In municipal wastewater treatment, anaerobic digestion is the slowest process requiring at least 15 day solids retention time (SRT). Treating only a small fraction of the total wastewater stream, anaerobic digesters require large reactor volumes and consistent heating (40°C). Thus, there is a growing need to investigate techniques to improve digestion efficiency. The long SRT requirement is a result of the time required for biological reactions such as hydrolysis and acetoclastic methanogenesis. There are numerous pretreatment methods which have so far been developed to particularly enhance hydrolysis. These pretreatment methods include thermalization, mechanical treatments, and chemical treatments. These methods aim to increase the degradability of the influent waste sludge which in turn will increase the efficiency of the digestion process. The goal of the research presented in this thesis is to enhance another limiting biological reaction: acetoclastic methanogenesis. Microbial electrolysis cell (MEC) technology was integrated into lab-scale anaerobic digesters in order to accelerate biosolids destruction under various SRT and temperature conditions. Various mathematical simulations were conducted using a developed steady-state ADM1 (Anaerobic Digestion Model No.1) model to further evaluate the performance of the digesters. The results of the research indicate that the proposed method is effective at shortened SRTs (e.g., 6 days) and can enhance the stability of anaerobic digestion when exposed to variations in temperature and influent composition. / Thesis / Master of Applied Science (MASc)

In Vietnam, the research and application of biogas technology were given a considerable attention in past 30 years. There is several biogas plant models apply in the suburban and rural areas where most people’s life is based on animal husbandry. Each biogas plant model own strong points or weakness that adapt to detail circumstances. The biogas plants play a key role within the VACB farming system especially in the Mekong Delta where produce more than 50% of yearly national agriculture production. This paper gives a comprehensive overview on the popular biogas models in the Mekong Delta through its development history. Knowing on the presented biogas technology in the Mekong Delta will lead the biogas-related organizations or private on biogas development at this region. / Ở Việt Nam việc nghiên cứu và ứng dụng công nghệ khí sinh học đã được chú ý trong 30 năm gần đây. Một số mô hình khí sinh học đã và đang được lắp đặt tại các vùng ngoại ô và nông thôn là những nơi tập trung nhiều hộ dân chăn nuôi heo. Có nhiều mô hình khí sinh học đã được triển khai, trong đó mỗi mô hình đều có những điểm mạnh và điểm yếu đáp ứng theo từng yêu cầu cụ thể. Ở ĐBSCL nơi sản xuất trên 50% sản lượng nông nghiệp của cả nước, hầm ủ khí sinh học đóng một vai trò quan trọng trong mô hình canh tác VACB. Bài báo này trình bày chi tiết các kiểu hầm ủ khí sinh học phổ biến tại ĐBSCL tương ứng với từng thời điểm phát triển của công nghệ này. Sự hiểu biết về các kiểu hầm ủ khí sinh học hiện tại ở ĐBSCL sẽ giúp các tổ chức hoặc cá nhân có liên quan trong việc định hướng phát triển công nghệ khí sinh học cho toàn vùng.

