Bioautographic determinations

Saponins la 7,411,430 -, bioautographic determination la 109 Sarcosine Ia435 lbl24 Scandium cations, detection la 144 Scanner, optical trains la 30,39 S-Chamber (small chamber) la 126,127 SCHiFF s bases lb 52 Scintillators la 12 Scopolamine lb 231,252,255,323 Scopoletin lb 216-218,365 Screening process lb 45 Sebacic acid la 178,233,249,308 Sebuthylazine lb 418 Selectivity, enhancement by derivatiza-tion la 55... 

A sensitive and specific bioautographic method for the identification of choline and its derivatives, was developed by Lewin and Marcus, utilizing a Neurospora crassa mutant [5]. As little as 0.03 y of choline chloride is detectable. The applicability of the method for detection of choline derivatives in lipid hydrolyzate is discussed. A method for determining the rate of diffusion of compounds from paper chromatograms into bioautograph agar is described. 

The antibacterial activity of the secoiridoids 14,15, 17-19, 20a, b, 28a and 38, and the caffeoyl esters of phenylethanoid glycosides 22 -27 has also been tested using the direct bioautographic TLC assay as published by Hamburger and Cordell [39]. Bacillus subtilis spp. and Pseudomonas fluorescens were the representatives of the gram-positive and gramnegative bacteria, respectively. The minimum inhibition amount (MIA) was determined. Cefotaxime was used as a positive control. 

A ready-to-use kit (Merck, Germany), called Chrom Biodip Antibiotika, has recently become available. This was developed for special direct bioautographic detection. This kit contains a premixed culture medium, Bacillus subtilis spore suspension, nutrient medium, and MTT detection reagent. Generally, these methods require only heater and therefore it is possible to use this detection in a conventional chemical laboratory. The total determination time is 21 h. The main advantages of this test kit are (1) the test needs little laboratory time and cost, (2) the user does not need to maintain strains of bacteria for the test, and (3) the spore suspension can be used at any time. 

Under suitable conditions, micro amounts could be determined coulometrically there is no example so far of this use. Very small amounts of vitamin have been determined with a microbiological turbidity test after they had been locaflsed bioautographically on a reference chromatogram (cf. p. 82) and extracted [128]. The quantitative determination of radioactive substances is treated in the following chapter. 

---