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Survival of Mycobacterium avium subsp. paratuberculosis in the intermediate and final digestion products of biogas plants
Author(s) -
Mazzone P.,
Corneli S.,
Di Paolo A.,
Maresca C.,
Felici A.,
Biagetti M.,
Ciullo M.,
Sebastiani C.,
Pezzotti G.,
Leo S.,
Ricchi M.,
Arrigoni N.
Publication year - 2018
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.13762
Subject(s) - paratuberculosis , mycobacterium avium subsp. paratuberculosis , biogas , mycobacterium , digestion (alchemy) , microbiology and biotechnology , biology , anaerobic digestion , bacteria , chemistry , methane , ecology , chromatography , genetics
Aims To evaluate the survival of Mycobacterium avium subsp. paratuberculosis ( MAP ) during anaerobic digestion ( AD ), we studied two different biogas plants loaded with manure and slurry from paratuberculosis‐infected dairy herds. Methods and Results Both plants were operating under mesophilic conditions, the first with a single digester and the second with a double digester. Mycobacterium avium subsp. paratuberculosis detection was performed by sampling each stage of the process, specifically the prefermenter, fermenter, liquid digestate and solid digestate stages, for 11 months. In both plants, MAP was isolated from the prefermenter stage. Only the final products, the solid and liquid digestates, of the one‐stage plant showed viable MAP , while no viable MAP was detected in the digestates of the two‐stage plant. Conclusions Mycobacterium avium subsp. paratuberculosis showed a significant decrease during subsequent steps of the AD process, particularly in the two‐stage plant. We suggest that the second digester maintained the digestate under anaerobic conditions for a longer period of time, thus reducing MAP survival and MAP load under the culture detection limit. Significance and Impact of the Study Our data are unable to exclude the presence of MAP in the final products of the biogas plants, particularly those products from the single digester; therefore, the use of digestates as fertilizers is a real concern related to the possible environmental contamination with MAP .