Soro de leite como meio de cultivo de micro-organismo antagonista a fungos micotoxigênicos

Abstract

A major problem in food production is the fungal contamination and deterioration, this can occur pre and post-harvest, providing at least 25% of the losses of food around the world and reaching 50% in some foods in tropical countries, to reduce these losses many countries make intensive use of pesticides, however due to the high degree of toxicity of these are being banned by many countries around the world. Alternatively to reduce fungal contamination, several authors reporting the biocontrol as a potential alternative, comes from the use of antagonists microorganisms. However most studies are focused on the test strains and identification of new compounds, being producing these micro-organisms neglected. The production of these microorganisms is a fundamental part of the economic feasibility of its application in this context the reuse of industrial residues rich in nutrients for use as a medium has been used by the industry as an alternative to synthetic culture medium that can become inexpensive for the process of production. The southwest region of Paraná is a greater producer of cheese, which produces every day a huge amount of whey, this contains a lot of protein, sugars and minerals. It is used as animal feed or sold at extremely low values, and in many cases discarded in nature without any treatment. This study aimed to use whey as culture medium for antagonistic microorganisms against mycotoxigenic fungi. Treatments were performed to verify the effect of whey as a growth medium, by analyzing the growth of the microorganism, the antagonist activity and ability to produce antifungal substantiate every 24 hours of cultivation from 0 hour to 144 hours of incubation against F. verticillioides. Was isolated from a total of 32 microorganisms, and only the strain L13 demonstrated activity against all the test fungi mycotoxigenic, this being chosen to perform the tests with whey medium. The maximum growth of the microorganism was 9.5 Log CFU.mL-1 (96 hours) in malt extract broth(CEM) medium and 8.5 log CFU.mL-1 (96h) in the middle of whey. While the highest inhibition was achieved at 72 hours in Whey based medium (18.66 mm) and CEM means (17,22 mm), showing that the cultivation in whey based medium did not affect the antagonist ability of strain L13. The use of whey as culture medium for the L13 microorganism proved possible and feasible, not changing their antagonistic capacity to test fungus. This is the first work reporting the use of whey for the production of microorganisms antagonistic to mycotoxigenic fungi as the first to report the potential of highly acidifying micro-organism for use in controlling mycotoxigenic fungi.