A 1-D tidal, salinity and water quality model that analyzes the general effects freshwater diversions have on the water quality of the Pontchartrain Estuary over a 17-year period is presented here. Using the modeled live algae concentrations in conjunction with the algal bloom probability model results produces an accurate prediction of algal bloom occurrences between 1990 and 2006. The model predicts that the addition of freshwater diversions into Maurepas swamp and increases to flow in the Bonnet Carré Spillway may cause more intense and frequent algal blooms to occur around the Pontchartrain Estuary. The model also predicts that high nutrient input events that occur earlier in the year (January/February) will not likely have algal blooms associated with them. When nutrient input events (even small events) occur in the late spring or early summer, algal blooms have a high probability of occurring when the salinity, temperature and light levels are sufficient.

Made available in DSpace on 2016-08-10T10:44:52Z (GMT). No. of bitstreams: 1 LUCAS CASSIANO GONCALVES PRUDENTE SILVA.pdf: 751405 bytes, checksum: 3c986fe2096faa277b68c1b41c862aff (MD5) Previous issue date: 2015-02-25 / Changes in the aquatic environment with respect to water quality tends to generate an environmental imbalance that influences us dependent beings that environment. This study aims to evaluate and compare 31 streams belonging to the sub-basins of the Meia Ponte, Piracanjuba and Santa Maria the physicochemical characteristics (nitrate, phosphate, conductivity, pH, turbidity, temperature, dissolved oxygen), hydrological (water speed ) and biological components of water (algal biomass) by sub-basin evaluate the relationship between algal biomass, with the concentration of nitrate and phosphate, and finally to evaluate the relationship between the abundance of fish with nitrate, phosphate , conductivity, pH, turbidity, algal biomass, temperature, dissolved oxygen and water velocity, considering all the sampled sub-basins. In each stream was given a 100m stretch where were the measurements of water features using handheld devices, except for nitrate, phosphate and algal biomass (chlorophyll α) whose concentrations were determined in the laboratory from samples water through the spectrophotometry method. The results showed that there are significant differences in the pH (between the sub-basin of the river Santa Maria and this Piracanjuba and the Half Bridge) and turbidity (between sub-basins Santa Maria and Meia Ponte), but was not found no relationship between algal biomass with the physical, chemical and hydrological aspects, however, was shown a relative abundance of fish with pH and conductivity. / Alterações no ambiente aquático no que tange à qualidade da água tende a gerar um desequilíbrio ambiental que influencia nos seres dependentes desse ambiente. Este trabalho objetiva avaliar e comparar em 31 riachos pertencentes às sub-bacias dos rios Meia Ponte, Piracanjuba e Santa Maria as características físicoquímicas (nitrato, fosfato, condutividade, pH, turbidez, temperatura, oxigênio dissolvido), hidrológicas (velocidade da água) e os componentes biológicos da água (biomassa de algas) por sub-bacia, avaliar a relação entre a biomassa das algas, com a concentração de nitrato e fosfato, e por fim avaliar a relação entre a abundância de peixes com o nitrato, fosfato, condutividade, pH, turbidez, biomassa de algas, temperatura, oxigênio dissolvido e velocidade da água, considerando todas as sub-bacias amostradas. Em cada riacho foi determinado um trecho de 100m, onde foram realizadas as medições das características da água utilizando-se equipamentos portáteis, exceto para o nitrato, fosfato e biomassa de algas (clorofila α) cujas concentrações foram determinadas em laboratório a partir de amostras de água através do método de espectrofotometria. Os resultados obtidos mostraram que existem diferenças significativa para o pH (entre a sub-bacia do rio Santa Maria e esta do Piracanjuba e Meia Ponte) e para a turbidez (entre as sub-bacias Santa Maria e Meia Ponte), porém não foi encontrada nenhuma relação entre a biomassa de algas com os aspectos físico-químicos e hidrológico, contudo, foi evidenciado uma relação da abundância de peixes com pH e a condutividade.

