African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 5223

Full Length Research Paper

Ultrastructural studies on the interaction between Bacillus subtilis MBI 600 (Integral®) and the rice sheath blight pathogen, Rhizoctonia solani

K. Vijay Krishna Kumar1, S. KR. Yellareddygari2, M. S. Reddy2, J. W. Kloepper2, K. S. Lawrence2, M. E. Miller3, H. Sudini4*, E.C. Surendranatha Reddy5, X. G. Zhou6 and D. E. Groth7
1Department of Entomology and Plant Pathology, Auburn University, Auburn, USA and Acharya N G Ranga Agricultural University, Hyderabad, India. 2Department of Entomology and Plant Pathology, Auburn University, Auburn, USA. 3Department of Biological Sciences, Auburn University, Auburn, USA. 4International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, India. 5Department of Genetics and Genomics, Yogi Vemana University, Kadapa, AP, India. 6Texas A & M University, Agri-Life Research & Extension Center, Texas, USA. 7Rice Research Station, LSU Ag Center, USA.
Email: [email protected]

  •  Accepted: 29 March 2013
  •  Published: 07 May 2013


The present study evaluated interactions of the biological control agent Bacillus subtilisstrain MBI 600 (Integral®) and Rhizoctonia solani, the rice sheath blight pathogen, through scanning electron microscopy (SEM). Ultrastructural effects related to antibiosis were studied by dual culture of B. subtilis (MBI 600) and R. solani on potato dextrose agar (PDA) plates. Hyphal growth near the inhibition zone was processed. To study the effects of hyperparasitism on fungal ultrastructure, Integral was sprayed on R. solani mycelia and observations were made three days later. Interactions of B. subtilis (MBI 600) and R.solani in planta were determined by spraying detached rice leaves with B. subtilis (MBI 600) and then inoculating with sclerotia of R. solani. In addition, sclerotia were dipped in Integral for 24 h, and cut sections were then observed. Overall the results indicate that B. subtilis (MBI 600) caused loss of structural integrity, shriveling, abnormal coiling, and lysis of the R. solani hyphae due to antibiosis and hyperparasitism in dual culture assays. On rice leaves, B. subtilis (MBI 600) also caused abnormal coiling, shriveling, and break down of hyphae. Sclerotia of R. solani dipped in Integral resulted in colonization of B. subtilis(MBI 600), maceration, and fragmentation of inner walls. Our results suggest that B. subtilis (MBI 600) from the product Integral was highly effective in suppressing R. solani.


Key words: Rice, Rhizoctonia solani, Bacillus subtilis, SEM, hyperparasitism, antibiosis.