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Many of the new generation fuels, although more sustainable, share some of the problems inherent to fossil fuels. Depending on the biomass/material that originated them, they can present different contaminants that can lead to environmental problems. Sulfur is one of the most common and problematic contaminants in fuels. It is released into the atmosphere in the form of SOx, leading to the formation of acid rains, which cause drastic environmental and infrastructural problems, as well as several types of health issues. High sulfur concentrations in fuels also result in a loss of efficiency of motors and energy generation systems, mostly due to corrosion and catalyst poisoning. The current thermochemical desulfurization process, hydrodesulfurization (HDS), is energy demanding, pollutant and has low efficiency against more complex organosulfur molecules. This led researchers to look for new alternatives. Biodesulfurization (BDS), is, as the name implies, the biological removal of sulfur from fuels using microorganisms as living biocatalysts. If correctly employed this process could be more efficient and less pollutant, since microorganisms directly target the sulfur atoms, even those present in complex molecular structures, such as dibenzothiophene (DBT). Moreover, microbial activity occurs at much lower temperatures and pressures, without the need for metal catalysts, resulting in a lower energy demand. While BDS is a promising technology, it is still at a low development stage, mostly due to some bottlenecks, which have been hindering its large-scale application. Similarly, to other biotechnological processes, it presents lower reaction rates, when compared to HDS, since it depends on the use of living organisms as catalysts. Furthermore, it must be performed under conditions that allow the microorganisms to maintain biological activity, limiting the range of applications. These conditions vary greatly depending on the microorganism selected, and their optimization can significantly increase the biodesulfurization activity of a biocatalyst. info:eu-repo/semantics/publishedVersion

One of the ways to make microbial bioprocesses more economically viable is to enhance valorization of high added value products resulting from the biomass, like carotenoids, which have a high market value. To recover these pigments from microbial biomass a good extraction method is required. Solvent extraction is one of the methods commonly used to extract carotenoids, however, solvent extractions are both material and time-consuming, and moreover also present some health and safety concerns. Ionic liquids (ILs) are a promising step forward to tackle some of these problems, even with their high price, and has been tested for the extraction of microorganism’s components. These “molten salts” are a group of compounds that have been known for a long time, but only in the last decades they have been attracting more attention from both researchers and industry. ILs are solvents that have a high solvation power for a wide range of molecules. ILs are salts with a melting point below 100ºC, which possess unique properties that depend on both the cation and anion present, high thermal and chemical stability, a large electrochemical window, great solvent power, non-flammability, and a negligible vapor pressure. Their versatility is one of their most attractive features, making them adaptable to many technologies. Therefore, ILs can be used to facilitate chemical reactions, extraction and separation, biotransformation, and can be used in biorefineries and other processes. As shown in previous works, Gordonia alkanivorans strain 1B has the capacity to produce carotenoids, however, since it was originally isolated form hydrocarbon rich environments, it is highly resistant to different organic solvents commonly used in extraction protocols. This makes the process slow and laborious, lowering yields and increasing solvent spending. As such, new extraction protocols must be developed and tested to obtain higher pigments yield. So, herein, the potential of ILs for carotenoids extraction was evaluated, since these compounds have been described as a good option to extract pigments produced by microorganisms. info:eu-repo/semantics/publishedVersion

The process of obtaining carotenoids, mainly towards sectors that may influence the human health, such as pharmaceutical and cosmetic, is strictly regulated because of the potential toxicity of the synthetically derived pigments. Thus, microbial pigments are in increasing demand since they are a promising natural and safe alternative source for various industrial applications. Gordonia alkanivorans strain 1B is a fructophilic desulfurizing bacterium, which was also shown to be a good producer of carotenoids. However, its production abilities presented a great variation, depending on the conditions it was submitted to. In previous works, both the carbon source and sulfur source, demonstrated a great influence in the total carotenoid concentration, especially when combined with the presence of a light source. So, in this study, a surface response methodology based on the Doehlert distribution for two factors (% of glucose in a mix glucose + fructose (10 g/L total sugars), and sulfate concentration) was used aiming to get the optimal carotenoids production by G. alkanivorans strain 1B. N/A

RESUMO: O Laboratório Nacional de Energia e Geologia (LNEG), nas suas áreas de competências reuniu as competências de anteriores instituições com um histórico de trabalho em Laboratórios com acreditação desde os anos 80. No LNEG, estes Laboratórios focaram-se em atividades da área de energia e geologia, mantendo as suas acreditações mas sentiram a necessidade de trabalhar em rede. info:eu-repo/semantics/publishedVersion

