AIDA AZRINA BINTI AZMI

English

国立大学法人長岡技術科学大学博士（工学）Articledoctoral thesi

AIDA, AZRINA BINTI AZMI

3743

Nagaoka University of Technology Institutional Repository

論文の内容の要旨 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 氏	 名	 	 	 	 	 	 Aida Azrina Binti Azmi	 	 The anaerobic sulfur oxidation reaction occurred in the upflow anaerobic sludge blanket (UASB) reactor treating municipal sewage is an interesting phenomenon where it occurred without the presence of electron acceptors. This phenomenon seems to be a new discovery where there were no studies reported previously regarding this phenomenon and the knowledge on this matter is still lacking and unclear. Therefore, several analyses were conducted to identify the factors that made this anaerobic sulfur oxidation to occur. In this study, anaerobic sulfur oxidation was regenerated by using bioelectrochemical reactor (BER) under several conditions, which were oxidation-reduction potential (ORP) control, non-ORP control, stirring and BES (2-bromo ethanedisulfonic acid) added condition, to investigate the effect of these parameters on the regeneration of anaerobic sulfur oxidation. Under the ORP control condition, the anaerobic sulfur oxidation was regenerated, whereas other conditions failed to regenerate the anaerobic sulfur oxidation reaction. The microbial community structures in the ORP control BER system, where the anaerobic sulfur oxidation were regenerated, were analyzed using cloning and terminal restriction fragment length polymorphism (T-RFLP) analyses. The results showed that phylum Proteobacteria was the major group observed where Syntrophobacteraceae and Desulfovibrionaceae family of sub-phylum δ-Proteobacteria were the most abundant bacteria groups found in the anaerobic sulfur oxidation reaction samples. These bacteria groups are known as sulfur reducing bacteria. The microbial community structures in the UASB reactor were also been analyzed and identified using cloning and T-RFLP analyses. The archaeal community had just relatively low and simple diversity which acetate-utilizing methanogen Methanosaeta spp. was the dominant group of the domain archaea at all times. Whereas, the bacterial community presented high diversity which genus Smithella of phylum Proteobacteria was the major bacterial group observed in the UASB reactor, followed by uncultured bacteria of phylum Caldiserica. The bacterial communities observed in the UASB reactor and in the anaerobic sulfur oxidation regenerated BER system showed a similar result where phylum Proteobacteria was the most abundant bacteria group found in the anaerobic sulfur oxidation samples. To gain greater insights into microbial biodiversity and its role in anaerobic sulfur oxidation, an extensive analysis of the abundance, distribution, characteristics and phylogenetic diversity of microorganisms exist in the UASB reactor was conducted by next generation sequencing analysis. Consistent with the results mentioned above, phylum Proteobacteria was the most abundant bacteria group observed during the period of anaerobic sulfur oxidation which genera Smithella as well as Desulfovibrio and Desulforhabdus were the major bacterial groups present. Besides phylum Proteobacteria, uncultured bacteria of the phylum Fusobacteria was also the major bacteria group observed during the period of anaerobic sulfur oxidation, where it demonstrated a sudden and marked increase in the second compared to the first oxidation period. Representatives of the phyla Caldiserica, which were the major bacterial group observed earlier, decreased gradually in number in both initial and second anaerobic sulfur oxidation period. However, only the genus Desulforhabdus and uncultured bacteria of the phylum Fusobacteria were influenced by the temperature which suggested that these two bacterial groups are likely to be related to the sulfur cycle and to play a role in anaerobic sulfur oxidation. From these observations, it can be suggested that this anaerobic sulfur oxidation reaction was mediated biologically by the microorganisms, and it can therefore be concluded that (i) genus Desulforhabdus, which is SRB, could have a dual function and can also act as SOB, and/or (ii) uncultured bacteria of the phylum Fusobacteria probably related and play an important role in anaerobic sulfur oxidation. However, further analyses are required to elucidate the pathways that are utilized by these bacteria to oxidize sulfur to sulfate and to gain greater insight into the basis of anaerobic sulfur oxidation in the UASB reactor. In addition, some other SRB probably have a dual function and play a role in anaerobic sulfur oxidation as well. These findings will be a novel discovery in this field of study and will give a great impact on the development of denitrification process of industrial wastewater treatment.  	 	 	 

Characterization and Profiling of Microbial Community Diversity Associated with Anaerobic Sulfur Oxidation in an Upflow Anaerobic Sludge Blanket Reactor Treating Municipal Sewage

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下水処理UASBリアクターにおいて嫌気的硫黄酸化反応に関与する微生物群集の解明

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