Colony formation by Bact. lactis aerogenes on solid media containing antibacterial agents

1952 ◽  
Vol 215 (1123) ◽  
pp. 565-565
Keyword(s):  
Inoculum Size ◽  
Survival Times ◽  
Fluctuation Test ◽  
Solid Media ◽  
Statistical Variation ◽  
Toxic Concentration ◽  
Solid Agar ◽  
Agar Media ◽  
Different Cultures ◽  
The Given

A study has been made of the formation of colonies of Bact. lactis aerogenes on solid agar media containing antibacterial substances (brilliant green, 1-phenyl semicarbazide, phenyl mercuric nitrate, phenol, thymol and chloramphenicol) at such concentrations that a small fraction only of the inoculated cells develop. The pattern of behaviour varies from drug to drug and sometimes from culture to culture with a given drug. As the toxic concentration increases, colonies diminish in number, in size or in both. Anomalous dependence in some cases upon inoculum size, and the appearance in others of satellites to the main colonies, indicate the operation of co-operative effects probably depending upon diffusion of metabolites or antagonists. The statistical variation in the number of developing colonies is greater for different cultures than for samples of a given culture (as in the well-known fluctuation test for mutations), but the behaviour of a culture may depend upon the aeration, and upon the precise conditions of the test. The variances show no apparent relation to the ease of production of resistance to the given drug. Nor does the scatter of the survival times in liquid media containing phenol (no resistance developable) differ much from that in chloramphenicol (resistant forms readily produced). Consideration of the factors determining the successful formation of a colony on a drug plate suggests that the fluctuation test for the demonstration of mutations must be applied with great reserve.

Colony formation by Bact. lactis aerogenes on solid media containing antibacterial agents

1952 ◽  
Vol 140 (900) ◽  
pp. 339-352 ◽  
Keyword(s):  
Inoculum Size ◽  
Survival Times ◽  
Fluctuation Test ◽  
Solid Media ◽  
Statistical Variation ◽  
Toxic Concentration ◽  
Solid Agar ◽  
Agar Media ◽  
Different Cultures ◽  
The Given

A study has been made of the formation of colonies of Bact. lactis aerogenes on solid agar media containing antibacterial substances (brilliant green, 1-phenyl semicarbazide, phenyl mercuric nitrate, phenol, thymol and chloramphenicol) at such concentrations that a small fraction only of the inoculated cells develop. The pattern of behaviour varies from drug to drug and sometimes from culture to culture with a given drug. As the toxic concentration increases, colonies diminish in number, in size, or in both. Anomalous dependence in some cases upon inoculum size, and the appearance in others of satellites to the main colonies, indicate the operation of co-operative effects probably depending upon diffusion of metabolites or antagonists. The statistical variation in the number of developing colonies is greater for different cultures than for samples of a given culture (as in the well-known fluctuation test for mutations), but the behaviour of a culture may depend upon the aeration, and upon the precise conditions of the test. The variances show no apparent relation to the ease of production of resistance to the given drug. Nor does the scatter of the survival times in liquid media containing phenol (no resistance developable) differ much from that in chloramphenicol (resistant forms readily produced). Consideration of the factors determining the successful formation of a colony on a drug plate suggests that the fluctuation test for the demonstration of mutations must be applied with great reserve.

The resistance of Bact. lactis aerogenes to proflavine (2:8-diaminoacridine) - I. The applicability of the statistical fluctuation test

1952 ◽  
Vol 211 (1105) ◽  
pp. 301-301
Keyword(s):  
Statistical Fluctuation ◽  
Marked Influence ◽  
Fluctuation Test ◽  
Development Of Resistance ◽  
Single Culture ◽  
Solid Media ◽  
Statistical Variation ◽  
Colony Number ◽  
The Times ◽  
Different Cultures

The number of colonies of Bact. lactis aerogenes appearing on solid media containing proflavine (2:8-diaminoacridine) under different conditions has been determined. The statistical variation is greater with samples taken from different cultures than with the same number taken from a given culture. This might appear to correspond to the Luria-Delbrück criterion that the resistant colonies are formed from spontaneously appearing mutants in the cultures under test. It is pointed out, however, that this greater variation may in the present example depend equally well upon other factors than mutations, since separate cultures cannot be so closely controlled as any single culture in respect of age, pH and degree of aeration. The effects of these factors are studied and it is shown that varying efficiency of aeration has a specially marked influence on the number of resistant survivors. It is shown, moreover, that there is a competition between the development of resistance and death of the population, and that the times at which the last surviving cell in a proflavine culture can be detected itself shows a very great variation. Thus the variation in the colony number can be a function of survival rather than of mutation. The form of the curve showing the initial decline of population followed by growth of resistant survivors is difficult to reconcile quantitatively with a simple form of the mutation hypothesis.

