Inactivation of E. coli O157:H7 in cultivable soil by fast and slow pyrolysis-generated biochar

• Published in: Foodborne pathogens and disease Vol. 11; no. 3; p. 215
• Main Authors: Gurtler, Joshua B, Boateng, Akwasi A, Han, Yanxue Helen, Douds, Jr, David D
• Format: Journal Article
• Language: English
• Published: United States 01.03.2014
• Subjects: Animals; Charcoal - pharmacology; Colony Count, Microbial; Escherichia coli O157 - drug effects; Escherichia coli O157 - growth & development; Escherichia coli O157 - isolation & purification; Horses; Humans; Panicum; Quercus; Soil; Soil Microbiology; Temperature; Wood
• ISSN: 1556-7125
• DOI: 10.1089/fpd.2013.1631

An exploratory study was performed to determine the influence of fast pyrolysis (FP) and slow pyrolysis (SP) biochars on enterohemorrhagic Escherichia coli O157:H7 (EHEC) in soil. Soil + EHEC (inoculated at 7 log colony-forming units [CFU]/g of soil) + 1 of 12 types of biochar (10% total weight:weight in soil) was stored at 22°C and sampled for 8 weeks. FP switchgrass and FP horse litter biochars inactivated 2.8 and 2.1 log CFU/g more EHEC than no-biochar soils by day 14. EHEC was undetectable by surface plating at weeks 4 and 5 in standard FP switchgrass, FP oak, and FP switchgrass pellet biochars. Conversely, EHEC populations in no-biochar control samples remained as high as 5.8 and 4.0 log CFU/g at weeks 4 and 5, respectively. Additionally, three more SP hardwood pellet biochars (generated at 500°C for 1 h, or 2 h, or generated at 700°C for 30 min) inactivated greater numbers of EHEC than did the no-biochar control samples during weeks 4 and 5. These results suggest that biochar can inactivate E. coli O157:H7 in cultivable soil, which might mitigate risks associated with EHEC contamination on fresh produce.