Student Number : 9902262G - MSc Dissertation - School of Molecular and Cell Biology - Faculty of Science / Anaerobic fermentative bacteria degrade waste components in landfills where methane (CH4) and carbon dioxide (CO2) are the primary biogases emitted and methanotrophic bacteria in the cover soil oxidise the emitted CH4. Three bi-phasic bench-scale landfill bioreactors were commissioned to evaluate soil nutrient addition effects on CH4 formation and oxidation and to isolate inherent soil methanotrophs using Nitrate Mineral Salts (NMS) medium. Set A soil contained no nutrient additions, Set B soil contained 50 μM nitrate and 150 μM phosphate and Set C soil contained dried sewage cake. Bioreactors were run for a 4 week period and pH, anaerobic gas emissions, volatile fatty acids (VFA), bacterial counts and scanning electron microscopy (SEM) analyses were performed. A pilot study revealed that pH dictated the stability of methanogenesis, where increased VFA levels inhibited methanogenesis. Furthermore, it was revealed that modifications of the NMS medium were needed to enrich for methanotrophs. An in depth study showed that the Set C anaerobic reactor produced the most methane with Set B the least. The hypothesis that methane oxidation in the soil could regulate methane formation in the waste could not be conclusively observed, as a lack of aeration in the soil reactors is believed to have prevented the proliferation of methanotrophs here. No methanotrophs were successfully isolated from soil, but rather major heterotrophic bacterial interference was observed. SEM revealed the presence of rod and cocci forms of bacteria in both leachate and soil, consistent with literature reports, which indicated that the bench-scale landfill bioreactors were capable of promoting bacterial growth.

MSc Med, Clinical Microbiology and Infectious Diseases, Faculty of Health Sciences,University of the Witwatersrand, 2009 / Anaerobic bacteria cause serious life-threatening infections such as endocarditis, sepsis, intra abdominal, pleuro-pulmonary and central nervous systems infections. Most infections are polymicrobial and involve aerobes and anaerobes. Empiric therapy is generally based on the expected pathogens and the particular type of infection. Even when specimens are cultured and anaerobes identified, not all laboratories perform susceptibility testing. The clinician often relies on published surveillance data when selecting treatment regimens. Antimicrobial susceptibility of anaerobic bacteria is becoming increasingly unpredictable. Resistance can vary significantly and patterns differ geographically, and even within units of the same hospital. From June 2005 until February 2007, 180 consecutive anaerobes isolated from relevant, non- repetitive clinical specimens were tested routinely with the E test method for susceptibility to amoxicillin/ clavulanate (XL), clindamycin (Cm), metronidazole (Mz), penicillin (Pg), ertapenem (Etp), cefoxitin (Fx), ceftriaxone (Tx), chloramphenicol (Cl), and piperacillin/tazobactam (Ptc). The results were read after 48hr incubation in anaerobic conditions. Specimen distribution was as follows: abdominal fluid (3), abscess (7), abdominal abscess (4), aspirates (3), blood cultures (27), bone (3), breast (3), drainage fluid (2), empyema (1), fluids (36), other (4), placental (1), pleural fluid (2), pus (41), tissues (34), umbilicus (1) and unknown sites (8). Bacteroides fragilis was isolated from 81 (45%) clinically significant specimens, followed by Clostridium perfringens 23 (13%), Peptostreptococcus anaerobius 15 (8%) and Prevotella melaniniogenicus 15 (8%). B. fragilis demonstrated a 97.5% resistance to penicillin and 12.3% resistance to metronidazole. C. perfringens exhibited no resistance to penicillin and metronidazole while P. anaerobius had 40% resistance to penicillin and no resistance to metronidazole. P. melaninogenicus was resistant to penicillin in 60% and 6.7% to metronidazole. Overall, chloramphenicol, piperacillin/tazobactam, ertapenem and amoxicillin/clavulanate demonstrated the highest activity to anaerobic isolates, 100%, 99.4%, 97.2% and 96.7%, respectively. Among the 180 tested anaerobes a total of 8.9% resistance has been observed with metronidazole and 81.7% sensitivity with clindamycin. Periodic surveillance to monitor the susceptibility profile of the B. fragilis group and other anaerobic organisms is recommended to create empirical guidelines for appropriate use of antimicrobial agents.