TEM processing procedure for a bacillus organism grown on solid media

1990 ◽  
Vol 48 (3) ◽  
pp. 624-625
Author(s):  
Jane Payne ◽  
Philip Coudron
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Fume Hood ◽  
Vacuum Aspiration ◽  
Solid Media ◽  
Transmission Electron ◽  
Solid Agar ◽  
Processing Procedure ◽  
Agar Media ◽  
Rat Bone

This transmission electron microscopy (TEM) procedure was designed to examine a gram positive spore-forming bacillus in colony on various solid agar media with minimal artifact. Cellular morphology and organization of colonies embedded in Poly/Bed 812 resin (P/B) were studied. It is a modification of procedures used for undecalcified rat bone and Stomatococcus mucilaginosus.Cultures were fixed and processed at room temperature (RT) under a fume hood. Solutions were added with a Pasteur pipet and removed by gentle vacuum aspiration. Other equipment used is shown in Figure 3. Cultures were fixed for 17-18 h in 10-20 ml of RT 2% phosphate buffered glutaraldehyde (422 mosm/KgH2O) within 5 m after removal from the incubator. After 3 (30 m) changes in 0.15 M phosphate buffer (PB = 209-213 mosm/KgH2O, pH 7.39-7.41), colony cut-outs (CCO) were made with a scalpel.

Recovery of Heat-stressed Spores of Bacillus stearothermophiluson Solid Media Containing Calcium- and Magnesium-deficient Agar

1993 ◽  
Vol 56 (8) ◽  
pp. 706-709 ◽  
Author(s):  
A. SIKES ◽  
S. WHITFIELD ◽  
D. J. ROSANO
Keyword(s):  
Bacillus Stearothermophilus ◽  
Dry Weight ◽  
Soluble Starch ◽  
Trace Minerals ◽  
Experimental Conditions ◽  
Recovery Potential ◽  
Solid Media ◽  
Solid Agar ◽  
Agar Media ◽  
Mg Content

Recovery of heat-stressed (121.1°C) spores of Bacillus stearothermophilus (ATCC 12980) produced on solid sporulation agar media (Cook and Brown) and recovered on antibiotic assay medium + 0.1% soluble starch agar media appeared to be dependent on the concentration of two trace metals, calcium (Ca) and magnesium (Mg), in the agar component of the nutrient growth medium. Results from the present investigation indicated that heat-stressed (121.1°C, 0–20 min) spores of B. stearothermophilus were not recovered on agar media containing commercial agar products from BBL, Bitek (Difco), and Oxoid; however, under similar experimental conditions, heat-stressed spores were recovered on solid agar media containing Bacto (Difco) or Acumedia agar products. Chemical analysis of the trace minerals content of all five agar products indicated that the Ca content (% dry weight) of BBL, Bitek, and Oxoid products was ≤0.01% of the dry weight; the Ca content of Bacto and Acumedia agars was 15- to 20-fold greater. Similarly, the Mg content varied considerably between agars. Bacto and Acumedia agar products contained 0.073 and 0.043% Mg, respectively; the Mg content of BBL, Bitek, and Oxoid products was 0.003, 0.006, and 0.0007%, respectively. The recovery potential of mineral-deficient agar media (Ca and Mg ≤0.01% of dry weight) was restored by increasing the Ca and Mg levels to those found in mineral sufficient agar media (≥0.2 and 0.06% Ca and Mg, respectively).

