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Investigation of microbial communities in water dispensers
박상정,Adeel Farooq,조혜준,김지혜,양미희,고영호,강성모,운노 타쯔야,정현미 한국응용생명화학회 2017 Applied Biological Chemistry (Appl Biol Chem) Vol.60 No.6
Water dispensers remove disinfectant residues from tap water and thus are commonly present in Korean households; however, microbial contamination in water dispensers has recently become a major issue. To understand the occurrence of microbial contamination in water dispensers, we investigated microbial contamination in different dispenser types through heterotrophic plate count (HPC) and MiSeq-based microbial community analyses. Two newly purchased water dispensers were placed in a basement room and left for approximately 2 months; the HPC analysis indicated microbial contamination in the drinking water collected from these dispensers (160,000 and 48,000 CFU/mL, respectively). Taxonomic classification indicated that the basement dispensers were likely contaminated by freshwater bacteria, such as Acidovorax and Methylotenera. However, two dispensers located at the half landing and the first floor showed lower microbial contamination (110 and 78 CFU/mL, respectively). Furthermore, frequently used dispenser on the first floor showed higher HPCs on the faucet surface, which were classified as general oral bacteria like Hyphobacterium. We also observed that a deserted dispenser (6-year-old with no maintenance) placed on the half landing showed the least HPCs, although it seemed to have lost its filtration ability. Our results suggested that removal of disinfectant residues leads to an increase in the freshwater bacterial population in water tanks within dispensers, which could be avoided by frequent water circulation.
파루크 아딜,운노타쯔야,Farooq, Adeel,Unno, Tatsuya The Microbiological Society of Korea 2018 미생물학회지 Vol.54 No.1
The objective of this study was to investigate the plasmid profiling of multi-drug resistant (MDR) Vibrio in influent (inflow) and effluent (discharged) water samples of fish farms in Jeju, South Korea. MDR isolates identified through disc diffusion susceptibility tests, were subjected to plasmid profiling. One hundred fifty Vibrio isolates were obtained from each influent and effluent water sample. All MDR isolates were subjected to plasmid profiling. Greater number of bacteria were enumerated from effluents (61%) comparing to influents (39%). High incidence of neomycin, sulfamethoxazole, amoxicillin and oxytetracycline resistance was observed among the isolates, which was higher in effluent samples. In contrast, Vibrio isolates were more susceptible to florfenicol, chloramphenicol, ciprofloxacin, and nalidixic acid. Among 99 (influent 39 and effluent 60) MDR isolates, a total of 58 (influent 38 and effluent 20) were found to bear plasmids ranging from 1.7 kb to >10 kb and showed 19 different antibiograms according to the size of plasmids. MDR isolates showed six and four distinct plasmid profiles in influent and effluent, respectively. Effluent samples contained more plasmid-carrying MDR Vibrio isolates with more diverse plasmid profiles and antibiograms, suggesting that fish farm tanks may serve as a reservoir of antibiotic resistance genes. The presence of plasmid-carrying MDR Vibrio isolates in fish farm effluent water may contribute to the dissemination of antibiotic resistance genes to the environments, which ultimately poses threat to human health. 이 실험은 제주도내 양식장으로부터 유입수와 방출수의 다제내성(MDR)을 가진 Vibrio 균의 plasmid profiling을 위해 진행하였다. Plasmid profiling을 위해 사용한 다제내성을 가진 균주는 디스크 확산법을 통해 확인하였고, 유입수와 방출수으로부터 각각 150개의 Vibrio 균주를 분리하였다. 모든 다제내성 균주를 대상으로 plasmid profiling을 실시하였으며, 유입수와 비교하여 방출수에서 많은Vibrio 균이 열거되었다(유입수 39%, 방출수 61%). 방출수에서는 neomycin, sulfamethoxazole, amoxicillin 및 oxytetracycline의 내성을 가진 균주가 유의적으로 많은 것으로 확인되었고, 대조적으로 Vibrio 균주는 florfenicol, chloramphenicol, ciprofloxacin 및 nalidixic acid에 더 민감한 것으로 확인이 되었다. 99종의 다제내성 균주(유입수 39종과 방출수 60종) 중에서 총 58종(유입수 38종과 방출수 20종)이 1.7 kb에서 10 kb 이상의 플라스미드를 가지고 있는 것을 확인하였으며 플라스미드 크기마다 19가지의 다른 다제내성 패턴을 보였다. 6종의 유입수와 4종의 방출수에서 다제내성 균주는 특이적인 plasmid profile이 확인되었다. 방출수 샘플은 보다 많은 플라스미드를 가진 다제내성 Vibrio 균주와 다양한 plasmid profile들과 다제내성 패턴을 가지고 있었고 이는 양식장의 저장탱크가 항생제내성 유전자의 저장소 역할을 할 수 있다는 점을 시사한다. 양식장의 방출수에서 plasmid를 가진 다제내성 Vibrio 균주의 존재는 항생제 내성 유전자의 전파에 기여할 수 있으며 이로 인해 인간의 건강을 위협할 수 있다.