Orientador: Antonio Roberto Balbo / Coorientadora: Célia Aparecida dos Reis / Banca: Marcelo Suetake / Banca: André Christovão Pio Martins / Resumo: Atualmente pesquisas sobre a produção de energia com menor impacto ambiental, com maior rendimento energético e, possivelmente, a um custo mínimo de produção, são de interesse mundial. Desta forma, a produção de energia renovável, com estas características, através de biodigestores torna-se uma alternativa relevante. Os biodigestores, em geral, consistem de biorreator que armazena matéria orgânica fresca (substrato ou biomassa) de origem humana, animal ou vegetal. A fermentação anaeróbica destes substratos produz um gás combustível (biogás) que pode ser utilizado como fonte de energia e o material remanescente no biodigestor pode ser usado como biofertilizante. O processo de biodigestão é complexo, pois envolve vários grupos de bactérias e o seu entendimento é importante para promoção de agentes que visam aumentar a eficiência dos biodigestores. Neste trabalho propõe-se um modelo dinâmico não linear para descrever o processo de fermentação da biomassa dentro do biodigestor. Realiza-se também uma análise do modelo mediante a técnica de Lyapunov, a qual possibilitou a investigação de soluções analíticas assintoticamente estáveis e um estudo de seu espaço de fase, que contempla a sua estabilidade assintótica. Simulações numéricas são realizadas para a validação dos resultados obtidos ao modelo proposto / Abstract: Nowadays, research on energy production with lower environmental impact, with higher energy efficiency and, possibly, at a minimum cost of production, is of worldwide interest. In this way, the production of renewable energy, with these characteristics, through biodigesters becomes a relevant alternative. Biodigesters generally consist of a chamber that stores fresh organic matter (substrate or biomass) of human, animal or plant origin. Anaerobic fermentation of these substrates produces a fuel gas (biogas) that can be used as an energy source and the remaining material in the biodigester can be used as biofertilizer. The biodigestion process is complex because it involves several groups of bacteria and its understanding is important to promote agents that aim to increase the efficiency of biodigesters. This essay proposes a dynamic non-linear model to describe the fermentation process of an Indian biodigester. It is also proposed an analysis of the model using the Lyapunov technique, which became possible the investigation of asymptotically stable analytical solutions and asymptotic stability and a study of its phase space, which contemplates its asymptotic stability. Numerical simulations are performed to convalidate the proposed model. / Mestre

by Kwok-wai Lo. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1987. / Bibliography: leaves 183-194.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Aim: The purpose of the present study was to compare the effects of an 8 week period of combined endurance and resistance training (concurrent training) with that of only endurance training on both maximum strength (1 RM) in the leg press test and performance in the 30 s Anaerobic Wingate Test (WANT) in moderately trained endurance cyclists. Method: Twenty male moderately trained cyclists were recruited for the investigation and were assigned to either an Endurance training group (E; n=10) or an Endurance Resistance training group (ER; n=10).  Subjects underwent 8 weeks (2 training sessions per week, 16 sessions in total) of concurrent training (60 min steady state cycling session followed by 6 sets 12 repetitions of leg press) or cycling only. Furthermore the subjects of the intervention completed both Pre and Post intervention testing in the 1RM leg press and the Wingate 30 s cycle test which was conducted twice (SRM cycle sprint 1 and SRM cycle sprint 2) within each testing session. Results: The results attained from the intervention were that the ER group demonstrated an increase in concentric leg strength within the one repetition maximum (1 RM) leg press test by 18.7 % from pre-test values 339 ± 42 to post test values 402 ± 59 kg. With regard to the Wingate cycle sprints there was significant improvement from pre to post test results in peak power of cycle sprint 1 from 1019 ± 110 watt to 1077 ± 153 watt 5.7 % and cycle sprint 2 from 1001 ± 131 to 1054 ± 161 watt, 5.3 % (P < 0.05) respectively. The E group showed no significant change in l RM or the Wingate cycle sprints after training. Conclusions: The main findings of the study is that an 8-week concurrent training intervention can lead to significant concentric strength gains in 1 RM leg press development and increased peak power within the Wingate 30 s cycle sprint when conducted by moderately trained cyclists.

