Showing papers on "Agar plate published in 1992"
TL;DR: Campy-Cefex allowed for easier differentiation of C. jejuni from other flora compared to differentiation on Campylobacter cefoperazone desoxycholate agar medium, and the selectivity for the organism was better than on Campy-BAP.
264 citations
TL;DR: When the roots of 28 plant species were surface sterilized and incubated on agar medium, endophytic actinomycetes in the root cortex were observed by direct microscopic observation and pure culture techniques.
Abstract: When the roots of 28 plant species were surface sterilized and incubated on agar medium, endophytic actinomycetes in the root cortex were observed by direct microscopic observation and pure culture techniques
223 citations
TL;DR: In this paper, the morphological change in colonies of Bacillus subtilis was investigated and patterns of colonies grown on the surface of thin agar plates were found to change drastically through the variation of environmental conditions; concentrations of nutrient C n and agar C a in the agar medium.
Abstract: We have investigated the morphological change in colonies of bacteria called Bacillus subtilis . Patterns of colonies grown on the surface of thin agar plates were found to change drastically through the variation of environmental conditions; concentrations of nutrient C n and agar C a in the agar medium. They were classified into five types; DLA-like, Eden-like, DBM-like, intermediate and homogeneously spreading. The active movement of individual bacterial cells was seen in expanding periphery of a colony at intermediate and low C a (soft agar medium). Such bacterial cell movements are found to induce the shift from DLA- and Eden-like patterns to those found for softer agar medium. Physical implication of the pattern changes is discussed.
138 citations
TL;DR: Elevations in short-term fluoride release levels were positively correlated with growth inhibition and in vitro inhibition of growth and adherence of five oral bacteria by glass-ionomer materials.
105 citations
TL;DR: Fungal inhibition in four commonly used agar media was improved by substituting natamycin (pimaricin) for cycloheximide, and the recovery of bacteria was not affected bynatamycin, whereas fungal contamination from a variety of samples was significantly suppressed.
Abstract: Fungal inhibition in four commonly used agar media was improved by substituting natamycin (pimaricin) for cycloheximide. The recovery of bacteria was not affected by natamycin, whereas fungal contamination from a variety of samples was significantly suppressed. Furthermore, natamycin lacks the occupational health hazards of cycloheximide. Medium-dependent natamycin degradation occurred during the preparation and refrigerated storage of agar plates, but the addition of natamycin at 21.6 μg/ml resulted in effective residual activity.
97 citations
TL;DR: New isolates of Aureobasidium pullulans were obtained from plant leaf surfaces gathered in San Diego County and exhibited an increased tendency toward yeastlike growth and reduced pigmentation.
Abstract: New isolates of Aureobasidium pullulans were obtained from plant leaf surfaces gathered in San Diego County The new fungal isolates were identified as A pullulans on the basis of the appearance of polymorphic colonies formed on agar plates, the electrophoretic profiles of repeated genomic DNA sequences, and the production of pullulan in shake flask cultures The isolates showed different degrees of pigmentation One of the natural isolates was nonpigmented under mock production conditions in liquid culture, but was still able to synthesize a reduced amount of pigment on agar plates at late times A mutagenic treatment with ethidium bromide produced derivatives of normally pigmented natural isolates that exhibited an increased tendency toward yeastlike growth and reduced pigmentation Additionally, some of the new isolates and mutant derivatives accumulated pullulan of relatively high molecular weight in the culture broths
86 citations
TL;DR: Tannin-protein complex (T-PC)-degrading enterobacteria (TPCDE) were isolated from the feces and from a layer of bacteria attached to the cecal wall of koalas as mentioned in this paper.
