Isolation, Characterization, and Identification of Root-Associated Endophytic Bacteria Producing Chitinase from Strawberry Plants

Abstract

Endophytic bacteria inhabiting root tissues represent a promising resource for biotechnological applications, particularly as chitinase producers for biological control. This study aimed to isolate, characterize, and identify chitinase-producing endophytic bacteria from strawberry (Fragaria spp.) roots. Root samples underwent a surface sterilization process and serial dilutions before being planted on selective media with a chitin colloidal substrate. They were then characterized morphologically and identified molecularly through analysis of the 16S rRNA gene. The results of the initial screening using agar medium with chitin colloidal substrate at a temperature of 37 °C yielded four bacterial isolates. Two of the bacterial isolates showed high chitinolytic index (CI), where isolate RS-A1 had a CI (1.55) and isolate RS-A2 had a CI (1.65). The electrophoresis of the 16S rRNA PCR product showed an amplicon of approximately 1300 bp. BLAST analysis against GenBank showed that isolate RS-A1 had 98.06% similarity to Acinetobacter baumannii, whereas isolate RS-A2 had 97.21% similarity to Bacillus aerius. The quantitative result of specific chitinase activity was highest in the RS-A2 isolate at 0.01146 U/mg, while that of the RS-A1 isolate was 0.00781 U/mg. These results indicate that endophytic bacteria from strawberry plant roots have the potential to act as biocontrol agents.

Keywords

• Acinetobacter baumannii
• Bacillus aerius
• chitinase
• endophytic bacteria