<p>It has been suggested that growth, production and community structure of bacterioplankton are dependent on resource availability. However, previous studies have only investigated the effect of either organic substrate mixtures or a few single organic substrates on the bacterioplankton community. The aims of this study were to investigate the impact of five different relevant carbon sources on the bacterioplankton community. This impact was evaluated comparing treatments on samples taken from Skagerrak and the Baltic Sea, in whole seawater cultures. Analysis of bacterial abundance, bacterial production (as leucine incorporation), bacterioplankton DNA community structure and colony-forming bacteria growing on agar plates were evaluated. Differences between carbon sources in terms of bacterial numbers were relatively small, with strong growth responses for L-amino acids, glucose, acetate and pyruvate with the only exception of glycolate where growth was lower. Bacterial production, on the other hand, presented marked differences, different patterns for each carbon source, especially in the Baltic Seawater. Furthermore, differences in colony size and number of colony forming bacteria in the different treatments were important. The analysis of DNA community from each experiment, by denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rDNA, allowed a visualization of the microbial community structure. Sequencing of the stronger bands on the gel revealed the identity of the dominant bacterial species. In terms of bacterioplankton community structure, differences between carbon sources and between environments were important. One unknown species belonging to gamma-proteobacteria was both unique and dominant for glucose treatment in the Baltic experiment. Another gamma-proteobacteria , a Vibrio was found to specialize in glucose in the Skagerrak experiment. One uncultured bacterium belonging to a alpha-proteobacteria, both unique and dominant was found in glycolate, also this in Skagerrak, another uncultured alpha-proteobacteria was clearly dominant for glucose treatment in Skagerrak. Some bands were also present in most treatments, e.g. uncultured species belonging to bacteroidetes in Skagerrak and beta-proteobacteria in Baltic, suggesting that those species are not specialized in consuming a single carbon source. As a conclusion different carbon sources clearly had an individual but important role for bacterioplankton properties. The properties also showed to be dependent on the environment.</p><p>Nr:6355</p>

It has been suggested that growth, production and community structure of bacterioplankton are dependent on resource availability. However, previous studies have only investigated the effect of either organic substrate mixtures or a few single organic substrates on the bacterioplankton community. The aims of this study were to investigate the impact of five different relevant carbon sources on the bacterioplankton community. This impact was evaluated comparing treatments on samples taken from Skagerrak and the Baltic Sea, in whole seawater cultures. Analysis of bacterial abundance, bacterial production (as leucine incorporation), bacterioplankton DNA community structure and colony-forming bacteria growing on agar plates were evaluated. Differences between carbon sources in terms of bacterial numbers were relatively small, with strong growth responses for L-amino acids, glucose, acetate and pyruvate with the only exception of glycolate where growth was lower. Bacterial production, on the other hand, presented marked differences, different patterns for each carbon source, especially in the Baltic Seawater. Furthermore, differences in colony size and number of colony forming bacteria in the different treatments were important. The analysis of DNA community from each experiment, by denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rDNA, allowed a visualization of the microbial community structure. Sequencing of the stronger bands on the gel revealed the identity of the dominant bacterial species. In terms of bacterioplankton community structure, differences between carbon sources and between environments were important. One unknown species belonging to gamma-proteobacteria was both unique and dominant for glucose treatment in the Baltic experiment. Another gamma-proteobacteria , a Vibrio was found to specialize in glucose in the Skagerrak experiment. One uncultured bacterium belonging to a alpha-proteobacteria, both unique and dominant was found in glycolate, also this in Skagerrak, another uncultured alpha-proteobacteria was clearly dominant for glucose treatment in Skagerrak. Some bands were also present in most treatments, e.g. uncultured species belonging to bacteroidetes in Skagerrak and beta-proteobacteria in Baltic, suggesting that those species are not specialized in consuming a single carbon source. As a conclusion different carbon sources clearly had an individual but important role for bacterioplankton properties. The properties also showed to be dependent on the environment. Nr:6355

