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.

Native Bacillus paralicheniformis isolate as a potential agent for phytopathogenic nematodes control

“…Several studies and patents report Bacillus cells or endospores as biological control agents, particularly against root-knot nematodes from the Meloidogyne genus; however, none of them surpassed the effectiveness reported here for B. paralicheniformis TB197. For example, the percent reduction in GI in field assays through the use of Bacillus altitudinis AMCC1040 ( Wang et al, 2021 ), B. subtilis Bs-1, B. cereus Bc-cm103 ( Cao et al, 2019 ), B. aryabhattai KMT-4 ( Yin et al, 2021 ), B. velezensis Bv-25 ( Antil et al, 2021 ), B. marisflavi CRB2 ( Tian et al, 2022 ), B. subtilis CRB7 and B. methylotrophicus ( Gowda et al, 2022 ) was <70%.…”

Suppressive Effect of Soil Microbiomes Associated with Tropical Fruit Trees on Meloidogyne enterolobii

“…The heatmap of the top 20 bacterial ( Figure 8 ) and fungal taxa ( Figure 9 ) indicated that B. aryabhattai was the most abundant bacterial species present in this sample, while an unidentified species of the Hypocreales order was the most abundant fungal strain. The occurrence of B. aryabhattai could explain the highest suppressiveness of M. enterolobii , as this bacterial species was shown to be very effective when it comes to nematode biocontrol; previous studies proved the nematicidal potential of this bacteria against M. javanica and the soybean cyst nematode ( Heterodera glycines ) [ 62 , 63 ]. Observations from these studies suggested that B. aryabhattai might prevent the hatching of J2 from eggs and reduce the number of H. glycines cysts and M. javanica galls on roots, while enhancing plant growth and J2 mortality in soil [ 62 , 63 ].…”

“…The occurrence of B. aryabhattai could explain the highest suppressiveness of M. enterolobii , as this bacterial species was shown to be very effective when it comes to nematode biocontrol; previous studies proved the nematicidal potential of this bacteria against M. javanica and the soybean cyst nematode ( Heterodera glycines ) [ 62 , 63 ]. Observations from these studies suggested that B. aryabhattai might prevent the hatching of J2 from eggs and reduce the number of H. glycines cysts and M. javanica galls on roots, while enhancing plant growth and J2 mortality in soil [ 62 , 63 ]. The analyses showed the presence of several hypocrealean fungi that are known for their nematode biocontrol potential.…”

Efficacy of Beneficial Microbes in Sustainable Management of Plant Parasitic Nematodes: A Review

“…During the pot experiment, the bacteria were able to reduce eggs by 73% and plant root galls by 80% compared to the chemically treated and untreated plants. Among the mechanisms, the bacterial strain was able to exhibit plant growth promoting traits such as indo-3-acetic acid (IAA), siderophores, ammonia, hydrogen cyanide, chitinase, and secondary metabolites with nematocidal activity and contributed to the suppression of nematodes [120]. Six rhizosphere bacterial isolates were studied for their ability to suppress and kill plant parasitic nematodes in the laboratory and greenhouse.…”

“…Many synthetic chemicals of non-organic origin are banned in many countries. These chemicals include barbofuran, carbosulfan, ethylene dibromide, and chloropicrin [120]. To achieve sustainable agriculture, researchers are formulating beneficial microbiomes and their metabolites into biopesticide useful in plant production [143].…”