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This study is aimed to provide comprehensive evaluation and mechanistic understanding of the impact of process intensification techniques applied in main and side stream wastewater treatment on biosolids management in terms of anaerobic digestion enhancement, dewaterability improvement, odor mitigation, as well as phosphorus and nitrogen removal. The first part of this study was conducted to understand the effect of anaerobic digester solids retention time (SRT) on odor emission from biosolids. A kinetic model and inhibitory studies showed the emission of methanethiol (MT), a representative odor compound, was primarily determined by the dynamic concurrence of MT production from amino acid and utilization by methanogens in the course of anaerobic digestion. MT emission pattern follows a bell-shape curve with SRT in anaerobic digesters. However, for digested and dewatered biosolids, SRT ranging from 15 to 50 days in anaerobic digesters demonstrated insignificant effect on the odor emission from biosolids. In contrast, the peak odor emission was found to exponentially increase with both shear intensity and polymer dose applied during dewatering. The second part of this study investigated the impact of process intensification practices on sludge dewatering performance. The integration of high-rate activated sludge process and anaerobic digestion elevated the sludge orthophosphate level, leading to struvite scaling and dewaterability deterioration. Superior orthophosphate removal, significant improvement of sludge dewaterability, and favorable economics were achieved through sludge conditioning by cerium chloride. Continuous flow aerobic granulation technology offered significant process intensification of mainstream treatment trains. However, its impact on biosolids management was not studied. This study showed that there was little dewaterability difference between aerobic granular sludge and activated sludge when polymer was not added. However, about 75% polymer saving and improved dewatering performance were observed with polymer addition. When subjected to high shear, a greater dewaterability deterioration was observed for granular sludge than activated sludge. The last part of this study is focused on the impact of anaerobic digestion process intensification through thermal treatment including pre-pasteurization, thermophilic anaerobic digestion, temperature phased anaerobic digestion, and thermal hydrolysis pretreatment. Improved methane production, pathogen reduction, dewatering performance, and odor mitigation were observed with the involvement of these high-temperature processes. However, special cautions and measure should be taken during the start-up of these high rate processes as they are more liable to digester souring. In addition, the in-depth understanding of the mechanism of recalcitrant dissolved organic nitrogen formation during sludge thermal pretreatment was provided. / Doctor of Philosophy / This study is aimed to provide comprehensive evaluation and mechanistic understanding of the impact of process intensification techniques applied in main and side stream wastewater treatment on biosolids management in terms of anaerobic digestion enhancement, dewaterability improvement, odor mitigation, as well as phosphorus and nitrogen removal. The first part of this study was conducted to understand the effect of anaerobic digester solids retention time (SRT) on odor emission from biosolids. A kinetic model and inhibitory studies showed the emission of methanethiol (MT), a representative odor compound, was primarily determined by the dynamic concurrence of MT production from amino acid and utilization by methanogens in the course of anaerobic digestion. MT emission pattern follows a bell-shape curve with SRT in anaerobic digesters. However, for digested and dewatered biosolids, SRT ranging from 15 to 50 days in anaerobic digesters demonstrated insignificant effect on the odor emission from biosolids. In contrast, the peak odor emission was found to exponentially increase with both shear intensity and polymer dose applied during dewatering. The second part of this study investigated the impact of process intensification practices on sludge dewatering performance. The integration of high-rate activated sludge process and anaerobic digestion elevated the sludge orthophosphate level, leading to struvite scaling and dewaterability deterioration. Superior orthophosphate removal, significant improvement of sludge dewaterability, and favorable economics were achieved through sludge conditioning by cerium chloride. Continuous flow aerobic granulation technology offered significant process intensification of mainstream treatment trains. However, its impact on biosolids management was not studied. This study showed that there was little dewaterability difference between aerobic granular sludge and activated sludge when polymer was not added. However, about 75% polymer saving and improved dewatering performance were observed with polymer addition. When subjected to high shear, a greater dewaterability deterioration was observed for granular sludge than activated sludge. The last part of this study is focused on the impact of anaerobic digestion process intensification through thermal treatment including pre-pasteurization, thermophilic anaerobic digestion, temperature phased anaerobic digestion, and thermal hydrolysis pretreatment. Improved methane production, pathogen reduction, dewatering performance, and odor mitigation were observed with the involvement of these high-temperature processes. However, special cautions and measure should be taken during the start-up of these high rate processes as they are more liable to digester souring. In addition, the in-depth understanding of the mechanism of recalcitrant dissolved organic nitrogen formation during sludge thermal pretreatment was provided.

Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2007. / The distillery industry generates large volumes of heavily polluted wastewater and thus effective wastewater treatment is essential. It has been reported that a chemical oxygen demand (COD) reduction of more than 90% can be achieved when wine distillery wastewater (WDWW) is treated in an upflow anaerobic sludge blanket (UASB) reactor. The first objective of this study was to investigate UASB treatment of WDWW and to try to enhance the efficiency by using ozonation treatments. Secondly, the impact of grain distillery wastewater (GDWW) on UASB granules was determined. The third objective was to determine whether ozonation and enzymatic treatment combinations might improve the biodegradability of GDWW and thus make GDWW more amenable to UASB treatment. It was found that UASB treatment combined with ozonation improved the WDWW treatment efficiency. When diluted WDWW (chemical oxygen demand COD = 4 000 mg.L-1) was ozonated (dose = 47 mg.L-1) in a 50 L venturi circulating contactor system, the COD reduction was 7%. When WDWW was treated in a laboratory-scale UASB reactor (substrate pH = 7.0, COD = 4 000 mg.L-1 and organic loading rate (OLR) = 4.0 kg COD.m-3.d-1), the COD reduction was 92%. When the UASB treatment was combined with either pre- or postozonation, the COD reduction was 94 and 96%, respectively. When UASB treatment was combined with pre- and post-ozonation, a COD reduction of 98% was achieved. The activity of the UASB granules was also found to improve over time, despite the addition of the ozonation treatment. It has been reported that operational problems occur when GDWW is treated in an UASB reactor as a result of the encapsulation of the granules. This was confirmed when granules from a full-scale UASB treating WDWW became encapsulated in a layer after being exposed to GDWW (COD = 4 000 mg.L-1) for 24 d. The results showed that the lipid content of the granules increased from 1.25 to 60.35 mg lipid.g-1 granule over the 24 d exposure period. Therefore, granules exposed to GDWW were encapsulated in a lipid-rich layer and as a result the contact between the GDWW and microbial consortium in the granules was reduced. The operational problems found during the industrial UASB treatment of GDWW were ascribed to the encapsulation of the granules. Combinations of ozonation (dose = 1 476 mg.L-1) generated in a 2 L bubble column and enzymatic treatments (1% FogFreeTM (FF) dosage and 2 d incubation at 35°C) were found to improve the biodegradability of GDWW. This improvement was in terms of lipid reduction in GDWW, granule activity and visual appearance of the encapsulating layer of the granules. The highest lipid reduction (90%), highest granule activity, lowest lipid content of the granules (3.74 ± 0.10 mg.g-1 granule) and best visual appearance were achieved in ozonated GDWW treated with 1% FF, followed by just ozonation. The higher lipid reduction and subsequent higher granule activity were ascribed to the reduction in lipids which resulted in the fact that fewer lipids were available to encapsulate the granules. As a result of the lipid reduction, the granule activity improved and the GDWW was made more amenable to UASB treatment. This study proved that UASB treatment combined with ozonation led to an enhancement of the treatment efficiency of WDWW. It was also found that the cause of the operational problems during UASB treatment of GDWW was as a result of the granules being encapsulated in a lipid-rich layer. It was established that treating GDWW prior to UASB treatment improved the biodegradability of GDWW. The data from the study showed that high lipid reduction in the GDWW directly led to better granule activity, lower granule lipid content and a thinner encapsulating layer. Based on the data from this study, it is recommended that GDWW be ozonated prior to other treatments because it can be done inline and the costs would be lower than that of enzymatic treatments.

