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In light of the growing demand for novel biocatalysts and enzyme production methods, this study aimed to evaluate the potential of Aspergillus tubingensis for producing lipase under submerged culture investigating the influence of culture time and inducer treatment. Moreover, this study also investigated conditions for the immobilization of A. tubingensis lipase by physical adsorption on styrene-divinylbenzene beads (Diaion HP-20), for these conditions to be applied to an alternative immobilization system with a packed-bed reactor. Furthermore, A. tubingensis lipase and its immobilized derivative were characterized in terms of their optimal ranges of pH and temperature. A. tubingensis was shown to be a good producer of lipase, obviating the need for inducer addition. The enzyme extract had a hydrolytic activity of 23 U mL-1 and achieved better performance in the pH range of 7.5 to 9.0 and in the temperature range of 20 to 50 °C. The proposed immobilization system was effective, yielding an immobilized derivative with enhanced hydrolytic activity (35 U g-1), optimum activity over a broader pH range (5.6 to 8.4), and increased tolerance to high temperatures (40 to 60 ℃). This research represents a first step toward lipase production from A. tubingensis under a submerged culture and the development of an alternative immobilization system with a packed-bed reactor. The proposed system holds promise for saving time and resources in future industrial applications.

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Brazil has one of the greatest biodiversities on the planet, where various crops play a strategic role in the country's economy. Among the highly appreciated biomasses is babassu, whose oil extraction generates residual babassu mesocarp (BM), which still needs new strategies for valorization. This work aimed to use BM as a support for the immobilization of Thermomyces lanuginosus lipase (TLL) in an 8.83 mL packed-bed reactor, followed by its application as a biocatalyst for the synthesis of hexyl laurate in an integrated process. Initially, the percolation of a solution containing 5 mg of TLL at 25 °C and flows ranging from 1.767 to 0.074 mL min-1 was investigated, where at the lowest flow rate tested (residence time of 2 h), it was possible to obtain an immobilized derivative with hydrolytic activity of 504.7 U g-1 and 31.7 % of recovered activity. Subsequent studies of treatment with n-hexane, as well as the effect of temperature on the immobilization process, were able to improve the activities of the final biocatalyst BM-TLLF, achieving a final hydrolysis activity of 7023 U g-1 and esterification activity of 430 U ⋅ g-1 against 142 U g-1 and 113.5 U g-1 respectively presented by the commercial TLIM biocatalyst. Desorption studies showed that the TL IM has 18 mg of protein per gram of support, compared to 4.92 mg presented by BM-TLL. Both biocatalysts were applied to synthesize hexyl laurate, achieving 98 % conversion at 40 °C within 2 h. Notably, BM-TLLF displayed exceptional recyclability, maintaining catalytic efficiency over 12 cycles. This reflects a productivity of 180 mg of product ⋅ h-1 U-1 of the enzyme, surpassing 46 mg h-1 U-1 obtained for TLIM. These results demonstrate the efficacy of continuous flow technology in creating a competitive and integrated process offering an exciting alternative for the valorization of residual lignocellulosic biomass.

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This work provides the basis for implementing a continuous treatment system using a bacterial consortium for wastewater containing a pesticide mixture of iprodione (IPR) and chlorpyrifos (CHL). Two bacterial strains (Achromobacter spanius C1 and Pseudomonas rhodesiae C4) isolated from the biomixture of a biopurification system were able to efficiently remove pesticides IPR and CHL at different concentrations (10 to 100 mg L-1) from the liquid medium as individual strains and free consortium. The half-life time (T1/2) for IPR and CHL was determined for individual strains and a free bacterial consortium. However, when the free bacterial consortium was used, a lower T1/2 was obtained, especially for CHL. Based on these results, an immobilized bacterial consortium was formulated with each bacterial strain encapsulated individually in alginate beads. Then, different inoculum concentrations (5, 10, and 15% w/v) of the immobilized consortium were evaluated in batch experiments for IPR and CHL removal. The inoculum concentration of 15% w/v demonstrated the highest pesticide removal. Using this inoculum concentration, the packed-bed bioreactor with an immobilized bacterial consortium was operated in continuous mode at different flow rates (30, 60, and 90 mL h-1) at a pesticide concentration of 50 mg L-1 each. The performance in the bioreactor demonstrated that it is possible to efficiently remove a pesticide mixture of IPR and CHL in a continuous system. The metabolites 3,5-dichloroaniline (3,5-DCA) and 3,5,6-trichloro-2-pyridinol (TCP) were produced, and a slight accumulation of TCP was observed. The bioreactor was influenced by TCP accumulation but was able to recover performance quickly. Finally, after 60 days of operation, the removal efficiency was 96% for IPR and 82% for CHL. The findings of this study demonstrate that it is possible to remove IPR and CHL from pesticide-containing wastewater in a continuous system.

