Title Page
Abstract
Contents
1. INTRODUCTION 11
2. MATERIALS AND METHODS 15
2.1. Sample collection 15
2.2. Sample preparation 15
2.2.1. Chinese cabbage 15
2.2.2. Soil 16
2.2.3. Irrigation water 16
2.3. Microbiological analyses 19
2.3.1. Total aerobic plate counts 19
2.3.2. Coliforms and Escherichia coli 19
2.3.3. Yeast and Mold 20
2.3.4. Bacillus cereus 20
2.3.5. Staphylococcus aureus 20
2.3.6. Clostridium perfringens 21
2.3.7. Listeria monocytogenes 21
2.3.8. Salmonella spp. 22
2.3.9. Escherichia coli 0157:H7 22
2.4. Statistical analysis 26
3. RESULTS AND DISCUSSION 27
3.1. Sample collection 27
3.2. Microbial levels by samples 29
3.3. Irrigation water with supply sources 31
3.4. Microbial levels by region 37
3.5. Variation of Microbial level by season 48
3.6. Microbial levels of Chinese cabbage in supply channel 54
3.7. Characteristics of microbial levels between cultivation method 58
4. CONCLUSION 61
REFERENCES 63
국문초록 67
Table 1. The selective media and incubation conditions for six pathogens 17
Table 2. Geographical and Seasonal classification of Chinese cabbage and environment 28
Table 3. Microbial levels of Irrigation water with supply sources 33
Table 4. Characteristics of microbial levels in surface water by collecting locations 34
Table 5. Contamination of pathogens in irrigation of water 35
Table 6. Characteristics of pathogens detection by type of water supply 36
Table 7. Microbial levels of Chinese cabbage, soil and irrigation water by regions 40
Table 8. Microbial levels of samples from different area in Gangwon 41
Table 9. Microbial levels of samples from different area in Jeonnam 42
Table 10. Microbial levels of samples from different area in Chungnam 43
Table 11. Comparison of pathogen detection in samples among regions 44
Table 12. Pathogenic microorganisms of samples from different area in Gangwon 45
Table 13. Pathogenic microorganisms of samples from different area in Jeonnam 46
Table 14. Pathogenic microorganisms of samples from different area in Chungnam 47
Table 15. Pathogenic microorganisms of samples by season 53
Table 16. Microbial levels of Chinese cabbage in supply channel 56
Table 17. Pathogens detection of Chinese cabbage in supply channel 57
Table 18. Characteristics of microbial levels between cultivation method 59
Table 19. Pathogens detection rate between cultivation method 60
Figure 1. Pretreatment method for Chinese cabbage and soil 24
Figure 2. Pretreatment method for Irrigation water 25
Figure 3. Microbial levels of outer and inner leaves of Chinese cabbage,... 30
Figure 4. Microbial levels of Chinese cabbage by season 50
Figure 5. Microbial levels of irrigation water by season 51
Figure 6. Microbial levels of soil by season 52