L'oxydation anaérobie du méthane (AOM) couplé à la réduction du sulfate (AOM-SR) est un processus biologique médié par méthanotrophes anaérobie (ANME) et de bactéries sulfato-réductrices. La communauté scientifique s'inquiète de AOM, en raison de sa pertinence dans la régulation du cycle global du carbone et de la potentielle application biotechnologique pour le traitement de sulfate riches eaux usées.Pour améliorer les connaissances récentes sur les conditions de distribution et d'enrichissement ANME, cette recherche a étudié AOM-SR avec les objectifs suivants: (i) caractériser les communautés microbiennes responsables de AOM dans les sédiments marins, (ii) de les enrichir dans les bioréacteurs avec différentes configurations, à savoir bioréacteur à membrane (MBR), filtre biotrickling (BTF) et bioréacteur à haute pression (HPB), et (iii) d'évaluer l'activité de l'ANME et le processus AOM dans différentes conditions de pression et de température.Les microbes habitant peu profonde dans les sédiments de Marine lac Grevelingen (Pays-Bas) ont été caractérisés et leur capacité de faire AOM-SR a été évaluée. Un test d'activité a été réalisée en discontinu pour 250 jours, AOM-SR est mise en évidence par la production de sulfure et de la prise concomitante de sulfate et de méthane dans des rapports équimolaires et il a été atteint 5 µmoles par gramme de poids par jour de taux de réduction du sulfate. L'analyse des séquences de gènes 16SrRNA a montré la présence de méthanotrophes anaérobie ANME-3 dans les sédiments marins du lac Grevelingen.Deux configurations de bioréacteurs, à savoir MBR et BTF ont été opérés dans des conditions ambiantes pendant 726 jours et 380 jours, respectivement, pour enrichir les micro-organismes de Ginsburg Mud Volcano performantes AOM. Les réacteurs sont exploités en mode fed-batch pour la phase liquide avec un apport continu de méthane. Dans le MBR, une membrane d'ultrafiltration externe a été utilisée pour retenir la biomasse, alors que, dans la BTF, la rétention de biomasse a été accomplie par la fixation de la biomasse sur le matériau d'emballage. AOM-SR a été enregistrée seulement après ~ 200 jours dans les deux configurations de bioréacteurs. L'opération du BTF a montré l'enrichissement de l'ANME dans le biofilm par la méthode Illumina Miseq, en particulier ANME-1 (40%) et ANME-2 (10%). Dans le MBR, les agrégats d'ANME-2 et Desulfosarcina ont été visualisées par CARD-FISH. La production d'acétate a été observée dans le MBR, ce qui indique que l'acétate était un possible intermédiaire d'AOM. Bien que les deux configurations de bioréacteurs ont montré de bonnes performances, le taux de réduction du sulfate était légèrement plus élevée et plus rapide dans la BTF (1,3 mM par jour âpres 280 jours) que le MBR (0,5 mM par jour jour âpres 380 jours).Afin de simuler les conditions de suintement froid et de différencier l'impact des conditions environnementales sur AOM, les sédiments fortement enrichi avec le clade ANME-2a ont été incubées dans HPB à différentes températures (4, 15 et 25 °C à 100 bars) et pressions (20, 100, 200 et 300 bar à 15 °C). L'incubation à une pression de 100 bar et 15 ° C a été observé comme la condition la plus appropriée pour la phylotype ANME-2a, qui est similaire aux conditions in situ (Capitaine Aryutinov Mud Volcano, Golfe de Cadix). L'incubation de ce sédiment aux conditions in situ pourrait être une option privilégiée pour obtenir une activité AOM-SR plus élevée.Dans cette thèse, il a été démontré expérimentalement que la rétention de la biomasse et l'approvisionnement continu de méthane peuvent favoriser la croissance de la lente communauté microbienne qui oxyde le méthane en anaérobiose dans des bioréacteurs, même dans des conditions ambiantes. Par conséquent, la localisation des habitats de ANME dans des environnements peu profonds et l'enrichissant dans des conditions ambiantes peut être avantageuse pour les futures applications de la biotechnologie environnementale / Anaerobic oxidation of methane (AOM) coupled to sulfate reduction (AOM-SR) is a biological process mediated by anaerobic methanotrophs (ANME) and sulfate reducing bacteria. Due to its relevance in regulating the global carbon cycle and potential biotechnological application for treating sulfate-rich wastewater, AOM-SR has drawn attention from the scientific community. However, the detailed knowledge on ANME community, its physiology and metabolic pathway are scarcely available, presumably due to the lack of either pure cultures or the difficulty to enrich the biomass. To enhance the recent knowledge on ANME distribution and enrichment conditions, this research investigated AOM-SR with the following objectives: (i) characterize the microbial communities responsible for AOM in marine sediment, (ii) enrich ANME in different bioreactor configurations, i.e. membrane bioreactor (MBR), biotrickling filter (BTF) and high pressure bioreactor (HPB), and (iii) assess the AOM-SR activity under different pressure and temperature conditions.The microbes inhabiting coastal sediments from Marine Lake Grevelingen (the Netherlands) was characterized and the ability of the