Process simulation and techno-economic assessment for direct production of advanced bioethanol using a genetically modified Synechocystis sp.

Lopes, Tiago F.; Cabanas, Catarina; Silva, André; Fonseca, Diana; Santos, Edgar; Guerra, Luís; Sheahan, Con; Reis, Alberto; Gı́rio, Francisco M.

doi:10.1016/j.biteb.2019.02.010

Cited by 30 publications

(22 citation statements)

References 30 publications

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“…Based on experimental data [25,38], we assumed that 18% of the culture is harvested on a daily basis. This means that 15 m 3 /day, 12.5 m 3 /day and 11.9 m 3 /day are harvested for the FPA, GWP and UHT respectively, and therefore 11.8 metric tons (81% dw), 3 metric tons (84% dw) and 3.2 metric tons (83% dw) of red algae are harvested in one year using the FPA, GWP and UHT technology respectively.…”

Section: Downstream Process (Algae Harvest and Drying)mentioning

confidence: 99%

Comparative life cycle assessment of astaxanthin production with Haematococcus pluvialis in different photobioreactor technologies

Onorato

Rösch

2020

Algal Research

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Haematococcus pluvialis is one of the most abundant sources of natural astaxanthin when compared with other microorganisms, and has attracted the interest of the market thanks to its health benefits. We investigated the environmental performance of the cultivation of H. pluvialis and the astaxanthin production processes through a comprehensive Life Cycle Analysis (LCA). This study compares the potential environmental impact of three photobioreactors (PBR) available on the market: the flat panel airlift , the green wall panel , and the unilayer horizontal tubular PBR . These systems have different technical settings: the flat panel airlift has a double-sided light emitting diode (LED) illumination system and is placed inside a building; the green wall panel is located outside and equipped with one-side LED lighting; the unilayer horizontal tubular is placed outside without any artificial lighting. Two different functional units were considered: one kg of H. pluvialis (80% dw) and 1 kg of astaxanthin. Where 1 kg of astaxanthin was selected as functional unit, as the content of astaxanthin in the biomass is low, the system expansion method was applied.The LCA results, based on original data from pilot-scale production, indicate that the system design, and the energy mix used have a significant environmental impact, due to differences in algae productivities and energy demand. For indoor systems, even with light-emitting diodes (LED), the energy demand for lighting is the main contributor to climate change. This contribution decreases significantly if the share of renewable energy increases. In the case of the green wall panel another main climate change contributor is the material used for the diode production, including tin and molybdenum. Although the astaxanthin yield is higher in the flat panel airlift and green wall panel, electricity production systems still const tute an environmental burden. For this reason, the system with the lowest environmental impact is the unilayer horizontal tubular, i.e. the photobioreactor where no artificial light is used.

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Section: Downstream Process (Algae Harvest and Drying)mentioning

confidence: 99%

Comparative life cycle assessment of astaxanthin production with Haematococcus pluvialis in different photobioreactor technologies

Onorato

Rösch

2020

Algal Research

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“…The journey towards the commercialisation of autotrophic bioethanol production is far from over, yet progress in ethanologenic cassette and chassis redesign has already increased ethanol titres by 24-fold [ 15 , 24 , 27 ]. Ethanol titres are currently 14-fold lower than the minimum required for the energy efficiency of ethanol recovery by distillation to become commercially viable, so step changes are needed, for this and other recovery methods [ 9 , 130 , 131 ]. Recent techno-economic analysis (TEA) of the viability of scaled cyanobacterial ethanol production suggested that the operational costs would be greater than the value of ethanol produced [ 9 ].…”

Section: Discussionmentioning

confidence: 99%

Combinatorial use of environmental stresses and genetic engineering to increase ethanol titres in cyanobacteria

Andrews

Faulkner

Toogood

et al. 2021

Biotechnol Biofuels

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Current industrial bioethanol production by yeast through fermentation generates carbon dioxide. Carbon neutral bioethanol production by cyanobacteria uses biological fixation (photosynthesis) of carbon dioxide or other waste inorganic carbon sources, whilst being sustainable and renewable. The first ethanologenic cyanobacterial process was developed over two decades ago using Synechococcus elongatus PCC 7942, by incorporating the recombinant pdc and adh genes from Zymomonas mobilis. Further engineering has increased bioethanol titres 24-fold, yet current levels are far below what is required for industrial application. At the heart of the problem is that the rate of carbon fixation cannot be drastically accelerated and carbon partitioning towards bioethanol production impacts on cell fitness. Key progress has been achieved by increasing the precursor pyruvate levels intracellularly, upregulating synthetic genes and knocking out pathways competing for pyruvate. Studies have shown that cyanobacteria accumulate high proportions of carbon reserves that are mobilised under specific environmental stresses or through pathway engineering to increase ethanol production. When used in conjunction with specific genetic knockouts, they supply significantly more carbon for ethanol production. This review will discuss the progress in generating ethanologenic cyanobacteria through chassis engineering, and exploring the impact of environmental stresses on increasing carbon flux towards ethanol production.

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“…The dramatic overproduction of greenhouse gas emissions is due to many factors, among which is an increasing demand of essential goods, whose production still relies on fossil resources [ 1 , 2 , 3 ]. In the context of the circular bioeconomy, microalgae and cyanobacteria have emerged as an important feedstock, as these microorganisms produce molecules which can be used as renewable raw materials to substitute fossil-based fuels, chemicals, food and plastics [ 4 , 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

An Alternative Exploitation of Synechocystis sp. PCC6803: A Cascade Approach for the Recovery of High Added-Value Products

et al. 2023

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Microalgal biomass represents a very interesting biological feedstock to be converted into several high-value products in a biorefinery approach. In this study, the cyanobacterium Synechocystis sp. PCC6803 was used to obtain different classes of molecules: proteins, carotenoids and lipids by using a cascade approach. In particular, the protein extract showed a selective cytotoxicity towards cancer cells, whereas carotenoids were found to be active as antioxidants both in vitro and on a cell-based model. Finally, for the first time, lipids were recovered from Synechocystis biomass as the last class of molecules and were successfully used as an alternative substrate for the production of polyhydroxyalkanoate (PHA) by the native PHA producer Pseudomonas resinovorans. Taken together, our results lead to a significant increase in the valorization of Synechocystis sp. PCC6803 biomass, thus allowing a possible offsetting of the process costs.

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Process simulation and techno-economic assessment for direct production of advanced bioethanol using a genetically modified Synechocystis sp.

Cited by 30 publications

References 30 publications

Comparative life cycle assessment of astaxanthin production with Haematococcus pluvialis in different photobioreactor technologies

Comparative life cycle assessment of astaxanthin production with Haematococcus pluvialis in different photobioreactor technologies

Combinatorial use of environmental stresses and genetic engineering to increase ethanol titres in cyanobacteria

An Alternative Exploitation of Synechocystis sp. PCC6803: A Cascade Approach for the Recovery of High Added-Value Products

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