| Title |
Chitinase Production by Bacillus thuringiensis and Bacillus licheniformis: Their Potential in Antifungal Biocontrol |
| Author |
Eman Zakaria Gomaa |
| Address |
Department of Biological and Geological Sciences, Faculty of Education, Ain Shams University, Roxy, 11435 Cairo, Egypt |
| Bibliography |
Journal of Microbiology, 50(1),103-111, 2012,
|
| DOI |
|
| Key Words |
Chitinase, Bacillus thuringiensis, Bacillus licheniformis, optimization, characterization, biological control |
| Abstract |
Thirty bacterial strains were isolated from the rhizosphere
of plants collected from Egypt and screened for production
of chitinase enzymes. Bacillus thuringiensis NM101-19 and
Bacillus licheniformis NM120-17 had the highest chitinolytic
activities amongst those investigated. The production
of chitinase by B. thuringiensis and B. licheniformis was optimized
using colloidal chitin medium amended with 1.5%
colloidal chitin, with casein as a nitrogen source, at 30°C after
five days of incubation. An enhancement of chitinase production
by the two species was observed by addition of sugar
substances and dried fungal mats to the colloidal chitin
media. The optimal conditions for chitinase activity by B.
thuringiensis and B. licheniformis were at 40°C, pH 7.0 and
pH 8.0, respectively. Na+, Mg2+, Cu2+, and Ca2+ caused enhancement
of enzyme activities whereas they were markedly
inhibited by Zn2+, Hg2+, and Ag+. In vitro, B. thuringiensis
and B. licheniformis chitinases had potential for cell wall lysis
of many phytopathogenic fungi tested. The addition of B.
thuringiensis chitinase was more effective than that of B. licheniformis
in increasing the germination of soybean seeds
infected with various phytopathogenic fungi. |
