Microbiological detection methods

ASTA has also made available a manual of microbiological methods (10) which contains 22 different procedures for the detection and enumeration of microorganisms occurring in spices. A handbook on clean spices for ASTA members (11) is available. 

Riboflavin can be assayed by chemical, en2ymatic, and microbiological methods. The most commonly used chemical method is fluorometry, which involves the measurement of intense yeUow-green fluorescence with a maximum at 565 nm in neutral aqueous solutions. The fluorometric deterrninations of flavins can be carried out by measuring the intensity of either the natural fluorescence of flavins or the fluorescence of lumiflavin formed by the irradiation of flavin in alkaline solution (68). The later development of a laser—fluorescence technique has extended the limits of detection for riboflavin by two orders of magnitude (69,70). 

In 1964, Netrawali et al.66 described fluorescence measurements of calcium leucovorin in NaHC03 solution after paper chromatography and reaction with acidic orcinol. The gray-blue fluorescent species formed on the developed paper-gram was very sensitive for leucovorin, showing a detection limit of 0.1 yg. In the eluting solution, however, the required concentration increased to 0.5 pg. Recovery by this method was 100 15%, and results obtained from fluorescence were lower by 10 to 20% than those obtained by microbiological methods. 

The improved methods introduced in the years 1940 to 1945 created new possibilities in this field. The Van Slyke method for quantitative determination of amino acids, based on the measurement of the volume of carbon dioxide evolved in the course of the reaction between amino acids and ninhydrin (V2), was much more reliable than the older methods. At the same time the microbiological methods designed for amino acid determinations (D3, S6) made possible the detection of very small concentrations of these compounds. The application of these... 

Microbiological methods classical microbiological tests can be used to detect C. botulinum. 

The traditional microbiological methods are very time consuming and sometimes limited concerning their interpretation. For that reason fast analysis methods as well as automated methods have been developed the latter are often used in specialised microbiological laboratories. During the last few years more and more modern biotechnological methods have been implemented into quality control, for example the enzyme-linked immunosorbent assay or more recently the polymerase chain reaction, which allows the detection of very specific microorganisms. 

Methods used in the screening phase should be able to detect the presence of as many drug residues as possible at the established for each drug level of interest, with a high sample throughput at low cost. Most microbiological methods... 

Microbiological methods reported for detection of erythromycin in fish are based either on a cylinder plate assay using Sarcina lutea (ATCC 9341) (122),... 

Rafii, F. Cerniglia, C. E. (1990). An anaerobic nondenaturing gel assay forthe detection of azoreductase from anaerobic bacteria. Journal of Microbiological Methods, 12, 139-48. 

Detection of biomass is an important application of analytical pyrolysis and it includes several topics. One such topic is the measurement of microbial biomass in attempts to substitute for traditional microbiological methods. Another topic is the detection of specific biomarkers for geochemical logging purposes. Pyrolytic studies were also useful in organic marine geochemistry [72]. An interesting application of biomass detection is the search for life in extraterrestrial samples. 

Shibl, A.M., Tawfik, A.F., El-Houfy, S. and Al-Shammary, F.J. Detection of lomefloxacin in biological fluids by HPLC and a microbiological method. /. Clin. Pliarm. Ther., 16, 353-359,1991. 

Kostrzynska, M., Leung, K.T., Lee, H. and Trevors, J.T. (2002) Green fluorescent protein-based biosensor for detecting SOS-inducing activity of genotoxic compounds. Journal of Microbiological Methods, 48, 43-51. 

Vesterlund, S., Paltta, J., Laukova, A., Karp, M., and Ouwehand, A.C. 2004. Rapid screening method for the detection of antimicrobial substances. Journal of Microbiological Methods 57 23-31. 

To control sterility or cleanness in hospital environment microbiology methods, laborious and time consuming (24-120 h), are used at present. To accelerate and simplify the sterility or cleanness control on different surfaces we applied bioluminescent assay of total bacterial contamination (TBC). Since the most surfaces analyzed in hospital contained low number of bacteria, below the detection limit of ATP-reagent used, incubation of the samples in nutritive medium followed by filtration through special luminometric microcuvettes Filtravette was applied. 

Conventional bacterial detection methods generally require laborious procedures and many hours or even days for complete analysis. The relatively large mass of bacterial cells, combined with the availability of antibodies to most species means that Pz immunosensor detection offers a very attractive alternative to microbiological methods. Generally giving results in minutes, with adequate sensitivity and selectivity. The earliest Pz immunosensors for bacterial detection have already been discussed [65,68,70]. 

The microbiological method using Lactobacillus phntarum, originally described by Snell and Wright (49), has been widely used for the determination of niacin in urine, serum, blood, foods, and tissues (16, 48,50,51,52). This organism is able to detect minute amounts of niacin (1-30 ng/mL) using a turbidimetric or titrimetric assay. 

Lytle, C.A., Can, Y.D. and White, D.C. (2000) Electrospray ionization/mass spectrometry compatible reversed-phase separation of phospholipids piperidine as a post-column modifier for negative ion detection, youma/ of Microbiological Methods 41,22 7-234. 

Ampicillin was identified by infrared spectroscopy. Chromotropic acid, sulfuric acid, ninhydrin and potassium cupri-tartrate tests are used to identify ampicillin. Electrophoresis in an agar gel is used for separation of penicillins. Spots are detected microbiologically. Thomas and Broadbridge described a method for the rapid separation and detection of mixtures of penicillins by low voltage electrophoresis. The penicillins are... 

Meyer M.H.F., Stehr M., BhujuS., Krause H.J., Hartmann M., Miethe R, Singh M., and Keusgen M. 2007b. Magnetic biosensor for the detection of Yersinia pestis. Journal of Microbiological Methods 68 218-224. 

FIGURE 4.37 (See color insert.) Comparison of the capabilities of four microbiological methods at detection of microorganisms in samples typical of the oil industry. (Reproduced from Eckert R. and Skovhus T.L., Materials Performance, 50, 8, 50-54, 2001. With permission.)... 

One important lesson from Figures 4.37 and 4.38 is that to be on the safe side, it is always prudent to combine culturing with other methods (such as qPCR). This golden rule, which can be dubbed as the rule of combination, is stated as always try to use available methods with each other, either various electrochemical detection methods or microbiological methods, or even MIC treatment methods (physical, chemical). 

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