Showing papers on "Agar plate published in 1991"
TL;DR: A new semi-quantitative agar plate test for the detection of extracellular rhamnolipids has been developed and can be applied to other glycolipid producing microorganims.
Abstract: A new semi-quantitative agar plate test for the detection of extracellular rhamnolipids has been developed. These biological anionic tensides (biosurfactants) form an insoluble ion pair with the cationic tenside cetyltrimethylammonium bromide and the basic dye methylene blue which was included in mineral agar plates. On the light blue agar, productive colonies ofPseudomonas spec. were surrounded by dark blue halos. The test is specific for anionic biosurfactants and can be applied to other glycolipid producing microorganims.
402 citations
TL;DR: The E Test results were as reliable as the results obtained by the standard antimicrobial susceptibility testing methods.
Abstract: The E Test (AB Biodisk, Solna, Sweden) is a new method for performing antimicrobial susceptibility tests. It consists of an impervious carrier (5- by 50-mm strip) with a predefined antimicrobic gradient which is placed on an inoculated agar plate and processed like a disk diffusion test. Results are generated directly as MICs from a continuous concentration gradient covering 15 twofold dilutions, and MICs are read where the edge of the inhibition zone intersects the strip. We compared the E Test with disk diffusion, broth microdilution, and agar dilution tests by using a challenge set of 195 gram-positive and gram-negative bacteria for 14 antimicrobial agents. Also, disk diffusion, broth microdilution, and agar dilution tests were compared with each other. All test method comparisons gave greater than 94% agreement for the category of susceptibility. The E Test category agreement with disk diffusion and broth microdilution was 95.1%, and with agar dilution it was 95.2%. The E Test results were as reliable as the results obtained by the standard antimicrobial susceptibility testing methods.
286 citations
TL;DR: Mycelial fungi, yeasts, and bacteria were isolated from strawberry plants and evaluated for biocontrol of Botrytis cinerea in strawberry and grouped into five categories using cluster analysis of the observations.
Abstract: Mycelial fungi, yeasts, and bacteria were isolated from strawberry plants and evaluated for biocontrol of Botrytis cinerea in strawberry. Comparative tests were done on leaf discs and detached petals in the laboratory and on attached leaves and flowers in the growth room, greenhouse, and field plots. In the various controlled environments, strawberry tissues were inoculated with the microorganisms (107 fungal spores or yeast cells, and 108 bacterial cfu/mL) and challenge-inoculated with the pathogen (106 spores/mL) after 24 h. After a further 24 h, inoculated tissues were transferred to an agar medium containing paraquat to kill the tissues and allow B. cinerea to sporulate within 5-7 d; sporulation density was estimated after 7 d for indirect quantification of infection and colonization. Biocontrol effectiveness of 230 isolates on leaf discs ranged from 0 to 100%; the organisms were grouped into five categories using cluster analysis of the observations, Eleven organisms, including representatives of eac...
147 citations
TL;DR: Conditions for reliable induction of embryogenesis from isolated microspores of Brassica oleracea var.
131 citations
TL;DR: Testing reproducibility of 25 phenotypic tests depended on growth inhibition, and each of these tolerance tests was performed by using three different basal media, and the basal medium which gave the optimum reproducecibility could be determined.
Abstract: Twenty type or other reference strains, each representing a different Campylobacter, Helicobacter, or Arcobacter taxon, were used to assess the reproducibility of 25 phenotypic tests that are used in the identification of such organisms. Twenty-two of the tests depended on growth inhibition, and each of these tolerance tests was performed by using three different basal media. Although the overall reproducibility of the tests with each basal medium exceeded 89%, the proportion of strains that were able to grow in a reproducible manner on the basal media varied from 100% for blood agar and 50% for nutrient agar to 5% for brucella agar. In general, test reproducibility was highest with the basal medium that supported the most luxuriant growth. For the majority of tests, the basal medium which gave the optimum reproducibility could be determined.
101 citations
TL;DR: The XLT4 medium significantly improved Salmonella isolation from chicken farm environmental drag-swab samples over the other selective plating media evaluated and strongly inhibit Proteus, Pseudomonas, Providencia, and many other nonsalmonellae.