This study evaluates the enhancement of anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) by microwave pretreatment (MW) at high temperatures (115, 145 and 175°C). The highest level of solubilization was achieved at 175ºC, with a supplemental water addition of 30% (SWA30). Pretreatments combining two modalities; MW heating in presence or absence of hydrogen peroxide (H2O2) was also investigated. Biochemical methane potential (BMP) tests were conducted on the whole OFMSW, as well as on the liquid fractions. The whole OFMSW pretreated at 115 and 145 ºC showed little improvement in biogas production over control. When pretreated at 175 ºC, biogas production decreased due to formation of refractory compounds, inhibiting digestion. For the liquid fraction of OFMSW, the effect of pretreatment on the cumulative biogas production (CBP) was more pronounced for supplemental water addition of 20% (SWA20) at 145 ºC. Combining MW and H2O2 modalities did not have a positive impact on OFMSW stabilization and enhanced biogas production. Based on the BMP assay results, the effects of MW pretreatment (145 ºC) on the AD of OFMSW (SWA20) were further evaluated in single and dual stage semi-continuous digesters at hydraulic retention times (HRTs) of 20, 15, 12 and 9 days. Overall, MW pretreatment did not enhance the AD of the whole waste at the HRTs tested. However, the use of a dual stage reactor digesting non pretreated whole OFMSW had the best performance with the shortest HRT of 9 days. Conversely, for free liquid after pretreatment in two stage reactors at 20 day HRT methane production was tripled. In general, the performance of the dual stage digesters surpassed that of the single stage reactors. Cyclic BMP assays indicated that using an appropriate fraction of recycled effluent leachate can be implemented without negatively effecting methanogenic activity and biogas production. Based on the results obtained in this study, digestion of OFMSW by dual stage reactors without pretreatment appears to provide the best potential for waste stabilization in terms of biogas production and yield, process stability and volumetric loading rates.

Anaerobic digestion of waste activated sludge can be improved if hydrolysis of particulate substrates is enhanced and available substrate is made more accessible by both breakup of the sludge matrix floc and rupture of the cell wall. Microwave (MW) pretreatment was suggested and studied as a way to improve digestion efficiency. The work done focuses on the effects of MW pretreatment on the characteristics of the sludge, due to thermal and athermal effects. It also evaluates the effects some process variables in the activated sludge process have on the pretreatment efficiency as well as the effect operating conditions in the downstream anaerobic digestion process have on the biodegradability efficiency of those sludges. Effects of athermal and thermal MW radiation were measured by use of a customized MW oven capable of providing MW radiation with uncoupled thermal and athermal effects. Athermal radiation was capable of increasing substrate present in the soluble phase of sludge, and had a positive effect in the digestion of athermal samples. The increases in biogas production and substrate solubilisation were smaller in magnitude than the increases measured for MW thermal tests. Further refining of the tests with athermal and thermal sludge, involved separation by size class of the solubilized substrate by means of ultrafiltration (UF), and revealed that changes in particle size distribution were significant not only for MW thermal tests, but also for athermal tests, with a particular emphasis in proteins in athermal tests. These changes had an effect on the biodegradability of the sludges by class size, with thermally pretreated sludge producing more biogas for smaller particles size classes but also exhibiting more inhibition. Tests were made with several combinations of sludge with different ages and subject to different MW pretreatment temperatures. The work showed that sludge age or solids retention time (SRT) has a significant effect on the pretreatment efficiency with maximum biogas improvements measured at different MW pretreatment temperatures depending on the SRT of the sludge tested, and with different behaviour for mesophilic and thermophilic digestion. Mesophilic tests showed greater improvements in terms of digestion effiency on average, but thermophilic tests showed more uniform performance, with a higher baseline efficiency. The presence of an optimum of MW pretreatment temperature and sludge SRT for maximal biogas production is more defined for mesophilic conditions than for thermophilic conditions. Semi-continuous studies were conducted with several combinations of single and two stage mesophilic and thermophilic digestors treating MW pretreated sludge and non-pretreated sludge. Staging and thermophilic digestion allowed the maintenance of a stable digestion process with high biogas productions and high solids removal efficiencies with production of sludge with good bacteriological characteristics for an very low residence time (5 d).