Abstract: Tannin-protein complex (T-PC)-degrading enterobacteria (T-PCDE) were isolated from the feces and from a layer of bacteria attached to the cecal wall of koalas. The T-PCDE were facultatively anaerobic, gram-negative, pleomorphic, nonmotile bacilli. The bacteria were also oxidase and catalase negative and resistant to vancomycin, reduced nitrates to nitrites, and grew on MacConkey agar. Growth on tannin-treated agar media showed a distinctive clear zone around the colony. From these observations, a selective agar plate medium (vancomycin- and tannin-treated Wilkins-Chalgren anaerobe agar) was developed to enumerate T-PCDE isolated from the feces of koalas. This medium was highly selective in the enumeration of the fecal T-PCDE and inhibited the growth of concomitant T-PC-degrading Streptococcus bovis. The T-PCDE were isolated from 10 of the 12 captive koalas studied; in 8 of these 10 koalas, the facultatively anaerobic bacterial flora was dominated (more than 60%) by T-PCDE. Viable numbers of T-PCDE were, in most of the animals, much larger (more than 100 times) than the numbers of T-PC-degrading S. bovis, suggesting that T-PCDE played a more active role in digesting T-PC in the alimentary tracts of koalas.
76 citations
TL;DR: This unit describes culture conditions for yeast mating type, diploid construction, sporulation, tetrad dissection, and random spore analysis using techniques similar to those for bacterial cultures.
Abstract: Yeast cultures can be grown, maintained, and stored in liquid media or on agar plates using techniques similar to those for bacterial cultures. This unit describes culture conditions for these basic techniques. Additional methods describe determination of yeast mating type, diploid construction, sporulation, tetrad dissection, and random spore analysis.
73 citations
TL;DR: The pH and acidity did not halt the growth of this pathogen during the manufacture of the cheese; furthermore, the values of these parameters were the same between the contaminated and control samples.
72 citations
TL;DR: The single blood agar plate culture and the antigen detection tests are insensitive, possibly leading the physician toward undertreatment and risking immunologic, local, or distant sequelae.
Abstract: Objective. —To compare the sensitivity of five group A streptococcal antigen detection systems and single blood agar plate culture with a two-plate culture method for diagnosis of streptococcal pharyngitis. Design. —Two simultaneous throat swabs were obtained from consecutive patients with suspected streptococcal pharyngitis. One swab was tested for streptococcal antigen by physicians' office nurses and the other was cultured on both aerobic blood agar and anaerobic trimethoprim-sulfamethoxazole blood agar plates. Setting. —Community office practice and community hospital laboratory. Participants. —Consecutive outpatients seen by one of four pediatricians or a family practice physician. Main Outcome Measures. —Results of rapid streptococcal antigen tests were compared with culture results either on a single aerobic blood agar plate or on the two-plate culture method. Results. —On throat swabs from 755 consecutive outpatients, the two-plate culture method detected 261 cases (defined as 100%) of group A streptococcal pharyngitis. The anaerobic trimethoprim-sulfamethoxazole plate alone, read at 1 and 2 days, detected 245 cases (94%). The blood agar plate used alone detected 189 cases (72%) at 2 days and 151 cases (58%) at 1 day. Antigen detection test results were positive for 106 throat specimens (41%), with individual kit sensitivity ranging from 31% to 50% compared with the two-plate culture method. Antigen detection test sensitivity decreased with decreasing colony counts. Antigen kit false-positivity rates varied from 0 to 28%. Conclusions. —We conclude that the single blood agar plate culture and the antigen detection tests are insensitive, possibly leading the physician toward undertreatment and risking immunologic, local, or distant sequelae. The two-plate culture method should be the standard of practice to rule out streptococcal pharyngitis. JAMA . 1992;267:695-697
70 citations
TL;DR: The colony lift method and DNA probes provided a sensitive, economical and quantitative method for enumerating cultivable microbial species in subgingival plaque samples, and the amplification provided by growing the organisms on agar plates facilitated determination of numbers of organisms in small plaque samples.