With the rise of antibiotic resistance, there is ongoing need to find new antibiotics. As bacteria develop resistance to the current classes of antibiotics available, it is imperative to discover new ways to target bacteria. In this thesis, I focused on one of the basic components that all bacteria need to survive: a source of carbon. Here, I explore whether we can exploit this aspect for drug discovery. For bacteria to colonize a host and cause an infection, it must first be able to meet its nutritional needs for growth. Different host infection sites will have different carbon sources available. Some sites, like the gut, will have commensal bacteria which will compete with invading pathogens for carbon sources. While we still lack understanding of the specific growth environment bacteria experience during infection, it is important to understand how bacteria grow when given different nutrients. For the first part of my work, I systematically probed the gene essentiality patterns of E. coli grown in different carbon sources. I generated a large dataset of growth phenotypes that I compiled into a user-friendly web-application, Carbon Phenotype Explorer (CarPE). I identified many poorly annotated genes, and further characterized the gene ydhC as an adenosine transporter. After characterizing how the growth of E. coli and the genes essential for survival change depending on each carbon source, I looked at whether antibiotic efficacy changed depending on the carbon source used. I found that growth in oxaloacetate alters the proton motive force and potentiates macrolide antibiotics. I also found that linezolid, a compound that does not work on gram-negative bacteria due to efflux, is more effective when adenosine is the carbon source. Together, this work forms a foundation for future research into studying how carbon sources can be exploited in the field of antibiotic discovery. / Thesis / Candidate in Philosophy / There is an urgent need for new antibiotics. Previous antibiotic discovery has primarily been conducted on bacteria growing in nutrient rich laboratory conditions. This led to antibiotics that targeted the same few bacterial processes. However, since bacteria need to survive in a host to cause an infection, there are targets that may be viable during an infection that we miss by using standard laboratory media. Bacteria need a source of carbon to survive, and each infection site contains different chemicals that bacteria can use as a source of carbon. My work studies how bacteria grow in the presence of different carbon sources. First, I systematically tested which bacterial genes are required for E. coli to grow in 30 different carbon sources. I then examined the effectiveness of antibiotics on bacteria grown using these different carbon sources. Together, this work helps us understand how changing carbon sources in the growth media we use to cultivate bacteria can change which genes are required and how it may change how bacteria survive antibiotic stress. When we discover the specific compositions of host infection environments, we can leverage this knowledge to find antibiotics that target these carbon acquisition pathways in bacteria.

The aim of this diploma thesis was to analyse waste water quality from RAS, verification of its possible cleaning in a model of wastewater treatment plant using heterotrophic bacteria, experimentally compare the influence of used carbon source in the initial phase of bacteria cultivation and evaluation of biofloc usage in fish feed. Analysed water was obtained from rearing tanks, sewage water from mechanical filtration and tap water for filling the system. Wastewater treatment plant (built according to AS VARIOcomp K model) was divided into 3 parts (primary settling, activated part, secondary settling) and then filled with water from running BFT system. For carbon source comparing experiment 4 groups were used: flour, glucose, acetate and glycerol, each in 3 replications. Cultivation took 28 days and at the end the nutritional composition of each BFT system was evaluated. Water analyses showed that sewage water from mechanical filtration is nutrient rich and contain big amount of undissolved solids. This water is not suitable for purification in conventional system without pre-treatment. The model of water treatment plant purified approximately 50 l of water from vortex per day which was pumped back into RAS. Probably it would be capable of purifying bigger volume. Bacteria cultivation using different carbon sources is very similar to start-up of nitrifying bacteria in biofilter at the beginning. It was proved that biofloc is also capable of removing nitrates from water. The biggest measured concentration among groups was 1695 +- 438 mg.l-1 NO3- and in 6 days it decreased to 493 +- 409 mg.l-1. The average FVI for flour, glucose, acetate and glycerol were 102 +- 57; 267 +- 59; 219 +- 26 and 293 +- 9 ml.l-1 at the end of cultivation. Experiment comparing carbon sources also proved that nutritional composition of biofloc is similar to composition of commercial feed. Heterotrophic bacteria are also capable to cumulate heavy metals and mineral matter over time. Experiment with added biofloc to feed in amount 0 %, 25 % and 50 % did not show any statistically significant differences (p < 0,05) on survival rate, FCR and SGR between the groups of juvenile grass carp (Ctenopharyngodon idella).

The methylotrophic yeast Pichia pastoris has become an efficient expression system for heterologous protein production. Different methods have been studied to enhance cell growth as well as the production of products of interest. Two of the major strategies for improving the product or biomass yields are optimizing bioprocess controls and cultivation conditions. In this work, the characteristics of this yeast system and of its different promoters are discussed, and the effect of operational strategies on cell growth and recombinant protein expression is also studied. The effect of different feeding strategies were studied and optimized for pGAP (glyceraldehyde-3-phosphate dehydrogenase)-regulated phytase production in P. pastoris. Alternative carbon sources were screened and the feasibility of using citric acid as a carbon source for recombinant protein production was also investigated. The effects of parameters such as the carbon source concentration and culture pH were studied using shake-flasks, and the effect of different feeding profiles on bioreactor performance was also investigated. Three feeding strategies, Stepwise feeding, Exponential feeding and DO-stat feeding were tested and DO-stat was found to be more efficient and led to a high phytase activity. A modified DO-stat method was investigated to overcome the oxygen limited condition in the standard DO-stat method. For the carbon source, citric acid showed promise in improving phytase expression. Further experiments in bioreactors performed with the presence of certain amount of citric acid showed that less glycerol could be used to achieve the same level of phytase activity.

