S.F.MALEEKA BEGUM AND V.SUBBURAM
Abstract
Soil samples were amended with graded concentration of Congored (25 to 150 mg kg 1). Samples were drawn at specified intervals of 2, 7, 15, 30, 45 and 60 days. Dilution technique followed by pour plate technique was employed for the enumeration of bacteria. The isolates were divided into various physiological groups on the basis of their ability to elaborate different hydrolytic enzymes. It is evident from our studies that the number of bacteria (CPU'S/g dry soil) with time in the control and congored treated soils increased up to 30 days of incubation and then exhibited a decreasing trend. In the treated soils also the same trend was observed. Although increasing concentration and period of incubation caused similar changes in all the soils, the magnitude of inhibitory effect of congored on the growth of the bacterial population varied in soils. In the control soils, amylolytic forms were dominant followed by ureolytic and caseinolytic forms. In Congo red treated soils, however, the order of dominance was altered, even though amylolytic forms showed dominance in five (SI, S2, S3, S4 and S8) out of 8 soils . Further the percentage of isolates capable of elaborating the enzyme activity decreased with increasing concentration and duration of exposure