Abstract: This study evaluated the feasibility of using a colony lift method and DNA probes to enumerate bacterial species cultured on primary isolation plates. Fourteen digoxigenin-labeled whole chromosomal DNA probes representing 12 subgingival species were validated by hybridization with colony lifts prepared from 249 reference strains of 51 species grown on Trypticase soy agar plates supplemented with 5% sheep blood. Colonies of reference strains were lifted onto Nytran filters from plates and treated to lyse cells, remove cellular proteins, denature and fix microbial DNA to the filters. Positive reactions were detected with an anti-digoxigenin antibody conjugated to alkaline phosphatase and revealed by bromo-chloro-indolyl phosphate and nitroblue tetrazolium. Cross-reactions were not observed for 13/14 probes, but 2 strains of Streptococcus mitis reacted with the probe to Streptococcus sanguis II. Subgingival plaque samples were taken by means of a sterile curette from mesiobuccal surfaces of teeth present in each of 26 subjects with differing periodontal disease states. Samples were dispersed, diluted, plated and incubated anaerobically for 7 d at 35 degrees C. Colonies were lifted as described above. Filters were cut into sections and hybridized with the 14 digoxigenin-labeled DNA probes. The probes were used to enumerate the test species and the total number of isolates was determined in 711 plaque samples. The colony lift method and DNA probes provided a sensitive, economical and quantitative method for enumerating cultivable microbial species in subgingival plaque samples. In addition, the amplification provided by growing the organisms on agar plates facilitated determination of numbers of organisms in small plaque samples, such as those from healthy sites.
TL;DR: It is illustrated that bacteria or their metabolic products are essential as nutrients for house fly maggot growth in blood agar; a wide variety of adventitious bacteria can contribute to the suitability of an organic substrate for maggot Growth; and a naturally occurring isolate of B. cereus limits house fly Magca domestica growth inBlood agar, a relationship that has not been reported previously.
Abstract: To investigate the relationship between immature (maggot) house flies, Musca domestica, and bacteria, we compared the development of sterile first-instar maggots in each of 10 pure blood agar cultures of bacteria with growth on sterile blood agar (negative control) and on standard house fly rearing medium (positive control). Nine species of bacteria representing gram-negative and gram-positive rods, coccoid, and micrococcoid cell types supported house fly growth on blood agar. One bacterium, a strain of Bacillus cereus, inhibited maggot growth. The percent pupation for maggots that developed in the presence of eight of nine bacteria (range, 41-69%), was significantly greater than in sterile blood agar (0-5%), and did not differ significantly from maggot growth in the rearing medium (50-90%). Average pupal weight for maggots that developed on blood agar with bacteria ranged from 19 to 21 mg, a reflection of favorable growth conditions. Average pupal weight in the presence of three bacteria (19.9, 19.4, and 19.4 mg) was significantly less than respective pupal weights in house fly rearing medium (24.0, 22.3, and 22.1 mg), but there was no difference in average pupal weight with six bacteria and the house fly rearing medium. These findings illustrate that bacteria or their metabolic products are essential as nutrients for house fly maggot growth in blood agar; a wide variety of adventitious bacteria can contribute to the suitability of an organic substrate for maggot growth; and a naturally occurring isolate of B. cereus limits house fly maggot growth in blood agar, a relationship that has not been reported previously.
TL;DR: The E test is found to be a simple, labor-efficient, and accurate method for MIC determination on an agar medium and to show excellent correlation with agar dilution results.
Abstract: The antimicrobial susceptibilities of 100 clinical isolates of Pseudomonas aeruginosa to six antipseudomonal antibiotics were tested by five methods: the National Committee for Clinical Laboratory Standards (NCCLS) methods for broth microdilution, agar dilution, and agar disk diffusion; the Vitek Automicrobic System method (Vitek Systems, Hazelwood, Mo.); and the PDM Epsilometer test (E test) (AB Biodisk, Solna, Sweden). The E test results showed excellent correlation with agar dilution results, with over 90% agreement within 1 doubling dilution between the E test and reference agar dilution MICs for all antimicrobial agents tested. The E test results also showed good correlation with the results from the reference agar disk diffusion method, with 90 to 99% complete agreement and 100% essential agreement on categories for all antibiotics tested (essential agreement is the agreement obtained when minor discrepancies are ignored). Comparison of categories with the E test and broth microdilution methods, using the broth microdilution method as the reference method, gave only 59% complete agreement for gentamicin, with 28 minor discrepancies and 13 very major discrepancies. Some discrepancies were observed between results from the E test and broth methods for gentamicin, with the broth microdilution and Vitek methods giving higher MICs than the E test and other methods using agar. The most recent NCCLS guidelines for broth dilution testing have reduced the recommended levels of cation supplementation, which may enhance future agreement between results for the aminoglycosides and P. aeruginosa on broth and on agar. We found that the E test offers a simple, labor-efficient, and accurate method for MIC determination on an agar medium.
