Toward nitrogen neutral biofuel production

Huo, Yi-Xin; Wernick, David G.; Liao, James C.

doi:10.1016/j.copbio.2011.10.005

Cited by 53 publications

(37 citation statements)

References 48 publications

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“…Several studies have reported an inverse proportional relation between the lipid content and growth rate of the selected microalgae species. In other words, the higher the growth rate the lower the lipid content (% of DW), and vice versa [6,30,31]. …”

Section: Resultsmentioning

confidence: 99%

Superior triacylglycerol (TAG) accumulation in starchless mutants of Scenedesmus obliquus: (I) mutant generation and characterization

Jaeger

Verbeek

Draaisma

et al. 2014

Biotechnol Biofuels

137

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BackgroundMicroalgae are a promising platform for producing neutral lipids, to be used in the application for biofuels or commodities in the feed and food industry. A very promising candidate is the oleaginous green microalga Scenedesmus obliquus, because it accumulates up to 45% w/w triacylglycerol (TAG) under nitrogen starvation. Under these conditions, starch is accumulated as well. Starch can amount up to 38% w/w under nitrogen starvation, which is a substantial part of the total carbon captured. When aiming for optimized TAG production, blocking the formation of starch could potentially increase carbon allocation towards TAG. In an attempt to increase TAG content, productivity and yield, starchless mutants of this high potential strain were generated using UV mutagenesis. Previous studies in Chlamydomonas reinhardtii have shown that blocking the starch synthesis yields higher TAG contents, although these TAG contents do not surpass those of oleaginous microalgae yet. So far no starchless mutants in oleaginous green microalgae have been isolated that result in higher TAG productivities.ResultsFive starchless mutants have been isolated successfully from over 3,500 mutants. The effect of the mutation on biomass and total fatty acid (TFA) and TAG productivity under nitrogen-replete and nitrogen-depleted conditions was studied. All five starchless mutants showed a decreased or completely absent starch content. In parallel, an increased TAG accumulation rate was observed for the starchless mutants and no substantial decrease in biomass productivity was perceived. The most promising mutant showed an increase in TFA productivity of 41% at 4 days after nitrogen depletion, reached a TAG content of 49.4% (% of dry weight) and had no substantial change in biomass productivity compared to the wild type.ConclusionsThe improved S. obliquus TAG production strains are the first starchless mutants in an oleaginous green microalga that show enhanced TAG content under photoautotrophic conditions. These results can pave the way towards a more feasible microalgae-driven TAG production platform.

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Section: Resultsmentioning

confidence: 99%

Superior triacylglycerol (TAG) accumulation in starchless mutants of Scenedesmus obliquus: (I) mutant generation and characterization

Jaeger

Verbeek

Draaisma

et al. 2014

Biotechnol Biofuels

137

View full text Add to dashboard Cite

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“…Many groups have proposed using thermochemical conversion and anaerobic digestion of biomass as potential sources of recycled nitrogen (Minowa et al, 1995; Chisti, 2008; Sialve et al, 2009; Jena et al, 2011; Biller et al, 2012; Huo et al, 2012; Garcia Alba et al, 2013; López Barreiro et al, 2013a). These degradative approaches have the benefit that phosphorous and nitrogen can be resupplied in an inorganic form, and theoretically enable the possibility of growing multiple culture generations from a single fertilizer input.…”

Section: Introductionmentioning

confidence: 99%

Amino Acids Are an Ineffective Fertilizer for Dunaliella spp. Growth

et al. 2017

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Autotrophic microalgae are a promising bioproducts platform. However, the fundamental requirements these organisms have for nitrogen fertilizer severely limit the impact and scale of their cultivation. As an alternative to inorganic fertilizers, we investigated the possibility of using amino acids from deconstructed biomass as a nitrogen source in the genus Dunaliella. We found that only four amino acids (glutamine, histidine, cysteine, and tryptophan) rescue Dunaliella spp. growth in nitrogen depleted media, and that supplementation of these amino acids altered the metabolic profile of Dunaliella cells. Our investigations revealed that histidine is transported across the cell membrane, and that glutamine and cysteine are not transported. Rather, glutamine, cysteine, and tryptophan are degraded in solution by a set of oxidative chemical reactions, releasing ammonium that in turn supports growth. Utilization of biomass-derived amino acids is therefore not a suitable option unless additional amino acid nitrogen uptake is enabled through genetic modifications of these algae.

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“…Deamination is a critical step toward the formation of keto acids (the precursors for higher alcohol generation) [78]. Considering the huge volumes of biomass that could be processed in biofuel refineries, the amount of protein waste product is likely to be substantial [79][80][81].…”

Section: Conversions Of Proteins Into Higher Alcoholmentioning

confidence: 99%

“…Carboxylic acid derivatives may be produced instead of alcohols which strictly dependent upon the redox state of the cells. In previous studies [78,88,89], metabolic engineering was applied to develop Escherichia coli that is able to deaminate protein hydrolysates, facilitating the conversion of proteins to C4, C5 alcohols at 56% of the theoretical yield [44]. Bacillus subtilis, E. coli, Saccharomyces cerevisiae and microalgae was used as protein sources, which yielded up to 4,035 mg L −1 of alcohols from biomass containing ~22 g L −1 of amino acids [44].…”

Section: Conversions Of Proteins Into Higher Alcoholmentioning

confidence: 99%

Utilization of Microalgal Biofractions for Bioethanol, Higher Alcohols, and Biodiesel Production: A Review

et al. 2017

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Abstract:Biomass is a crucial energy resource used for the generation of electricity and transportation fuels. Microalgae exhibit a high content of biocomponents which makes them a potential feedstock for the generation of ecofriendly biofuels. Biofuels derived from microalgae are suitable carbon-neutral replacements for petroleum. Fermentation is the major process for metabolic conversion of microalgal biocompounds into biofuels such as bioethanol and higher alcohols. In this review, we explored the use of all three major biocomponents of microalgal biomass including carbohydrates, proteins, and lipids for maximum biofuel generation. Application of several pretreatment methods for enhancement the bioavailability of substrates (simple sugar, amino acid, and fatty acid) was discussed. This review goes one step further to discuss how to direct these biocomponents for the generation of various biofuels (bioethanol, higher alcohol, and biodiesel) through fermentation and transesterification processes. Such an approach would result in the maximum utilization of biomasses for economically feasible biofuel production.

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Toward nitrogen neutral biofuel production

Cited by 53 publications

References 48 publications

Superior triacylglycerol (TAG) accumulation in starchless mutants of Scenedesmus obliquus: (I) mutant generation and characterization

Superior triacylglycerol (TAG) accumulation in starchless mutants of Scenedesmus obliquus: (I) mutant generation and characterization

Amino Acids Are an Ineffective Fertilizer for Dunaliella spp. Growth

Utilization of Microalgal Biofractions for Bioethanol, Higher Alcohols, and Biodiesel Production: A Review

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