| Congresso Brasileiro de Microbiologia 2023 | Resumo: 878-2 | ||||
Resumo:Anthracnose caused by fungi belonging to the Colletotrichum genus has been a huge problem for postharvest quality of tropical fruits due to the severity of the disease that causes high losses for fruit commercialization. Strategies used to control post-harvest diseases in fruits typically include the use of synthetic fungicides, which has stimulated the emergence of resistant pathogens, and increased the financial and environmental costs, suggesting the necessity of new approaches with fungitoxic effects. Lactic acid bacteria (LAB) could produce several metabolites with antimicrobial activity, implying a role as emerging resources for the biocontrol of anthracnose in fruits. This study assessed the effects of different LAB to control Colletotrichum species associated to anthracnose in tropical fruits. Three different strains of LAB (Levilactobacillus brevis 59, Lactiplantibacillus pentosus 129, and Limosilactobacillus fermentum 263) were tested separately against five species of Colletotrichum: C. tropicale LM 679, C. fructicola LM 680, C. siamense LM 681, C. tropicale LM 683 and C. chrysophi LM 685. LAB Screening antifungal activity was performed with agar spot method (five days, 25 ± 0.5 °C). Results were expressed as % of mycelial growth inhibition (MGI%) using the formula MGI%= [(CT - TT) / CT] × 100, CT is the total mycelial growth of the fungi in control assay, and TT is the total mycelial growth of the fungi in media with the tested LAB strain. Cell-free supernatants (CFS) were tested to measure in vitro antagonistic activity against the germination of Colletotrichum spores (106 conidia/mL) using agar well diffusion method (72 h, 25 ± 0.5 °C). The inhibition diameters around the wells were measured in millimeters and categorized as: (I) ineffective, diameter less than 1 mm; moderate, diameter between 1 and 5 mm; and strong, diameter higher than 5 mm. Analysis of variance (ANOVA) and Tukey's post hoc test were performed to determine differences (p<0.05) between tested microorganisms. LAB were able to reduce mycelial growth of the different Colletotrichum species, with values of MGI% between 77.2%-81.1% for C. tropicale(/i) LM 679; 69.5%-76.6% for C. fructicola LM 680; 63.9%-100% for C. siamense LM 681; 65.6-81.4% for C. tropicale LM 683, and 76.7%-84% for C. chrysophi LM 685. The highest MGI% values were caused by L. fermentum 263 (70.6%-100.0%) (p>0.05). In order to determine whether the antifungal activity was due antagonism or the production of metabolites, the cell free supernatant (CFS) of the tested LAB were also evaluated. Higher inhibitory effect of CFS was observed against C. tropicale LM 679 (10.8 ±1.3%) and the lowest inhibitory effect was against C. fructicola LM 680 (2.9 ±1.1%) (p≤0.05). L. brevis 59, L. pentosus 129, and L. fermentum 263 showed potential to reduce the growth of different Colletotrichum species and could be investigated as a biocontrol to improve postharvest quality of tropical fruits. Palavras-chave: Anthracnose, Biocontrol, Colletotrichum spp., Post-harvest quality, Tropical fruits Agência de fomento:Conselho Nacional de Desenvolvimento Científico e Tecnológico. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior | |||||