temperature (30 degrees C) represent random inclusion of haploid genomes into ascospores and exhibit normal viability, meiotic chromosome segregation and recombination. Genetic analysis and ultrastructural studies indicate that the function encoded by the sop3 locus is specifically required for the enclosure of the products of meiosis in prospore walls.

Diploidy↗

PubMed1996

Rapid detection of group B streptococcal colonization of the genital tract by a commercial optical immunoassay.

The performance of a commercial optical immunoassay (OIA) was compared at two institutions with that of routine agar and broth culture methods for the detection of group B streptococcal (GBS) colonization of the genital tract. The Strep B OIA (Bio Star, USA) was used to test 962 vaginal swabs from pregnant women for the presence of GBS antigen. The prevalence of GBS vaginal colonization in this population was 22.4%. The OIA results were compared with those of culture on trypticase soy agar with 5% sheep blood (TSA) and broth enhanced culture (Lim broth). Sensitivity and specificity values of the OIA method compared to TSA culture alone were 82.5% and 91.8%, respectively. The sensitivity of the OIA method was equivalent to that of TSA culture (62.4% vs. 64.4%; p > 0.5, chi 2 = 0.01) when the data were compared with broth culture. The extent of colonization affected the sensitivity of the OIA method: 100% of 4+, 94% of 3+, 96% of 2+, and 63% of 1+ TSA plates were detected by the OIA test. The commercial OIA method demonstrated sensitivity equivalent to that of TSA culture for the detection of GBS colonization. The OIA test offers two additional advantages over culture: reduced time required to obtain results (30 min vs. days) and the ability to detect GBS antigen in samples with compromised viability. The results of this study suggest that the Strep B OIA test can be a useful diagnostic tool in the management of early-onset GBS disease.

Antigens, Bacterial↗

PubMed1999

Pulsed high electric field causes 'all or nothing' membrane damage in Listeria monocytogenes and Salmonella typhimurium, but membrane H+-ATPase is not a primary target.

Salmonella typhimurium (CRA 1005) was more sensitive than Listeria monocytogenes (NCTC 11994) to pulsed high electric field (PHEF) treatment in distilled water (10, 15 and 20 kV/cm), 10 mM Tris-maleate buffer, pH 7.4 (15 kV/cm) and model beef broth (0.75%, w/v; 15 kV/cm). Sublethal injury could not be detected using a selective medium plating technique, indicating that bacterial inactivation by PHEF may be an 'all or nothing' event. PHEF-induced membrane permeabilisation resulted in an increase in the leakage of UV-absorbing material from the bacteria (UV-leakage) and a decreased ability of L. monocytogenes to maintain a pH gradient. A lack of correlation between the inhibition of H+-ATPase activity and PHEF treatment, cell viability or UV-leakage indicates that this enzyme is probably not a primary site of bacterial inactivation despite its role in the maintenance of internal pH.

Cell Membrane↗

PubMed1988

Immunomodulatory effects of staphylococcal lipoteichoic acid in early Listeria monocytogenes infection in Balb/c-mice.

Balb/c-mice were intravenously infected with 5 X 10(4) viable cells of Listeria monocytogenes SLCC 4013. Liver, lung and spleen of the animals showed heavy organ colonization 48 h after infection. Pretreatment of experimental animals with staphylococcal lipoteichoic acid (LTA; 2 mg i.p. 7 and 3 days before challenge) significantly reduced the bacterial count in these organs. In vitro, peritoneal macrophages from LTA-treated mice significantly reduced listerial viability as compared to control cells (p less than 0.0025). In vitro, exposure of macrophages from non-treated animals to LTA did not influence their bacterial killing ability.

Animals↗

PubMed1998

Antimycobacterial activity of substituted isosteres of pyridine- and pyrazinecarboxylic acids.

Pyrazines and pyridines substituted with alkylated tetrazoles, esterified vinylogous carboxylic acids, and ketosulfides were synthesized as precursors of antimycobacterial agents which, after penetration of the mycobacterial cell wall, could be biotransformed by esterases or peroxidase-catalases. The expected products are tetrazoles, a vinylogous carboxylic acid, and CH-acidic ketosulfoxides, isosteres of pyrazinoic and nicotinic acids, which should inhibit mycobacterial growth when released inside the bacterial cell. The growth inhibitory activity of the synthesized compounds against the H37Rv strain of Mycobacterium tuberculosis was determined to assess the viability of this concept. It was shown that all of the compounds designed as lipophilic precursors were more active than the unmodified polar isosteres of pyrazinoic and nicotinic acids.

Antitubercular Agents↗

PubMed2003

Calcaelin, a new protein with translation-inhibiting, antiproliferative and antimitogenic activities from the mosaic puffball mushroom Calvatia caelata.

