EVALUATION OF MICROBIAL RISK IN SOIL
AMENDED WITH ORGANIC FERTILIZERS FROM
STABILIZED SWINE MANURE WASTE |
Il Han1,3, Young Shin Lee2, and Joonhong Park3† |
1Department of Civil Engineering and Environmental Sciences, Korea Military Academy, Nowon-Gu, Gongneung-Dong PO Box 77, Seoul, 139-799 Korea 2Department of Environmental Engineering, Hanseu University, Daegok Ri 360, Haemi-Myun, Seosan-Si, Chungcheongnam-Do, 356-706 Korea 3Department of Civil and Environmental Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul, 120-749 Korea |
Corresponding Author:
Joonhong Park ,Tel: +82-02-2123-5798, Fax: +82-02-312-5798, Email: parkj@yonsei.ac.kr |
Received: July 9, 2007; Accepted: August 10, 2007. |
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ABSTRACT |
This study evaluated microbial risk that could develop within soil microbial communities after
amended with organic fertilizers from stabilized swine manure waste. For this purpose, we assessed the
occurrences and competitiveness of antibiotic resistance and pathogenicity in soil microbial communities that
were amended with swine manure wastes stabilized by a traditional lagoon fermentation process and an
autothermal thermophilic aerobic digestion process, respectively. According to laboratory cultivation detection
analysis, soil applications of the stabilized organic fertilizers resulted in increases in absolute abundances of
antibiotic resistant bacteria and of two tested pathogenic bacteria indicators. The increase in occurrences
might be due to the overall growth of microbial communities by the supplement of nutrients from the
fertilizers. Meanwhile, the soil applications were found to reduce competitiveness for various types of
antibiotic resistant bacteria in the soil microbial communities, as indicated by the decrease in relative
abundances (of total viable heterotrophic bacteria). However, competitiveness of pathogens in response to
the fertilization was pathogens-specific, since the relative abundance of Staphylococcus was decreased by the
soil applications, while the relative abundance of Salmonella was increased. Further testes revealed that no
MAR (multiple antibiotic resistance) occurrence was detected among cultivated pathogen colonies. These
findings suggest that microbial risk in the soil amended with the fertilizers may not be critical to public
health. However, because of the increased occurrences of antibiotic resistance and pathogenicity resulted
from the overall microbial growth by the nutrient supply from the fertilizers, potential microbial risk could
not be completely ruled out in the organic-fertilized soil samples. |
Keywords:
Antibiotic resistant bacteria | Autothermal thermophilic aerobic digestion | Lagoon fermentation |
Multiple antibiotic resistance (MAR) | Pathogen |
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