TL;DR: Ribotyping can effectively differentiate otherwise indistinguishable strains of bacteria, thus providing a powerful tool for investigation of waterborne diseases and bacteriological problems within water treatment plants and distribution systems.
Abstract: We have investigated the usefulness of ribotyping for the differentiation of aeromonads isolated from five patients with gastroenteritis and from the source water, treatment plant, and distribution system of a small public water supply. Aeromonas hydrophila and Aeromonas caviae were isolated from fecal specimens preserved in Cary-Blair transport medium by using blood ampicillin agar or alkaline peptone water (pH 8.4) subcultured to blood ampicillin agar plates. A. hydrophila, Aeromonas sobria, and A. caviae were isolated from duplicate 100-ml water samples by the membrane filter technique by using ampicillin dextrin agar for quantitative determination of growth and alkaline peptone water enrichment for detection of the presence or absence of aeromonads below the detection limit of the membrane filter method. In addition, free chlorine residuals and pH values were determined for all water samples and heterotrophic plate counts and total and fecal coliform analyses were performed on them. Ribotyping patterns of aeromonads recovered from well 1, detention basin, sand filter, softener, and distribution samples were compared with those of the five clinical isolates. All patient strains were unique; however, identical ribotypes of A. hydrophila and A. sobria isolated from multiple sites in the water system indicated colonization of a well, sand filters, and the softener, with the potential for sporadic contamination of distribution water. Plant operational deficiencies were noted and corrected. Ribotyping can effectively differentiate otherwise indistinguishable strains of bacteria, thus providing a powerful tool for investigation of waterborne diseases and bacteriological problems within water treatment plants and distribution systems.
TL;DR: In this article, the authors observed that Bacillus subtilis colonies show periodic growth on agar plates and that the concentration gradient of peptone particles at the growing perimeter of a colony would be essentially involved in the periodic growth.
Abstract: Bacillus subtilis colonies show periodic growth on agar plates. The organism has been observed to show several colony morphologies including diffusion-limited aggregation (DLA) type, dense branching morphology (DBM), Eden type, and spreading without producing openings. The agar concentration for the periodic growth is higher than that of DBM and lower than that of DLA or Eden type. The nutrient (peptone) concentration for the periodic growth is higher than that of DLA and DBM and lower than that of Eden type. The colony grows towards a place with higher peptone concentration. These findings suggest that the diffusion of nutrient particles, i.e. the concentration gradient of peptone particles at the growing perimeter of a colony, would be essentially involved in the periodic growth. The distance between concentric rings of a colony is constant and intervention between two colonies is not observed, unlike the Liesegang ring.
TL;DR: Many mutant strains showing resistance to 2-deoxy-d-glucose (DG) on minimal medium containing glycerol as a carbon source were induced from Aspergillus niger WU-2223L, a citric acid-producing strain, and were classifiable into two types according to their growth characteristics.
Abstract: Many mutant strains showing resistance to 2-deoxy-d-glucose (DG) on minimal medium containing glycerol as a carbon source were induced from Aspergillus niger WU-2223L, a citric acid-producing strain. The mutant strains were classifiable into two types according to their growth characteristics. On the agar plates containing glucose as a sole carbon source, mutant strains of the first type showed good growth irrespective of the presence or absence of DG. When cultivated in shake cultures, some strains of the first type, such as DGR1–2, showed faster glucose consumption and growth than strain WU-2223L. The period for citric acid production shortened from 9 days for strain WU-2223L to 6–7 days for these mutant strains. The levels and yields of citric acid production of the mutant strains were almost the same as those of strain WU-2223L. The mutant strains of the second type, however, showed very slow or no growth on both the agar plates containing glucose and fructose as sole carbon sources. In shake cultures, mutant strains such as DGR2-8 showed decreased glucose consumption rates, resulting in very low production of citric acid.