91 citations
TL;DR: The type strains of six Campylobacter species or subspecies were examined in eight tests used for the identification of such organisms, and 95% confidence limits for viable counts done on these basal media indicated that blood agar may yield more consistent results than the other agars examined.
Abstract: The type strains of six Campylobacter species or subspecies were examined in eight tests used for the identification of such organisms. False-positive results were obtained in certain tests (growth on 1% bile, brilliant green, selenite, trimethylamine-N-oxide, 2,3,5-triphenyl tetrazolium chloride, and minimal media) when an inoculum yielding 10(7) to 10(8) CFU/ml was used. Each tolerance test was examined with blood, nutrient, and brucella agars as basal media. The type of basal medium used could also affect the test outcome. With the inoculum standardized to a density yielding approximately 10(6) CFU/ml, reproducible and pertinent results were obtained, provided an appropriate basal medium was used. However, 95% confidence limits for viable counts done on these basal media indicated that blood agar may yield more consistent results than the other agars examined.
91 citations
TL;DR: A Bacillus subtilis strain was found to grow through the diffusion-limited aggregation (DLA) process on agar plates as mentioned in this paper, and the organism was spotted on the agar plate containing a low concentration of peptone as a single nutrient and incubated at 35°C.
Abstract: A Bacillus subtilis strain is found to grow through the diffusion-limited aggregation (DLA) process on agar plates. The organism is spotted on the agar plate containing a low concentration of peptone as a single nutrient and incubated at 35°C. The colony pattern grown on the plate surface is self-similar with the fractal dimension of 1.73±0.02. Bacterial DLA branches are shown to grow in a concentration field of nutrient from the fact that they grow predominantly in the direction of higher nutrient concentration. The colonial morphology varies with the nutrient and agar concentrations of an agar plate, including DLA, a round type, dense branching morphology (DBM), and a spreading without openings. Two neighboring colonies repulse each other in DLA and DBM types only. On an agar plate containing glycerol the colony becomes remarkably round, quite different from the DLA morphology.
87 citations
TL;DR: Microgard, a commercially available fermented milk product containing antimicrobial metabolites, was a potent inhibitor for Gram-negative bacteria such as Pseudomonas, Salmonella, and Yersinia when 1% concentration was incorporated into agar media.
75 citations
TL;DR: Slime isolated after growth of four strains of coagulase-negative staphylococci on chemically defined medium plus agar was rich in galactose, but when sterile agar plates were extracted with saline, high-molecular-weight material with similar properties was obtained that also was galactOSE-rich.
Abstract: Slime isolated after growth of four strains of coagulase-negative staphylococci on chemically defined medium plus agar was rich in galactose. However, when sterile agar plates were extracted with saline, high-molecular-weight material with similar properties was obtained that also was galactose-rich. Most of the dry weight attributed to slime, and probably all the galactose, originated from agar. Slime isolated by gel and ion-exchange chromatography from liquid culture in the same medium contained glycerol phosphate, glucose (no galactose), glucosamine, alanine, uronate, an unidentified component, and protein. Separation of protein from carbohydrate was achieved by affinity chromatography. [14C]glucose in the medium labeled the carbohydrate polymer; [14C]amino acids chiefly labeled extracellular proteins. Slime from bacteria grown on medium solidified with silica gel or on dialysis membrane above an agar surface showed essentially the same composition and behavior after purification as the material isolated from liquid culture.
66 citations
TL;DR: Employing 7H11 agar medium at pH 6.6, clarithromycin is more active at a physiologic than at an acidic pH, and the MICs on 10% OADC (oleic acid-albumin-dextrose-catalase)-enriched Mueller-Hinton agar at pH 7.3 were also 2 log2 dilutions lower than those measured on 7H 11 agar.
Abstract: Employing 7H11 agar medium at pH 6.6, the MICs of clarithromycin for 50% (MIC50) and 90% (MIC90) of 19 strains of Mycobacterium avium complex were 8 and 16 micrograms/ml, respectively. However, the MICs were 2 to 3 log2 dilutions lower in the 7H11 medium adjusted to pH 7.4, and the MICs on 10% OADC (oleic acid-albumin-dextrose-catalase)-enriched Mueller-Hinton agar at pH 7.3 were also 2 log2 dilutions lower than those measured on 7H11 agar at pH 6.6. Therefore, clarithromycin is more active at a physiologic than at an acidic pH.
