The chitinolytic rhizobacterium Serratia plymuthica HRO-C48 was previously selected as a biocontrol agent of phytopathogenic fungi. One endochitinase (E.C. 3.2.1.14), CHIT60, and one N-acetyl-ß-1,4-D-hexosaminidase (E.C. 3.2.1.52), CHIT100, were purified and characterized. The endochitinase CHIT60, with an apparent molecular mass of 60.5 kDa, had a N-terminal amino acid sequence highly similar to that of chitinases A from Serratia liquefaciens and Serratia marcescens. The enzyme activity had its peak at 55°C and pH 5.4, and increased by more than 20% in the presence of 10 mM Ca2+, Co2+ or Mn2+. Activity was inhibited by 80% in the presence of 10 mM Cu2+. CHIT100 appeared to be a monomeric enzyme with a molecular mass of 95.6 kDa and a pI of 6.8. Optimal activity was obtained at 43°C and pH 6.6, and decreased by more than 90 % in the presence of 10 mM Co2+ or Cu2+. CHIT100 (100 µg ml-1) inhibited spore germination and germ tube elongation of the phytopathogenic fungus Botrytis cinerea by 28% and 31.6%, respectively. With CHIT60 (100 µg ml-'), the effect was more pronounced: 78 % inhibition of of germination and 63.9% inhibition of germ tube elongation.
Purification and properties of two chitinolytic enzymes of Serratia plymuthica HRO-C48.
2001
Abstract
The chitinolytic rhizobacterium Serratia plymuthica HRO-C48 was previously selected as a biocontrol agent of phytopathogenic fungi. One endochitinase (E.C. 3.2.1.14), CHIT60, and one N-acetyl-ß-1,4-D-hexosaminidase (E.C. 3.2.1.52), CHIT100, were purified and characterized. The endochitinase CHIT60, with an apparent molecular mass of 60.5 kDa, had a N-terminal amino acid sequence highly similar to that of chitinases A from Serratia liquefaciens and Serratia marcescens. The enzyme activity had its peak at 55°C and pH 5.4, and increased by more than 20% in the presence of 10 mM Ca2+, Co2+ or Mn2+. Activity was inhibited by 80% in the presence of 10 mM Cu2+. CHIT100 appeared to be a monomeric enzyme with a molecular mass of 95.6 kDa and a pI of 6.8. Optimal activity was obtained at 43°C and pH 6.6, and decreased by more than 90 % in the presence of 10 mM Co2+ or Cu2+. CHIT100 (100 µg ml-1) inhibited spore germination and germ tube elongation of the phytopathogenic fungus Botrytis cinerea by 28% and 31.6%, respectively. With CHIT60 (100 µg ml-'), the effect was more pronounced: 78 % inhibition of of germination and 63.9% inhibition of germ tube elongation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
