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1.
Environ Res ; 258: 119482, 2024 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-38914252

RESUMO

In this study, we studied the hydrocracking of waste chicken oil (WCO) catalyzed by mesoporous SO42-/KIT-6. The study included WCO extraction, SO42-/KIT-6 catalyst synthesis, hydrocracking, and catalytic characterization. XRD patterns revealed intense peaks in the low-angle region, with shoulder peaks showing an increase in sulphate loading from 10% to 30%. The BET-specific surface area for the pure KIT-6 supports measured at 1003 m2/g, indicative of a well-defined mesoporous structure. Thermogravimetric analysis (TGA) showed a two-stage weight loss, attributed to the elimination of hydrated water (about 200 °C) and decomposition of sulphate ions (400-450 °C). SEM analysis highlighted the surface morphology of the active SK-2 catalyst. Hydrocatalytic and catalytic cracking reactions were performed, and about 99.8% conversion was achieved with 20 mL/H H2 flow, whereas higher production of bioliquids was observed at a flow of 15 mL/h. The hydrocracking mechanism was also studied to understand the formation of lower hydrocarbons. GC analyses of simulated distilled gasoline, kerosene, and diesel showed diverse hydrocarbon compositions. For engine testing, non-hydrocracked fuel rose to 28 kW at 3000 rpm and declined to 21 kW at 3500 rpm. Emission analysis revealed decreasing trends in NOX emissions of hydrogen-rich blends, with values of 65 ppm, 54 ppm, and 48 ppm for petrol, NHBL, and HBL, respectively. Similarly, SO2 emissions reduced from petrol to NHBL and HBL at 910 ppm, 800 ppm, and 600 ppm, respectively, suggesting reduced environmental impact. CO emissions exhibited a substantial reduction in NHBL (0.90%) and HBL (0.54%) compared to petrol (2.70%), emphasizing the cleaner combustion characteristics. Our results provide a comprehensive exploration of waste chicken oil hydrocracking, emphasizing catalyst synthesis, fuel characterization, engine performance, and environmental impact, thereby contributing valuable insights to the field of sustainable bioenergy.

2.
Appl Microbiol Biotechnol ; 108(1): 33, 2024 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38175234

RESUMO

Due to the limited resources and environmental problems associated with fossil fuels, there is a growing interest in utilizing renewable resources for the production of biofuels through microbial fermentation. Isobutanol is a promising biofuel that could potentially replace gasoline. However, its production efficiency is currently limited by the use of naturally isolated microorganisms. These naturally isolated microorganisms often encounter problems such as a limited range of substrates, low tolerance to solvents or inhibitors, feedback inhibition, and an imbalanced redox state. This makes it difficult to improve their production efficiency through traditional process optimization methods. Fortunately, recent advancements in genetic engineering technologies have made it possible to enhance microbial hosts for the increased production of isobutanol from renewable resources. This review provides a summary of the strategies and synthetic biology approaches that have been employed in the past few years to improve naturally isolated or non-natural microbial hosts for the enhanced production of isobutanol by utilizing different renewable resources. Furthermore, it also discusses the challenges that are faced by engineered microbial hosts and presents future perspectives to enhancing isobutanol production. KEY POINTS: • Promising potential of isobutanol to replace gasoline • Engineering of native and non-native microbial host for isobutanol production • Challenges and opportunities for enhanced isobutanol production.


Assuntos
Biocombustíveis , Gasolina , Butanóis , Clonagem Molecular
3.
Bioprocess Biosyst Eng ; 47(7): 971-990, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38554183

RESUMO

The use of nanomaterials in biofuel production from lignocellulosic biomass offers a promising approach to simultaneously address environmental sustainability and economic viability. This review provides an overview of the environmental and economic implications of integrating nanotechnology into biofuel production from low-cost lignocellulosic biomass. In this review, we highlight the potential benefits and challenges of nano-based biofuel production. Nanomaterials provide opportunities to improve feedstock pretreatment, enzymatic hydrolysis, fermentation, and catalysis, resulting in enhanced process efficiency, lower energy consumption, and reduced environmental impact. Conducting life cycle assessments is crucial for evaluating the overall environmental footprint of biofuel production. An economic perspective that focuses on the cost implications of utilizing nanomaterials in biofuel production is also discussed. A comprehensive understanding of both environmental and economic dimensions is essential to fully harness the potential of nanomaterials in biofuel production from lignocellulosic biomass and to move towards sustainable future energy.


