| Summary: | 碩士 === 國立中興大學 === 獸醫微生物學研究所 === 91 === This study aimed to isolate nitrifying bacteria for aerobic composting and to determine their phylogenetic relationship. The mass amount of ammonia produced during aerobic composting is converted into nitrite or nitrate mainly by aerobic nitrifying bacteria. Using the ammonia sulfate enrichment medium, we obtained nine isolates of ammonia-oxidizing bacteria from compost samples. Among these isolates, five isolates, designated as A3, A21, A24, A31 and A34 were Gram negative bacteria. Four isolates, including B2, B21, B22 and B23 were Gram postive bacteria. Based on the morphology and staining characteristics, we divided the nine isolates of ammonia-oxidizing bacteria into four groups. Among them, A31, A34 and B21 were identified as Aeromonas encheleia, Aeromonas hydrophila DNA group 1 and Corynebacterium jeikeium, respectively, by using Biolog Microstation System that analyzes the biochemical characteristics of bacteria. Obtaining the 16S rDNA sequences further allowed us to determine A3 of group 1 as Agrobacterium sp., A21 of group 2 as Agrobacterium tumefaciens, B2 of group 4 as Brevundimonas diminuta. Finally, primers were synthesized according to the conserved region of ammonia monooxygenase (AMO) gene A (amoA), specific DNA fragments were amplified from bacterial isolates by PCR, and DNA sequences were aligned with amoA of ammonia-oxidizing bacteria. The results showed that DNA fragment amplified from A21 had 49.4％ similarity with Nitrosospira sp. LT2Fb and that from A24 had 50.5％ similarity with Nitrosomonas sp. Nm59, which were autotrophic ammonia-oxidizing bacteria.
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