Title: Survival of Salmonella, Escherichia coli 0157:H7, non-0157 shiga toxin producing E.coli, and potential surrogate bacteria in crop soil as affected by the addition of fast pyrolysis-generated switchgrass biochar Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 28, 2013
Publication Date: July 31, 2013
Citation: Gurtler, J., Boateng, A.A., Douds, D.D., Bailey, R. 2013. Survival of Salmonella, Escherichia coli 0157:H7, non-0157 shiga toxin producing E.coli, and potential surrogate bacteria in crop soil as affected by the addition of fast pyrolysis-generated switchgrass biochar. Meeting Abstract. IAFP Annual Meeting, Charlotte, NC., July 28-31, 2013.Volume 1, Page 1. Technical Abstract: Fast pyrolysis of switchgrass (and resultant biochar) can be used for bio-fuel production, soil amendments for fertilizing crops, binding heavy metals, and sequestering environmental biocarbon. To determine the influence of fast pyrolysis-generated switchgrass biochar on survival of foodborne pathogens and potential surrogate bacteria in soil. Soil was amended with 7.5% biochar and inoculated with one of the following seven bacterial composites: E. coli O157:H7 (EHEC), Salmonella enterica, non-O157 Shiga toxin E. coli (STEC), ATCC nonpathogenic E. coli (BSL-1), attenuated EHEC-A, ATCC-attenuated EHEC-B, and attenuated Salmonella at 6.9 – 8.0 log CFU/g of soil, 6.9 percent moisture, sealed, and stored at 22 degrees Celcius. Twenty-four hours after inoculation, all biochar-amended soil populations were 0.33 – 1.40 log CFU/g lower than biochar-free soils, except for STEC, which declined by 1.51 log CFU in both soils. By day 5, populations of STEC and EHEC-A in biochar-amended soil were only detectable by enrichment. Pathogens, detectable by spread plating, declined 1.77-3.56 log in biochar-free soil and 2.58-4.36 log in biochar-amended soil, while surrogates were reduced 1.81-2.77 and 4.55-5.80 log in biochar-free and biochar-amended soils, respectively. By day 11, populations of STEC, EHEC-A and BSL-1 E. coli in biochar-amended soil were only detected by enrichment. Pathogens, detectable by direct plating, declined 2.12-5.03 log in biochar-free soil and 3.64-5.77 log in biochar-amended soil, while plating-detectable surrogates declined by 2.73-4.49 and 4.28 -4.94 log in biochar-free and biochar-amended soils, respectively. The lowest 11-day (log CFU) reductions in biochar-free soils for pathogens and surrogates, respectively, were O157:H7 (2.12) and EHEC-B (2.73), while the lowest declines in biochar-amended soils were Salmonella (3.64), and attenuated-Salmonella (4.28). By day 11, pathogen populations were 0.81-3.65 log lower in biochar-amended soil when compared with biochar-free soil. Biochar is effective for inactivating pathogenic EHEC, STEC and Salmonella in soil. Attenuated Salmonella and EHEC-B composites may be effective soil surrogate microorganisms.