TL;DR: A new method using the chromogenic substrate 5-bromo-4-chloro-3-indolyl-α-d-galactoside was developed for the differential enumeration of Bifidobacterium spp.
TL;DR: An agar medium was developed for the isolation and identification of Xanthomonas campestris pv.
Abstract: An agar medium was developed for the isolation and identification of Xanthomonas campestris pv. vesicatoria, the causal agent of bacterial spot of pepper and tomato. The new medium, designated as CKTM, contained soy peptone, Bacto tryptone, dextrose, L-glutamine, L-histidine, ammonium phosphate, potassium phosphate, magnesium sulfate, calcium chloride, Pourite, and agar (...)
TL;DR: The spiral gradient agar Dilution technique is a reasonable alternative to the conventional agar dilution technique for susceptibility testing of anaerobic bacteria.
Abstract: Antimicrobial susceptibility tests were performed on brucella laked blood agar with 340 isolates and 14 antimicrobial agents by the standard agar dilution technique and the spiral gradient technique in which antibiotic concentrations were established by diffusion from the agar surface. For comparison, spiral gradient MICs were determined by calculating antimicrobial concentrations at growth endpoints and rounding up to the next twofold incremental concentration. The cumulative percentage of strains susceptible at the breakpoint determined from spiral gradient data was within 10%, generally, of the percentage of strains susceptible at the breakpoint determined from agar dilution data. The overall agreement between the two techniques (within one doubling dilution) was 90.6%. The spiral gradient agar dilution technique is a reasonable alternative to the conventional agar dilution technique for susceptibility testing of anaerobic bacteria.
TL;DR: An agar medium developed to improve the recovery of Septoria nodorum from wheat seed was compared with oxgall agar, the most selective agarmedium currently used, and growth of most other seedborne fungi was reduced by greater than 95%, but Fusarium spp.
Abstract: An agar medium (designated SNAW), developed to improve the recovery of Septoria nodorum from wheat seed, was compared with oxgall agar, the most selective agar medium currently used. Metabolites produced by S. nodorum on oxgall agar fluoresce under near ultraviolet light, but the fungus does not sporulate. Growth of other seedborne fungi is only partially suppressed. On SNAW, S. nodorum fluoresces and sporulates within 7 days. Growth of most other seedborne fungi was reduced by greater than 95%, but Fusarium spp. were reduced only 74% (...)
Patent•
08 Feb 1991
TL;DR: In this paper, a rapid process for detecting pathogenic microorganisms in products for human consumption comprises contacting the microorganisms with a methylumbelliferone substrate, which is then hydrolyzed into methylUMB by an enzyme given off by the micro organisms.
Abstract: A rapid process for detecting pathogenic microorganisms in products for human consumption comprises contacting the microorganisms with a methylumbelliferone substrate. The substrate is hydrolyzed into methylumbelliferone by an enzyme given off by the microorganisms. Hydrolysis is accelerated by sodium lauryl sulfate, which renders the microorganisms more permeable to the substrate, the enzyme, or both. The methylumbelliferone is detected by its fluorescence, either in solution or on an agar medium supporting microcolonies formed from individual microorganisms.
TL;DR: This medium provides an inexpensive means for simple and rapid presumptive identification of E. coli and coliforms and for the differentiation within the Klebsiella-Enterobacter and the Proteus-Providencia-Morganella group.
TL;DR: Alkalinization of gelatin in an agar medium is a convenient and sensitive method to detect degradation of gelatin, particularly by Pseudomonas fluorescens, but this method may not be applicable to some species.
Abstract: Five methods for detecting degradation of gelatin by bacteria were compared. These were liquefaction in nutrient broth, hydrolysis in nutrient agar, hydrolysis of charcoal gelatin strips, degradation of the gelatin on strips of photographic film, and alkalinization of gelatin agar. Degradation of photographic film is a rapid and convenient method but, like hydrolysis of gelatin in broth and in agar, may fail to detect weakly positive strains of bacteria. Alkalinization of gelatin in an agar medium is a convenient and sensitive method to detect degradation of gelatin, particularly by Pseudomonas fluorescens, but this method may not be applicable to some species.