Assuntos
Biocombustíveis , Biomassa , Lignina , Lignina/metabolismo , Lignina/química , Biocombustíveis/economia , Nanoestruturas/química , Nanotecnologia/economia
4.
Biotechnol Appl Biochem ; 70(2): 537-552, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35751426

RESUMO

There are three prominent alcohol dehydrogenases superfamilies: short-chain, medium-chain, and iron-containing alcohol dehydrogenases (FeADHs). Many members are valuable catalysts for producing industrially relevant products such as active pharmaceutical intermediates, chiral synthons, biopolymers, biofuels, and secondary metabolites. However, FeADHs are the least explored enzymes among the superfamilies for commercial tenacities. They portray a conserved structure having a "tunnel-like" cofactor and substrate binding site with particular functions, despite representing high sequence diversity. Interestingly, phylogenetic analysis demarcates enzymes catalyzing distinct native substrates where closely related clades convert similar molecules. Further, homologs from various mesophilic and thermophilic microbes have been explored for designing a solvent and temperature-resistant enzyme for industrial purposes. The review explores different iron-containing alcohol dehydrogenases potential engineering of the enzymes and substrates helpful in manufacturing commercial products.


Assuntos
Álcool Desidrogenase , Ferro , Álcool Desidrogenase/genética , Álcool Desidrogenase/química , Álcool Desidrogenase/metabolismo , Filogenia , Sequência de Aminoácidos , Sítios de Ligação
5.
J Environ Manage ; 324: 116415, 2022 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-36206653

RESUMO

Remediation by algae is a very effective strategy for avoiding the use of costly, environmentally harmful chemicals in wastewater treatment. Recently, industries based on biomass, especially the bioenergy sector, are getting increasing attention due to their environmental acceptability. However, their practical application is still limited due to the growing cost of raw materials such as algal biomass, harvesting and processing limitations. Potential use of algal biomass includes nutrients recovery, heavy metals removal, COD, BOD, coliforms, and other disease-causing pathogens reduction and production of bioenergy and valuable products. However, the production of algal biomass using the variable composition of different wastewater streams as a source of growing medium and the application of treated water for subsequent use in agriculture for irrigation has remained a challenging task. The present review highlights and discusses the potential role of algae in removing beneficial nutrients from different wastewater streams with complex chemical compositions as a biorefinery concept and subsequent use of produced algal biomass for bioenergy and bioactive compounds. Moreover, challenges in producing algal biomass using various wastewater streams and ways to alleviate the stress caused by the toxic and high concentrations of nutrients in the wastewater stream have been discussed in detail. The technology will be economically feasible and publicly accepted by reducing the cost of algal biomass production and reducing the loaded or attached concentration of micropollutants and pathogenic microorganisms. Algal strain improvement, consortium development, biofilm formation, building an advanced cultivation reactor system, biorefinery concept development, and life-cycle assessment are all possible options for attaining a sustainable solution for sustainable biofuel production. Furthermore, producing valuable compounds, including pharmaceutical, nutraceutical and pigment contents generated from algal biomass during biofuel production, could also help reduce the cost of wastewater management by microalgae.


