scholarly journals Application of metabolic controls for the maximization of lipid production in semicontinuous fermentation

2017 ◽  
Vol 114 (27) ◽  
pp. E5308-E5316 ◽  
Author(s):  
Jingyang Xu ◽  
Nian Liu ◽  
Kangjian Qiao ◽  
Sebastian Vogg ◽  
Gregory Stephanopoulos

Acetic acid can be generated through syngas fermentation, lignocellulosic biomass degradation, and organic waste anaerobic digestion. Microbial conversion of acetate into triacylglycerols for biofuel production has many advantages, including low-cost or even negative-cost feedstock and environmental benefits. The main issue stems from the dilute nature of acetate produced in such systems, which is costly to be processed on an industrial scale. To tackle this problem, we established an efficient bioprocess for converting dilute acetate into lipids, using the oleaginous yeast Yarrowia lipolytica in a semicontinuous system. The implemented design used low-strength acetic acid in both salt and acid forms as carbon substrate and a cross-filtration module for cell recycling. Feed controls for acetic acid and nitrogen based on metabolic models and online measurement of the respiratory quotient were used. The optimized process was able to sustain high-density cell culture using acetic acid of only 3% and achieved a lipid titer, yield, and productivity of 115 g/L, 0.16 g/g, and 0.8 g⋅L−1⋅h−1, respectively. No carbon substrate was detected in the effluent stream, indicating complete utilization of acetate. These results represent a more than twofold increase in lipid production metrics compared with the current best-performing results using concentrated acetic acid as carbon feed.

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Hossein Alishah Aratboni ◽  
Nahid Rafiei ◽  
Raul Garcia-Granados ◽  
Abbas Alemzadeh ◽  
José Rubén Morones-Ramírez

Abstract The use of fossil fuels has been strongly related to critical problems currently affecting society, such as: global warming, global greenhouse effects and pollution. These problems have affected the homeostasis of living organisms worldwide at an alarming rate. Due to this, it is imperative to look for alternatives to the use of fossil fuels and one of the relevant substitutes are biofuels. There are different types of biofuels (categories and generations) that have been previously explored, but recently, the use of microalgae has been strongly considered for the production of biofuels since they present a series of advantages over other biofuel production sources: (a) they don’t need arable land to grow and therefore do not compete with food crops (like biofuels produced from corn, sugar cane and other plants) and; (b) they exhibit rapid biomass production containing high oil contents, at least 15 to 20 times higher than land based oleaginous crops. Hence, these unicellular photosynthetic microorganisms have received great attention from researches to use them in the large-scale production of biofuels. However, one disadvantage of using microalgae is the high economic cost due to the low-yields of lipid content in the microalgae biomass. Thus, development of different methods to enhance microalgae biomass, as well as lipid content in the microalgae cells, would lead to the development of a sustainable low-cost process to produce biofuels. Within the last 10 years, many studies have reported different methods and strategies to induce lipid production to obtain higher lipid accumulation in the biomass of microalgae cells; however, there is not a comprehensive review in the literature that highlights, compares and discusses these strategies. Here, we review these strategies which include modulating light intensity in cultures, controlling and varying CO2 levels and temperature, inducing nutrient starvation in the culture, the implementation of stress by incorporating heavy metal or inducing a high salinity condition, and the use of metabolic and genetic engineering techniques coupled with nanotechnology.


Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5960
Author(s):  
Rahul Saini ◽  
Krishnamoorthy Hegde ◽  
Carlos Saul Osorio-Gonzalez ◽  
Satinder Kaur Brar ◽  
Pierre Vezina

The study aims to explore microbial lipid production using an abundant and low-cost lignocellulosic biomass derived from forestry residues. Sugar-rich undetoxified hydrolysate was prepared using hardwood and softwood sawdust and used for lipid production as a carbon source from an oleaginous yeast, Rhodosporidium toruloides-1588. The maximum biomass obtained was 17.09 and 19.56 g/L in hardwood and softwood hydrolysate, respectively. Sugar consumption in both hydrolysates was >95%, with a maximum lipid accumulation of 36.68% at 104 h and 35.24% at 96 h. Moreover, R. toruloides-1588 exhibited tolerance to several toxic compounds such as phenols, organic acids and furans present in hydrolysates. The lipid characterization showed several monosaturated and polyunsaturated fatty acids, making it a potential feedstock for biofuels and oleochemicals production. This study confirms the credibility of R. toruloides-1588 as a suitable lipid producer using hydrolysates from forestry residues as a substrate. Additionally, lipids obtained from R. toruloides-1588 could be a potential feedstock for advanced biofuel production as well as for food and pharmaceutical applications.


RSC Advances ◽  
2018 ◽  
Vol 8 (49) ◽  
pp. 27963-27972 ◽  
Author(s):  
Zhenlin Han ◽  
Alex Park ◽  
Wei Wen Su

Seed oil from papaya waste was validated as a novel carbon substrate for Yarrowia lipolytica to produce high-value products.


2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Srikanth Reddy Medipally ◽  
Fatimah Md. Yusoff ◽  
Sanjoy Banerjee ◽  
M. Shariff

The world energy crisis and increased greenhouse gas emissions have driven the search for alternative and environmentally friendly renewable energy sources. According to life cycle analysis, microalgae biofuel is identified as one of the major renewable energy sources for sustainable development, with potential to replace the fossil-based fuels. Microalgae biofuel was devoid of the major drawbacks associated with oil crops and lignocelluloses-based biofuels. Algae-based biofuels are technically and economically viable and cost competitive, require no additional lands, require minimal water use, and mitigate atmospheric CO2. However, commercial production of microalgae biodiesel is still not feasible due to the low biomass concentration and costly downstream processes. The viability of microalgae biodiesel production can be achieved by designing advanced photobioreactors, developing low cost technologies for biomass harvesting, drying, and oil extraction. Commercial production can also be accomplished by improving the genetic engineering strategies to control environmental stress conditions and by engineering metabolic pathways for high lipid production. In addition, new emerging technologies such as algal-bacterial interactions for enhancement of microalgae growth and lipid production are also explored. This review focuses mainly on the problems encountered in the commercial production of microalgae biofuels and the possible techniques to overcome these difficulties.


