濕地是天然生態系統中重要的一環，具有生態保育及水質淨化弁鄐H工濕地系統(constructed wetland system) 佔絕大多數，其研究與應用目的，大多是將人工濕地當作二級處理或高級處理程序，處理都市污水、工業污水，人工濕地對於金屬、化學污染物質及物理污染因子均可提供良好的去除效能。然而欲進一步再利用經處理過後之污水，則需對於其中所含的微生物或致病菌種類與數量作進一步探討。基於此，本研究以二行社區人工濕地生態淨水系統為場址，探討人工濕地系統中微生物（包括大腸桿菌、大腸桿菌群、沙門氏菌、金黃色葡萄球菌、弧菌、腸球菌等）的分布、處理效能，並探討病原性指標菌大腸桿菌之致病基因，此外，並評估人工濕地系統中不同處理階段大腸桿菌抗生素耐受性表現情形及抗生素耐受性基因之相關研究。
歷經一年半之研究結果顯示，此自然生態人工濕地淨化系統，對於民生污水中病原性微生物確實有削減之效，尤其對大腸桿菌之削減能力最為顯著，約有近1000倍之削減能力。
對病原性大腸桿菌基因檢測試驗中，所分離之312 株大腸桿菌（Escherichia coli, E. coli），具熱穩定性毒素基因（heat stable toxin gene , ST gene）及熱不穩定性毒素基因（heat labile toxin gene, LT gene）分別有 45株及120 株。含熱穩定性毒素基因之E. coli其分布為原進水點（Influent）有6 株，氧化塘（Lagoon）有16 株，free water surface flow system（FWS）有14 株，subsurface flow system（SSF）有9 株，最後放流水點（Effluent）則未檢測出含ST gene 之E. coli；含熱不穩定性毒素基因之E. coli其分布為原進水點有18 株，氧化塘有43 株，FWS 有36 株，SFW 有22 株，最後放流水點則有1 株；分離出之312 株大腸桿菌對於大腸桿菌志賀氏毒素基因（shigatoxin gene）之檢測，則皆呈負反應。
大腸桿菌抗生素耐受性試驗中，所使用七種抗生素以cefotaxone、chloramphenicol、nalidixic acid 等抗生素對大腸桿菌有較強的抑制作用。將傳統檢測與基因之抗生素耐受檢測結果相比較，對tetracycline具耐受性之E.coli 在原進水點（Influent）傳統檢測與基因檢測結果相符皆為36株；氧化塘（Lagoon）中對tetracycline具耐受性者傳統檢測有80株，基因檢測有72株；在free water surface flow（FWS）中對tetracycline具耐受性者傳統檢測有71株，基因檢測有66株; subsurface flow system（SSF）中對tetracycline具耐受性者傳統檢測有42株，基因檢測35株；而最後放流水（Effluent）對tetracycline
具耐受性者傳統檢測有4株，基因檢測法有2株。
對streptomycin具耐受性之E. coli 在原進水點中傳統檢測有37株，基因檢測結果有34株；氧化塘中傳統檢測有83株，基因檢測有69株; FWS傳統檢測有77株，基因檢測有60株;SSF中傳統檢測有53株，基因檢測29株；最後放流水中傳統檢測有4株，基因檢測則未檢測出含strA抗生素素耐受性基因之E. coli. Constructed wetlands for wastewater purification are characterized by the advantage of moderate capital costs as well as very low energy consumption and maintenance requirement.The use of constructed wetlands technology toremove metals,objection able chemical and physical contaminants are reported,but less attention has been directed toward examination of the efficacy of constructed wetlands for reduction of enteric microorganisms or pathogens from domestic sewage effluents.Less information is available on the fate of pathogenic microorganisms during on the constructed wetland treatment of sewage effluents.
The primary objective in this study was to monitor the efficiency of constructed wetlands designed to remove the pathogens. Influent to effluent samples collected once two weeks over a period of one and half year for each site will determine the reduction in total counts, fecal coliform, Escherichia coli,Salmonella and other bacteria. The plot profiles of microflora and coliform cellsare ten fold dilutions or more during the untreatment water and treatment withthe wetland system. Investigation on the contamination of E. coli cells in thewetland showed that exponential reductions (103).
The number of isolated E. coli from the wetlands were accessed by polymerase chain reaction (PCR), with primers of heat stable toxin gene、primers of heat labile toxin gene and primers of shigatoxin gene . The results showed that the numbers of ST gene and LT gene E.coli had 45 and 120 respectively. From the influent to effluent, the numbers of enterotoxigenic E.coli decreased with distance.
In view of the interested in the possible role played by municipal wastewater system in the selection of antibiotic resistant bacteria were investigated using Escherichia coli as indicator organisms. Antimicrobialsusceptibility testing was performed on a total 312 environmental E. coli isolates.Among the 7 antimicrobial agents tested, resistances were more frequent for cefotaxone, chloramphenicol, nalidixic acid than others. The distribution of theresistance determinants, for tetracycline and streptomycin was assessed by PCR.
Significant difference in the distribution of resistance determinants for tetracycline (tetA) and streptomycin (strA) was observed between the NCCLS mothod and PCR methods.