Assuntos
Biocombustíveis , Microalgas , Águas Residuárias , Biodegradação Ambiental , Biomassa
6.
Environ Sci Technol ; 55(15): 10794-10804, 2021 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-34297551

RESUMO

Utilization of marginal land for growing dedicated bioenergy crops for second-generation biofuels is appealing to avoid conflicts with food production. This study develops a novel framework to quantify marginal land for the Contiguous United States (CONUS) based on a history of satellite-observed land use change (LUC) over the 2008-2015 period. Frequent LUC between crop and noncrop is assumed to be an indicator of economically marginal land; this land is also likely to have a lower opportunity cost of conversion from food crop to bioenergy crop production. We first present an approach to identify cropland in transition using the time series of Cropland Data Layer (CDL) land cover product and determine the amount of land that can be considered marginal with a high degree of confidence vs with uncertainty across the CONUS. We find that the biophysical characteristics of this land and its productivity and environmental vulnerability vary across the land and lie in between that of permanent cropland and permanent natural vegetation/bare areas; this land also has relatively low intrinsic value and agricultural profit but a high financial burden and economic risk. We find that the total area of marginal land with confidence vs with uncertainty is 10.2 and 58.4 million hectares, respectively, and mainly located along the 100th meridian. Only a portion of this marginal land (1.4-2.2 million hectares with confidence and 14.8-19.4 million hectares with uncertainty) is in the rainfed region and not in crop production and, thus, suitable for producing energy crops without diverting land from food crops in 2016. These estimates are much smaller than the estimates obtained by previous studies, which consider all biophysically low-quality land to be marginal without considering economical marginality. The estimate of marginal land for bioenergy crops obtained in this study is an indicator of the availability of economically marginal land that is suitable for bioenergy crop production; whether this land is actually converted to bioenergy crops will depend on the market conditions. We note the inability to conduct field-level validation of cropland in transition and leave it to future advances in technology to ground-truth land use change and its relationship to economically marginal land.


Assuntos
Agricultura , Produtos Agrícolas , Biocombustíveis , Estados Unidos
7.
Microb Cell Fact ; 19(1): 79, 2020 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-32220254

RESUMO

BACKGROUND: Owing to the increase in energy consumption, fossil fuel resources are gradually depleting which has led to the growing environmental concerns; therefore, scientists are being urged to produce sustainable and ecofriendly fuels. Thus, there is a growing interest in the generation of biofuels from renewable energy resources using microbial fermentation. MAIN TEXT: Butanol is a promising biofuel that can substitute for gasoline; unfortunately, natural microorganisms pose challenges for the economical production of 1-butanol at an industrial scale. The availability of genetic and molecular tools to engineer existing native pathways or create synthetic pathways have made non-native hosts a good choice for the production of 1-butanol from renewable resources. Non-native hosts have several distinct advantages, including using of cost-efficient feedstock, solvent tolerant and reduction of contamination risk. Therefore, engineering non-native hosts to produce biofuels is a promising approach towards achieving sustainability. This paper reviews the currently employed strategies and synthetic biology approaches used to produce 1-butanol in non-native hosts over the past few years. In addition, current challenges faced in using non-native hosts and the possible solutions that can help improve 1-butanol production are also discussed. CONCLUSION: Non-native organisms have the potential to realize commercial production of 1- butanol from renewable resources. Future research should focus on substrate utilization, cofactor imbalance, and promoter selection to boost 1-butanol production in non-native hosts. Moreover, the application of robust genetic engineering approaches is required for metabolic engineering of microorganisms to make them industrially feasible for 1-butanol production.


Assuntos
1-Butanol/metabolismo , Engenharia Genética/métodos
8.
Bioprocess Biosyst Eng ; 43(6): 971-980, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32008095

RESUMO

Salinity (NaCl) stress treatment is a strategy to induce lipid accumulation in microalgae. This study aimed to investigate the effect of a combination of two salts (NaCl/CaCl2) on lipid productivity of Chlamydomonas reinhardtii. C. reinhardtii was cultured in a two-stage culture comprising 9-day active growth in C medium followed by 3-day salt stress in C medium with various concentrations of NaCl (50‒200 mM)/CaCl2 (100 mM). In salt stress stage, NaCl (200 mM), CaCl2 (100 mM), and the NaCl/CaCl2 mixture inhibited growth but increased the lipid content in C. reinhardtii in comparison with NaCl (0, 50, and 100 mM) conditions. Combinatorial treatment with 100 mM NaCl/100 mM CaCl2 resulted in the highest lipid content (73.4%) and lipid productivity (10.9 mg/L/days), being 3.5- and 2.1-fold, respectively, in salt-free control conditions, and 1.8- and 1.5-folds, respectively, with 200 mM NaCl. Furthermore, 100 mM NaCl/100 mM CaCl2 treatment markedly upregulated glycerol-3-phosphate dehydrogenase (GPDH), lysophosphatidic acid acyltransferase (LPAAT), and diacylglycerol acyltransferase (DAGAT), which are involved in lipid accumulation in C. reinhardtii. The upregulation of these genes with 100 mM NaCl/100 mM CaCl2 resulted in the highest lipid content in C. reinhardtii. Therefore, stress treatment using two salts, 100 mM NaCl/100 mM CaCl2, is a potentially promising strategy to enhance lipid productivity in microalgae.