microorganisms to carry out AOM-SR was assessed. By performing batch activity tests for over 250 days, AOM-SR was evidenced by sulfide production and the concomitant consumption of sulfate and methane at approximately equimolar ratios and a sulfate reduction rate of 5 µmol sulfate per gram dry weight per day was attained. Sequence analysis of 16S rRNA genes showed the presence of ANME-3 in the Marine Lake Grevelingen sediment.Two bioreactor configurations, i.e. MBR and BTF were operated under ambient conditions for 726 days and 380 days, respectively, to enrich the microorganisms from Ginsburg Mud Volcano performing AOM. The reactors were operated in fed-batch mode for the liquid phase with a continuous supply of gaseous methane. In the MBR, an external ultra-filtration membrane was used to retain the biomass, whereas, in the BTF, biomass retention was achieved via biomass attachment to the packing material. AOM-SR was recorded only after ~ 200 days in both bioreactor configurations. The BTF operation showed the enrichment of ANME in the biofilm by Illumina Miseq method, especially ANME-1 (40%) and ANME-2 (10%). Interestingly, in the MBR, aggregates of ANME-2 and Desulfosarcina were visualized by CARD-FISH. Acetate production was observed in the MBR, indicating that acetate was a possible intermediate of AOM. Although both bioreactor configurations showed good performance and resilience capacities for AOM enrichment, the sulfate reduction rate was slightly higher and faster in the BTF (1.3 mM day-1 at day 280) than the MBR (0.5 mM day-1 at day 380).In order to simulate cold seep conditions and differentiate the impact of environmental conditions on AOM activities, sediment highly enriched with the ANME-2a clade was incubated in HPB at different temperature (4, 15 and 25 oC at 100 bar) and pressure (20, 100, 200 and 300 bar at 15 oC) conditions. The incubation at 100 bar pressure and 15 oC was observed to be the most suitable condition for the ANME-2a phylotype, which is similar to in-situ conditions where the biomass was sampled, i.e. Captain Aryutinov Mud Volcano, Gulf of Cadiz. The incubations at 200 and 300 bar pressures showed the depletion in activities after 30 days of incubation. Incubation of AOM hosting sediment at in-situ condition could be a preferred option for achieving high AOM activities and sulfate reduction rates.In this thesis, it has been experimentally demonstrated that biomass retention and the continuous supply of methane can favor the growth of the slow growing anaerobic methane oxidizing community in bioreactors even under ambient conditions. Therefore, locating ANME habitats in shallow environments and enriching them at ambient conditions can be advantageous for future environmental biotechnology applications

Contamination of perchlorate and chlorate in nature is primarily the result of various industrial processes. The microbial respiration of these oxyanions of chlorine plays a major role in reducing the society’s impact on the environment. The focus with this thesis is to investigate the oxygen-dependent regulation of key components involved in the chlorate respiration in the gram‑negative bacterium Ideonella dechloratans. Chlorate metabolism is based on the action of the enzymes chlorate reductase and chlorite dismutase and results in the end products molecular oxygen and chloride ion. Up‑regulation of chlorite dismutase activity in the absence of oxygen is demonstrated to occur at the transcriptional level, with the participation of the transcriptional fumarate and nitrate reduction regulator (FNR). Also, the chlorate reductase enzyme was shown to be regulated at the transcriptional level with the possible involvement of additional regulating mechanisms as well. Interestingly, the corresponding chlorate reductase operon was found to be part of a polycistronic mRNA which also comprises the gene for a cytochrome c and a putative transcriptional regulator protein.

Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Scientists and biochemical engineers alike are very interested in the control and regulation of free-energy metabolism in micro-organisms, whether the findings purely satisfy scientific curiosity or translate into the meeting of biotechnology company deadlines. We used a rather fundamental approach to investigate experimentally the control and regulation of yeast free-energy metabolism in anaerobic chemostat cultures using supply-demand analysis. This conceptually simple, quantitative framework, however, may lead to insight into the control properties of various metabolic pathways to be used in biotechnological applications. Supply-demand analysis is based on the theoretical framework of metabolic control analysis (MCA).Sections (of arbitrary size) of a metabolic pathway are grouped together around a linking metabolite. Those steps that produce the intermediate are combined into the supply block while the reactions that remove/consume the intermediate are grouped together as the demand. The elasticity coefficients of the supply and demand blocks (with regard to the linking metabolite concentration) can be used to determine the flux and concentration control coefficients by using the traditional MCAsummation and connectivity theorems. Supply and demand rate characteristics are a powerful visual approach to determine and display the control structure of the pathway under consideration and sets supply-demand analysis apart from traditional top-down analysis. Our first tool of analysis was a structured kinetic model of yeast growing in a chemos tat, constructed by using methods developed in our research group for modelling systems with variable volumes. Independent perturbations of the linking metabolite concentration resulted in a control profile where the control resided mainly in the demand (flux control coefficient of 0.92), as a result of a large negative supply elasticity. This elasticity, however, varied greatly under different conditions, leading to increased flux control by the supply in some cases. We extended our research to an experimental setup of Saccharomyces cerevisiae growing in a glucose-limited chemos tat supplemented with yeast extract as a source of carbon intermediates. This allowed glucose to act solely as the freeenergy source, as confirmed by balancing the glucose flux with the fluxes towards the fermentation products, ethanol and carbon dioxide. We obtained the supply rate characteristic by perturbing the ATPdemand through the addition of benzoate, which uncouples the proton gradient across the cell membrane. The demand rate characteristic was obtained by perturbing the ATP supply through changes in the dilution rate and thus the residual glucose concentration in the fermentor. The concentrations of ATPand ADPwere measured using a luciferase bioluminescence assay, while the fermentation products were measured with HPLCand C02 with an acoustic off-gas analyser. For our experimental conditions the flux-control of energy metabolism resided predominantly in the supply with respect to the linking metabolite [ATP]/[ADP](chosen as an indication of the free-energy state of the cell), i.e. a flux control coefficient of 0.90. Further, the [ATP]/[ADP]was under strong homeostatic control, as evidenced by the low [ATP]/[ADP]control coefficients of ± 0.12. We adjusted the structured kinetic model by varying strategic parameters, so that the results resembled the experimental observations more closely. However, the kinetics of our core model seem to be too simplistic to capture fully the extent of regulation displayed by the experimental system. The model did, however, reveal the regulatory importance of glucose transport into the cell. We conclude that the control and regulation of free energy metabolism in yeast strongly depend on the culturing conditions and on the steady state being analysed. / AFRIKAANSE OPSOMMING: Wetenskaplikes sowel as biochemiese ingenieurs is dikwels geïnteresseerd in die beheer en regulering van vry-energie metabolisme in mikro-organismes, hetsy die bevindinge suiwer wetenskaplike nuuskierigheid bevredig of die haalbaarheid van biotegnologie-maatskappy-mikpunte beteken. Ons het 'n redelik fundamentele benadering gevolg om die beheer en regulering van vry-energie metabolisme in gis eksperimenteel te bepaal in anaerobiese chemostaatkulture met behulp van aanbod- aanvraag analise. Dit is 'n konseptueel eenvoudige, kwantitatiewe raamwerk met die potensiaal om insig te gee in die beheereienskappe van verskeie metaboliese paaie wat nuttig kan wees in biotegnologiese toepassings. Aanbod-aanvraag analise is gebaseer op die teoretiese onderbou van metaboliese kontrole-analise (MKA).Dele (van arbitrêre grootte) van 'n metaboliese pad word gegroepeer rondom 'n verbindingsmetaboliet. Die stappe wat die intermediaat produseer word gekombineer as die aanbod terwyl die reaksies wat die intermediaat verbruik, saamgegroepeer word as die aanvraag. Die elastisiteitskoëffisiënte van die aanbod en aanvraag blokke (met betrekking tot die verbindingsmetabolietkonsentrasie) kan gebruik word om die fluksie en konsentrasie kontrolekoëffisiënte te bereken