| Congresso Brasileiro de Microbiologia 2023 | Resumo: 989-2 | ||||
Resumo:Anthracnose caused by Colletotrichum species has been a major problem for maintaining the postharvest quality of mango (Mangifera indica L.) due to the severity of the developed symptoms. Chemical fungicides have traditionally been used to control postharvest fungal diseases in these fruits. However, due to the deleterious effects related to the continuous use of these products and the restrictions of their application in internal and external market, there has been an effort for the development of effective alternative methods effective to control anthracnose inf fruit. Application of biological control agents, such as lactic acid bacteria (LAB), has been considered an innovative biopreservation strategy, extending the storage period of fruits. This study evaluated the efficacy of a mixed LAB culture in controlling different pathogenic species of Colletotrichum causing anthracnose in fruits through in vitro experiments. Three LAB strains (Levilactobacillus brevis 59, Lactiplantibacillus pentosus 129, and Limosilactobacillus fermentum 263 in 1:1:1 ratio) were used to form the mixed culture (9 – 10 log CFU/g). Mixed culture was tested against six species of Colletotrichum that causes anthracnose in mango (C. asianum, C. fructicola, C. tropicale, C. siamense, C. karstii, and C. gloeosporioides). The antifungal activity of the mixed LAB culture was evaluated using the agar spot, diffusion in agar wells, and competition for nutrients method (5 days of incubation at 25 ± 0.5 °C). Results were expressed as % of inhibition of mycelial growth (IMG %), 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 mixed culture of LAB. The results were expressed as average ± standard deviation. Analysis of variance (ANOVA) followed by post hoc Tukey test were run to determine differences (p <0.05) among the results. Mixed LAB culture effectively inhibited the mycelial growth of all tested Colletotrichum isolates, with MGI% values in the range of 62.8 – 85.33% (agar spot method). To confirm the antifungal activity, the agar-well diffusion method was applied, and the mixed culture caused total mycelial growth inhibition (MGI%: 100%) on all target Colletotrichum isolated. The nutrient competition method showed that even at lower nutrient concentrations, mixed LAB culture inhibited Colletotrichum mycelial growth (MGI% up to 43%). The tested mixed LAB culture could be a promising biocontrol strategy for different pathogenic Colletotrichum species and can be used to control the development of anthracnose in mango. Palavras-chave: Biological control, Colletotrichum spp., lactic acid bacteria, postharvest, tropical fruits Agência de fomento:Conselho Nacional de Desenvolvimento Científico e Tecnológico and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior. | |||||