Agar medium

The agar [9002-18-0] plate method consists of adding a known quantity of sample, usually 1.0 or 0.1 mL, depending on the concentration of bacteria, to a sterile petti plate and then mixing the sample with a sterile nutrient medium. After the agar medium solidifies, the petti plate is incubated at 32°C for 48 hours after which the bacterial colonies are counted and the number expressed ia terms of a 1 mL or 1 g sample. This procedure measures the number of viable organisms present and able to grow under test conditions, ie, 32°C. 

Other simple tests include the soil burial test used to demonstrate the biodegradabiUty of polycaprolactone (25), following its disappearance as a function of time, and the clear 2one method which indicates biodegradation by the formation of a clear 2one in an agar medium of the test polymer or plastic as it is consumed (26). The burial test is still used as a confirmatory test method in the real-world environment after quantitative laboratory methods indicate bio degradation. 

Cell culture. The Helianthus annuus 1805 cell culture was grown in Linsmayer-Skoog medium (9), supplemented with 0.2 mg/L 2.4 - dichlorphenoxyacetic acid and 3% sucrose. The callus cultures were kept in an agar medium of the same composition. They were grown in a thermostat in the dark at 26-28 °C for two weeks and could be stored up to two months in a refrigerator. 

Liquid hydrocarbons have been adsorbed on silica powder and dispersed in the agar medium. The silica may be autoclaved (Baruah et al. 1967), though this may be avoided by sterilizing the silica by heating, and carrying out the sorption and removal of solvents such as acetone or dichloromethane under sterile conditions. 

Siderophore production by rhizosphere bacteria that are culturable on agar media has been estimated by plating out colonies on an indicator agar medium containing chrome azurol, a weak iron-chelating complex that changes color upon... 

Because viruses only replicate inside living cells, research on viruses requires use of appropriate hosts. For the study of bacterial viruses, pure cultures are used either in liquid or on semi-solid (agar) medium. Because bacteria are so easy to culture, it is quite easy to study bacterial viruses and this is why such detailed knowledge of bacterial virus reproduction is available. 

Plaques are essentially windows in the lawn of confluent cell growth. With bacterial viruses, plaques may be obtained when virus particles are mixed into a thin layer of host bacteria which is spread out as an agar overlay on the surface of an agar medium. During incubation of the culture, the bacteria grow and form a turbid layer which is visible... 

Elmholt S, Labouriau R, Hestbjerg H and Nielsen J M (1999), Detection and estimation of conidial abundance of Penicillium verrucosum in soil by dilution plating on a selective and diagnostic agar medium (DYSG, ) Mycol. Res., 103, 887-895. 

The first LAPS utilized silicone nitride (S3N4) as a pH-sensitive layer [68], A light-addressable high resolution pH imaging sensor was applied to the detection of spatially resolved metabolic activity of Escherichia coli colonies on agar medium [69], For a silicone substrate thickness of 20 pm the reported spatial resolution was about 10 pm. The observed pH distribution was in good agreement with the results of simulation based on a two-dimensional diffusion model. 

Hara AH, Linderen JE, KayaHK. (1981) Monoxenic mass production of the entomogenous nematode, Neoaplectana carpocapsae (Wieser), On dog food/agar medium, USDA/SEA, AAT-W-16... 

The hot liquid agar medium was mixed by magnetic stirring and cooled to 45 °C in a temperature-controlled water bath. Then the agar was poured into three Petri dishes and solidified by cooling to room temperature. 

V. M. Cooke, R. J. Miles, R. G. Price, and A. C. Richardson, A novel chromogenic ester agar medium for detection of Salmonellae, Appl. Environ. Microbiol., 65 (1999) 807-812. 

Figure 10. Production of malondialdehyde, the change in Chlorella viability and uptake of O3 by a suspension of Chlorella cells. A sample from a culture of 38°C grown C. sorokiniana uflr. pacificensis (3 X10 cells/ml autotrophic medium) was treated with 180 ppm ozone. Thiobarbituric acid reactants were assayed by the method of Heath b- Packer (23), viable cells by plating on glucose-supplemented agar medium, and ozone uptake on a Cary spectrophotometer as described in Figures 6-8.

Luria-Bertani (LB, 1.0% polypeptone, 0.5% yeast extract, 1.0% NaCl, pH 7.0) medium containing 100 pg/mL ampicillin (LB-amp) and LB-amp agar medium (LB containing... 

The resulting solution is then overlaid onto Petri dishes containing a minimal glucose agar medium (with a trace of histidine to allow cell division) and incubated in the dark for 48-72 h at 37°C. The plates are removed from the incubator and any colonies present are counted. 

After the second rinse has been filtered, a final 100-ml portion containing less than 100 cfu of the specific challenge microorganism is passed through the filter. This filter is then transferred to the appropriate recovery agar medium and incubated for recovery. 

It is assumed in the direct transfer method under sterility tests that the recovery medium will allow for growth of all surviving microorganisms. The liquid medium in that test must serve to neutralize any antimicrobial properties of the test solution and to support the growth of the microorganisms. The treatment groups described above (antimicrobial neutralization for recovery on agar medium) can be used for validation of the recovery method, with the proportions of product and recovery medium varied to achieve adequate neutralization. 

Promptly pour into each petri dish about 15 to 20 ml of sterile melted tryptone soya agar medium previously melted and cooled to approximately 45°C. 

Pour one plate with uninoculated agar medium and uninoculated diluent as negative control. 

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