Ettlia oleoabundans, a freshwater green microalga, was grown under different environmental conditions to study its growth, lipid yield and quality for a better understanding of the fundamental physiology of this oleaginous species. E. oleoabundans showed steady increase in biomass under low temperature and low light intensity, and at high temperature lipid cell content significantly increased independent of nitrate depletion. Studies on light quality showed that red light treatment did not change the biomass concentration, but stimulated lipid yield especially oleic acid, the most desirable biodiesel precursor. Moreover, no photoreversibility in lipid production was observed when applying alternating short-term red and far-red lights, which left the phytochrome effect still an open question. In addition, carbon dioxide enrichment via an air sparging system significantly boosted exponential growth and increased carbon conversion efficiency. Finally, a practical study demonstrated the feasibility of growing E. oleoabundans for high lipid production using a diluted agricultural anaerobic waste effluent as the medium. Together, these studies showed the potential of E. oleoabundans as a promising high yield feedstock for the production of high quality biodiesel.

A eutrofização de ambientes aquáticos continentais é um processo lento e natural, mas que tem se intensificado sobremaneira devido a influência das atividades antrópicas. Uma das consequências da eutrofização artificial são florações de algas cada vez mais frequentes e intensas. Alguns grupos de algas, como as cianobactérias, podem produzir toxinas que representam um risco para o homem e para a biota aquática e, por isso, sua floração merece atenção especial. O Lago Guaíba é um importante corpo hídrico do Estado do Rio Grande do Sul e o principal manancial do município de Porto Alegre. A sua bacia hidrográfica ocupa cerca de 30% da área do estado e os principais rios - Jacuí, Caí, Sinos e Gravataí - drenam áreas de intenso uso agrícola e industrial. No Lago Guaíba, as florações têm sido frequentes, principalmente na última década e representam um sério desafio ambiental. Neste contexto, o objetivo da presente pesquisa foi avaliar o potencial de identificação dos episódios de floração de algas no Lago Guaíba a partir da integração de dados radiométricos in situ adquiridos simultaneamente a dados limnológicos (clorofila-a, total de sólidos em suspensão, transparência da água, entre outros) e imagens de satélite. Para a obtenção dos espectros de reflectância foi utilizado o espectrorradiômetro portátil FieldSpec® HandHeld, com coleta em 16 pontos amostrais definidos a priori. Os trabalhos de campo ocorreram em março de 2012, maio de 2013 e abril de 2014. Os espectros foram correlacionados com medidas de variáveis limnológicas obtidas simultaneamente. Para a análise espaço-temporal das florações foram selecionadas 10 imagens produzidas pelos satélites Landsat 5 e 7 (sensores TM e ETM+) disponibilizadas pelo Serviço Geológico dos Estados Unidos (USGS), corrigidas para os efeitos da atmosfera e convertidas em reflectância de superfície. Estas imagens foram obtidas nos meses de verão e outono, entre os anos de 2005 e 2012, e coincidiram com as datas das florações identificadas pelo Departamento Municipal de Água e Esgotos (DMAE) do município de Porto Alegre. Três rotinas de processamento foram aplicadas às imagens: 1) o Índice de Vegetação por Diferença Normalizada (NDVI); 2) o Modelo Linear de Mistura Espectral (MLME) e 3) a Análise por Componentes Principais (ACP). Durante a coleta dos espectros em campo não houve florações, mas, ainda assim, estes permitiram identificar padrões de reflectância do lago em diferentes áreas e situações climáticas, bem como a influência da clorofila-a e dos sólidos em suspensão na resposta espectral da água. Os principais resultados do processamento das imagens de satélite foram: a) o NDVI é adequado para o mapeamento da abrangência e intensidade das florações e que resultados superiores a -0,2 indicam áreas de floração; b) o MLME apresentou limitações para o mapeamento das florações relacionadas à dificuldade de obtenção de bons espectros de referência diretamente sobre as imagens, mas permitiu avaliar as variações espaciais das características da água; c) a técnica da ACP ampliou as correlações dos