In Vitro Study on the efficacy of Bacillus subtilis strain bst cell concentrations and cell-free filtrates on hatching and mobility of Rotylench ulus reniformis*

A preliminary in vitro screening trial with 3 isolates of Bucillussubtilis (Bs_t, Bs₁, & Bs₂) was evaluated for their efficacy against Rotylenclzulus reniformis. Only Bs_t isolate inhibited hatching and caused mortality of immature females/males of the nematode. Therefore, it was further evaluated with varying cell concentrations (10⁴ to 10¹⁰ cells/ml) along with undiluted cell-free culture filtrate (S) and its dilutions (S/4, S/8, S/16 and S/20) on hatching and mortality of R. reniformis at 3 exposure periods. Both cell concentrations as well as cell-free filtrates inhibited hatching and caused mortality of immature females/males of the nematode. However, significant mortality of immature females/males in the cell-free filtrate was observed at S/8 dilution and above. The observed efficacy was concentration dependent.