2021 ◽  
Vol 13 (12) ◽  
pp. 6921
Author(s):  
Laura Sisti ◽  
Annamaria Celli ◽  
Grazia Totaro ◽  
Patrizia Cinelli ◽  
Francesca Signori ◽  
...  

In recent years, the circular economy and sustainability have gained attention in the food industry aimed at recycling food industrial waste and residues. For example, several plant-based materials are nowadays used in packaging and biofuel production. Among them, by-products and waste from coffee processing constitute a largely available, low cost, good quality resource. Coffee production includes many steps, in which by-products are generated including coffee pulp, coffee husks, silver skin and spent coffee. This review aims to analyze the reasons why coffee waste can be considered as a valuable source in recycling strategies for the sustainable production of bio-based chemicals, materials and fuels. It addresses the most recent advances in monomer, polymer and plastic filler productions and applications based on the development of viable biorefinery technologies. The exploration of strategies to unlock the potential of this biomass for fuel productions is also revised. Coffee by-products valorization is a clear example of waste biorefinery. Future applications in areas such as biomedicine, food packaging and material technology should be taken into consideration. However, further efforts in techno-economic analysis and the assessment of the feasibility of valorization processes on an industrial scale are needed.


2015 ◽  
Vol 184 ◽  
pp. 202-214 ◽  
Author(s):  
Abbas Mehrabadi ◽  
Rupert Craggs ◽  
Mohammed M. Farid

2014 ◽  
Vol 7 (1) ◽  
pp. 42 ◽  
Author(s):  
Fabio Santomauro ◽  
Fraeya M Whiffin ◽  
Rod J Scott ◽  
Christopher J Chuck

Author(s):  
Fábio C. Barbosa

Freight rail carriers have been continuously challenged to reduce costs and comply with increasingly stringent environmental standards, into a continuously competing and environmentally driven industry. In this context, current availability and relative abundance of clean and low cost non conventional gas reserves have aroused a comprehensive reevaluation of rail industry into fuel option, especially where freight rail are strongly diesel based. Countries in which rail sector is required to play an important role in transport matrix, where fuel expenditures currently accounts for a significant share of operational costs, like Australia, Brazil, United States and other continental countries, can be seen as strong candidates to adopt fuel alternatives to diesel fueled freight railways. Moreover, from an environmental perspective, the use of alternative fuels (like natural gas) for locomotive traction may allow rail freight carriers to comply with emission standards into a less technologically complex and costly way. In this context, liquefied natural gas (LNG) fueled freight locomotives are seen as a strong potential near-term driver for natural gas use in rail sector, with its intrinsic cost and environmental benefits and with the potential to revolutionize rail industry much like the transition from steam to diesel experienced into the fifties, as well as the more recent advent of use of alternating current diesel-electric locomotives. LNG rail fueled approach has been focused on both retrofitting existing locomotive diesel engines, as well as on original manufactured engines. Given the lower polluting potential of natural gas heavy engines, when compared to diesel counterparts, LNG locomotives can be used to comply with increasingly restrictive Particulate Matter (PM) and Nitrogen Oxides (NOx) emission standards with less technological complexity (engine design and aftertreatment hardware) and their intrinsic lower associated costs. Prior to commercial operation of LNG locomotives, there are some technical, operational and economic hurdles that need to be addressed, i.e. : i) locomotive engine and fuel tender car technological maturity and reliability improvement; ii) regulation improvement, basically focused on operational safety and interchange operations; iii) current and long term diesel - gas price differential, a decisive driver, and, finally, iv) LNG infrastructure requirements (fueling facilities, locomotives and tender car specifications). This work involved an extensive research into already published works to present an overview of LNG use in freight rail industry into a technical, operational and economical perspective, followed by a critical evaluation of its potential into some relevant freight rail markets, such as United States, Brazil and Australia, as well as some European non electrified rail freight lines.


Author(s):  
Judita Koreivienė ◽  
Robertas Valčiukas ◽  
Jūratė Karosienė ◽  
Pranas Baltrėnas

Industry, transport and unsustainable agriculture result in the increased quantity of wastewater, release of nutrients and emission of carbon dioxide that promotes eutrophication of water bodies and global climate change. the application of microalgae for phycoremediation, their biomass use for human needs may increase sustainability and have a positive effect on the regional development. The experiments were carried out in order to establish the feasibility of treating the local municipal wastewater with microalgae consortia and their biomass potential for biofuel production. The results revealed that Chlorella/Scenedesmus consortium eliminated up to 99.7–99.9% of inorganic phosphorus and up to 88.6–96.4% of inorganic nitrogen from the wastewater within three weeks. The ammonium removal was more efficient than that of nitrate. Chlorella algae grew better in diluted, while Scenedesmus – in the concentrated wastewater. The consortium treated wastewater more efficiently than a single species. The maximum biomass (3.04 g/L) of algal consortium was estimated in concentrated wastewater. Algae accumulated 0.65–1.37 g of CO2/L per day in their biomass. Tus, Chlorella/Scenedesmus consortium is a promising tool for nutrients elimination from the local wastewater under the climatic conditions specific to Lithuania. However, none of the two species were able to accumulate lipids under the nitrogen starvation conditions.


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