TL;DR: R2 seedling populations from self-fertilized R1 plants of 4 varieties were tested for Fusarium resistance by artificial infections in the greenhouse, and 3% of the regenerated R2 plants have been found to be more resistant than the original cultivars.
Abstract: Calluses of spring and winter wheats (Triticum aestivum L.) were selected for Fusarium resistance in vitro, using the double-layer culture technique. Potato-dextrose agar medium in vials was inoculated with mycelia of Fusarium graminearum and F. culmorum. After one week, fungal cells were killed by autoclaving and the agar medium containing the thermostable toxic metabolites was overlayered with MS callus-growing medium. Later, wheat calluses were placed on the upper medium for 4–5 weeks, and from the surviving calluses plants were regenerated. R2 seedling populations from self-fertilized R1 plants of 4 varieties were tested for Fusarium resistance by artificial infections in the greenhouse, and 3% of the regenerated R2 plants have been found to be more resistant than the original cultivars.
TL;DR: The type strain of Listeria monocytogenes differs from wild-type L. monocyTogenes strains in more characteristics than just the previously reported deficiency in hemolytic activity and virulence in the murine infection model.
Abstract: The type strain of Listeria monocytogenes differs from wild-type L. monocytogenes strains in more characteristics than just the previously reported deficiency in hemolytic activity and virulence in the murine infection model. The type strain from the American Type Culture Collection (strain ATCC 15313) produces lecithinase, is hemolytic on rabbit (but not sheep) blood agar, lacks motility, and shows limited cytopathogenic effects on Caco-2 monolayers, whereas the type strain from the Special Listeria Culture Collection (strain SLCC 53) is unable to produce lecithinase, is nonhemolytic on rabbit or sheep blood agar, is motile, and shows no cytopathogenic effects on Caco-2 monolayers.
TL;DR: An acute fasciitis and myositis associated with HPS infection in primary SPF sows in susceptible specific pathogen-free (SPF) hogs is described.
Abstract: Hemophilus parasuis (HPS) infection is frequently associated with polyserositis and meningitis (Glasser’s disease). HPS infection is recognized as a serious infection in susceptible specific pathogen-free (SPF) hogs. Acute HPS septicemia 4 or pneumonia, without polyserositis, has also been reported. This report describes an acute fasciitis and myositis associated with HPS infection in primary SPF sows. Thirty SPF sows were inappetent, weak, and ataxic. Several of these sows had swollen heads and 7 sows died over a 48hour period. Rectal temperatures ranged from 105 to 108 F. The remaining 23 sows responded to antibiotic therapy and recovered fully, suggesting a bacterial infection. The sows were second parity and were ceasarian derived through an SPF laboratory. They had no previous disease problems. Two of the 7 sows were necropsied. One sow had extensive subcutaneous edema of the head region (Fig. 1). Lesions of septicemia, polyserositis, or pneumonia were not present. The other sow lacked significant gross lesions. The lung, liver, and meninges of both sows were cultured aerobically in 5% bovine blood agar, 5% bovine blood Columbia agar, MacConkey agar, and mannitol salt agar, and on a 5% ovine blood agar plate with a Staphylococcus epidermidis nurse streak incubated under 5% CO, atmosphere. No bacteria were isolated from the above organs of either sow. The masseter muscle from 1 sow was cultured on a bovine blood agar plate under anaerobic conditions as well as with a Staphylococcus epidermidis nurse streak under 5% CO, atmosphere. These procedures failed to identify any anaerobic bacteria. Tiny, smooth, grayish colored, translucent, nonhemolytic bacterial colonies satellited the Staphy-
TL;DR: It was concluded that the MUG method, in conjunction with the membrane filtration technique using mFC agar is faster, easier and cheaper than the standard procedure for the examination of seawater and sediment samples.
TL;DR: It is concluded that the modified CMBA and CMA media are superior to modified CCFA medium for recovery of C difficile and that culture on BA following alcohol treatment is a superior and costeffective method for detecting C Difficile from clinical fecal specimens.
