Bacterial strains screening

For example, a screening of 416 strains (71 bacterial strains, 45 actinomycetes, 59 yeast, 60 basidiomycetes, 33 marine fungi, and 148 filamentous fungi) has been performed to look for microorganisms that display reductase activity in the absence of oxidase activity [8b]. A new microorganism, Diplogdasinospora grovesii IMI... 

Extensive screening methodology was used to find the suitable microorganism. As a result, K. pneumoniae IFO 3319 out of 450 bacterial strains was found to give the corresponding (2J, 3S)-hydroxy ester with 99% de and >99% ee in kilogram scale quantitatively [29g]. 

Identification of azo dye degrading bacterial strains for use in bioaugmentation typically involves a stepwise process to isolate potential strains and screen them for their ability to degrade different dyes. A number of strategies have been devised to isolate such bacteria to achieve consistent and reproducible results in biotreatment systems (Fig. 2). Specific methods that have been employed for the isolation of microbial strains capable of degrading azo dyes are summarized in Table 2. 

However, recent investigations on the effect of the tissue matrix on the detection limits attained by this test have indicated that ceftiofur, sulfonamides, streptomycin, and some macrolide antibiotics cannot be detected in intact meat with the plates and the bacterial strains prescribed in the European four-plate test (81, 82). Two plates of this system were not found suitable for screening sulfamethazine or streptomycin at levels far above the MRL the third plate detected tetracyclines and -lactams up to the MRL levels whereas the fourth was sensitive to -lactams and some but not all macrolides. Detection, on the other hand, of the fluoroquinolones enrofloxacin and ciprofloxacin could only be made possible by an additional Escherichia coli plate not included in the four-plate test. 

P. Xu, T. Yano, K. Yamamoto, H. Suzuki and H. Kumagai, Screening for bacterial strains producing lactate oxidase, J. Ferm. Bioeng., 81 (1996) 357-359. 

Adapted media for the microbial strains potato dextrose broth (PDB, Difco) used at half-strength (12 g/L for filamentous fungi supplemented with antibiotics) and Poor broth (PB, 1% bactotryptone, 0.9% NaCl w/v, pH 7.4) if bacterial strains for activity screening during isolation. 

The Ames Salmonella typhimurium assay [3, 21-26] is the most widely used test to evaluate the mutagenic activity of xenobiotic compounds. The assay serves as a quick and relatively inexpensive test to estimate the carcinogenic potential of a compound. It makes use of a variety of bacterial strains to screen compounds for... 

Scientists at Bristol-Myers Squibb, after screening various microorganisms, selected a bacterial strain of Acinetobacter calcoaceticus SC 13876 to reduce a 3,5-dioxo ester 20 to the dihydroxy ester 21 (Scheme 19.13).103 The diol 21 is a key intermediate in the synthesis of an HMG-CoA reductase inhibitor (22). In a 1-L batch reaction, a yield of 92% was obtained with an optical purity... 

In another study, screening was carried out for reduction of substituted benzazepin-2,3-dione 23 to a 3-hydroxy derivative 24 (Scheme 19.14). This was accomplished by a bacterial strain of Rhodococcus fascians ATCC 12975 (Norcardia salmonicolor SC 6310) with a conversion of 97% and an optical purity of >99.9%. This reaction product 24 is a key intermediate in the synthesis of the calcium antagonist SQ 31,765 (25).104 105 The Bristol-Myers Squibb group has also shown the selective reduction of the (3-keto ester, methyl-4-chloro-3-oxobutanoate, by the fungus Geotrichum candidum SC 5469 to the corresponding (,S )-hydroxy ester.106... 

The screening of natural products became highly popular following the discovery of penicillin from a mould. Plants, fungi, and bacterial strains were collected from all round the world in an effort to find other metabolites with useful biological activities. This led in particular to an impressive arsenal of antibacterial agents (Chapter 9). Screening of natural products from plant and microbial sources continues today in... 

The first generation process started with the chemical synthesis of the (R,S)-amide. There were several possible synthetic routes (Fig. 8) via the (R,S)-nitrile or (R,S)-acid [19, 20], A microbial screening program resulted in the isolation of several bacterial strains containing amidases that could specifically hydrolyze the (R)-amide. One of these strains, Comomonas acidivorans A 18 was particularly effective [21]. After the hydrolysis of the unwanted isomer the product (S)-2,2-dimethylcy-clopropane carboxamide was isolated from the bio-solution using a combination of salting-out and solvent extraction. This process had some intrinsic problems ... 

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