Assuntos
Cloreto de Cálcio/farmacologia , Chlamydomonas reinhardtii/crescimento & desenvolvimento , Lipídeos/biossíntese , Pressão Osmótica/efeitos dos fármacos , Cloreto de Sódio/farmacologia
9.
Physiol Mol Biol Plants ; 26(5): 871-883, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32377038

RESUMO

Triacontanol (TRIA) being an endogenous plant growth regulator facilitates numerous plant metabolic activities leading to better growth and development. Moreover, TRIA plays essential roles in alleviating the stress-accrued alterations in crop plants via modulating the activation of the stress tolerance mechanisms. The present article critically focuses on the role of exogenously applied TRIA in morpho-physiology and biochemistry of plants for example, in terms of growth, photosynthesis, enzymatic activity, biofuel synthesis, yield and quality under normal and stressful conditions. This article also enlightens the mode of action of TRIA and its interaction with other phytohormones in regulating the physio-biochemical processes in counteracting the stress-induced damages in plants.

10.
J Proteome Res ; 18(7): 2735-2746, 2019 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-31081631

RESUMO

Predicting enzyme function and enzyme subclasses is always a key objective in fields such as biotechnology, biochemistry, medicinal chemistry, physiology, and so on. The Protein Data Bank (PDB) is the largest information archive of biological macromolecular structures, with more than 150 000 entries for proteins, nucleic acids, and complex assemblies. Among these entries, there are more than 4000 proteins whose functions remain unknown because no detectable homology to proteins whose functions are known has been found. The problem is that our ability to isolate proteins and identify their sequences far exceeds our ability to assign them a defined function. As a result, there is a growing interest in this topic, and several methods have been developed to identify protein function based on these innovative approaches. In this work, we have applied perturbation theory to an original data set consisting of 19 187 enzymes representing all 59 subclasses present in the protein data bank. In addition, we developed a series of artificial neural network models able to predict enzyme-enzyme pairs of query-template sequences with accuracy, specificity, and sensitivity greater than 90% in both training and validation series. As a likely application of this methodology and to further validate our approach, we used our novel model to predict a set of enzymes belonging to the yeast Pichia stipites. This yeast has been widely studied because it is commonly present in nature and produces a high ethanol yield by converting lignocellulosic biomass into bioethanol through the xylose reductase enzyme. Using this premise, we tested our model on 222 enzymes including xylose reductase, that is, the enzyme responsible for the conversion of biomass into bioethanol.


Assuntos
Biocombustíveis/microbiologia , Enzimas/classificação , Proteoma/análise , Aldeído Redutase , Etanol/metabolismo , Lignina/metabolismo , Métodos , Modelos Teóricos , Redes Neurais de Computação , Pichia/enzimologia
11.
Crit Rev Biotechnol ; 38(3): 351-368, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-28764567

