| Congresso Brasileiro de Microbiologia 2023 | Resumo: 878-1 | ||||
Resumo:The production of anthracnose-free fruits has traditionally relied on the use of synthetic fungicides. However, the application of these agents presents environmental and health risks, increasing the demand for innovative and safe strategies to the management of phytopathogens. The formulation of natural antimicrobials from extracts of fruit by-products appears as a potential alternative to this end. Furthermore, fermentation by lactic acid bacteria (LAB) can enhance antifungal properties due to the production of bioactive compounds in fermented substrates. This study aimed to evaluate in vitro the potential of using different extracts of fruit by-products fermented with LAB to control Colletotrichum species that cause anthracnose (C. siamense CMM 4077, C. siamense LM 681 and C. chrysophi LM 685). By-products of acerola, cajá, cashew, guava, mango, and grape fruits were collected in fruit processing industries, processed, autoclaved (121 °C, 1 atm, 15 minutes), and stored (-18 ± 2 °C). Subsequently, suspensions of LAB strains (Levilactobacillus brevis 59, Lactiplantibacillus pentosus 129, Limosilactobacillus fermentum 263, in co-culture at a ratio of 1:1:1) were prepared. For the formation of fermented products, the by-products were diluted in a 1:5 ratio in sterilized distilled water, autoclaved, and subsequently inoculated with the mixed culture at a concentration of approximately 9 log CFU/mL. The fermentation process took place at a temperature of 37 ºC for 72 h in an orbital shaker (200 rpm) under aerobic conditions. The LAB viable cell counts and pH analyzes were performed. The fermented extracts were obtained in 80% methanol solvent in a 1:5 ratio, using an orbital shaker homogenizer at 200 rpm for 2h. The homogenates were centrifuged, the liquid part filtered through filters with 0.45 μm membranes, and the solid part extracted again according to the described conditions. Extracts obtained after 24 and 72 h of fermentation were used to evaluate the antifungal activity through the diffusion method in agar wells, with results expressed as % of mycelial growth inhibition (MGI%). The pH of the fermented extracts increased with the processing time, with values ranging from 3.13 to 3.89, depending on the evaluated by-product. At time zero of fermentation, the LAB viable cell count was greater than 9 log CFU/mL and after 72 h of fermentation it dropped (p≤0.05) to ≥6 log CFU/mL. After 24 h of fermentation, all extracts (p>0.05) were able to reduce the mycelial growth of the different Colletotrichum species, with %MGI values ranging from 22.6 to 35% for C. siamense (CMM 4077); 21.98 to 29.2% for C. siamense (LM 681); and 34.2 to 37.4% for C. chrysophi (LM 685). After 72 h of fermentation, even with a reduction in the viable cell count, the %MGI ranged from 25.2 - 39.8%, with emphasis on extracts with cashew by-product. These results were similar or slightly lower than those observed in in vitro assays with the synthetic fungicides azoxystrobin at 1 μg i.a./mL (9 to 45%) and carbendazim at 20 μg/mL (~ 40%). The application of extracts of fruit by-products fermented with LAB showed antifungal potential against Colletotrichum species, and could be considered to formulate strategies for the management of anthracnose in fruits. Palavras-chave: Colletotrichum spp., Fermentation, Fruit waste, Lactic acid bacteria, Plant extracts Agência de fomento:Conselho Nacional de Desenvolvimento Científico e Tecnológico. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior | |||||