Evaluation of the occurrence of sporulating and nonsporulating pathogenic bacteria in manure and in digestate of five agricultural biogas plants

In this study, three replicates of manure and digestate were collected from five farm biogas plants receiving animal manure in order to assess the occurrence and concentrations of sporulating (Clostridium botulinum,Clostridioides difficile,Clostridium perfringens) and nonsporulating (Listeria monocytogenes, thermotolerantCampylobacter spp.,Salmonella,Escherichia coli, enterococci) bacteria. Concentrations ofE. coli, enterococci, andC. perfringens in digestates ranged from 102 to 104, 104 to 105, and<103 to 7  × 105 CFU/g, respectively.Salmonella andC. difficile were detected in manure and digestate from the five biogas plants at concentrations ranging from<1.3 to>7  × 102 MPN/g and from 1.3 to 3 × 102 MPN/g, respectively. ThermotolerantCampylobacter, detected in all the manures, was only found in two digestates at a concentration of cells ranging from<10 to 2.6  × 102 CFU/g.Listeria monocytogenes andC. botulinum were detected in three manures and four digestates. The bacterial counts ofL. monocytogenes andC. botulinum did not exceed 3  × 102 and 14  MPN/g, respectively.C. botulinum type B was detected at very low level in both the manure and digestate of farm biogas plants with no botulism history. The levels of pathogenic bacteria in both manure and digestate suggested that some bacteria can persist throughout AD.

Source: MicrobiologyOpen - September 29, 2019 Category: Microbiology Authors: Caroline Le Mar échal, Céline Druilhe, Elisabeth Repérant, Evelyne Boscher, Sandra Rouxel, Sophie Le Roux, Typhaine Poëzévara, Christine Ziebal, Catherine Houdayer, Bérengère Nagard, Frédéric Barbut, Anne‐Marie Pourcher, Martine Den Tags: ORIGINAL ARTICLE Source Type: research