RESUMO

Microalgae are a potential candidate for biofuel production and environmental treatment because of their specific characteristics (e.g. fast growth, carbon neutral, and rich lipid accumulations). However, several primary bottlenecks still exist in current technologies, including low biomass conversion efficiency, bio-invasion from the external environment, limited or costly nutrient sources, and high energy and capital input for harvest, and stalling its industrial progression. Coupling biofuel production with environmental treatment renders microalgae a more feasible feedstock. This review focuses on microalgae biotechnologies for both bioenergy generation and environmental treatment (e.g. CO2 sequestration and wastewater reclamation). Different intelligent technologies have been developed, especially during the last decade, to eliminate the bottlenecks, including mixotrophic/heterotrophic cultivation, immobilization, and co-cultivation. It has been realized that any single purpose for the cultivation of microalgae is not an economically feasible option. Combinations of applications in biorefineries are gradually reckoned to be necessary as it provides more economically feasible and environmentally sustainable operations. This presents microalgae as a special niche occupier linking the fields of energy and environmental sciences and technologies. The integrated application of microalgae is also proven by most of the life-cycle analysis studies. This study summarizes the latest development of primary microalgal biotechnologies in the two areas that will bring researchers a comprehensive view towards industrialization with an economic perspective.


Assuntos
Biocombustíveis , Meio Ambiente , Microalgas/metabolismo , Biotecnologia , Células Imobilizadas/metabolismo , Microalgas/citologia , Microalgas/crescimento & desenvolvimento , Águas Residuárias
12.
Biotechnol Bioeng ; 115(6): 1450-1464, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29460958

RESUMO

Harnessing the metabolic potential of uncultured microbial communities is a compelling opportunity for the biotechnology industry, an approach that would vastly expand the portfolio of usable feedstocks. Methane is particularly promising because it is abundant and energy-rich, yet the most efficient methane-activating metabolic pathways involve mixed communities of anaerobic methanotrophic archaea and sulfate reducing bacteria. These communities oxidize methane at high catabolic efficiency and produce chemically reduced by-products at a comparable rate and in near-stoichiometric proportion to methane consumption. These reduced compounds can be used for feedstock and downstream chemical production, and at the production rates observed in situ they are an appealing, cost-effective prospect. Notably, the microbial constituents responsible for this bioconversion are most prominent in select deep-sea sediments, and while they can be kept active at surface pressures, they have not yet been cultured in the lab. In an industrial capacity, deep-sea sediments could be periodically recovered and replenished, but the associated technical challenges and substantial costs make this an untenable approach for full-scale operations. In this study, we present a novel method for incorporating methanotrophic communities into bioindustrial processes through abstraction onto low mass, easily transportable carbon cloth artificial substrates. Using Gulf of Mexico methane seep sediment as inoculum, optimal physicochemical parameters were established for methane-oxidizing, sulfide-generating mesocosm incubations. Metabolic activity required >∼40% seawater salinity, peaking at 100% salinity and 35 °C. Microbial communities were successfully transferred to a carbon cloth substrate, and rates of methane-dependent sulfide production increased more than threefold per unit volume. Phylogenetic analyses indicated that carbon cloth-based communities were substantially streamlined and were dominated by Desulfotomaculum geothermicum. Fluorescence in situ hybridization microscopy with carbon cloth fibers revealed a novel spatial arrangement of anaerobic methanotrophs and sulfate reducing bacteria suggestive of an electronic coupling enabled by the artificial substrate. This system: 1) enables a more targeted manipulation of methane-activating microbial communities using a low-mass and sediment-free substrate; 2) holds promise for the simultaneous consumption of a strong greenhouse gas and the generation of usable downstream products; and 3) furthers the broader adoption of uncultured, mixed microbial communities for biotechnological use.


Assuntos
Archaea/metabolismo , Sedimentos Geológicos/microbiologia , Metano/metabolismo , Microbiota , Sulfetos/metabolismo , Bactérias Redutoras de Enxofre/metabolismo , Anaerobiose , Archaea/isolamento & purificação , Biotransformação , Fenômenos Químicos , Golfo do México , Gás Natural , Oxirredução , Salinidade , Bactérias Redutoras de Enxofre/isolamento & purificação , Temperatura
13.
Adv Exp Med Biol ; 979: 269-283, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28429326

