The ability of antagonistic rhizobacteria that isolated from tomato rhizosphere soil from Mashhad, Iran to control tomato damping off disease was investigated. A total of twenty bacterial isolates were isolated and tested in vitro for their antagonistic activity against Rhizoctonia solani (Thanatephorus cucumeris) by using duel culture assay. The mycelial growth of pathogen was suppressed after placing Rhizoctonia solani and the isolates on the opposite side of the same petri dish. Cell wall degrading enzymes secreted by bacterial isolates were investigated to reveal their ability to degrade cell wall components of phytopathogens such as cellulase, protease and chitinase. Cellulase assay showed positive results in 16 bacterial isolates while 14 isolates of bacteria had protease positive result. Chitinase test gave positive result in 13 isolated bacteria. Among the isolates tested, six bacterial isolates choosing randomly were identified using universal primers and DNA sequencing as Stenotrophomonas sp. strain P7T6-4 (accession number MH665546.1), Pseudomonas aeruginosa strain P2R9-4 (accession number MH628051.1), Pseudomonas aeruginosa strain C2R4 (accession number MH628049.1) and Pseudomonas aeruginosa strain P1T30-9 (accession number MH628050.1), Serratia sp. strain E10-9 (accession number MH665545.1), and Raoultella sp. strain F9-1 (accession number MH665598.1). Our data revealed that antagonistic bacteria showed potential feasible alternative as ecofriendly biological control of Rhizoctonia solani damping off disease of tomato plants.

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