Determination methods microbiological

EN 12225, Geotextiles and geotextile-related products. Method for determining the microbiological resistance by a soil burial test, 2000. 

NOTE The present guidance does not lay down detailed methods for determining the microbiological and particulate cleanliness of air, surfaces etc. Reference is made to other compendia such as the CEN/ISO Standards. 

Several B vitamins, including folic acid, niacin, pyridoxine, and pantothenic acid, are routinely determined using microbiological assays, details of which can be found in the AOAC Official Methods of Analysis. Standard methods for thiamine determination using fluorimetric detection are also detailed in the AOAC methods in addition, LC techniques are now being used routinely for thiamine and other B vitamins, e.g., riboflavin. 

EN 12225 2000 Geotextiles and Geotextile-related Products - Method for Determining the Microbiological Resistance by a Soil Burial Test... 

Microbioassay. A microbioassay is a microbiological determination method mainly used for biochemicals. The amounts of chemicals are measured based on the growth levels of microorganisms. Chemicals support or inhibit their growth. 

Pantothenic acid in food is determined with microbiological or ELISA (cf. 2.6.3) techniques. A gas chromatographic method using a C-isotopomer of pantothenic acid as the internal standard is very accurate and much more sensitive. Table 6.7 lists data on pantothenic acid occurrence in food. 

The vitamin B-6 content in foods and tissues is determined by microbiological assay, chemical methods, and animal bioassays. The animal bioassays, using either the rat or chick, are time consuming, expensive, and variable therefore, they have been generally replaced by microbiological and chemical methods. 

Luminol chemiluminescence has also been recommended for measuring bacteria populations (304,305). The luminol—hydrogen peroxide reaction is catalyzed by the iron porphyrins contained in bacteria, and the light intensity is proportional to the bacterial concentration. The method is rapid, especially compared to the two-day period required by the microbiological plate-count method, and it correlates weU with the latter when used to determine bacteria... 

For most assays, the incorporated pantothenic acid has to be Hberated en2ymatically. Usually, a combination of pantotheinase and alkaline phosphatase is used to hberate the bound pantothenic acid. The official method for pantothenic acid of the Association of Official Analytical Chemists (AOAC) is the microbiological assay that uses U. Plantarium (A.TCC 8014) as the test organism (71). Samples are extracted at 121°C at pH 5.6—5.7, proteins are precipitated at pH 4.5, and the resulting clear extracts are adjusted to pH 6.8 prior to assay. This procedure is only suitable to determine calcium pantothenate or other free forms of pantothenic acid. 

In biological materials, various nonspecific precipitants have been used in the gravimetric deterrnination of choline, including potassium triiodide, platinum chloride, gold chloride, and phosphotungstic acid (28). Choline may also be determined spectrophotometricaHy and by microbiological, enzymatic, and physiological assay methods. 

Gravimetric, photometric, chromatographic, enzymatic, and microbiological methods for the determination of amino acids are reviewed and discussed. Marked advances have been made during the present decade in methods applicable to the determination of amino acids, and with the development of new analytical methods it should soon be possible to determine all the amino acids of biological importance with a degree of accuracy sufficient for practical as well as many theoretical purposes. 

The percentages of amino acids in silk fibroin which Poison et al. (224) found by direct visual and indirect photometric analysis of ninhydrin paper-partition chromatograms are shown in Table VII. The percentages obtained for alanine, glycine, and serine appear to be reasonably accurate, inasmuch as they agree closely with those found by other methods. It would be of interest to determine alanine by the microbiological method reported recently by Sauberlich and Baumann (238), in view of the widely different values found for this amino acid by the described ninhydrin-chromatographic procedure and the selec-... 

In more recent times chemically defined basal media have been elaborated, on which the growth of various lactic acid bacteria is luxuriant and acid production is near-optimal. The proportions of the nutrients in the basal media have been determined which induce maximum sensitivity of the organisms for the test substance and minimize the stimulatory or inhibitory action of other nutrilites introduced with the test sample. Assay conditions have been provided which permit the attainment of satisfactory precision and accuracy in the determination of amino acids. Experimental techniques have been provided which facilitate the microbiological determination of amino acids. On the whole, microbiological procedures now available for the determination of all the amino acids except hydroxy-proline are convenient, reasonably accurate, and applicable to the assay of purified proteins, food, blood, urine, plant products, and other types of biological materials. On the other hand, it is improbable that any microbiological procedure approaches perfection and it is to be expected that old methods will be improved and new ones proposed by the many investigators interested in this problem. 

Table XII. Microbiological Assay Methods First Used to Determine Amino Acids...

Specifics on the types and rates of microbiological attack. These must be determined by using other methods such as chemical and microbiological analysis of the solution and materials from the corrosion sites. Consideration must be given to limitations of electrochemical techniques for MIC studies, noted previously under Corrosion Testing Laboratory Tests and subsequent subsections. 

Fig- 5-7 Results (lU/mg) of an interlaboratory study to determinate the potency of tylosin CRS 1 by microbiological assay (diffusion method). 

T. Nikata, K. Sumida, J. Kato, and H. Ohtake, Rapid method for determining bacterial-behavioural responses to chemical stimulii. Applied and Environmental Microbiology 58 2250 (1992). 

Tchetche, A. G., Quantitative determination of vitamin PP or niacin in Coffea canephora var. robusta by a microbiological method using Lactobacillus arabinosus, Colloq. Sci. Int. Cafe, 8, 147, 1977. (CA92 196459)... 

---