RESUMO

In Euglena cells under anaerobic conditions, paramylon, the storage polysaccharide, is promptly degraded and converted to wax esters. The wax esters synthesized are composed of saturated fatty acids and alcohols with chain lengths of 10-18, and the major constituents are myristic acid and myristyl alcohol. Since the anaerobic cells gain ATP through the conversion of paramylon to wax esters, the phenomenon is named "wax ester fermentation". The wax ester fermentation is quite unique in that the end products, i.e. wax esters, have relatively high molecular weights, are insoluble in water, and accumulate in the cells, in contrast to the common fermentation end products such as lactic acid and ethanol.A unique metabolic pathway involved in the wax ester fermentation is the mitochondrial fatty acid synthetic system. In this system, fatty acid are synthesized by the reversal of ß-oxidation with an exception that trans-2-enoyl-CoA reductase functions instead of acyl-CoA dehydrogenase. Therefore, acetyl-CoA is directly used as a C2 donor in this fatty acid synthesis, and the conversion of acetyl-CoA to malonyl-CoA, which requires ATP, is not necessary. Consequently, the mitochondrial fatty acid synthetic system makes possible the net gain of ATP through the synthesis of wax esters from paramylon. In addition, acetyl-CoA is provided in the anaerobic cells from pyruvate by the action of a unique enzyme, oxygen sensitive pyruvate:NADP+ oxidoreductase, instead of the common pyruvate dehydrogenase multienzyme complex.Wax esters produced by anaerobic Euglena are promising biofuels because myristic acid (C14:0) in contrast to other algal produced fatty acids, such as palmitic acid (C16:0) and stearic acid (C18:0), has a low freezing point making it suitable as a drop-in jet fuel. To improve wax ester production, the molecular mechanisms by which wax ester fermentation is regulated in response to aerobic and anaerobic conditions have been gradually elucidated by identifying individual genes related to the wax ester fermentation metabolic pathway and by comprehensive gene/protein expression analysis. In addition, expression of the cyanobacterial Calvin cycle fructose-1,6-bisphosphatase/sedohepturose-1,7-bisphosphatase, in Euglena provided photosynthesis resulting in increased paramylon accumulation enhancing wax ester production. This chapter will discuss the biochemistry of the wax ester fermentation, recent advances in our understanding of the regulation of the wax ester fermentation and genetic engineering approaches to increase production of wax esters for biofuels.


Assuntos
Biocombustíveis , Euglena/metabolismo , Ácidos Graxos/metabolismo , Álcoois Graxos/metabolismo , Proteínas de Protozoários/metabolismo , Anaerobiose/fisiologia , Euglena/genética , Proteínas de Protozoários/genética
14.
J Environ Manage ; 203(Pt 3): 867-871, 2017 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-28991538

RESUMO

There is a growing concern about how to minimize the impact of human activities on the environment. Already nowadays, in some places adaptation efforts are needed in order to avoid the irreversibility of negative human activities. Due to climate changes, and corresponding environmental and social changes, there is a great need for a more sustainable development of mankind. Over the years, research studies that analyzed the sustainable development of different communities with a multi-disciplinary approach, stressed the necessity of preserving the environment for next generations. Therefore, responsible and conscientious management of the environment is a pillar of the sustainable development concept. This review introduction article provides an overview of the recent top scientific publications related to sustainable development that mostly originated from previous SDEWES conferences.


Assuntos
Conservação dos Recursos Naturais , Meio Ambiente , Humanos
15.
Plant Cell Physiol ; 56(12): 2467-77, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26468506

RESUMO

An RND (resistance-nodulation-division)-type transporter having the capacity to export free fatty acids (FFAs) was identified in the cyanobacterium Synechococcus elongatus strain PCC 7942 during characterization of a mutant strain engineered to produce FFAs. The basic strategy for construction of the FFA-producing mutant was a commonly used one, involving inactivation of the endogenous acyl-acyl carrier protein synthetase gene (aas) and introduction of a foreign thioesterase gene ('tesA), but a nitrate transport mutant NA3 was used as the parental strain to achieve slow, nitrate-limited growth in batch cultures. Also, a nitrogen-regulated promoter PnirA was used to drive 'tesA to maximize thioesterase expression during the nitrate-limited growth. The resulting mutant (dAS2T) was, however, incapable of growth under the conditions of nitrate limitation, presumably due to toxicity associated with FFA overproduction. Incubation of the mutant culture under the non-permissive conditions allowed for isolation of a pseudorevertant (dAS2T-pr1) capable of growth on nitrate. Genome sequence and gene expression analyses of this strain suggested that expression of an RND-type efflux system had rescued growth on nitrate. Targeted inactivation of the RND-type transporter genes in the wild-type strain resulted in loss of tolerance to exogenously added FFAs including capric, lauric, myristic, oleic and linolenic acids. Overexpression of the genes in dAS2T, on the other hand, enhanced FFA excretion and cell growth in nitrate-containing medium, verifying that the genes encode an efflux pump for FFAs. These results demonstrate the importance of the efflux system in efficient FFA production using genetically engineered cyanobacteria.


