京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20953号 / 理博第4405号 / 新制||理||1633(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 中野 伸一, 教授 木庭 啓介, 教授 中川 尚史 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

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The use of the herbicide glyphosate and its formulations on protein-rich feedstuff for cattle leads to a considerable intake of glyphosate into the rumen of the animals, where glyphosate may potentially impair the 5-enolpyruvylshikimate-3-phosphate pathway of the commensal microbiota, which could cause dysbiosis or proliferation of pathogenic microorganisms. Here, we evaluated the effects of pure glyphosate and the formulations Durano TF and Roundup® LB plus in different concentrations on the fermentation pattern, community composition and metabolic activity of the rumen microbiota using the Rumen Simulation Technique (RUSITEC). Application of the compounds in three concentrations (0.1mg/l, 1.0mg/l or 10mg/l, n=4 each) for 9days did not affect fermentation parameters such as pH, redox potential, NH3-N concentration and production of short-chain fatty acids compared to a control group. Microbial protein synthesis and the degradation of different feed fractions did not vary among the treatments. None of the used compounds or concentrations did affect the microbial diversity or abundance of microbial taxa. Metaproteomics revealed that the present metabolic pathways including the shikimate pathway were not affected by addition of glyphosate, Durano TF or Roundup® LB plus. In conclusion, neither pure glyphosate, nor its formulations Durano TF and Roundup® LB plus did affect the bacterial communities of the rumen.

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Hansson, L. Detektion av makrolidresistens hos Mycoplasma genitalium med Panther Fusion. Examensarbete i biomedicinsk laboratorievetenskal 15 högskolepoäng. Malmö universitet: Fakulteten för hälsa och samhälle, institutionen för Biomedicinsk Vetenskap, 2023.   Mycoplasma genitalium är en sexuellt överförbar mikroorganism som infekterar både män och kvinnor, som behandlas oftast med azitromycin med ett ökande problem av antibiotikaresistens. För M. genitalium är makrolidresistens det främsta hotet mot behandling, och har kopplats till fyra punktmutationer i region V i 23S rRNA-genen: A2071G, A2072G, A2072C samt A2071T (M. genitalium G-37, GenBank NR_077054.1). Projektet har undersökt möjligheten att ersätta nuvarande in house realtids-PCR metod för makrolidresistensbestämning med ett integrerat nukleinsyra-reningssteg och realtids-PCR med Panther Fusion (Hologic) hos Klinisk mikrobiologi i Lund. Under projektet analyserades 55 patientprover som samlades under perioden januari-februari 2023 i Region Skåne, som blivit positiva vid M. genitalium testning. Dessa prover har därefter analyserats av personal med nuvarande ABI-metod för resistensbestämning och sedan analyserats på Panther Fusion. Nuvarande ABI-metod resulterade i positiv signal för 91% (50/55) av patientprover positiva vid M. genitalium analys och makrolidresistensmutation hos 25 % (14/55), medan Panther Fusion metoden resulterade i positiv signal för 81 % (45/55) av positiva M. genitalium prover och påvisade resistensmutation hos 20 % (11/55) av proverna.

Despite the wealth of research into strategies for microbiome modulation, studies of microbiome management in pig hosts have found mixed results. A refined understanding of the patterns of microbiome assembly during the host’s early life, when management strategies are most commonly applied, is necessary for the development of successful management practices. Here, we study the development of the pig gut microbial community in a monitoring experiment, sampling the microbiome of pigs in a commercial farm intensively during the first month of life. We found that the community’s taxonomic richness increased linearly with host age. Furthermore, rapid changes across communities occurred in stages, and non-linear patterns in relative abundance were commonly observed among dominant taxa across host age, consistent with primary succession. Our results highlight the importance of understanding the patterns of microbiome assembly during host development, and identify successional stages as windows of opportunity for future research.

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BTX biodegradation rates, biochemical expression patterns and microbial ecology were studied under anoxic (denitrifying), anoxic/microaerobic/aerobic, and anoxic/microaerobic conditions in activated sludge sequencing batch reactors. The studies showed that toluene and m-xylene were denitrified via benzoyl-CoA reductase. Although benzene, o-, and p-xylene were recalcitrant under denitrifying conditions, they were biodegraded under microaerobic (< 0.2 mg/L dissolved oxygen) and nitrate or nitrite (NOx)-supplemented microaerobic conditions. The patterns of the specific enzymes associated with BTX biodegradation under microaerobic conditions indicated that the three compounds were metabolized by oxygen-dependent pathways. The expression levels of catechol 1, 2-dioxygenase and catechol 2, 3-dioxygenase under microaerobic conditions were induced to levels as high as under aerobic conditions (> 4 mg/L dissolved oxygen). Benzene, o-, and p-xylene biodegradation rates were twice as fast under NO_x-supplemented compared to NO_x-free microaerobic conditions, and the specific biodegradation rates under aerobic and NO_x-supplemented microaerobic conditions were comparable. 16S rRNA probes targeting representative toluene-degraders were used to investigate the microbial communities in the three sequencing batch reactors by using a dot blot hybridization technique. The hybridization results suggest that multiple redox environments fostered a more diverse microbial community and the activities of the target organisms in the reactors with multiple redox environments were higher than in the single redox reactor. Additionally, facultative toluene-degraders appeared to play a less significant role than the strict anoxic and aerobic toluene-degraders in all three SBRs. / Ph. D.