Isolation and characterization of Bacteroides host strains of bacteriophages suitable for tracking sources of fecal pollution in Thailand's water | |
| Author | Suchada Bosup |
| Call Number | AIT Thesis no.EV-12-17 |
| Subject(s) | Bacteroides Water--Measurement |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management Inter-University Program on Environmental Toxicology, Technology and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Bacteroides is a genus of gram negative, rod shape, anaerobic bacteria that inhabits in the intestinal tract of warm-blooded animals. Generally, the Bacteroides performs the host for it bacteriophages to proliferate inside. Bacteriophages of Bacteroides have been reported to be used to indicate fecal contamination in the water. This group of phages has also been stated to be able to track sources of fecal pollution from human vs animals origins. However, different geographic areas might have the different capacity of the phage detection. Consequently, the appropriate Bacteroides host strains for detecting their bacteriophages were required for the development of the microbial source tracking in Thailand. The objectives of this study were to (1) isolate Bacteroides host strains from human-derived wastewater samples; (2) validate the Bacteroides host strains with human-and animal-derived wastewater samples; and (3) study the sensitivity of the Bacteroides host strains with exposure to widely-used pesticides paraquat and ethion. Five Bacteroides host strains H148, H368, H510, H513 and H648were isolated from 17 human-derived influent wastewater samples in Bangkok and nearby with 4 steps of isolations, and compared with reference B. fragilis strains ATCC 51477 and ATCC 700786. After isolation steps, five Bacteroides host strains were validated with 18 human-derived wastewater samples and 14 animal-derived wastewater samples in Bangkok and nearby for sensitivity and specificity of the phage detection. Also, total coliforms and E. coli were measured as the indication of the water quality. For the sensitivity of the phage detection, Bacteroides host strains H648, ATCC 700786, H148, and H513 appeared to show high sensitivity to human-derived wastewaters as they provided more positive detection of phage than the reference B. fragilis ATCC 51477. Bacteroides host strain H648 appeared to detect relatively high amount of phages in human-derived water samples when compared to other isolated strains and the references B. fragilis strains ATCC 51477 and ATCC 700786. For the isolated strain H148, it showed highest specificity to human wastewaters due to the highest positive number of phage detection in water samples of human origin but highest negative number of phage detection of animal-derived water samples. On the other hand, the isolate H648 detected high concentration of phages from a diary cattle wastewater sample. Moreover, the isolate H513 presented moderate sensitivity in human-derived wastewater detection, but less specificity to human sewage when high concentration was also detected from a sheep wastewater sample. The results also showed that the B. fragilis strain ATCC 51477 did not seem to be suitable for use in Thailand, due to its low sensitivity in detecting phages from human wastewaters. Therefore, Bacteroides host strain H148 should be the best representative among 5 isolated Bacteroides host strains for Thailand’s water. The survival rate of the isolated Bacteroides host strain H148 was tested with pH 6.0 and 8.0buffer solutions at 30 ̊C in anaerobic conditions within 69 hr. Bacteroides host strain H148 showed the higher survival rate at pH 8.0. As a result, pH 8.0 was selected for the sensitivity testing with the widely-used paraquat and ethion in further step. The results of the sensitivity testing showed the effects of paraquat to the declination of Bacteroides host strain H148 from 30 hr to 69 hr. In contrast, for ethion, there was no effect to Bacteroides host strain H148 in this study. In conclusion, five Bacteroides host strains H148, H368, H510, H513 and H648 were isolated from Thailand’s water. The isolated H148 showed the best performance in term of high sensitivity and specificity to fecal contaminations of human origin for the phage detection. Also, when characterized with paraquat and ethion, the results showed the effects of paraquat to Bacteroides host strain H148, while ethion did not. |
| Year | 2012 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Kwanrawee Sirikanchana; |
| Examination Committee(s) | Preeda Pakpian;Nuchanart Rangkadilok; |
| Scholarship Donor(s) | Chulabhorn Research Institute;Mahidol University;Royal Thai Government Fellowship; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology - Chulabhorn Research Institute - Mahidol University, 2012 |