Abstract: Dowell reported in 1980 that two selective media, cycloserine mannitol agar (CMA) and cycloserine mannitol blood agar (CMBA), developed at the Centers for Disease Control (CDC), gave better results than cycloserine fructose egg-yolk agar or cycloserine cefoxitin fructose egg-yolk agar in the isolation of Clostridium difficile from feces and in the quantitative recovery of the organism from pure cultures. In 1983, Bartley and Dowell modified the basal medium for CMA and CMBA by deleting L-leucine and Lserine; since then, the modified media has been used for isolating C difficile from feces. In this study, we compared the modified CMA and CMBA media with cycloserine cefoxitin fructose agar (CCFA) in the quantitative recovery of C difficile isolates and modified CCFA from two vendors in the isolation of C difficile from feces. In addition, all fecal specimens were cultured on CDC anaerobe blood agar (BA) after treatment for 1 hour with 95% ethyl alcohol (BA-ETOH). Of 350 fecal specimens examined using all media, 105 yielded C difficile . Of the 105 specimens, 80 were positive with CMBA (76%), 68 with CMA (65%), 44 with CCFA (vendor A) (42%), 38 with CCFA (vendor B) (36%), and 95 with BA-ETOH (90%). The selective media ranked as follows in quantitative recovery of 24 C difficile strains from pure cultures: CMBA>CMA>CCFA. We conclude that the modified CMBA and CMA media are superior to modified CCFA medium for recovery of C difficile and that culture on BA following alcohol treatment is a superior and costeffective method for detecting C difficile from clinical fecal specimens.
TL;DR: Two strains, Fe1 and Fe2, of iron-oxidizing bacteria from acid drainage water at the Matsuo mine showed dissimilar characteristics of red-brown colonies on FeSO4-9K silica gel plates, however, these bacteria, identified as Thiobacillus ferrooxidans, were different strains.
Abstract: Two strains, Fe1 and Fe2, of iron-oxidizing bacteria from acid drainage water at the Matsuo mine showed dissimilar characteristics of red-brown colonies on FeSO4-9K silica gel plates. The Fe1 colonies were large and irregular. The Fe2 colonies were minute and circular. These bacteria, identified as Thiobacillus ferrooxidans on the basis of their physiological and chemotaxonomical properties (fatty acid composition, ubiquinone type, and DNA base composition), were different strains. Fe2 differed from Fe1 in its extremely low oxidizing activity of sulfur and thiosulfate. Two strains, S2 and S3, of sulfur-oxidizing bacteria were separately isolated on Na2S2O3-9K silica gel plates and agar plates, respectively. However, S2 and S3 formed pale brown and pale yellow colonies on the silica gel and agar plates, respectively. Since these two strains were identical in their properties, they were judged to be quite similar or the same strain. From their morphological, physiological, and chemotaxonomical properties, they were identified as Thiobacillus thiooxidans. The oxidation characteristics of both sulfur and thiosulfate by the strains of iron- and sulfur-oxidizing bacteria were also investigated.
TL;DR: Addition of egg yolk to Palcam agar seems to be benificial for the recovery of sublethally injured cells and recovery of L. monocytogenes was higher after 48 h incubation for all media tested.
TL;DR: An agar plate test was used to screen bacteria and fungi for their ability to oxidatively couple 2,6-dimethoxyphenol and trametes versicolor and Pseudomonas lemonnieri were found to be the most efficient organisms to catalyse the coupling reaction.
TL;DR: This study tested two dental materials in factory-sealed containers for the presence of bacteria that may be a source of infection and inoculated them onto chocolate agar plates and into thioglycolate broths with appropriate controls.
Abstract: This study tested two dental materials in factory-sealed containers for the presence of bacteria that may be a source of infection. Twenty samples of two dental materials found to have contamination in a pilot study were taken from unopened containers using a sterile technique. The samples were inoculated onto chocolate agar plates and into thioglycolate broths with appropriate controls. Plates were examined, colonies were enumerated, Gram stained, and identified. The resulting contamination frequencies were compared for statistical significance using Fisher's exact test. Organisms were isolated from 10% of the negative inoculation control agar plates, while none of the control broths showed contamination. The alginate (irreversible hydrocolloid) showed contamination in 50% of the plates and in 65% of the broths ( p p p > 0.05).
