Abstract
Stem canker and black scurf of potato, caused by
Rhizoctonia solani
, can be serious diseases causing an economically significant damage. Biocontrol activity of
Bacillus subtilis
ATCC 11774 against the
Rhizoctonia
diseases of potato was investigated in this study. Chitinase enzyme was optimally produced by
B. subtilis
under batch fermentation conditions similar to those of the potato-growing soil. The maximum chitinase was obtained at initial pH 8 and 30 °C.
In vitro
, the lytic action of the
B. subtilis
chitinase was detected releasing 355 u.g GlcNAc mh1 from the cell wall extract of
R. solani
and suggesting the presence of various chitinase enzymes in the bacterial filtrate. In dual culture test, the antagonistic behavior of
B. subtilis
resulted in the inhibition of the radial growth of
R. solani
by 48.1% after 4 days. Moreover, the extracted
B. subtilis
chitinase reduced the growth
oiR. solani
by 42.3% when incorporated with the PDA plates. Under greenhouse conditions, application of a bacterial suspension of
B. subtilis
at 109 cell mL
−1
significantly reduced the disease incidence of stem canker and black scurf to 22.3 and 30%, respectively. In addition, it significantly improved some biochemical parameters, growth and tubers yield. Our findings indicate two points; firstly,
B. subtilis
possesses a good biocontrol activity against
Rhizoctonia
diseases of potato, secondly, the harmonization and suitability of the soil conditions to the growth and activity of
B. subtilis
guaranteed a high controlling capacity against the target pathogen.