Matching Items (5)
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- All Subjects: Cyanobacteria
- Creators: Nielsen, David
Description
This thesis focused on the development of a system that can sense light intensity and then control a smart film to provide the optimal light intensity for cyanobacteria. The overarching goal of this project is to further the study of biofuels as an alternative energy source by increasing growth rates. If more algae or cyanobacteria can be grown per day, then the cost to produce the biofuel will decrease. To achieve this goal, PDLC (polymer dispersed liquid crystal) film was selected to be controlled due to its unique properties. It can be controlled with electricity and has variable states, in other words, not restricted to simply on or off. It also blocks 80% ultraviolet light and reduces thermal heat gain by 40% which is an important consideration for outdoor growing situations. To control the film, a simple control system was created using an Arduino Uno, SainSmart 8 channel relay board, an inverter, and a power supply. A relay board was utilized to manage the 40 volts required by the PDLC film and protected the electronics on the Arduino Uno. To sense the light intensity, the Arduino Uno was connected to a photoresistor, which changes resistance with light intensity. A 15 day test of two flasks of Cyanobacteria Synechocycstis sp. 6803, one shaded by the PDLC film, and the other unshaded, yielded 65% difference in optical densities. Overall, the experiment showed promise for controlling light intensity for photobioreactors. Ideally, this research will help to optimize light intensities when growing cyanobacteria or algae outdoors or it will help to discover what an ideal light intensity is by allowing a researcher unprecedented control.
ContributorsRoney, Kitt Alicia (Author) / Nielsen, David (Thesis director) / Middleton, James (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2015-05
Description
In our modern world the source of for many chemicals is to acquire and refine oil. This process is becoming an expensive to the environment and to human health. Alternative processes for acquiring the final product have been developed but still need work. One product that is valuable is butanol. The normal process for butanol production is very intensive but there is a method to produce butanol from bacteria. This process is better because it is more environmentally safe than using oil. One problem however is that when the bacteria produce too much butanol it reaches the toxicity limit and stops the production of butanol. In order to keep butanol from reaching the toxicity limit an adsorbent is used to remove the butanol without harming the bacteria. The adsorbent is a mesoporous carbon powder that allows the butanol to be adsorbed on it. This thesis explores different designs for a magnetic separation process to extract the carbon powder from the culture.
ContributorsChabra, Rohin (Author) / Nielsen, David (Thesis director) / Torres, Cesar (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2015-05
Description
Measuring changes in concentration within a dynamic system can be accomplished with a simple Arduino powered system. Currently, the system is utilized in cyanobacteria CO2 fixation experiments, where the fixation rates of multiple cultures can be measured simultaneously. The system employs solenoids in parallel and can be applied for n number of outlet streams, all are connected to one large manifold which feeds to a CO2 concentration probe. In the future, the system can be modified to fit other simple dynamic gas systems.
ContributorsInnes, Sean (Author) / Nielsen, David (Thesis director) / Jones, Christopher (Committee member) / Barrett, The Honors College (Contributor)
Created2021-12
Improving cyanobacterial hydrogen production through bioprospecting of natural microbial communities
Description
Some cyanobacteria can generate hydrogen (H2) under certain physiological conditions and are considered potential agents for biohydrogen production. However, they also present low amounts of H2 production, a reaction reversal towards H2 consumption, and O2 sensitivity. Most attempts to improve H2 production have involved genetic or metabolic engineering approaches. I used a bio-prospecting approach instead to find novel strains that are naturally more apt for biohydrogen production. A set of 36, phylogenetically diverse strains isolated from terrestrial, freshwater and marine environments were probed for their potential to produce H2 from excess reductant. Two distinct patterns in H2 production were detected. Strains displaying Pattern 1, as previously known from Synechocystis sp. PCC 6803, produced H2 only temporarily, reverting to H2 consumption within a short time and after reaching only moderately high H2 concentrations. By contrast, Pattern 2 cyanobacteria, in the genera Lyngbya and Microcoleus, displayed high production rates, did not reverse the direction of the reaction and reached much higher steady-state H2 concentrations. L. aestuarii BL J, an isolate from marine intertidal mats, had the fastest production rates and reached the highest steady-state concentrations, 15-fold higher than that observed in Synechocystis sp. PCC 6803. Because all Pattern 2 strains originated in intertidal microbial mats that become anoxic in dark, it was hypothesized that their strong hydrogenogenic capacity may have evolved to aid in fermentation of the photosynthate. When forced to ferment, these cyanobacteria display similarly desirable characteristics of physiological H2 production. Again, L. aestuarii BL J had the fastest specific rates and attained the highest H2 concentrations during fermentation, which proceeded via a mixed-acid pathway to yield acetate, ethanol, lactate, H2, CO2 and pyruvate. The genome of L. aestuarii BL J was sequenced and bioinformatically compared to other cyanobacterial genomes to ascertain any potential genetic or structural basis for powerful H2 production. The association hcp exclusively in Pattern 2 strains suggests its possible role in increased H2 production. This study demonstrates the value of bioprospecting approaches to biotechnology, pointing to the strain L. aestuarii BL J as a source of useful genetic information or as a potential platform for biohydrogen production.
ContributorsKothari, Ankita (Author) / Garcia-Pichel, Ferran (Thesis advisor) / Vermaas, Willem F J (Committee member) / Rittmann, Bruce (Committee member) / Torres, Cesar (Committee member) / Arizona State University (Publisher)
Created2013
Description
Cyanobacteria have the potential to efficiently produce L-serine, an industrially important amino acid, directly from CO2 and sunlight, which is a more sustainable and inexpensive source of energy as compared to current methods. The research aims to engineer a strain of Cyanobacterium Synechococcus sp. PCC 7002 that increases L-serine production by mutating regulatory mechanisms that natively inhibit its production and encoding an exporter. While an excess of L-serine was not found in the supernatant of the cell cultures, with further fine tuning of the metabolic pathway and culture conditions, high titers of L-serine can be found. With the base strain engineered, the work can be extended and optimized by deleting degradation pathways, tuning gene expression levels, optimizing growth conditions, and investigating the effects of nitrogen supplementation for the strain.
ContributorsAbed, Omar (Author) / Nielsen, David (Thesis director) / Jones, Christopher (Committee member) / Chemical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05