Aeromonas hydrophila in Shellfish Growing Waters: Incidence and Media Evaluation

1989 ◽  
Vol 52 (1) ◽  
pp. 7-12 ◽  
Author(s):  
CARLOS ABEYTA ◽  
STEPHEN D. WEAGANT ◽  
CHARLES A. KAYSNER ◽  
MARLEEN M. WEKELL ◽  
ROBERT F. STOTT ◽  
...  
Keyword(s):  
Aeromonas Hydrophila ◽  
Environmental Samples ◽  
Enterotoxin Production ◽  
Beef Extract ◽  
Solid Agar ◽  
Agar Media

Levels of Aeromonas hydrophila determined for the shellfish growing area of Grays Harbor, Washington, ranged from 3 to 4600/100 g in oysters and from 3 to 2400/100 ml in water. Of isolates tested, 80% produced a hemolysin, a trait reported to correlate with enterotoxin production and pathogenicity. Two enrichment broths, Tryptic Soy Broth with ampicillin (TSBA) and Modified Rimler Shotts Broth (MRSB) were compared in combination with three solid agar media: Rimler Shotts (RS), Peptone Beef Extract Glycogen (PBG), and MacConkey's (MCA) agars. TSBA was far superior to MRSB in isolating this species from the environmental samples tested.

scholarly journals BIOLOGICAL METHOD OF STRUGGLE AGAINST THE BASIC WRECKERS OF THE SWEET CORN IN R. OF MOLDOVA

1970 ◽  
Vol 62 ◽  
Author(s):  
Asea Timus ◽  
N. Croitoru
Keyword(s):  
Sweet Corn ◽  
Ecological Status ◽  
Climatic Conditions ◽  
Biological Method ◽  
Trichogramma Evanescens ◽  
Biological Methods ◽  
Year 2000 ◽  
Different Cultures ◽  
The Given ◽  
Harmful Species

Every year, the demand of ecological products in the world is increasing more and more. Republic of Moldova also aspires to expand the areas of agricultural crops to get production with the "ecological" status. The sweet corn, is one of these cultures and every year the areas increase. However, because of the considerable develop of harmful insects on cultural fields, the damage reaches up to 15-20 % and more it is necessary to take measures of struggle. One of these, is a biological method and in this case it has appeared effective. For the period of sweet corn cultivation, excepting for the technology observance of cultivation of the given culture, there have been used biological methods of struggle against harmful insects. Depending on climatic conditions of each zone of the country where it is grown up this culture, different species of harmful insects develop. In R. Moldova, begining with year 2000, have been registered the following harmful species of insects on sweet corn: Aphis spp. (Aphididae); Agrotis spp. (Elateridae); Blaps halophila Fisch. (Tenebrionidae); Phylotreta spp. (Chrysomelidae); Helicoverpa armigera Hubner (Noctuidae) Ostrinia nubilalis Hb. (Pyraustidae). The constant useful fauna which develops due to these harmful species is: Nabis spp. (Miridae); Chrysopa spp., (Chrysopidae); Coccinella spp. (Coccinelidae) and others. That is why, annually are let out individuals from species Trichogramma evanescens W., to reduce the number of harmful species H. armigera Hubner. This species annually damages on different cultures, including on sweet corn. The results on released trichogrammas in 2005, for struggle against harmful species H. armigera Hubner, are presented in this work.

Relationship of growth conditions to desiccation tolerance of Salmonella enterica, Escherichia coli, and Listeria monocytogenes

2021 ◽  
Author(s):  
Rachel K Streufert ◽  
Susanne E Keller ◽  
Joelle K Salazar
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Desiccation Tolerance ◽  
Salmonella Enterica ◽  
Growth Conditions ◽  
Initial Population ◽  
Desiccation Resistance ◽  
E Coli ◽  
Solid Media ◽  
Agar Media

Growth on solid media as sessile cells is believed to increase the desiccation tolerance of Salmonella enterica . However, the reasons behind increased resistance have not been well explored. In addition, the same effect has not been examined for other foodborne pathogens such as pathogenic Escherichia coli or Listeria monocytogenes . The purpose of this research was two-fold: first, to determine the role of oxygenation during growth on the desiccation resistance of S. enterica , E. coli , and L. monocytogenes , and second, to determine the effect of sessile versus planktonic growth on the desiccation resistance of these pathogens. Three different serotypes each of Salmonella , E. coli , and L. monocytogenes were cultured in trypticase soy broth with 0.6% yeast extract (TSBYE), with (aerobic) shaking or on TSBYE with agar (TSAYE) under either aerobic or anaerobic conditions and harvested in stationary phase. After adding cell suspensions to cellulose filter disks, pathogen survival was determined by enumeration at 0 and after drying for 24 h. Results showed statistical differences in harvested initial populations prior to drying (0 h). For Salmonella , a correlation was found between high initial population and greater survival on desiccation (p = 0.05). In addition, statistical differences (p ≤ 0.05) between survival based on growth type were identified. However, differences found were not the same for the three pathogens, or between their serotypes. In general, Salmonella and E. coli desiccation resistance followed the pattern of aerobic agar media ≥ liquid media ≥ anaerobic agar media. For L. monocytogenes serotypes, resistance to desiccation was not statistically different based on mode of growth. These results indicate growth on solid media under aerobic conditions is not always necessary for optimal desiccation survival but may be beneficial when the desiccation resistance of the test serotype is unknown.