Fresh fruiting bodies of the mushroom Calvatia caelata, commonly known as the mosaic puffball, were extracted with 10 mM Tris-HCl buffer (pH 7.2). The extract was subjected to a chromatographic procedure which has been successfully used to isolate ribosome-inactivating proteins from plants. It was first applied to an Affi-gel blue gel column previously equilibrated and eluted with 10 mM Tris-HCl buffer. The adsorbed fraction eluted with 1.5 M NaCl in the buffer was then purified by chromatography on DEAE-cellulose in the same buffer. The unadsorbed fraction yielded essentially a single peak when it was chromatographed on a column of Mono S. When the peak was then gel filtered on Superdex 75, it yielded a homogeneous peak with a molecular mass of 39 kDa. The protein, which was designated calcaelin, was dissociated into two subunits with a molecular mass of 19 kDa and 20 kDa, respectively, in SDS-polyacrylamide gel electrophoresis. The two bands exhibited the same N-terminal amino acid sequence which was somewhat similar to those of plant ribosome-inactivating proteins. A lesser degree of sequence homology to the fungal ribosome inactivating proteins alpha-sarcin and restrictocin was detected. Calcaelin inhibited translation in rabbit reticulocyte lysate with an IC 50 value of 4 nM and displayed a heat-labile RNase activity of 1.58 U/mg toward yeast tRNA. It exhibited an antimitogenic activity toward mouse splenocytes, and it reduced the viability of breast cancer cells. There was no hemagglutinating, antibacterial or antifungal activity.

Animals↗

PubMed1990

The survival of subgingival plaque bacteria in an amine fluoride-containing gel.

Subgingival plaque samples from 20 patients with chronic inflammatory periodontal disease were exposed to a commercial gel formulation containing 2 amine fluorides. The MIC of the gel for these samples ranged from 33 to 260 micrograms/ml with a modal value of 260 micrograms/ml. In each sample, the most resistant organisms (i.e., those organisms surviving at one doubling dilution below the MIC) were identified. 33 such organisms were isolated, of which 22 (67%) were strict anaerobes, and 25 (75%) were Gram negative. The 2 most frequent isolates were Bacteroides ruminicola ss. brevis and a Selenomonas species, neither of which is a recognised periodontopathogen. The gel had a rapid effect on the viability of the bacteria in the plaque samples, the 90% kill time being 17 min or less for 90% of the samples (range less than 5 to 71 min).

Adult↗

PubMed1974

Effect of chelating agents on the susceptibility of some strains of gram-negative bacteria to some antibacterial agents.

The effects of ethylenediaminetetraacetic acid and related chelating agents on the susceptibility of Pseudomonas aeruginosa and other strains of gram-negative bacteria to some beta-lactam antibiotics and some non-antibiotic antibacterial agents have been studied by two methods: (i) the determination of minimal inhibitory concentrations in the presence and absence of a chelating agent; and (ii) pretreatment with a chelating agent, followed by exposure for up to 120 min at 37 C to a beta-lactam drug in a nutrient medium or to the other type of antibacterial agent in a non-nutrient environment. The pretreatment technique gave the more significant results, especially with chlorhexidine, cetrimide, and benzalkonium chloride. Chelating agents that had previously been found to give a low order of activity as measured by effects on bacterial viability nevertheless appeared to induce some changes in the surface layers of the treated organisms, rendering them susceptible to sub-inhibitory concentrations of non-antibiotic drugs.

Anti-Bacterial Agents↗

PubMed2001

Fluorescent acid-fast microscopy for measuring phagocytosis of Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum by Tetrahymena pyriformis and their intracellular growth.

Fluorescent acid-fast microscopy (FAM) was used to enumerate intracellular Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum in the ciliated phagocytic protozoan Tetrahymena pyriformis. There was a linear relationship between FAM and colony counts of M. avium cells both from cultures and within protozoa. The Ziehl-Neelsen acid-fast stain could not be used to enumerate intracellular mycobacteria because uninfected protozoa contained acid-fast, bacterium-like particles. Starved, 7-day-old cultures of T. pyriformis transferred into fresh medium readily phagocytized M. avium, M. intracellulare, and M. scrofulaceum. Phagocytosis was rapid and reached a maximum in 30 min. M. avium, M. intracellulare, and M. scrofulaceum grew within T. pyriformis, increasing by factors of 4- to 40-fold after 5 days at 30 degrees C. Intracellular M. avium numbers remained constant over a 25-day period of growth (by transfer) of T. pyriformis. Intracellular M. avium cells also survived protozoan encystment and germination. The growth and viability of T. pyriformis were not affected by mycobacterial infection. The results suggest that free-living phagocytic protozoa may be natural hosts and reservoirs for M. avium, M. intracellulare, and M. scrofulaceum.

Animals↗

PubMed1998

Ingredient supplementation effects on viability of probiotic bacteria in yogurt.

