Bacterial colonies

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. 

Nitrocellulo.se filter replica of bacterial colonie.s carrying different DNA fragment.s... 

In each cycle, the library of mutated genes is first inserted in a standard bacterial host such as Escherichia coli or Bacillus subtilis. Subsequently, bacterial colonies are plated out on agar plates and harvested individually by a colony picker. Each colony is placed in a separate well of a microtiter plate containing nutrient broth, so that the bacteria grow and produce the protein of interest. Because each colony originates... 

Following several cycles of mutagenesis using the E. coli XLl-Red mutator strain and transformation of the plasmid library into E. coli, a total of about 150 000 bacterial colonies were assayed for activity using a colorimetric prescreen [100]. The best mutant Asn336Ser showed a 47-fold increase in activity and a 5.8-fold enhancement... 

Probe A molecule used to detect the presence of a specific fragment of DNA or RNA in, for instance, a bacterial colony that is formed from a genetic library or during analysis by blot transfer techniques common probes are cDNA molecules, synthetic oligodeoxynucleotides of defined sequence, or antibodies to specific proteins. 

Table 1.2 Appearance of bacterial colonies on bismuth sulphite agar...

Winkler, M. A. Hickman, R. K. Golden, A. Aboleneen, H. Analysis of recombinant protein expression by MALDI-TOF mass spectrometry of bacterial colonies. BioTechniques 2000, 28,890,892,894-895. 

Numerous systems in science change with time or in space plants and bacterial colonies grow, chemicals react, gases diffuse. The conventional way to model time-dependent processes is through sets of differential equations, but if no analytical solution to the equations is known, so that it is necessary to use numerical integration, these may be computationally expensive to solve. 

Cellular automata models can be used to model many systems that vary in both space and time, for example, the growth of a bacterial colony (Figure 6.1),... 

In some systems the boundaries may be ignored, as the focus of the simulation is static. If a prototype bacterial colony is placed at the center of a large CA simulation, it may grow, but will not move as a whole. If the CA is run for... 

A Petri dish containing bacterial colonies is blotted with nitrocellulose paper. This transfers a large portion of each colony to the paper, which is saturated with a solution that lyses (breaks open) the cells. The DNA of the lysed colonies is denatured with alkali. The nitrocellulose paper is neutralized, washed, and the paper either baked in an oven or treated with ultraviolet light to immobilize the denatured DNA. The DNA on the paper is hybridized with the labeled probe of interest, and the excess label is washed off. The dried paper is exposed to photographic film and the film developed. The exposed spots on the film can be matched with the colonies on the master plate and colonies picked off for further study. 

Each bacterial colony growing on artificial culture medium is assumed to arise from a single organism colony forming unit (CFU) values therefore reflect the number of viable organisms recovered. 

Andre et al. [8] discuss the determination of adenosine-5 -triphosphate by luciferin-luciferase assay. This method was applied to the determination of adenosine-5 -triphosphate in bacterial colonies filtered from samples of polluted water after incubation for different periods. The adenosine-5 -triphosphate was extracted from the residue in the filter and the amount compared with the biochemical oxygen demand of the filtered water. The oxygen uptake rate and the rate of formation of adenosine-5 -triphosphate were then plotted against time, the two curves being similar in up to three to four days incubation, after which adenosine-5 -triphosphate production declined markedly, although oxygen uptake continued to increase. 

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