Antagonistic potential of Bacillus spp. for the control of Colletotrichum gloeosporioides on avocado (Persea americana Mill.) 'Hass'

Abstract

One of the most important phytosanitary diseases affecting the production and marketing of the 'Hass' avocado fruit is anthracnose, mainly caused by the fungus Colletotrichum gloeosporioides. This disease is controlled with synthetic fungicides, which can cause harm to humans and the environment. Due to this, safer alternatives have been sought, such as biological control. The objective of this study was to isolate and characterize Bacillus spp. strains that biocontrol C. gloeosporioides in 'Hass' avocado fruits. The isolation, purification, and molecular identification of bacteria with biocontroller capacity was carried out. In vitro and in vivo tests were carried out against the pathogen C. gloeosporioides. Furthermore, the percentage inhibition of spore germination, enzymatic profile, and nutrient assimilation were determined. Forty-three native bacterial strains were isolated from the 'Hass' avocado fruit. The strains that showed the greatest antagonistic capacity in vivo against C. gloeosporioides were Bacillus pumilus AB31, B. thuringiensis AB30, B. thuringiensis AB7, and B. thuringiensis AB21. These strains could produce extracellular enzymes, such as phosphatases, proteases, and β-glucosidase, as well as the assimilation of D-ribose and trehalose. The above favors their antagonistic activity. Four strains of the genus Bacillus (one B. pumilus and three B. thuringiensis) can control C. gloeosporioides in 'Hass' avocado.