TL;DR: The influence of potassium tellurite (PT) and brain heart infusion agar (Difco), two components of modified Listeria selective agar medium (LSAMm), on the hemolytic phenotype of Listersia spp.
Abstract: The influence of potassium tellurite (PT) and brain heart infusion agar (Difco), two components of modified Listeria selective agar medium (LSAMm), on the hemolytic phenotype of Listeria spp. was studied. L. monocytogenes and L. ivanovii displayed bigger zones of hemolysis on brain heart intusion agar compared with on Columbia agar base. The addition of PT increased the sizes of zones of hemolysis displayed by L. monocytogenes. This effect seemed to be produced by the enhancement of the cytolytic effect of listeriolysin O. PT decreased the hemolysis produced by L. ivanovii, and this effect seemed to be due to an inhibition of the sphingomyelinase C produced by this species.
TL;DR: It is proposed that the proliferative rate of the parental bacterial population exerted selective pressure on the expression of new clonal variants in Moraxella bovis colonies, resulting in circular colonies when the inoculum was stabbed at a single point.
Abstract: SUMMARY: Moraxella bovis was found to colonize the interface between agar and the polystyrene Petri dish, producing circular colonies when the inoculum was stabbed at a single point. The bacteria occurred in a thin layer of nearly uniform thickness, and colonial expansion occurred in at least two temporal phases. In the first phase, the radial colonial expansion was slow and non-linear. In the second phase, the radial expansion was linear. The interfacial colonies possessed three characteristic concentric growth zones. At the periphery was a narrow ring zone that enclosed another wider ring zone, which, in turn, surrounded a central circular zone. Different bacterial phase variants were recovered from these zones. The two outer ring zones yielded bacteria that formed agar surface colonies of spreading-corroding morphology, while cells from the innermost zone always yielded colonies with a different morphology. The uniform thickness of the colonies implied that replication was restricted to the outermost ring, and that the bacteria within the inner ring and inner circle had entered a quiescent state. The inner ring appeared to represent the lag in time needed for the replicative form to differentiate into the quiescent form. A different kind of variant was associated with wedge-shaped sectors within the colonies. The greatest number of these clonal variants appeared shortly after inoculation and their frequency decreased after the onset of linear growth. The period of slowest colonization coincided with highest frequency of clonal variant expression. It is proposed that the proliferative rate of the parental bacterial population exerted selective pressure on the expression of new clonal variants.
TL;DR: A new semiselective agar medium, NCP-88, was developed for isolating Clavibacter michiganensis subsp.
Abstract: A new semiselective agar medium, NCP-88, was developed for isolating Clavibacter michiganensis subsp. sepedonicus, the cause of bacterial ring rot, from infected potato plant parts. Important selective components of this nutrient agar, yeast extract, and salts medium are mannitol, polymyxin B-sulfate, nalidixic acid, and cycloheximide. NCP-88 permitted a better balance between plating efficiency and selectivity than did other reported semiselective media (.)
TL;DR: The sensitivity of the agar plate method for the diagnosis of Strongyloides stercoralis was studied experimentally and it was demonstrated that this method was sensitive enough to detect S. stercalis even when only a few worms were present.
Abstract: The sensitivity of the agar plate method for the diagnosis of Strongyloides stercoralis was studied experimentally. Results demonstrated that this method was sensitive enough to detect S. stercoralis even when only a few worms were present.
TL;DR: Division of the Micromycetes into different groups according to their consumption of the phenolic compound and the appearance of new metabolites was allowed according to the taxonomic position of the strains.
