PSIII-25 - Isolation of a deoxynivalenol (DON)-degrading microbial consortia from soil

Abstract: Mycotoxins, such as deoxynivalenol (DON) produced by Fusarium, are harmful fungal secondary metabolic products that cause economic losses and health risks to humans and livestock. Measures to control and prevent feed contamination with DON are necessary to ensure the safety of livestock. These include strategies based on preventing fungal contamination of feed, or limiting contaminants in feed through mycotoxin adsorption and degradation. Soil is a valuable source of diverse microbial communities, potentially harboring DON-degrading bacteria that can be developed into feed additives to mitigate DON. This study aimed to identify microbial consortia from diverse soil samples, that could degrade DON. Soil from central (Lacombe, LA) and southern (Lethbridge, LE) Alberta were used as microbial inoculant. These soils were suspected to host Fusarium spp. which could produce DON in cereal crops growing upon them. The LE samples were further categorized into soil amended with manure (LE-MA) or non-manure (LE-UF). Prior to the study, soil pH and moisture content were measured. After soil collection, field-moist samples were mixed with DON-contaminated wheat (10% w/w, day 0) and each soil type was divided into triplicate pots and placed in a controlled environment for 32 d. On days 0, 7, 14 and 32, subsamples were collected from pots, serially diluted in a limited medium containing DON (10 µg/mL) as the only carbon source, and incubated for 2 weeks (30°C). The degradation of DON in bacterial cultures was calculated using ELISA. The LA soil was slightly acidic (pH 6.4) compared to LE-MA (7.3) and LE-UF (pH 7.0), while moisture content was greater in LA (18.4%) than LE-MA (14.7%) and LE-UF (13.5%) soils. DON-degrading activity was only detected in LA soil samples, and was highest after 7 days of incubation (21%). We are currently isolating individual bacteria from LA soil for identification and are characterizing the soil microbiota using 16S rRNA sequencing. Overall, this study showed that soil contained bacteria capable of degrading DON, however variation existed depending on soil source.