Assuntos
Proteínas de Bactérias/metabolismo , Ácidos Graxos não Esterificados/metabolismo , Synechococcus/metabolismo , Sequência de Bases , Transporte Biológico , Genes de Plantas , Mutação/genética , Nitratos/metabolismo , Filogenia , Synechococcus/genética , Synechococcus/crescimento & desenvolvimento
16.
Plant Cell Physiol ; 56(8): 1608-15, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26063393

RESUMO

Most organisms capable of oxygenic photosynthesis have an aas gene encoding an acyl-acyl carrier protein synthetase (Aas), which activates free fatty acids (FFAs) via esterification to acyl carrier protein. Cyanobacterial aas mutants are often used for studies aimed at photosynthetic production of biofuels because the mutation leads to intracellular accumulation of FFAs and their secretion into the external medium, but the physiological significance of the production of FFAs and their recycling involving Aas has remained unclear. Using an aas-deficient mutant of Synechococcus elongatus strain PCC 7942, we show here that remodeling of membrane lipids is activated by high-intensity light and that the recycling of FFAs is essential for acclimation to high-light conditions. Unlike wild-type cells, the mutant cells could not increase their growth rate as the light intensity was increased from 50 to 400 µmol photons m(-2) s(-1), and the high-light-grown mutant cells accumulated FFAs and the lysolipids derived from all the four major classes of membrane lipids, revealing high-light-induced lipid deacylation. The high-light-grown mutant cells showed much lower PSII activity and Chl contents as compared with the wild-type cells or low-light-grown mutant cells. The loss of Aas accelerated photodamage of PSII but did not affect the repair process of PSII, indicating that PSII is destabilized in the mutant. Thus, Aas is essential for acclimation of the cyanobacterium to high-light conditions. The relevance of the present finding s to biofuel production using cyanobacteria is discussed.


Assuntos
Carbono-Enxofre Ligases/metabolismo , Synechococcus/enzimologia , Aclimatação , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Carbono-Enxofre Ligases/genética , Ácidos Graxos não Esterificados/metabolismo , Luz , Lipídeos de Membrana/metabolismo , Mutação , Fotossíntese/fisiologia , Fotossíntese/efeitos da radiação , Complexo de Proteína do Fotossistema II/fisiologia , Complexo de Proteína do Fotossistema II/efeitos da radiação , Synechococcus/genética , Synechococcus/fisiologia , Synechococcus/efeitos da radiação
17.
J Appl Microbiol ; 119(3): 605-19, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26095690

RESUMO

Sustainable economic and industrial growth is the need of the hour and it requires renewable energy resources having better performance and compatibility with existing fuel infrastructure from biological routes. Isoprenoids (C ≥ 5) can be a potential alternative due to their diverse nature and physiochemical properties similar to that of petroleum based fuels. In the past decade, extensive research has been done to utilize metabolic engineering strategies in micro-organisms primarily, (i) to overcome the limitations associated with their natural and non-natural production and (ii) to develop commercially competent microbial strain for isoprenoid-based biofuel production. This review briefly describes the engineered isoprenoid biosynthetic pathways in well-characterized microbial systems for the production of several isoprenoid-based biofuels and fuel precursors.


