TOXICITY SCREENING OF AZO-DYES USING THREE MICROBIAL TEST SYSTEMSP.B. DOCTOR, S.K. GHOSH, A. DERASARI AND P.K. KULKARNI
Toxicity of two widely used azo-dyes in cotton textile printing factories at Jetpur, Parrot Green (Ramazan Green) and Golden Yellow have been worked out in three microbial systems. The EC50 (mg/L) values of Golden Yellow and Parrot Green were 16.0 and 28.5 respectively, Physical factors like pH, temperature, incubation period and colour and their impact on the determination of toxicity end point by the Microtox System have been worked out. In case of motility test which employs Spirillum volutans as the test organism, the Minimum Effective Centrations (MEC") were 20 mg/L and 35 mg/L for Golden Yellow and Parrot Green respectively. In the third system using B. cereus as the test bacterium, the toxicity of the Patrrot Green was found to be 25 mg/L. However, the toxicity of the Golden Yellow was not possible to determine in this growth zone inhibition test. Out of these three systems, Microtox appeared to be the most sensitive test while growth zone inhibition test was the most simple one. However, this system needs further testing of toxicity screening using a variety of dyes since there is a deferential response of B. cexeus against the two azo dyes-Parrot Green and Golden Yellow.
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