Antimicrobial activity of volatile organic compounds and their effect on lipid peroxidation and electrolyte loss in Colletotrichum gloeosporioides and Colletotrichum acutatum mycelia

Anthracnose is an important plant disease and is the main disease affecting guava (Psidium guajava) post-harvest, leading to economic losses and limiting fruit export. Because of the indiscriminate use of fungicides, along with environmental and food safety concerns, alternative methods of disease control are warranted. The yeast Saccharomyces cerevisiae produces a mixture of volatile organic compounds (VOCs) that show in vitro antimicrobial activity against various phytopathogens, with the compounds 3-methyl-1-butanol (3M1B) and 2-methyl-1-butanol (2M1B) being primarily responsible for this activity. Considering the potential of using VOCs for controlling post-harvest anthracnose, this study aimed to evaluate the in vitro effect of 3M1B and 2M1B on the development of Colletotrichum gloeosporioides and C. acutatum, the causal agents of the disease in guava, and to elucidate the possible modes of action of these antimicrobials. The mycelial growth of the plant pathogens was inhibited similarly by 3M1B and 2M1B, and complete inhibition occurred at doses ≥1 μL×mL-1 of air. Exposure of fungi to the VOCs increased the peroxidation levels of membrane lipids, indicating the occurrence of oxidative stress, in addition to increasing the non-selective permeability of the plasma membrane. Therefore, both 3M1B and 2M1B show potential to control C. gloeosporioides and C. acutatum.