Screening of indigenous actinobacteria as biological control agents of Colletotrichum capsici and increasing chili production

Abstract

Background Anthracnose disease caused by Colletotrichum capsici is a major disease in chili plants that is difficult to control. Actinobacteria have potential biological control agents for C. capsici because of their antifungal properties and dominant presence in soil. The study aimed to obtain actinobacteria isolates that have the potential to control anthracnose in planta and increase the growth and production of chili plants. The study consisted of three stages: isolation, selection, and characterization of the best actinobacteria isolates. A total of 20 isolates of indigenous actinobacteria were isolated, and 16 isolates were successfully selected based on the results of the biosafety test. Results The in planta test showed that eight isolates could control anthracnose with 100% effectiveness. Of the eight isolates, as many as five players increased the production of chili plants by 169.51–218.53 g. Actinobacterial isolates that have the potential to control anthracnose disease in planta and increase the growth and production of chili plants are ARAI 3221, ARAC 3221, ARAC 2211, ARAC 3321, and ARTI 1312. These isolates produced indole acetic acid (IAA) with concentrations of 25.82–88.87 ppm, and four isolates were able to dissolve phosphate. Five isolates produced chitinase enzyme with the chitinolytic index of 0.32–1.78. Conclusion The introduction of actinobacteria in chili plants was also proven to extend the incubation period, reduce the incidence of disease, and reduce the severity of anthracnose disease compared to negative controls and mancozeb. Actinobacteria can suppress pathogenic microorganisms that can inhibit plant growth. Actinobacteria have the potential to increase the growth and production of chili plants. The results of 16S rRNA sequences showed that the five potential isolates were identified as Streptomyces cellulose, S. fradiae, S. olivaceus, S. pseudogriseolus, and S. griseoflavus.