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Deoxyribonuclease activities in Myxococcus coralloides D.
M M Martínez-Cañamero1, J Muñoz, A L Extremera
1Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Spain.
The Journal of Applied Bacteriology
|August 1, 1991
Summary
Myxococcus coralloides D secretes cell-bound deoxyribonucleases (DNases) with distinct properties. These enzymes show varying temperature and pH optima, metal ion dependencies, and salt tolerances, aiding in their characterization.
Area of Science:
- Microbiology
- Enzymology
- Biochemistry
Background:
- Myxobacteria are known for producing extracellular enzymes.
- Cell-bound deoxyribonucleases (DNases) in Myxococcus species are less characterized.
- Understanding DNase activity is crucial for microbial physiology and biotechnology.
Purpose of the Study:
- To isolate and characterize cell-bound DNases from Myxococcus coralloides D.
- To determine the enzymatic properties including optimal conditions and cofactor requirements.
- To compare DNase production with other myxobacterial strains.
Main Methods:
- Cell-bound DNases were extracted during the exponential growth phase.
- Enzyme fractionation was performed using Sephadex G-200 gel filtration.
- Enzyme activity was assayed under varying temperature, pH, salt concentrations, and in the presence of metal ions.
- Molecular weights were estimated using gel filtration and SDS-PAGE.
Main Results:
- Three distinct DNase activities (G, M, and P) were identified with higher production in M. coralloides D compared to other strains.
- Optimal temperatures ranged from 25-37°C, with broad activity between 20-45°C.
- Optimal pH was 8.0, with high activity between pH 6.0-9.0.
- DNases M and P were sensitive to NaCl, while DNase G was less affected.
- Divalent metal ions (Mg2+, Mn2+) were essential cofactors, with other ions acting as inhibitors.
- Estimated molecular weights were 44 kDa (G), 49 kDa (M), and 39 kDa (P).
Conclusions:
- Myxococcus coralloides D produces unique cell-bound DNases with distinct biochemical properties.
- These DNases exhibit differential responses to environmental factors and metal ions.
- The characterization provides insights into the enzymatic repertoire of myxobacteria.