Evaluación in vitro de la actividad antagonista de las bacterias ácido-lácticas aisladas de alimentos fermentados sobre Penicillium sp y Aspergillus sp de granos de quinua

Abstract

Filamentous fungi are the most common food spoilage organisms that can cause financial problems, including health problems, due to the production of mycotoxins. The present screening study focused on evaluating the antagonist activity of lactic acid bacteria (LAB) isolated from fermented foods on Penicillium sp and Aspergillus sp isolated from grains of quinoa, Chenopodium quinoa Willdenow, stored in a trade organization in the city of Riobamba. Isolated LABs were examined on Man, Rogosa and Sharpe (MRS) agar from: pickles, chicha; cheese with milk culture and whey and other products with registered trademarks: Kumis Alpina, Megalabs Multiflora, Choozit TM81 Danisco. The bacteria were characterized at the genus level by means of their macro and microscopic morphology, catalase, oxidase and Gram stain tests, they were purified to be subjected to the antagonism test and a bank of the bioactive strains was prepared. As antagonism indicators, Penicillium sp and Aspergillus sp were isolated and identified, these were taken from quinoa grains from different areas of the Chimborazo province: Colta, Guamote and Calpi, obtaining eleven Penicillium and four Aspergillus isolates. The fungi Penicillium Cp 1.3 and Aspergillus Gm 1.6. participated in the Malta agar plate overlay test against forty strains of BAL with potential antifungal bioactivity. The frequency of BAL isolates with mean Penicillium sp suppression was 22.5%, similarly with Aspergillus sp it was obtained that 15% represents a mean suppression; being the isolated strains of pickles and milk serum those that showed superior antifungal activity. It is recommended to carry out a genotypic study of the fungal isolates and LAB, in order to know the participating specie and promote the use of bioactive strains during harvest, postharvest and storage of quinoa.