Most probable number count

The deconvolved or restored object that we seek is the most probable number-count set nm. This is called the maximum-likelihood (ML) estimate of the object. It obeys simply... 

Teske A., Wawer C., Muyzer G., and Ramsing N. B. (1996) Distribution of sulfate-reducing bacteria in a stratified fjord (Manager Fjord, Denmark) as evaluated by most-probable-number counts and denaturing gradient gel electrophoresis of PCR-amplified ribosomal DNA fragments. Appl. Environ. Microbiol. 62, 1405—1415. 

Most probable number(counts based on the proportion of liquid cultures growing after receiving low inocula)... 

The water analysis is incomplete unless the number of coliform bacteria present is determined as well. A multiple-tube fermentation technique can be used to enumerate positive presumptive, confirmed, and fecal coliform tests. Results of the tests are expressed in terms of the most probable number (MPN). That is, the count is based on a statistical analysis of sets of tubes in a series of serial dilutions. MPN is related to a sample volume of 100 ml. Thus, an MPN of 10 means 10 coliforms per 100 ml of water. 

The other method of enumerating coliforms is through the use of the multiple-tube technique. This method is statistical in nature and the result is reported as the most probable number (MPN) of organisms. Hence, the other name of this method is the MPN technique. This technique is an extension of the qualitative techniques of presumptive, confirmed, and completed tests. In other words, MPN results can be a presumptive, confirmed, and completed MPNs. The number of tubes liberating gases is counted from each of the set of hve tubes. This information is then used to compute the most probable number of organisms in the sample per 100 mL. 

A direct microscopic count of the particles was carried out using the Fuchs-rosenthal chamber [15]. Most probable number of Cu(0H] particles (P[vj) contained in 1 mm in the presence of DBS, at pH 8, = 4.72 mmol/dm and... 

It is important that the growth of cultures be measured and related to the rate of mineral oxidation, and, if possible, that the numbers of cells on the mineral surface and in suspension in the medium be determined. The growth of cultures on a mineral-containing medium cannot be followed by turbidity or Coulter Counter measurements due to interference from the mineral particles. Microscopic counting has been used to evaluate bacterial numbers in the supernatant solution, but cells attached to the mineral surfaces cannot be counted nor can active and inactive cells be differentiated. The most-probable-number... 

The resulting UV intensity can then be used to determine the UV dose. A pathogen inactivation experiment result is related to the UV dose. The typical experiment will consist of most probable number (MPN) procedure for bacteria, a plaque count procedure... 

For microbiology measurements, calibration is not performed as such. In fact the analyst often counts colonies (bacteria) or plaques (holes) in cultures (viruses, phages) or positive tubes (most probable number techniques) which are supposed to be issued from one single biological particle. The growth of the particle depends on the medium in which this growth is done. 

In microbiology two fundamental types of measurements are used by the analyst. The simplest ones consist in counting colonies on culture media in a Petri dish. Another principle consists in evaluating the most probable number of microbes by inoculating sub-samples into multiple tubes. The result of the latter is given by statistical tables. For both types of methods results are only available after a few days. For the presence of very few microbes, so-called presence/absence tests have been developed by microbiologists. They are mainly used for the detection of pathogenic microbes. For the last two types... 

In all cases, the analyst will count cfp. The RMs of BCR are not certified through most probable number techniques (MPN). Microbiological CRMs are always certified through (a) given method(s) i.e. the certified value depends upon the analytical method. For all these reasons and particularities, special rules for the use of CRMs in microbiology have been developed by RIVM for BCR. The following sections dealing with the use of CRMs are directly extracted from a report prepared by J.A. van Dommelen [12]. 

Fermentation in multiple tubes. Subculturing of the positive tubes on a confirmation medium. Count according to MPN (most probable number) or... 

Most probable number (MPN) A statistical method of measuring bacterial growth, used when samples contain too few organisms to give reliable measures by the plate-count method. 

Three methods may be used for the enumeration membrane filtration, plate count, and most probable number (MPN) method. The advantages of the membrane filter method are its low limit of detection (LOD) of < 1 CFU/g or mL and the efficient separation of the micro-organisms from components of the product, particularly antimicrobial agents. For the pour-plate method, the sample is generally 1 10 dissolved in the diluent, and 1 mL of the dilution is mixed with the agar. This corresponds to a LOD of 10 CFU/g or mL. The LOD is sometimes higher (e.g. 100 CFU/g or mL) if the product needs to be further diluted due to microbial inhibition, or lower in case of products with low microbial acceptance criteria. If the spread plate count technique is used the LOD is a factor of ten higher (>100 CFU/g or mL), because only 0.1 mL of the... 

Cultivation Techniques Microslicing, Most Probable Number (MPN) Technique, and Plate Counting... 

For the usual accurate analytical method, the mean f is assumed identical with the true value, and observed errors are attributed to an indefinitely large number of small causes operating at random. The standard deviation, s, depends upon these small causes and may assume any value mean and standard deviation are wholly independent, so that an infinite number of distribution curves is conceivable. As we have seen, x-ray emission spectrography considered as a random process differs sharply from such a usual case. Under ideal conditions, the individual counts must lie upon the unique Gaussian curve for which the standard deviation is the square root of the mean. This unique Gaussian is a fluctuation curve, not an error curve in the strictest sense there is no true value of N such as that presumably corresponding to a of Section 10.1—there is only a most probable value N. 

If the test solutes show reasonable peak asymmetry with lower than average plate count values for well retained solutes (k > 2) the column is most probably poorly packed. The number of theoretical plates, normalized to one meter column length by... 

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