Assuntos
Bactérias/genética , Bactérias/metabolismo , Biocombustíveis/análise , Engenharia Metabólica , Terpenos/metabolismo , Vias Biossintéticas , Microbiologia Industrial
18.
ChemSusChem ; : e202301786, 2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38587989

RESUMO

In this study, a cost-effective and stable heterogeneous acidic carbocatalyst (CZnLS950) derived from Na-lignosulfonate (LS), a side product of the paper industry, was employed to produce hydrocarbon fuels through the pyrolysis of waste cooking oil (WCO) and crude natural-oil extracted from sunflower seeds, aligning with the principles of the circular economy. To enhance its practicality in industrial settings, the catalyst was synthesized in pellet form, enabling easy separation from the biofuel produced during the reaction. CZnLS950 exhibited remarkable catalytic efficiency in the pyrolysis of WCO, resulting in a 71 wt. % liquid biofuel yield under mild conditions. This performance is attributed to the unique synthesis procedure of acidic carbocatalyst, which utilizes LS and nano ZnO (20 nm) to create a hierarchical pore structure with acidic properties (1.1 mmol of NH3 g-1). Stability and reusability of the carbocatalyst were evaluated, and the results showed excellent stability with small catalytic deactivation (~5 wt. %) after the fourth use. Attempts at distinct catalytic mechanisms for WCO and sunflower seeds crude natural-oil pyrolysis were provided to understand the processes involved in obtaining the two different biofuels produced. Overall, this study sets the stage for exploring Lignosulfonate-based materials to achieve renewable biofuel from recycling streams.

19.
Bioresour Technol ; 400: 130697, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38614145

RESUMO

Effects of a phosphorus-solubilizing bacteria (PSB) Bacillus megatherium on growth and lipid production of Chlorella sorokiniana were investigated in synthesized swine wastewater with dissolved inorganic phosphorus (DIP), insoluble inorganic phosphorus (IIP), and organic phosphorus (OP). The results showed that the PSB significantly promoted the algal growth in OP and IIP, by 1.10 and 1.78-fold, respectively. The algal lipid accumulation was also greatly triggered, respectively by 4.39, 1.68, and 1.38-fold in DIP, IIP, and OP. Moreover, compared with DIP, OP improved the oxidation stability of algal lipid by increasing the proportion of saturated fatty acids (43.8 % vs 27.9 %), while the PSB tended to adjust it to moderate ranges (30.2-41.6 %). Further, the transcriptome analysis verified the OP and/or PSB-induced up-regulated genes involving photosynthesis, lipid metabolism, signal transduction, etc. This study provided novel insights to enhance microalgae-based nutrient removal combined with biofuel production in practical wastewater, especially with complex forms of phosphorus.


Assuntos
Chlorella , Lipídeos , Fosfatos , Águas Residuárias , Águas Residuárias/microbiologia , Animais , Chlorella/metabolismo , Chlorella/crescimento & desenvolvimento , Suínos , Fosfatos/metabolismo , Lipídeos/biossíntese , Fósforo/metabolismo , Metabolismo dos Lipídeos , Solubilidade , Bacillus/metabolismo
20.
Bioresour Technol ; 401: 130751, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38685517

RESUMO

Rare earth elements (REEs) are pivotal for advanced technologies, driving a surge in global demand. Import dependency on clean energy minerals raises concerns about supply chain vulnerabilities and geopolitical risks. Conventional REEs productionis resource-intensive and environmentally harmful, necessitating a sustainable supply approach. Phytomining (agromining) utilizes plants for eco-friendly REE extraction, contributing to the circular economy and exploiting untapped metal resources in enriched soils. Critical parameters like soil pH, Casparian strip, and REE valence influence soil and plant uptake bioavailability. Hyperaccumulator species efficiently accumulate REEs, serving as energy resources. Despite a lack of a comprehensive database, phytomining exhibits lower environmental impacts due to minimal chemical usage and CO2 absorption. This review proposes phytomining as a system for REEs extraction, remediating contaminated areas, and rehabilitating abandoned mines. The phytomining of REEs offers a promising avenue for sustainable REEs extraction but requires technological advancements to realize its full potential.


Assuntos
Metais Terras Raras , Plantas , Plantas/metabolismo , Biodegradação Ambiental , Poluentes do Solo/metabolismo , Solo/química , Mineração
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