Abstract: The ability of 953 strains of Micromycetes to grow with vanillic acid (0.5 g/l) was investigated. Toxicity assays were performed on malt extract/agar medium, while consumption was estimated by growing fungi on solid synthetic medium with vanillic acid as sole carbon source. More than half of the tested strains grew in both conditions. After cultivation on solid media, 296 strains were selected and cultivated in liquid synthetic medium. These experiments allowed division of the Micromycetes into different groups according to their consumption of the phenolic compound and the appearance of new metabolites. Results were related to the taxonomic position of the strains.
TL;DR: A monoclonal antibody recognizing a genus-specific epitope on the 60-kDa heat shock protein of all Legionella species was used in a colony blot enzyme-linked immunosorbent assay for the rapid identification of Legionella cultures on agar plates.
Abstract: We recently developed a monoclonal antibody immunoglobulin G2a (2125) recognizing a genus-specific epitope on the 60-kDa heat shock protein of all Legionella species. In the current study, this antibody was used in a colony blot enzyme-linked immunosorbent assay for the rapid identification of Legionella cultures on agar plates. The whole protocol was completed in less than 2 h. All 59 Legionella species and serogroups that were tested gave a positive signal. No unspecific reactions with nonlegionellae were observed. This test is a rapid procedure for the identification of legionellae growing on agar medium to the genus level. Images
TL;DR: Plant plants, Solanum tuberosum cv.
Abstract: Treatments of sporangia and zoospores of Phytophthora infestans race 1234 with methionine or riboflavin for durations of up to 8 h under fluorescent light did not affect its colonization of rye-seed agar In contrast, exposure of sporangia and zoospores to methionine-riboflavin mixture for 2 h or more resulted in the failure of race 1234 to grow when transferred to rye-seed agar medium Hyphal growth of races 1234 and 0, when incubated in liquid synthetic medium, was inhibited by free riboflavin Potato plants, Solanum tuberosum cv Kennebec, when pretreated with a methionine–riboflavin mixture and then spray inoculated with race 1234 developed fewer diseased leaves per plant than plants pretreated with water, methionine, or riboflavin Key words: Solanum tuberosum, hydroxyl radical, superoxide anion
Journal Article•
TL;DR: These dip-slide tests provided suitable and simple methods for screening salivary lactobacilli and ms levels which may have a useful role in the assessment of caries risk.
Abstract: Mutans streptococci (ms) and lactobacilli levels were determined by conventional and commercial dip-slide methods in three groups of young subjects, aged 5-6 years (93 subjects), 12-13 years (78 subjects) and 18-20 years (81 subjects). Using the same paraffin-stimulated saliva samples, ms and lactobacilli were estimated by conventional viable counts on modified mitis-salivarius agar (MSB) and Rogosa agar plates, and by inoculation of Dentocult SM and Dentocult LB dip-slides (Orion Diagnostica, Finland). The salivary ms and lactobacilli counts obtained from conventional agar plates were significantly correlated (P < 0.0001) with the dip-slide estimates of these organisms (Kendal Tau = 0.56, 0.71 respectively). Subjects in Group 2 showed the highest proportion (77 per cent) of individuals with salivary ms levels above 2.5 x 10(5) cfu/ml saliva; 99 per cent of that group had detectable levels of lactobacilli. Significantly different median salivary ms and lactobacilli levels were demonstrated between all groups except for lactobacilli levels between Groups 2 and 3. These dip-slide tests provided suitable and simple methods for screening salivary lactobacilli and ms levels which may have a useful role in the assessment of caries risk.
TL;DR: APW enrichment broth and CPC isolation agar were more efficient for recovery of V. vulnificus from oysters than other broth and agar combinations.
TL;DR: R3A agar was seen to be the most suitable for population studies, however, colony development was slower, which makes it unsuitable for plate counts, whereas R3A lets most cells develop into colonies within the first 5 days of incubation.
TL;DR: A method was developed for the detection and isolation of strains producing exclusively the l-(+)- isomer of lactic acid using an enzymatic stereospecific reaction involving d-(-)-lactate dehydrogenase and linked to a staining reaction.
