title: Chitinase production by Bacillus subtilis ATCC 11774 and its effect on biocontrol of Rhizoctonia diseases of potato.
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 μg GlcNAc ml⁻¹ 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 of R. 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.
authors.affiliation: Microbial Activity Unit, Microbiology Department, Soils, Water and Environment Research Institute , Agricultural Research Center, Giza , Egypt.
authors.forename: Wesam I A
authors.initials: WI
authors.lastname: Saber
authors.affiliation: Seed Pathology Research Department, Plant Pathology Research Institute , Agricultural Research Center, Giza , Egypt.
authors.forename: Khalid M
authors.initials: KM
authors.lastname: Ghoneem
authors.affiliation: Botany and Microbiology Department, Faculty of Science, King Saud University , Riyadh , Saudi Arabia.
authors.forename: Abdulaziz A
authors.initials: AA
authors.lastname: Al-Askar
authors.affiliation: Science Department, Teachers College, King Saud University , Riyadh , Saudi Arabia.|Plant Protection and Biomolecular Diagnosis Department, Arid Lands Cultivation Research Institute , City of Scientific Research and Technology Applications, Alexandria , Egypt.
authors.forename: Younes M
authors.initials: YM
authors.lastname: Rashad
authors.affiliation: Mycology and Plant Diseases Survey Department, Plant Pathology Research Institute , Agricultural Research Center, Giza , Egypt.
authors.forename: Abeer A
authors.initials: AA
authors.lastname: Ali
authors.affiliation: Microbial Activity Unit, Microbiology Department, Soils, Water and Environment Research Institute , Agricultural Research Center, Giza , Egypt.
authors.forename: Ehsan M
authors.initials: EM
authors.lastname: Rashad
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology*; D061046:Biological Control Agents; D002688:Chitinases / Q000096:biosynthesis*; D010935:Plant Diseases / Q000382:microbiology / Q000517:prevention & control*; D012232:Rhizoctonia / Q000472:pathogenicity*; D011198:Solanum tuberosum / Q000382:microbiology*
chemical_list: D061046:Biological Control Agents; D002688:Chitinases
keywords: Antagonism; antifungal; biological control; black scurf; stem canker disease