dados das imagens com a Chl-a e as cianobactérias em comparação ao NDVI, e a classificação nãosupervisionada das principais componentes permitiu identificar as áreas (clusters) de floração, assim como áreas onde outros componentes atuavam. Os fatores que contribuíram para o estabelecimento de florações no lago foram: menor velocidade do fluxo da água, menor profundidade da coluna d´água, menor velocidade do vento e menores índices de precipitação pluviométrica, associados à maior disponibilidade de luminosidade e oferta de nutrientes. Concluí-se que as técnicas empregadas foram adequadas para o mapeamento de florações e que análises que utilizam dados de diferentes naturezas podem incrementar as metodologias existentes e abrir novas possibilidades de identificação e monitoramento de algas. / The eutrophication of freshwater ecosystems is a slow and natural process, but that has intensified greatly because of the influence of human activity. One of the consequences of artificial eutrophication are increasingly frequent and intense algae blooms. Some genera groups of algae, and cyanobacteria can produce toxins that pose a risk to humans and aquatic biota and therefore blooms deserve special attention. The Guaiba Lake is an important water body in the State of Rio Grande do Sul and the main source of Porto Alegre city. Its basin covers about 30% of the state area and major rivers - Jacuí, Caí, Sinos and Gravataí - drain areas of intense agricultural and industrial use. In the Guaiba Lake, blooms have been frequent, especially in the last decade and represent a serious environmental challenge. In this context, the objective of this study was to evaluate the potential for identification of episodes of algal bloom in the Guaiba Lake from the integration of radiometric data in situ simultaneously acquired with limnology data (chlorophyll-a, suspended solids total, water transparency, etc.) and satellite images. To obtain the reflectance spectra a portable spectroradiometer FieldSpec® HandHeld was used, with a collection of 16 sampling points defined a priori. The fieldwork took place in March 2012, May 2013 and April 2014. The spectra were correlated with limnological variables obtained simultaneously. For the spatio-temporal analysis of the blooms 10 images produced by Landsat satellites 5 and 7 (TM and ETM+ sensors) were selected and provided by United States Geological Survey (USGS), adjusted for the effects of the atmosphere and converted to surface reflectance. These images were produced in the months of summer and fall, between the years 2005 and 2012, and coincided with the dates of the blooms identified by the Municipal Department of Water and Sewerage (DMAE) in the city of Porto Alegre. Three processing routines were applied to images: 1) Normalized Difference Vegetation Index (NDVI); 2) Linear Spectral Mixture Model (LSMM) and 3) the Analysis by Principal Component (ACP). During the collection of spectra in the field no bloom was identified, but even so it was possible to identificaty reflectance standards in different areas and climatic conditions in the Lake as well as the influence of chlorophyll-a and suspended solids in the spectral response of the water. The main results of the satellite images processing were: a) the NDVI is suitable for mapping the scope and intensity of blooms and results greater than -0.2 indicate flowering areas; b) the LSMM presented limitations for mapping the blooms related to the difficulty of obtaining good reference spectra directly on the images but allowed the evaluation of spatial variations of water features; c) the technique of ACP increased correlations of image data with Chl-a and cyanobacteria compared to NDVI, and non-supervised classification of the principal component identified in the flowering cluster areas as well as areas where other components were at play. Factors that contributed to the establishment of blooms in the lake were slower rate of water flow, the less depth of the water column, lower wind speed and lower levels of rainfall, combined with the greater availability of light and nutrient supply. It was concluded that the techniques used were suitable for mapping blooms and the analysis using data from different natures can improve existing methodologies and open new possibilities for identification and monitoring of algae.