Abstract: A method was developed for the detection and isolation, within a population of lactic acid bacteria, of strains producing exclusively the l-(+)- isomer of lactic acid; the visual detection of colonies of these particular strains can be carried out directly on agar plates (50 to 70 colonies per plate). The method is based on an enzymatic stereospecific reaction involving d-(-)-lactate dehydrogenase and linked to a staining reaction; the diffusion area of the d-(-)- isomer stains red around the d-(-)- and the dl-lactic acid-producing colonies, while the colonies producing exclusively l-(+)-lactic acid are detected by the absence of the colored halo. The intensity of staining was increased when cellulose powder and Tween 20 were added to the agar medium.
TL;DR: Glucose autoclaved in an alkaline phosphate solution results in the production of a moiety that is nonmutagenic but can interact with a series of 4‐[2‐(aryl)ethenyl]‐2,6‐dimethylphenols to result in an increase in bacterial revertants that is dependent on the amount of HGS in the minimal agar plates.
Abstract: Glucose autoclaved in an alkaline phosphate solution (heated glucose+salts, HGS) results in the production of a moiety that is nonmutagenic but can interact with a series of 4-[2-(aryl)ethenyl]-2,6-dimethylphenols to result in an increase in bacterial revertants that is dependent on the amount of HGS in the minimal agar plates. The reaction between the HGS and the chemical to form a mutagen is independent of the presence of bacteria, does not result in a nutritive analog to enhance growth of the auxotrophic bacteria, and is effective only in Salmonella typhimurium and Escherichia coli strains that contain the plasmid pKM101. A sufficient amount of this glucose product may be formed in normal plate preparation to produce apparent mutagenic activity of these chemicals.
TL;DR: In this paper, Dendritic crystals of ammonium chloride (NH 4 Cl) have been grown two-dimensionalally on the surface of agar medium and a rich variety of morphologies of dendrites, such as DLA-like structure and dense-branching morphology, were found to be observed.
Abstract: Dendritic crystals of ammonium chloride (NH 4 Cl) have been grown two-dimensionally on the surface of agar medium. Varying initial concentrations of agar and ammonium chloride in the agar medium, a rich variety of morphologies of dendrites, such as DLA-like structure and dense-branching morphology, were found to be observed. They were classified into five main types according to their pattern characteristics. We report the morphological phase diagram and typical patterns obtained in the present experiments.
TL;DR: The rate and amount of growth of 4 field isolates and reference strain ATCC 6223 of Francisella tularensis were evaluated on isolation media with 2 different agar bases and with different supplements and incubated at 25 C, 35 C, and 42 C and the addition of cysteine did not alter any biochemical reactions.
Abstract: The rate and amount of growth of 4 field isolates and reference strain ATCC 6223 of Francisella tularensis were evaluated on isolation media with 2 different agar bases and with different supplements and incubated at 25 C, 35 C, and 42 C. Biochemical reactions on conventional differential media with and without cysteine were evaluated. Two of the field isolates and the reference strain were F. tularensis subspecies tularensis (formerly biovar tularensis or Type A), and 2 isolates were subspecies holarctica (formerly subspecies palaearctica or Type B). Bacto cystine heart blood agar supplemented with 1% hemoglobin, glucose cystine heart blood agar, and brain-heart infusion blood agar supported good growth of all 4 field strains, with the most luxuriant growth occurring on Bacto cystine heart blood agar with hemoglobin. Heart infusion blood agar and trypticase soy blood agar supported growth of the field isolates, although growth was diminished and delayed. Strain 6223 was distinctly fastidious and failed to grow on heart infusion or trypticase soy blood agars. Growth of strain 6223 was best on Bacto cystine heart blood agar with hemoglobin. The agar base did not affect growth unless the supplements became limiting, in which case Bacto agar base generally supported growth better than BiTek agar base. Incubation at 35 C was optimum for all 5 strains. Growth at 42 C was slow, with the greatest decrease in the rate and amount of growth occurring with field isolates of F. tularensis subspecies tularensis. Strain 6223 did not grow at 25 C, and the 4 field isolates grew slowly at the lower temperature.(ABSTRACT TRUNCATED AT 250 WORDS)