Patent•
04 Mar 1991
TL;DR: In this paper, an automated apparatus for the determination of MIC and the count of viable bacteria, having a remarkably improved operation efficiency compared with conventional apparatuses and capable of automatically and continuously performing all procedures comprising the dilution of specimen, the preparation of agar plate, dilution and inoculation of bacterial suspension and the judgment of the cultivation result.
Abstract: PURPOSE:To provide an automated apparatus for the determination of MIC and the count of viable bacteria, having a remarkably improved operation efficiency compared with conventional apparatuses and capable of automatically and continuously performing all procedures comprising the dilution of specimen, the preparation of agar plate, the dilution and inoculation of bacterial suspension and the judgment of the cultivation result. CONSTITUTION:A specimen in a specimen test tube is sucked with a micropipette 30 which is automatically transferred in X, Y and Z directions by a robot. The sucked specimen is ejected into a test tube 12 while injecting a dilution liquid into the tube to effect the 1st dilution. Thereafter, the diluted specimen liquid diluted to a prescribed concentration is pipetted to a petri dish 10 by similar method and a prescribed amount of an agar medium is pipetted and added to the specimen liquid. The diluted specimen liquid and the agar medium are mixed with each other (41) by rotating the petri dish 10 with a rotary disk placed under a conveyor 11. After the mixing operation, the dish is passed through a cooling hood 45 on the conveyor 11 and solidified by cooling to obtain an agar plate. The surface of the agar plate is inoculated with an objective microorganism by an inoculation rod interposing prescribed spaces. A series of MIC determination procedures such as cultivation at a specific temperature over a specific period are automatically and continuously performed.
TL;DR: A new filter paper bridge technique was compared with the existing agarmedium for callus initiation, multiplication, and plant regeneration of wheat and the yield of both total and embryogenic callus was doubled and significantly higher number of regenerants was obtained on filter paper bridges compared to agar medium.
Abstract: Callus growth and development involve a complex relationship between the explants used to initiate callus, the constituents of the medium and the environmental conditions during culturing. Use of high molecular weight osmotica such as polyethylene glycol (PEG-4000) results in non-solidification of agar medium used for culturing and selection. Thus, a new filter paper bridge technique was compared with the existing agar medium for callus initiation, multiplication, and plant regeneration of wheat. The yield of both total and embryogenic callus was doubled and significantly higher number of regenerants was obtained on filter paper bridges compared to agar medium.
01 Apr 1991-Zentralblatt Fur Bakteriologie-international Journal of Medical Microbiology Virology Parasitology and Infectious Diseases
TL;DR: The technique used for the direct counting of L. monocytogenes on these two selective media does not allow the detection of a low contamination of foods, but Palcam agar and Oxford agar offer the advantages of a great reduction of the development of the contaminating microflora and a clearly less fastidious reading.
Abstract: Summary 391 different foods were examined in order to compare three selective isolation media for Listeria: blood agar with nalidixic acid, Palcam agar, Listeria selective Oxford medium (Oxford agar). The percentage of positive samples (presence of Listeria in 25 g) obtained on the three media after an enrichment procedure is identical: 15.8%. The species L. monocytogenes is found in respectively 8.43%, 8.43% and 8.18% of the foods examined on Palcam agar, Oxford agar and nalidixic acid agar; this represents more than 50% of the isolates of the genus Listeria. However, Palcam agar and Oxford agar offer the advantages of a great reduction of the development of the contaminating micro flora and a clearly less fastidious reading. The technique used for the direct counting of L. monocytogenes on these two selective media does not allow the detection of a low contamination of foods (theoretical positivity threshold = 100 Listeria / g): 65.2% of the positive samples would not have been detected without prior enrichment. 41.1 % of the isolated L. monocytogenes belong to serovar 1/2a, 5.8% to serovar 1/2b, 20.58% to serovar 1/2c, 5.8% to serovar 3b and 24.47% to serovar 4b.