abstract: Carbon dioxide (CO2) levels in the atmosphere have reached unprecedented levels due to increasing anthropogenic emissions and increasing energy demand. CO2 capture and utilization can aid in stabilizing atmospheric CO2 levels and producing carbon-neutral fuels. Utilizing hollow fiber membranes (HFMs) for microalgal cultivation accomplishes that via bubbleless gas-transfer, preventing CO2 loss to the atmosphere. Various lengths and geometries of HFMs were used to deliver CO2 to a sodium carbonate solution. A model was developed to calculate CO2 flux, mass-transfer coefficient (KL), and volumetric mass-transfer coefficient (KLa) based on carbonate equilibrium and the alkalinity of the solution. The model was also applied to a sparging system, whose performance was compared with that of the HFMs. Typically, HFMs are operated in closed-end mode or open-end mode. The former is characterized by a high transfer efficiency, while the latter provides the advantage of a high transfer rate. HFMs were evaluated for both modes of operation and a varying inlet CO2 concentration to determine the effect of inert gas and water vapor accumulation on transfer rates. For pure CO2, a closed-end module operated as efficiently as an open-end module. Closed-end modules perform significantly worse when CO2-enriched air was supplied. This was shown by the KLa values calculated using the model. Finally, a mass-balance model was constructed for the lumen of the membranes in order to provide insight into the gas-concentration profiles inside the fiber lumen. For dilute CO2 inlet streams, accumulation of inert gases -- nitrogen (N2), oxygen (O2), and water vapor (H2O) -- significantly affected module performance by reducing the average CO2 partial pressure in the membrane and diminishing the amount of interfacial mass-transfer area available for CO2 transfer. / Dissertation/Thesis / Masters Thesis Chemical Engineering 2018

Global warming is becoming more concerned by the public. The escalating atmospheric CO₂ level has introduced the intensification of greenhouse effect which brought enormous impact to the environment and climate. Among different methods for CO₂ mitigation, biological treatment on CO₂ emission using microalgae is regarded to be more economical and beneficial. On the other hand, countries around the world are projected to face water scarcity in the coming decades. Therefore alternatives to the finite fresh water resources for consumption have to be explored. Seawater has been introduced for toilet flushing in Hong Kong since 1950s. The flushing water is mixed with the consumed fresh water in the sewage treatment process to give a sewage effluent with high salinity, which still contains nutrients to support the growth of algal cells. Using sewage effluent as an algal culture medium not only can have a lower operation cost while saving fresh water for food crops, but also the effluent can be purified before discharging. Besides Hong Kong, there is an increase in numbers of cities incorporating seawater in toilet flushing systems as an economical and sustainable solution to fresh water scarcity. / Taking sustainable development into consideration, the use of algal cell for the fixation of CO₂ in saline sewage effluent is proposed, which should be an effective mitigation for CO₂ emissions, removal of nutrient in sewage effluent as well as production of useful products such as biofuel feedstock. In order to find out a suitable algal species for CO₂ the bioremediation, commercially available algal strains were compared against the locally isolated species on the growth and CO₂ removal efficiency in saline sewage effluent. Chlorogonium capillatum, the algal strain isolated from a local fish pond, was found to be the best candidate for CO₂ sequestration and nutrient removal in the non-sterile saline sewage effluent since it could grow much better in the presence of other microorganisms, comparing with the majority of other algal species could not grow under this situation. / The effect of CO₂ enhancement on algal photosynthetic rate and growth was studied in terms of the change in cell number, biomass and lipid production, and the fatty acid profile. The optimisation of CO₂ mitigation was