Watcharasukarn Montira, Kaparaju Prasad, Steyer Jean-Philippe, Krogfelt Karen A, Angelidaki Irini
Department of Environmental Engineering, Technical University of Denmark, Building 115, 2800 Kgs. Lyngby, Denmark.
Microb Ecol. 2009 Aug;58(2):221-30. doi: 10.1007/s00248-009-9497-9. Epub 2009 Mar 5.
This study was conducted to identify an indicator organism(s) in evaluating the pathogen-reducing capacity of biogas plants. Fresh cow manure containing 10(4) to 10(5) colony forming unit (CFU) per milliliter of Escherichia coli and Enterococcus faecalis along with an inoculated Clostridium perfringens strain were exposed to 37 degrees C for 15 days, 55 degrees C for 48 h, and 70 degrees C for 24 h. C. perfringens was the most heat-resistant organism followed by E. faecalis, while E. coli was the most heat-sensitive organism. E. coli was reduced below detection limit at all temperatures with log(10) reductions of 4.94 (10 s), 4.37 (40 min), and 2.6 (5 days) at 70 degrees C, 55 degrees C, and 37 degrees C, respectively. Maximum log(10) reductions for E. faecalis were 1.77 at 70 degrees C (1 day), 1.7 at 55 degrees C (2 days) and 3.13 at 37 degrees C (15 days). For C. perfringens, maximum log(10) reduction at 37 degrees C was 1.35 log(10) units (15 days) compared to less than 1 unit at 55 and 70 degrees C. Modeling results showed that E. faecalis and C. perfringens had higher amount of heat-resistant fraction than E. coli. Thus, E. faecalis and C. perfringens can be used as indicator organisms to evaluate pathogen-reducing capacity in biogas plants at high temperatures of 55 degrees C and 70 degrees C while at 37 degrees C E. coli could also be included as indicator organism.
本研究旨在确定一种指示生物，用于评估沼气厂的病原体减少能力。将每毫升含有10⁴至10⁵菌落形成单位（CFU）的大肠杆菌和粪肠球菌的新鲜牛粪，以及接种的产气荚膜梭菌菌株分别在37℃下暴露15天、55℃下暴露48小时和70℃下暴露24小时。产气荚膜梭菌是最耐热的生物，其次是粪肠球菌，而大肠杆菌是最热敏的生物。在所有温度下，大肠杆菌均降至检测限以下，在70℃、55℃和37℃时，log₁₀减少量分别为4.94（10秒）、4.37（40分钟）和2.6（5天）。粪肠球菌在70℃（1天）、55℃（2天）和37℃（15天）时的最大log₁₀减少量分别为1.77、1.7和3.13。对于产气荚膜梭菌，37℃时的最大log₁₀减少量为1.35 log₁₀单位（15天），而在55℃和70℃时小于1个单位。建模结果表明，粪肠球菌和产气荚膜梭菌的耐热部分含量高于大肠杆菌。因此，粪肠球菌和产气荚膜梭菌可作为指示生物，用于评估55℃和70℃高温下沼气厂的病原体减少能力，而在37℃时，大肠杆菌也可作为指示生物。
