Selection of Chitinolytic Bacteria as Biological Control of Colletotrichum capsici

ABSTRACT

Aims: The objectives of this study were to screen chitinolytic bacteria isolated from soil of Taman Nasional Bukit Duabelas, Jambi, Indonesia. Isolates were selected based on chitinolytic index and antagonism activity of Colletotrichum capsici. Chitinase enzyme from selected isolates was investigated for growth inhibition of C. capsici. Methodology and results: Two chitinolytic bacteria were selected based on their ability to degrade colloidal chitin and inhibit of the growth of C. capsici. Those isolates were KAHN 15.12 and SAHA 12.12, identified as Serratia marcescens and Bacillus thuringiensis respectively based on 16S rRNA gene. The chitinase maximum specific activity of isolate KAHN 15.12 was 52.03 U/mg after 36 h of incubation and SAHA 12.12 was 45.67 U/mg after 24 h of incubation. The enzyme was precipitated by ammonium sulfate 40% and 60% respectively for KAHN 15.12 and SAHA 12.12. The precipitated chitinases were active over a broad range of pH (5 to 10) and temperature (20 to 80 °C). Enzymes were stable in optimum temperature for 180 min. The precipitated of chitinase KAHN 15.12 and SAHA 12.12 had five and two protein bands respectively on SDS-PAGE gel. Chitinases exhibited an antifungal activity against C. capsici at concentration of 60 ppm. Conclusion, significance and impact of study Isolates KAHN 15.12 and SAHA 12.12 were successfully selected by their ability to degrade colloidal chitin and inhibit the growth of C. capsici. The isolates had a broad range of pH and temperature, moreover relatively stable at the optimum temperature. Chitinase was effective as biological control for anthracnose caused by C. capsici in chilli.