achieved by deploying the response surface methodology (RSM) approach with a model describing the change in CO₂ consumption rate being developed. In the minimal run resolution V (MR5) screening test, it was found that salinity, pH, CO₂ and PO₄³⁻-P levels were influential to CO₂ removal by C. capillatum in non-sterile sewage effluent. Further optimisation of the CO₂ consumption rate was performed using the Box-Behnken design. The results of study showed that C. capillatum was able to deliver its maximum CO₂ consumption rate at 58.96 mg L⁻¹ d⁻¹ at the optimal condition, which was very close to the ordinary condition in the average sewage. In addition, the lipid content of C. capillatum could reach 24.26±2.67% with fatty acid profile conforming to typical biodiesel composition, delivering a high potential for biofuel feedstock production. Together with a high nutrient removal rate, C. capillatum could be used to produce a promising waste-recycling oriented simultaneous treatment system. / Since the CO₂ consumption rate was not dependent to light intensity, the spectral effects on the light-enhanced algal growth and carbon sequestration were investigated to find the best culture condition and how the carbon sequestration process was being influenced. Five LED light spectra were chosen for the analysis and it was found that growth parameters and cell compositions were influenced by the colour of the light very differently. The results indicated that under the irradiation of white LED light, C. capillatum had the highest CO₂ consumption rate and lipid content. Red LED light induced the highest amount of cellular protein as well as the chlorophyll a content. However, the performance of the light dependent reaction of the red LED light culture did not show apparent improvement. Regarding the CO₂ fixation enzyme, the spectral effect on RuBisCO content was marginal and there was no obvious relationship between the light induced CO₂ consumption and solely the light induced RuBisCO content change. Chemical analysis on the algal biomass indicated the C. capillatum culture would be a suitable microbial system to mitigate CO₂ emission, remove nutrients from saline sewage effluent and produce biomass suitable for biofuel production. / This study delivers a bioremediation system which is capable of simultaneous CO₂ mitigation, nutrient removal and biofuel feedstock production with a newly isolated algal species in a waste recycling manner. The findings of this study are not limited to the application locally in Hong Kong, but hopefully all these can also be useful in similar works in other places to help with the sustainable development. / 全球暖化正越來越受到公眾關注，大氣中不斷上升的二氧化碳水平已經加劇了溫室效應，並對環境和氣候帶來了巨大的影響。在不同的二氧化碳緩減方法中，利用生物方法以微藻處理二氧化碳排放被認為是更具效率和回報價值。另一方面，世界各地已經預計會在未來幾十年面臨水荒，因此是有必須要為有限的淡水資源尋找代替品。自五十年代起，香港便引入了海水作沖廁用途。沖廁用水會在污水處理過程中混合經使用過的淡水而產生高鹽度的污水，而污水當中仍含有營養物質，以支持藻類細胞生長。使用污水作為藻類培養介質不但可以降低營運成本，並有助於節省淡水用以耕種糧食作物，而且可以在污水排出前進行純化。除香港以外，一些引入海水用於沖廁系統的城市數目正在增加。 / 考慮到可持續發展，我們提出利用微藻細胞在帶鹽污水中進行二氧化碳固定。這應該是一個有效的緩解二氧化碳排放，清除污水中養份，以及產生有價值產品的綜合方案。為了找出一種合適的微藻進行生物整治，我們比較了市面上買到的品種和於本地環境分離出來的藻種於帶鹽污水中生長和去除二氧化碳的表現。經過實驗後我們確定一種從魚塘中分離出來的綠梭藻(Chlorogonium capillatum)是能夠在未經消毒的帶鹽污水中進行碳封存和去除養份的最佳選擇，因為綠梭藻能夠在其他微生物存在下仍可以良好地生長，反觀其他大多數的藻種就不能在這情況生長。 / 我們從細胞數、生物量、脂質和脂肪酸譜的變化方面研究了二氧化碳量增強對微藻光合速率和生長的影響。我們利用了反應曲面法(Response Surface Methodology)對微藻的二氧化碳緩減進行最佳化，並將二氧化碳緩減率的變化製成模型。在條件篩選實驗，我們找出鹽度、酸鹼、二氧化碳和磷質水平是會影響二氧化碳緩減率。在隨後的二氧化碳緩減率的最佳化後，綠梭藻的最大二氧化碳緩減率為58.69微克每公升每天。研究發現綠梭藻能夠於接近平常環境條件下達成最高效的二氧化碳緩減。除此之外，綠梭藻的脂質含量可達24.26±2.67百份比。加上脂肪酸分佈符合典型的生物柴油成份和具有高度養份去除率，綠梭藻可以用來創造以廢物回收作主導的多功能的生物修復系統。 / 由於二氧化碳緩減率並不依賴於光的強度，我們進行了光譜對微藻生長和碳封存的影響的研究，以找出最佳的培養條件和了解碳吸收的過程如何被影響。我們分析了五種發光二極管光譜，發現燈光顏色對微藻的生長參數和細胞組合物有明顯的影響。結果顯示，在白色燈的照射下，綠梭藻有最高的二氧化碳緩減率和脂質含量。紅色燈引發了最高的細胞蛋白質，以及葉綠素a含量。然而，紅光並沒有明顯提升光依賴反應。關於固定二氧化碳的酶，光譜對羧化/加氧酶的數量變化效果細微。另外，羧化/加氧酶跟二氧化碳緩減率之間沒有明顯關係。從微藻生物質中的化學分析，我們認為綠梭藻是一個合適的微生物系統以達成二氧化碳的排放緩減，去除帶鹽污水中的養份和生產適用於生物燃料製造的生物質。 / 這項研究提供了一個生物修復系統，它能夠以廢品回收方式同時減少二氧化碳排放、去除營養和生產製作生物燃料的原料。這項研究的結果並不只限於香港使用，我們希望這些東西也可以應在其地方類似的工程上，為可持續發展出力。 / Lee, Kwan Yin. / Thesis Ph.D. Chinese University of Hong Kong 2015. / Includes bibliographical references (leaves 115-134). / Abstracts also in Chinese. / Title from PDF title page (viewed on 05, January, 2017). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