In Sweden and other Nordic countries, Free Water Surface (FWS) constructed wetlands are widely used for advanced sewage treatment. This study was performed in an experimental wetlands system in order to research the seasonal dynamics and interferences in N removal under cold climate condition. According to the result of study, as expected, N removal in FWS wetlands is strong related to temperature, the removal rates are higher in late summer and autumn than in spring and early summer. Removal at similar temperatures are quite different when they are in different months. For instance, in the study, the average N removal in June is significant different from N removal in September (P＜0.001), indicating that there are other factors affecting the N removal, different treatment wetlands have different situations. N removal in two different periods (March to July &amp; August to December) were extracted for covariance analysis, it indicated that they are significant different. Besides that, the r2-value of correlation test showed that total N removal rate in FWS constructed wetlands is higher in relation to temperature in autumn and winter (r2-value is 0.4449) than in spring and summer (r2-value is 0.3857). Generally speaking, the dynamics of N removal in FWS wetlands is not steady and variable even at similar temperatures. Finally, I find the temperature of excess heating from district heating which has been used by the residents’ house in Sweden is high enough to heat up the temperature in FWS wetlands. That is a valuable improvement to be put forward.

Graphene, a two-dimensional counterpart of three-dimensional graphite, has attracted significant interest, due to its distinctive electrical and mechanical properties, for developing electronic, optoelectronic, and sensor technologies. In general, doping of graphene is important, as it gives rise to p-type and n-type materials, and it adjusts the work function of the graphene. This adjustment is necessary in order to control charge injection and collection in devices such as solar cells and light emitting devices. Current methods for graphene doping involve high temperature process or interactions with chemicals that are not stable. Moreover, the process of transferring graphene from its growth substrate and its exposure to the environment results in a host of chemical groups that can become attached to the film and alter its electronic properties by accepting or donating electrons/holes. Intentional and controllable doping of the graphene, however, requires a deeper understanding of the impact of these groups. The proposed research will attempt to clarify the unintentional doping mechanism in graphene through adsorption or desorption of gas/vapor molecules found in standard environments. A low temperature, controllable and defect-free method for doping graphene layers will also be studied through modifying the interface of graphene and its support substrate with self-assembled monolayers (SAMs) which changes the work function and charge carriers in the graphene layer. Furthermore, current methods of chemical vapor deposition synthesis of graphene requires the film to be transferred onto a second substrate when the metal layer used for growth is not compatible with device fabrication or operation. To address this issue, the proposed work will investigate a new method for wafer scale, transfer-free synthesis of graphene on dielectric substrates using new carbon sources. This technique allows patterned synthesis on the target substrate and is compatible with standard device fabrication technologies; hence, it opens a new pathway for low cost, large area synthesis of graphene films.

One of the most important parameters affecting hydrogen production in photofermentation process is the type of carbon and nitrogen sources. For this reason in this research, the effect of different nitrogen sources (5mM ammonium chloride and 2mM glutamate) and acetate concentrations (40

In this research, we dealt with the original landfill leachate, and put the flowing water by a traditional second one that has dealt with of sewage factory directly with the constructed wetland systems in lab-scale. The purpose the study is to compare the experimental results after dealing the leachate by different constructed wetland process systems which was judge at if the, can reach the water quality standard. The constructed wetland systems in the study were set up in a greenhouse on campus, which were operated between May 2004 and July 2003. Constructed wetland systematic attitude, include Free Water Surface System (FWS) and Subsurface Flow System (SSF) contact but two type constructed wetland system that become mainly. In the test use different waste water sources to feet the systems, and we planted different species of plants, and add extra carbon source. Thus, we can divide the experiment into two stages: (1) From July of 2003 to December of 2003. (2) From February of 2004 to May of 2004. In each stage, we tested three experiment group P1, P2 and total nitrogen of P3 except that the rate is 37¡Ó20%, 50¡Ó11% respectively and -6.1¡Ó37.8%. The removal efficiencies of ammonia nitrogen were estimated equal to 84¡Ó11%, 94¡Ó4% and 60¡Ó24% respectively. For total phosphorus and phosphate, P1 , P2 and P3 system were measured equal to 37¡Ó14%, 68¡Ó16% and 77¡Ó16%and 44¡Ó16%, 75¡Ó8% and 80¡Ó17% respectively . The ammonia nitrogen temperature correction coefficient (£c value) were calculated to be 0.921, 0.949, 0.926, 1.043 and 0.785 for P1, P2, P3, U1 and U2 system, respectively. The phosphate temperature correction coefficients (£c values ) were measured to be 1.006, 0.981, 1.070, 1.235 and 0.843 respectively for P1, P2, P3, U1 and U2 system. In order to increase the removal efficiencies of total nitrogen, it was always by adding carbon source. The experimental result showed, that it is add carbon source wait by system to SSF , its President nitrogen is it flow water pollution load leave 2g/m2/day nearly to put to have, and has not added water pollution load has flowed in the putting of the carbon source nearly has 6g/m2/day left, And nearly remain under 1g/m2/day in the putting and flowing water pollution load of TON, and not added the putting of the carbon source water pollution load has flowed nearly has 2-3g/m2/day left. This result showed that high total nitrogen removal efficiencies were by adding carbon source.

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