Abstract

Two different azo dyes known as acid fast red (AFR) and Congo red (CR) were examined for their decolorization by five strains of actinomycetes (Streptomyces globosus, Streptomyces alanosinicus, Streptomyces ruber, Streptomyces gancidicus, and Nocardiopsis aegyptia) under shake and static conditions.Streptomyces globosus decolorized AFR by 81.6% under static condition while 70.2% dye removal was achieved under shake conditions. Application of Plackett-Burman statistical design revealed that the main factors that affected biosorption capacity were the starch concentration and the inoculum size. Under static conditions, increasing the inoculum size and decreasing starch concentration increased the biosorption % up to 1.14 fold with time reduction, while increasing both the inoculum size and starch concentration under shake conditions increased the biosorption % up to 1.09 fold only. A trial for the use of potato peel for more economic biomass production of S. globous was carried out and (2 g/50 ml) and dried potato peel had the optimum concentration for maximum biomass production (0.3 g/50 ml) which led to considerable biosorption capacity (89.4%). Electron microscopy studies confirmed the dye removal.

Key words: Azo dyes, Biosorption, Streptomyces globosus, Plackett-Burman design.

Abbreviation

AFR,Acid fast red; CR, Congo red.