Resazurin solution

To evaluate bacterial contamination of wool fibers, it is suggested to use an index suggested by A. 1. Sapozhnikova, which characterizes discoloration rate of resazurin solution, a weak organic dye and currently hydrogen acceptor. It is also indicator of both presence and activity of reductase enzyme [40]. 

Resazurin is a chemical redox indicator that functions like the tetrazolium compounds. The resazurin reduction assay approach has successfully replaced tritiated thymidine incorporation for some HTS applications (Ahmed, Gogal, and Walsh 1994 Shum et al. 2008). Resazurin can be dissolved in physiological buffers resulting in an intense blue solution that is added directly to growing... 

The irradiation of the phenoxazin-3-one dye, resazurin (21), in the presence of tertiary amines results in its efficient deoxygenation via the triplet state, forming the dye resorufin (22). The radiolysis/photolysis of aqueous solutions of pyrimidines produces radicals which are the result, in general, of 1-electron reduction involving hydrated electrons. The structures of the radicals were assigned on the basis of their by EPR spectra. The study included 2-hydroxypyrimidine... 

Resazurin test The resazurin test is much quicker than the methylene blue test. Milk is mixed to aerate it and 10 ml placed in a tube. Resazurin dye solution (made from a standard tablet) is added, the tube sealed, inverted twice, and incubated at 37.5 C for 10 min. If actively reducing bacteria are present, the... 

Figure 7. UV/VIS spectrum (300-700 nm) of resazurin [I] solution containing yogurt.

Nutrients (P, N, Fe, Mg, Ca, K) and trace elements required for aerobic degradation (Mn, Cu, Co, Ni, B, Mo, Se) are provided by the mineral nutrient solutions defined by the ASTM and ISO methods. Also added are the reduction agent sodium sulfide and the redox indicator resazurin. The main difference between these two mineral nutrient solutions is the buffer system used (hydrogen carbonate buffer with ASTM and hydrogen phosphate buffer with ISO standard). While the ISO methods quantifies the CO2 dissolved in water and considers it when calculating the degradation rates, the ASTM method does not offer this option [286]. 

The usual aerobic medium is plain nutrient broth, adjusted so that it has a final pH value after sterilisation of 7 2-7 8. The anaerobic medium is the same nutrient broth with the addition of 0 5 per cent cystine, 0 05-0 07 per cent agar, 0 05 per cent glucose, 0 05 per cent sodium thioglycollate and 0 1 per cent of a 1 in 1,000 aqueous solution of resazurin, and adjusted so that the final pH value after sterilisation is between 7-2 and 7 8. Both media may be filled in about 50-ml or 250-ml amounts into tubes plugged with cotton wool or into screw-capped bottles if bottles are used, they should be of such a size that they are not more than two-thirds filled with the aerobic medium, but for the anaerobic medium they should be filled to the neck to minimise the access of oxygen. If the anaerobic medium shows a pink colour extending to more than about one inch below the surface it should be heated in flowing steam for twenty to thirty minutes, and subsequently cooled immediately prior to use. 

The method is based on resazurin ability to lose color in the presence of reductase, which is microorganisms metabohte, due to redox reaction proceeding. This enables judging about quantity of active microorganisms present in the studied objects by solution discoloration degree. 

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