On the potential of Bacillus aryabhattai KMT-4 against Meloidogyne javanica

Abstract Background Nematodes (Meloidogyne spp.) are a major reason behind the global crop yield reduction. The bacterial strain KMT-4 was isolated from nematode-affected tomato (Solanum lycopersicum) rhizosphere at research farms, Hisar, India, and screened for its biocontrol potential against root-knot nematode Meloidogyne javanica as well as checked for its effect on plant growth and yield. Results The bacterium KMT-4 was identified as Bacillus aryabhattai based on phenotypic characters and 16S rRNA sequence analysis. During in vitro studies, hatching and mortality of M. javanica were significantly affected due to the antagonistic behavior exhibited by the bacterium. In addition to this, KMT-4 also displayed various direct as well as indirect plant growth-promoting attributes like siderophore production, growth hormone (IAA) production, ammonia excretion, hydrogen cyanide production, and chitinase activity. A pot house experiment conducted on brinjal resulted in nearly 73% reduction in eggs, while 80% reduction in galls in the plant root compared to the untreated and chemically treated plants. The final nematode population also reduced significantly in KMT-4 treatment. It was 1141.6 J2/200cc soil in control and reduced to 108 J2/200 cc soil inoculated with KMT-4. Similar results were obtained in field experiments on brinjal and cucumber conducted in years 2018 and 2019, respectively. Also, a notable enhancement in the plant growth was observed in both pot house experiment and field trials. Conclusion The possession of nematicidal activity along with plant growth-promoting properties in B. aryabhattai KMT-4 warrants its employment as a potent biological control agent against M. javanica and a promising substitute of chemical nematicides.