met behulp van die sommasie en konnektwiteit teoremas van MKA.Aanbod en aanvraag snelheidskenmerkgrafieke is 'n treffende visuele benadering om die kontroleprofiel van die betrokke metaboliese pad te bepaal en te vertoon. Hierdie kenmerk onderskei aanbod-aanvraag analise van bo-na-onder analise. Die eerste deel van ons ondersoek het behels 'n gestruktureerde kinetiese model (van gis wat groei in 'n chemostaat) met behulp van metodes wat in ons groep ontwikkel is om sisteme met variërende volumes te modelleer. Onafhanklike perturbasies van die verbindingsmetaboliet konsentrasie het gelei tot 'n kontroleprofiel waar die kontrole hoofsaaklik in die aanvraag gesetel was (fluksie kontrolekoëffisiënt van 0.92), as gevolg van 'n groot negatiewe aanbod-elastisiteit. Hierdie elastisiteit kan egter grootliks varieer tydens verskillende kondisies, wat lei tot 'n toenemende fluksle-beheer deur die aanbod in sommige gevalle. Ons het ons navorsing uitgebrei na 'n eksperimentele opstelling van Saccharomyces cerevisiae wat groei in 'n glukose-gelimiteerde chemostaat, aangevul met gisekstrak as 'n bron van koolstof-Intermediate. Dit bring mee dat glukose slegs as energiebron dien; dit is wel bevestig deur balanse op te stel van die koolstoffluksie vanaf glukose na koolstofdioksied en etanol as die fermentasieprodukte. Die aanbod snelheidskenmerkgrafiek is gegenereer deur die aanvraag van ATP te manipuleer deur middel van toevoeging van bensoaat, wat die protongradiënt oor die selmembraan ontkoppel. Die snelheidskenmerkgrafiek Vir die aanvraag is gegenereer deur die aanbod van ATP te manipuleer deur middel van 'n variasie in die verdunningstempo en sodoende die residuele glukose konsentrasie in die fermentor. Die konsentrasies van ATPen ADPis bepaal deur middel van 'n lusiferase bioluminessensie-essai, terwyl die fermentasieprodukte met 'n HPLCen CO2 met 'n akoestiese aflaatgasanaliseerder gemeet is. Vir die betrokke eksperimentele toestande was die flukste-kontrole van energiemetabolisme oorwegend in die aanbod met betrekking tot die verbindingsmetaboliet, [ATP]/[ADP](gekies as aanduiding van die vrye-energiestatus van die sel), naamlik 'n fluksie kontrolekoëffisiënt van 0.90. Verder was die [ATP]/[ADP]onder sterk homeostatiese beheer soos duidelik blyk uit die lae [ATP]j[ADP] kontrolekoëffisiënte van ± 0.12. Ons het die gestruktureerde kinetiese model aangepas deur strategiese parameters te verander om sodoende die eksperimentele gedrag te probeer naboots. Die kinetika van ons kernmodel blyk egter te simplisties te wees om die volle omvang van die regulering van die eksperimentele sisteem te vertoon. Die model het egter die belang van glukose transport oor die selmembraan aan die lig gebring. Ons kom tot die gevolgtrekking dat die beheer en regulering van vrye-energie metabolisme in gis sterk afhang van die groeitoestande sowel as die spesifieke bestendige toestand wat ondersoek word.

Die klassische Identifizierung von obligat anaeroben Bakterien ist mit einem hohen Labor- und Zeitaufwand verbunden. Um festzustellen, ob die Identifizierung mittels Matrix-unterstützter Laser-Desorption/Ionisation und Massenspektrometrie mit Flugzeitanalysator (Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry; MALDI-TOF MS) ein Verfahren ist, um obligate Anaerobier eindeutig zu identifizieren, wurde mit der vorliegenden Arbeit die Identifizierung von unterschiedlichen Spezies der B. fragilis Gruppe mittels MALDI-TOF MS untersucht. Hierfür wurden 105 obligate Anaerobier der B. fragilis Gruppe aus der Stammsammlung des Institutes für Medizinische Mikrobiologie und Infektionsepidemiologie der Universität Leipzig untersucht. Es fanden sich für die untersuchten Erreger Spektren mit sehr guter Auflösung. Eine Identifizierung und Differenzierung war eindeutig möglich. Unter Verwendung dieser Daten wurde eine Referenzdatenbank erstellt. Die erhaltenen Ergebnisse wurden mittels einer verblindeten Studie überprüft, wobei 52 von 53 (98,1%) der untersuchten Stämme eindeutig identifiziert werden konnten. Dies schließt ebenfalls die Identifizierung und Differenzierung von 15 Metronidazol-sensiblen/ Enterotoxin-negativen, 8 Metronidazol-resistenten/ Enterotoxin-negativen und 8 Metronidazol-sensiblen/ Enterotoxin-positiven B. fragilis Stämmen ein. Die Identifizierung mittels MALDI-TOF MS ist somit eine zuverlässige Methode zur Identifizierung von obligaten Anaerobiern der B. fragilis Gruppe. Weiterhin finden sich Hinweise, dass ein Nachweis von Resistenz-, Virulenz- und Pathogenitätsfaktoren mittels MALDI-TOF MS bei diesen Erregern möglich ist.