Atmospheric nutrient loading and transport though precipitation and dry deposition is one of the least understood yet one of the most important pathways of nutrient transport into many lakes. These nutrients, phosphorus and nitrogen, are essential for aquatic life and often play major roles in algae blooms that occur in lakes and reservoirs. Often heavy algal growth intensifies a variety of water quality problems. Utah Lake may be even more susceptible to atmospheric deposition due to its large surface area to volume ratio and proximity to Great Basin dust sources. In this study, eight months of atmospheric deposition data were collected and analyzed from five locations near Utah Lake. Geospatial maps were created to show the temporal distribution of phosphorus and nitrogen. Evaluation of the atmospheric deposition results indicate that between 8 to 350 tons of total phosphorus and 46 to 460 tons of dissolved inorganic nitrogen were deposited onto the surface of Utah Lake over an eight-month period. Both estimates were based on assuming that the deposition decreased exponentially from the sampling station to the middle of the lake. The large difference results from using only samples with no visible particles or insects present to give the low estimate and all samples to give the high estimate. These nutrient loading values are very significant in that it has been estimated that only about 17 tons year-1 of phosphorus and about 200 tons year-1 of nitrogen are needed to support a eutrophic level of algal growth in Utah Lake. Atmospheric deposition was found to be a major contributor in providing a eutrophic nutrient load to Utah Lake. Further, it is likely that the actual deposition loading is much higher than 8 tons per 8 months thus indicating that deposition alone adds a eutrophic phosphorus loading to the lake. Since conditions are similar in much of the Great Basin and other areas of Western United States, this seems to be a very significant finding relative to nutrient evaluation and feasible management scenarios. The results also indicate that one might expect to see more cyanobacteria blooms (Harmful Algal Blooms) in shallow ponds in this area if atmospheric deposition is the main source of nutrients, since N to P ratios are low and thus more situations arise where a shortage of ionic nitrogen favors these nitrogen-fixing cyanobacteria.

Recently, biogenic carbonates have received much attention as potential proxies of environmental change; however, a major pathway of elemental incorporation is often overlooked when making interpretations or designing experiments. This research experimentally examines the influence of diet on elemental composition in juvenile shells of the bay scallop, Argopecten irradians concentricus, and the northern quahog, Mercenaria mercenaria. Exploratory trials were conducted using Argopecten irradians concentricus juveniles fed different algal diets: Isochrysis, Chaetoceros, Pavlova, Tetraselmis, or a mix of all four in a 2:1:2:2 ratio. No differences between the left and right valves were revealed, thus, subsequent analysis of the dietary influence on shell chemistry utilized both valves. Only Mg/Ca and K/Ca were significantly different between the diet groups, though different influences were determined. Experiments with juvenile Mercenaria mercenaria compared shell chemistries among clams fed unicellular diets of Isochrysis sp. (CCMP1324), Pavlova pinguis (CCMP609), Chaetoceros mulleri (CCMP1316), Isochrysis sp. (CCMP1611) culture, Pavlova sp. (CCMP1209), or Chaetoceros galvestonensis (CCMP186), a mixed diet of all species in equal ratios (Mixed), or no food (starvation control). The results indicate that diet can influence shell chemistry either directly or indirectly, with degree of influence varying by diet and mollusc species. Additional information concerning the use of alternative element ratios and changes in the shell chemistry due to starvation-induced stress are also presented. Altogether, the present research provides valuable information concerning shell dynamics and potential diet-associated fluxes, thus demonstrating the need to consider the composition of dietary inputs when assessing environmental associations with elemental shell chemistries.

