Isolation of Methanotrophic Bacteria from Landfill and Its Application
| Autor: | Tian-yi Wu, 吳恬宜 |
|---|---|
| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 Methane is an important greenhouse gas, and the concentrations of methane increase at the rate of 0.5-0.8 % year-1 recently. Most of methane is produced biologically by a group of strictly anaerobic bacteria in highly reduced environments. Landfill is one of the important biogenic methane sources. Methanotrophs are important regulators of methane fluxes from the landfill to atmosphere. There is very limited information presently available on the community structure of methanotrophs in landfills in Taiwan. The study is an investigation on the community structure of methanotrophs as revealed by molecular method in Nan-Sa-Lun landfills in Tainan. The methanotrophic strains will be isolated by enrichment culture and thereby subsequent loss of a variety of other methanotroph. Furthermore, methanotrophic isolates will be sampled by PCR amplification and cloning of particulate methane dehydrogenase (mxaF) gene and 16S rDNA from the total soil population. The isolated will be selected from different cover-age (0-2, 3-5 and 5-7 year-old) landfill soils. The number of methanotrophs in the surface layer of landfill soils will also determined by most-probable number (MPN) method. The 7 test strains (SA2、SA4、SA6、SA9、SA14、SA15 and SD1) obtained from in the 0-2 year-old, one strain (SC2) from 5-7 year-old landfill. SA6, SA9 and SA15 are Gram-positive strains；SA2, SA4, SA14, SC2 and SD1 are Gram-negative strains. All test strains could be detected by oxidase test. Only SA6 and SA14 could be detected by catalase test. Phylogenic analysis of the test strains were identified by 2 primers specific for the 16S rDNA and mxaF gene by NCBI database and MEGA software. Database searches indicated that SA2, SA4 andSC2 are monophyly from the phylogenic tree constructed by 16 S rDNA and would not hybridize to the Type I and Type II methanotrophs. SA6, SA9, SA14, SA15 and SD1 are most closely related to a group Methanobacterium sp.(Type II methanotroph) by phylogenic analysis of partial DNA sequence of mxaF. Changes in various factors of methane concentration, soil water content and incubation temperature will also be estimated based on incubation experiments. The maximum oxidation rates for methane were found in 30℃, 5 % CH4 and moisture content of 20%. Inoculation of methanotrophic isolates would also promote the methane oxidation rates more than 2-5 days. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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