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The suppressive effects of microbial inoculants on cotton seedling mortality were assessed in Rhizoctonia solani-infested soil. Per cent mortality ranged from 16 to 32 (60-120 days after sowing, DAS) and significant differences were recorded at 120 DAS, especially after drenching with compost tea of Azotobacter sp. and Anabaena torulosa-Trichoderma viride-biofilmed formulations. The activity of hydrolytic enzymes was reduced in diseased root tissues due to a majority of the microbially inoculated treatments, compared with healthy root tissues. Per cent changes in the amounts of glomalin-related soil proteins ( GRSPs) were 2 to 85% greater than those of the uninoculated experimental controls. These microbial inoculants altered the rhizosphere bacterial communities as evident from the Denaturing gradient gel electrophoresis ( DGGE) banding patterns and, also reduced the population of R. solani. While the copy numbers of the internal transcribed spacer ( ITS) gene of R. solani in the uninoculated (infested soil) were approximately 1.47 × 1011 per g soil, they were 1.34-1.42 × 105 per g soil after the application of A. torulosa, Anabaena laxa and A. torulosa-Bacillus sp. Increases in yield (ranging from 3 to 23%) due to various microbial inoculants relative to uninoculated controls illustrated their promise as plant growth-promoting and disease-suppressing agents. This study illustrates the modulation of rhizosphere ecology through microbial inoculants as a mechanism of disease suppression and sustaining plant growth. [ABSTRACT FROM AUTHOR]