Primary isolation media for Legionnaires disease bacterium

1978 ◽  
Vol 8 (3) ◽  
pp. 320-325 ◽  
Author(s):  
J C Feeley ◽  
G W Gorman ◽  
R E Weaver ◽  
D C Mackel ◽  
H W Smith
Keyword(s):  
Oxygen Tension ◽  
Primary Isolation ◽  
Ferric Pyrophosphate ◽  
Mueller Hinton ◽  
Cysteine Hydrochloride ◽  
Mueller Hinton Agar ◽  
Agar Media ◽  
Legionnaires Disease ◽  
Isolation Media ◽  
Different Cultures

Yolk sac suspensions infected with the Legionnaires disease bacterium (LDB) were plated onto 17 different bacteriological agar media. The LDB grew only on Mueller-Hinton agar supplemented with 1% Iso Vitale X and 1% hemoglobin (MH-IH). This medium was subsequently analyzed to determine the components required to support growth of the LDB. L-Cysteine hydrochloride can replace the Iso Vitale X reagent, and soluble ferric pyrophosphate can replace hemoglobin. A new medium, F-G agar, was formulated incorporating these chemicals. Different cultures conditions (oxygen tension, temperature, and pH) were also evaluated. The LDB grew optimally at 35 degrees C under 2.5% CO2 on the F-G agar adjusted to pH 6.9. When infected tissues were inoculated onto both F-G agar and MH-IH, the F-G agar produced colonies of the LDB more rapidly and in greater numbers than did MH-IH.

The Use of Fluorogenic Substrates To Measure Fungal Presence and Activity in Soil

1998 ◽  
Vol 64 (2) ◽  
pp. 613-617 ◽  
Author(s):  
Morten Miller ◽  
Ansa Palojärvi ◽  
Andrea Rangger ◽  
Morten Reeslev ◽  
Annelise Kjøller
Keyword(s):  
Fungal Biomass ◽  
Phospholipid Fatty Acid ◽  
Soil Samples ◽  
Fluorogenic Substrates ◽  
Link Type ◽  
Solid Media ◽  
Enzyme Substrates ◽  
Agar Media ◽  
Number Of Bacteria ◽  
Selection Of

ABSTRACT Our objective was to determine if 4-methylumbelliferyl-labelled enzyme substrates could be used to detect and quantify specific components of chitinase and cellulase activities as specific indicators of the presence and activity of fungal biomass. The fluorogenic substrates 4-methylumbelliferyl (MUF)N-acetyl-β-d-glucosaminide and MUF β-d-lactoside were used for the detection and quantification of β-N-acetylglucosaminidase (EC 3.2.1.30 ) (NAGase) and endo 1,4-β-glucanase (EC 3.2.1.4 )/cellobiohydrolase (EC3.2.1.91 ) (CELase), respectively. Culture screenings on solid media showed a widespread ability to produce NAGase among a taxonomically diverse selection of fungi on media with and without added chitin. NAGase activity was expressed only in a limited number of bacteria and on media supplemented with chitin. The CELase activity was observed only in a limited number of fungi and bacteria. Bacterial CELase activity was expressed on agar media containing a cellulose-derived substrate. In soil samples, NAGase activity was significantly correlated with estimates of fungal biomass, based on the content of two fungus-specific indicator molecules, 18:2ω6 phospholipid fatty acid (PLFA) and ergosterol. CELase activity was significantly correlated with the PLFA-based estimate of fungal biomass in the soil, but no correlation was found with ergosterol-based estimates of fungal biomass.

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