Harvesting of algal biomass presents a large barrier to the success of biofuels made from algae feedstock. Small cell sizes coupled with dilute concentrations of biomass in lagoon systems make separation an expensive and energy intense-process. The rotating algal biofilm reactor (RABR) has been developed at USU to provide a sustainable technology solution to this issue. Algae cells grown as a biofilm are concentrated in one location for ease of harvesting of high density biomass. A mathematical model of this biofilm system was developed based on data generated from three pilot scale reactors at the City of Logan, Utah wastewater reclamation plant. The data were fit using nonlinear regression to a modified logistic growth equation. The logistic growth equation was used to estimate nitrogen and phosphorus removal from the system, and to find the best harvesting time for the reactors. These values were extrapolated to determine yields of methane and biodiesel from algae biomass that could be used to provide energy to the City of Logan if these reactors were implemented at full scale. For transesterification into biodiesel, algae need to have high lipid content. Algae biofilms have been relatively unexplored in terms of cell lipid composition accumulation and changes with regard to environmental stressors. Results indicated that biofilm biomass was largely unaffected by nutrient stresses. Neither nitrogen limitation nor excess inorganic carbon triggered a significant change in lipid content. Biofilm algae grown with indoor lighting produced an average of 4.2% lipid content by dry weight. Biofilm algae gown outdoors yielded an average of 6.2% lipid content by dry weight.

We explored using de-oiled algal biomass (algal cake) as a low-value substrate for production of lactic acid in fermentations with Lactobacillus casei, and strategies for increasing lactic acid production at low pH. L. casei 12A algal cake (AC) fermentations showed carbohydrate and amino acid availability limit growth and lactic acid production. These nutritional requirements were effectively addressed with enzymatic hydrolysis of the AC using α-amylase, cellulase, and pepsin. Producing 0.075 g lactic acid per g AC from AC digested with all three enzymes. We explored heterologous expression of the cellulase gene (celE) from Clostridium thermocellum and the α-amylase gene (amyA) from Streptococcus bovis in L. casei 12A. Functional activity of CelE was not detected, but low-level activity of AmyA was achieved, and increased > 1.5-fold using a previously designed synthetic promoter. Nonetheless, the improvement was insufficient to significantly increase lactic acid production. Thus, substantial optimization of amyA and celE expression in L. casei 12A would be needed to achieve activities needed to increase lactic acid production from AC. We explored transient inactivation of MutS as a method for inducing hypermutability and increasing adaptability of L. casei 12A and ATCC 334 to lactic acid at low pH. The wild type cells and their ΔmutS derivatives were subject to a 100-day adaptive evolution experiment, followed by repair of the ΔmutS lesion in representative isolates. Growth studies at pH 4.0 revealed that all four adapted strains grew more rapidly, to higher cell densities, and produced significantly more lactic acid than untreated wild-type cells. The greatest increases were observed from the adapted ΔmutS derivatives. Further examination of the 12A adapted ΔmutS derivative identified morphological changes, and increased survival at pH 2.5. Genome sequence analysis confirmed transient MutS inactivation decreased DNA replication fidelity, and identified potential genotypic changes in 12A that might contribute to increased acid lactic acid resistance. Targeted inactivation of three genes identified in the adapted 12A ΔmutS derivative revealed that a NADH dehydrogenase (ndh), phosphate transport ATP-binding protein PstB (pstB), and two-component signal transduction system (TCS) quorum-sensing histidine kinase (hpk) contribute to increased acid resistance in 12A.