PAPER-MILL EFFLUENT DECOLORIZATION BY 50 STREPTOMYCES STRAINS

Fifty actinomycete strains isolated from lignocellulosic substrates we re examined for the ability to remove the color from a paper mill effl uent obtained after semichemical alkaline pulping of wheat straw. Stre ptomyces sp. strains UAH 15, UAH 23, UAH 30, and UAH 51 were selected for their ability to decolorize the effluent in a liquid medium contai ning 1% (wt/vol) glycerol, 0.2% (wt/vol) ammonium sulfate, and 80% (vo l/vol) effluent. The highest levels of decolorization achieved after t he strains grew were 60 to 65%. Strains UAH 30 and UAH 51 were selecte d for further study because of their different patterns of effluent de colorization during growth. Fractionation of the decolorized effluent by gel permeation chromatography demonstrated that there were reductio ns in the levels of absorbance of the high- and medium-molecular-weigh t compounds. These fractions were mainly responsible for the color of the effluent, while the last fractions, the low-molecular-weight compo unds, could have been responsible for the residual color of the decolo rized effluent. Thin-layer chromatography revealed significant differe nces among the patterns of bands corresponding to the acidified supern atants obtained after precipitation of alkali-lignin from the effluent samples decolorized by different Streptomyces strains.