| Title | Identification and Characterization of an Anti-fungi Fusarium oxysporum f. sp. cucumerium Protease from the Bacillus subtilis Strain N7 |
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| Author | Yi Luo, Lifei Sun, Zhen Zhu, Wei Ran*, and Qirong Shen |
| Address | Jiangsu Key Lab for Organic Solid Waste Utilization, Nanjing Agricultural University, Nanjing 210095, P. R. China |
| Bibliography | Journal of Microbiology, 51(3),359-366, 2013, |
| DOI | 10.1007/s12275-013-2627-6 |
| Key Words | purification, characterization, Bacillus subtilis, anti-fungal protease, self-formed adaptor PCR |
| Abstract | A newly discovered alkaline antifungal protease named P6 from Bacillus subtilis N7 was purified and partially characterized. B. subtilis N7 culture filtrates were purified by 30–60% (NH4)2SO4 precipitation, anion-exchange chromatography and gel filtration chromatography. Sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) revealed a single band of 41.38 kDa. Peptide sequence of protease P6 was determined using a 4800 Plus MALDI TOF/TOFTM Analyzer System. Self-Formed Adaptor PCR (SEFA-PCR) was used to amplify the 1,149 bp open read frame of P6. Dimensional structure prediction using Automatic Modeling Mode software showed that the protease P6 consisted of two β-barrel domains. Purified P6 strongly inhibited spore and mycelium growth of Fusarium oxysporum f. sp. cucumerium (FOC) by causing hypha lysis when the concentration was 25 μg/ml. Characterization of the purified protease indicated that it had substrate specificity for gelatin and was highly active at pH 8.0–10.6 and 70°C. The P6 protease was inhibited by EDTA (2 mmol/L), phenyl methyl sulfonyl fluoride (PMSF, 1 mmol/L), Na+, Fe3+, Cu2+, Mg2+ (5 mmol/L each) and H2O2 (2%, v/v). However, protease activity was activated by Ca2+, K+, Mn2+ (5 mmol/L each), mercaptoethanol (2%, v/v) and Tween 80 (1%, v/v). In additon, activity was also affected by organic solvents such as acetone, normal butanol and ethanol, but not hexane (25%, v/v each). |