The present investigation studied the effects of cysteine, whey powder, whey protein concentrate, acid casein hydrolysates, or tryptone on the viability of Streptococcus thermophilus, Lactobacillus acidophilus, and bifidobacteria. Changes in pH, titratable acidity, redox potential, and viability of bacteria were monitored during 24 h of fermentation and refrigerated storage (4 degrees C) of yogurt for 35 d. The incubation time that was needed to reach pH 4.5 was considerably affected by the added ingredients. Also, the drop in pH or the increase in acidity and redox potential was dependent on the added ingredients. The addition of cysteine, whey protein concentrate, acid casein hydrolysates, or tryptone improved the viability of bifidobacteria to a variable extent, but whey powder failed to improve their viability. The morphology of S. thermophilus, as shown by electron microscopy, was affected by cysteine at 500 mg/L, possibly as a result of reduced redox potential. Sodium dodecyl sulfate-PAGE and amino acid analyses suggested that the nitrogen source in the form of peptides and amino acids improved the viability of bifidobacteria in yogurt made with a commercial ABT (Lactobacillus acidophilus, bifidobacteria, and Streptococcus thermophilus) starter culture, which showed a dramatic decline in the counts of this organism in previous studies.

Bacteria↗

PubMed1979

Ribosomal protein alterations in thiostrepton- and Micrococcin-resistant mutants of Bacillus subtilis.

Ribosomal proteins of parental thiostrepton- and micrococcin-sensitive Bacillus subtilis cysA14 and thiostrepton-and micrococcin-resistant mutants were compared. Several electrophoretic and immunochemical techniques showed unambiguously that BS-L11 was not present on 50 S ribosomal subunits from the six thiostrepton-resistant mutants. Protein BS-L11 reappeared in all six revertants from thiostrepton resistance to thiostrepton sensitivity. No definitive protein alteration could be ascribed to the mutation from micrococcin sensitivity to resistance. It was also demonstrated that B. subtilis protein BS-L11 is homologous to Escherichia coli ribosomal protein L11. The finding that ribosomes from thiostrepton-resistant mutants do not contain protein L11 suggests that L11 not only is involved in binding of thiostrepton, but also, when mutationally altered, confers resistance to this antibiotic. Although the ribosomes of these strains do not contain protein L11, all thiostrepton-resistant mutants showed the same viability as the parental strain. Thus protein L11 cannot be obligatory for the structure and function of the ribosome.

Anti-Bacterial Agents↗

PubMed2005

Preparation and in vitro evaluation of radioiodinated bakuchiol as an anti tumor agent.

Bakuchiol, extracted from the plant Psoralea corylifolia, has been proven to have anti-tumor, cytotoxic, anti-microbial and anti-inflammatory activity. In order to study if radiolabeled bakuchiol exhibits enhanced cytotoxicity, bakuchiol was radiolabeled with 125I. In-vitro uptake studies of 125I-bakuchiol were carried out using LS-A (lymphosarcoma) and barcl-95 (radiation-induced thymic lymphoma) ascitic and solid tumor cells of murine origin. In both LS-A and barcl-95, 125I-bakuchiol showed significant uptake. Viability studies showed that the radioiodinated compound showed greater cytotoxic effect than bakuchiol.

Animals↗

PubMed2000

The flow cytometry of Bacillus anthracis spores revisited.

BACKGROUND: The potential use of Bacillus anthracis spores as a weapon of terror has rekindled interest in the rapid detection and identification of the spores of these bacteria. Prior efforts to utilize flow cytometry (FCM) for this purpose resulted in tedious and time-consuming protocols. Advances in rapid immunoassays suggest a reinvestigation of the use of FCM because this may allow for the development of a rapid and sensitive system for detection and/or identification of spores in suspect samples. METHODS: In this study, antiserum was raised in goats using three different strains of B. anthracis spores as the immunogen. The resultant antibodies were purified, labeled with fluorescein, and evaluated for use in an immunoassay on a Coulter Epics XL flow cytometer. In the protocol that was developed, fluorescein-labeled antibodies are simply mixed with the sample, allowed to incubate, and then analyzed on the flow cytometer. Washes and centrifugation were eliminated. RESULTS: The results showed that a rapid (5 min) and sensitive immunological analysis was feasible. The detection limit (approximately 10(3) colony-forming units [CFU]/ ml) varied with strain, but there was no difference in the detection limit between live and irradiated spores. In addition, the power of FCM was utilized to minimize false-positive reactions among similar species of Bacillus by placing constraints on scatter and fluorescence intensity. The data also suggest that scatter might be useful to determine spore viability. CONCLUSION: This study shows that FCM may be an effective platform on which to perform immunological analysis for the detection and/or presumptive identification of B. anthracis spores. Published 2000 Wiley-Liss, Inc.

Animals↗