| Congresso Brasileiro de Microbiologia 2023 | Resumo: 989-1 | ||||
Resumo:Guava (Psidium guajava L.) is a tropical fruit widely consumed due to their pleasant taste and nutritional composition. Anthracnose caused by Colletotrichum spp. is considered the main post-harvest diseases that attack guava due to the severity of the symptoms. Chemical fungicides have traditionally been used to control anthracnose. Among emerging technologies, the application of biological control, such as lactic acid bacteria (LAB), is considered an innovative biopreservation strategy. Application of biocontrol agents in combination with coating materials could increase their efficacy in inhibiting the growth of phytopathogens. This study aimed to develop and apply a coating formulated with sodium alginate supplemented with a mixed LAB culture to control the development of anthracnose in guava. Antifungal activity of the mixed culture of LAB (Levilactobacillus brevis 59, Lactiplantibacillus pentosus 129, and Limosilactobacillus fermentum 263, 1:1:1 ratio) against four species of Colletotrichum (C. fructicola, C. siamense, C. tropicale, and C. chrysophilum) was evaluated using the agar spot, diffusion in agar wells and competition for nutrients methods (5 days of incubation, 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 mixed LAB culture. Coating formulated with sodium alginate (1.5%) and mixed LAB culture (9 – 10 log CFU/g) was applied to guavas cv. Paluma contaminated by Colletotrichum species, and the results expressed as % reduction in anthracnose lesion diameter (RLDA%) (storage 15 days of at 25 ± 0.5 °C). Analysis of variance (ANOVA) followed by post hoc Tukey test were run to determine differences (p <0.05) among the results. Mixed culture of LAB strains inhibited the mycelial growth of the four tested Colletotrichum isolates, being found MGI% values in the range of 77.16 –100% by agar spot method. To confirm the antifungal activity of the mixed culture of LAB, the agar-well diffusion method was applied, and a high inhibition of mycelial growth was observed (MGI% between 90.57 and 100%). The nutrient competition methods showed that even at lower nutrient concentrations, the mixed LAB culture was able to survive and inhibit mycelial growth of Colletotrichum (MGI% up to 51%). Application of coating with mixed culture of LAB strains delayed the development and decreased the severity of anthracnose lesions with ALDR% > 50% (after 15 days) in guava artificially contaminated with tested Colletotrichum species. Coating formulated with sodium alginate and mixed LAB culture could be innovative biocontrol strategies for protecting guava from the development of anthracnose, prolonging the storage period of this fruit. Palavras-chave: Biopreservation, Coatings, Colletotrichum spp., lactic acid bacteria, Psidium guajava L. Agência de fomento:Conselho Nacional de Desenvolvimento Científico e Tecnológico. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior | |||||