Lignocellulosic biomass is envisaged as an important raw material for bioethanol production due to its low cost and high availability. Sugarcane bagasse (SCB), a fibrous residue of cane stalks left over after crushing and extraction of the juice from sugarcane; it is one of the largest cellulosic agro-industrial by-products. Tons of SCB are produced in Brazil as a waste of sugar and ethanol industries. This lignocellulosic by-product is a potential renewable source for 2G-bioethanol production. Usually, SCB is pretreated using alkaline and/or acid treatments viewing higher ethanol yields. The main goal of this study was to optimize the delignification of SCB towards the higher availability of glucans and xylans for further enzymatic hydrolysis to obtain sugar-rich syrups that will be more readily fermented to bioethanol. The delignification was carried out by autoclaving the biomass with KOH and the influence of KOH concentration (1-10%) and the autoclave time (10-60 min) were evaluated through a statistical design. Experimental distribution for two factors according to the Doehlert uniform design was used to produce response surfaces. The responses studied in this design were the percentage of hemicellulose, lignin and total polysaccharides. The results showed that from the two factors evaluated, the KOH concentration was the one that most influenced the response observed and that the treatments of SCB with KOH 5-10% for 35 minutes of autoclave at 121ºC and 1 atm led to the highest rates of lignin extraction. Using KOH treatment, a significant reduction of lignin content in SCB was observed, namely from 19% to 5%. Scanning electron micrographs of SCB pre-treated with 10% KOH for 35 minutes demonstrated a change in the structure of the material, with the appearance of broken structures, which can be attributed to the alkaline treatment. To validate the experiments, the SCB pretreated in the optimal conditions (95% of total polysaccharides) was further hydrolyzed with commercial enzymes and the enzymatic hydrolysis performance was evaluated.

Background:Biodesulfurization (BDS) is a complementary technology to hydrodesulfurization since it allows the removal of recalcitrant sulfur compounds present in fossil fuels. The cost of culture medium to produce the biocatalysts is still one limitation for BDS application. Carob pulp, as an alternative carbon source, can reduce this cost. However, the presence of sulfates is critical, since BDS is inhibited at very low concentrations. Thus, the goal of this work was to optimize the process of sulfur precipitation on carob pulp liquor. Result:The effect of BaCl2 concentration (0–0.5%) and exposure time (6–36 h) on sulfate removal from carob pulp liquor was studied according to a statistical design following the Doehlert distribution for two factors. This experimental design determined that 0.5% BaCl2 concentration for 21 h were adequate conditions for sulfate removal from carob pulp liquor using BDS.Conclusion:These results demonstrate that it is possible to use alternative carbon sources derived from agro-industrial wastes for BDS, even those with high sulfur levels. For future industrial application, an inexpensive culture medium would have to be employed in a large-scale process and carob pulp liquor could be the carbon source.

Some yeasts like Rhodosporidium toruloides are oleaginous and can be used for biodiesel production. In addition, some strains are able to produce valuable carotenoid pigments which are of great commercial interest, contributing significantly to reduce the biodiesel production costs. Carotenoid extraction and quantification are time consuming, generate high amounts of waste and require the use of considerable amounts of biomass. Flow Cytometry (FC) can monitor carotenoids accumulation in yeasts, at line, and with a high statistical resolution, during growth. Moreover, during the cultivation it is important to assess cell physiological states, since injured or dead cells decrease the bioprocess yield. If this information is obtained near real time, it is possible to change the process control strategy in order to achieve the maximum lipid and carotenoid productivities. To obtain a more sustainable biodiesel production, it is also important to use low cost substrates, such as industrial by-products. In the present work, different low cost substrates were used as carbon sources [glycerol as a biodiesel byproduct, sugarcane molasses and carob pulp (syrup) as a cheap by-product of the food industry in the European south countries] to produce lipids and carotenoids by the yeast R. toruloides NCYC 921, and a comparison was made. Flow cytometry was used to monitor carotenoid content and cell viability (enzymatic activity, membrane potential and membrane integrity) during all the yeast cultivations.

A process for biological upgrading of recycled paper sludge (RPS) was developed based on the enzymatic hydrolysis of major sludge components (cellulose and xylan) with commercial enzymes and fermentation of the resulting sugars into ethanol or lactic acid with adequate microbial strains. The process was implemented performing both steps sequentially (SHF) or simultaneously (SSF). Cellulosic and hemicellulosic fractions of RPS were completely converted by enzymatic hydrolysis (using Celluclast®1.5L with Novozym®188) into the constitutive glucose and xylose. Ethanol was produced from the RPS hydrolysate by the yeast Pichia stipitis CBS 5773. A slightly higher conversion yield was attained on SHF process, corresponding to an ethanol concentration of 19.6 g L-1, but 179 hours were needed. The SSF process was completed after 48 hours of incubation allowing the production of 18.6 g L-1 of ethanol from 178.6 g L-1 of dried RPS, corresponding to an overall conversion yield of 51% of the available carbohydrates on the initial substrate. Maximum production of lactic acid (LA) with Lactobacillus rhamnosus ATCC 7469 was obtained by performing the SSF process: 73 g L-1 of LA was achieved, corresponding to a maximum productivity of 2.9 g L-1 h-1, with 0.97 g LA produced per g of carbohydrates on initial sludge. The present results demonstrate the feasibility of the biological conversion of the ultimate waste obtained in the paper recycling loop into a biofuel (bioethanol) or an important chemical intermediate (LA, precursor of bioplastics), under the concept of a multi-purpose biorefinery.