This thesis describes the characterization of benzene-degrading denitrifying cultures. Four objectives were pursued. The first objective was to identify conditions that promote or inhibit benzene decomposition and thus, to improve the biodegradation capacity of the cultures. FeS, resazurin, and nitrite had a detrimental impact on benzene degradation, whereas addition of supernatant from an active culture improved the benzene degradation activity by reducing the lag times. The second objective was to determine the microbial community composition in enrichment cultures and to identify the bacterial species that mediate benzene mineralization. Five dominant bacterial Operational Taxonomic Units (OTUs) were identified. The most abundant phylotype was related to the gram-positive Peptococcaceae family. Other bacteria present were closely affiliated with Dechloromonas, Azoarcus, Chlorobi and Anammox species. To correlate the growth of these specific microbes with benzene degradation, the abundance of specific 16S rRNA genes was monitored during mineralization process using quantitative polymerase chain reaction (qPCR). Based on the result of qPCR experiments and information about the metabolisms of the above bacteria, a syntrophic mode of benzene degradation was hypothesized to occur under denitrifying conditions. In this process, Peptococcaceae initiate attack on benzene, and ferment benzene to hydrogen and low molecular weight products such as acetate. These products are then consumed by nitrate-respiring Azoarcus and Dechloromonas or phototrophic Chlorobi. Anammox bacteria recycle and detoxify nitrite, and stabilize the culture. The third objective was to isolate and characterize pure cultures with the ability to mineralize benzene anaerobically. Dechloromonas- and Dechlorosoma-like microorganisms were isolated from several benzene-degrading microcosms. Theses bacteria, however, were not able to metabolize benzene anaerobically. The fourth objective was to investigate the key metabolic steps in the anaerobic benzene degradation pathway and to identify enzymes that are involved in this process. Differential transcription during growth of the culture on benzene versus growth on a metabolite of benzene degradation, i.e. benzoate was examined. Carboxylase-related genes were specifically transcribed in the presence of benzene. Furthermore, mRNA sequences corresponding to the genes that encode different enzymes of the benzoyl-CoA degradation pathway were present in the culture. These findings suggest that mineralization of benzene starts by its activation to benzoate through a carboxylation reaction catalyzed by benzene carboxylase. Benzoate is further metabolized through benzoyl-CoA pathway.

Anaerobic oxidation of methane (AOM) in peatlands was investigated using 13carbon isotope tracers. Existence of AOM in marine and freshwater ecosystems is well known, but only recently has solid evidence for this process been demonstrated in northern peat accumulating wetland ecosystems. The primary objective of this thesis research was to characterize rates of AOM in peatlands across site types (bogs and fens with varying physicochemical properties) and latitudinal gradients. It was found that AOM was ubiquitous process across North American sites and dominant in fens over bogs, however carbon derived from methane was similar in both types of peatlands. Though, none of the proposed electron acceptors hypothesized stimulated AOM. AOM had a combined, average rate of 2.9 nmol methane kg-1s-1, which would translate to an approximate global consumption of 24 Tg methane annually. This mass of methane is equivalent to almost 7% of all annual anthropogenic carbon dioxide emissions.