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This work aimed to produce porous poly-hydroxybutyrate (PHB) pellets in order to evaluate the pellets as a support for immobilization of the metagenomic lipase, LipG9. Four types of pelletized PHB particles with different morphological characteristics were obtained using the double emulsion and solvent evaporation technique (DESE). The micropores of these PHB pellets had similar average diameters (about 3 nm), but the pellets had different specific surface areas: 11.7 m2 g-1 for the PHB powder, 8.4 m2  g-1 for the control pellets (Ø < 0.5 mm, produced without the pore forming agent), 10.0 m2  g-1 for the small pellets (Ø < 0.5 mm), 9.5 m2  g-1 for the medium pellets (0.5 < Ø < 0.8 mm) and 8.4 m2  g-1 for the large pellets (Ø > 1.4 mm). Purified LipG9 was immobilized by adsorption on these pellets, and the results were compared with those obtained with PHB powder. The highest immobilization yield (83%) was obtained for the medium PHB pellets, followed by large (76%) and small (55%) PHB pellets. The activity of LipG9 immobilized on the pellets, for the synthesis of ethyl oleate in n-hexane, was highest for the medium pellets (22 U g-1 ). The immobilization yield was high for PHB powder (99%) but the esterification activity was slightly lower (20 U g-1 ). These results show that pelletized PHB beads can be used for the immobilization of lipases, with the advantage that pelletized PHB will perform better than PHB powder in large-scale enzyme bioreactors.

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In this work, ultrasound was used to assist the ethanolysis of castor oil in a solvent-free system, catalyzed by a dry fermented solid containing the lipase from Burkholderia contaminans (BCFS). Reactions were done at 45°C. The maximum conversion in Erlenmeyer flasks was 71% in 96 h, using a loading of 9% (mass of BCFS in relation to the mass of triacylglycerols in the castor oil) and a molar ratio of ethanol:oil of 6:1, with addition of ethanol in 12 steps. In a packed-bed reactor containing 12 g of BCFS, the conversions were 78% in 48 h, and 83% in 72 h with an ethanol to oil molar ratio of 3:1 and treatment with an ultrasound probe, with maximum power of 500 W, frequency of 20 kHz, and 75% of the maximum power. These results are promising given that, with an ultrasound assisted bioreactor, a higher conversion in a shorter time was achieved, with a lower ethanol to oil molar ratio than was the case in the Erlenmeyer flasks without ultrasound.

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In recent years, residual glycerol from biodiesel synthesis made this chemical a cheap, readily available carbon source to bioprocess, which is also a form to reduce costs in the fuel industry. We propose and describe a bioprocess using fluidized and packed-bed continuous bioreactors to convert this residual glycerol into value-added products such as 1,3-propanediol (1,3-PD) and 2,3-butanediol (2,3-BD), largely used in the chemical industry. The bacterium Klebsiella pneumoniae BLh-1, strain isolated by us, was immobilized in the permeable support of polyvinyl alcohol (LentiKats®). After testing different dilution rates (D) for all bioreactor configurations, the best obtained productivities of 1,3-PD was 8.69 g L-1  h-1 at a D = 0.45 h-1 , and 2.99 g L-1  h-1 at a D = 0.30 h-1 for 2,3-BD, both in the packed-bed configuration. In the fluidized-bed reactor, the highest productivity values achieved were 4.48 and 1.16 g L-1  h-1 for 1,3-PD and 2,3-BD, respectively, both at D = 0.33 h-1 . These results show the potential of setting up a bioprocess based on continuous cultures using immobilized K. pneumoniae BLh-1 in PVA matrices in order to efficiently convert the abundant surplus of glycerol into commercially important chemicals such as 1,3-PD and 2,3-BD.

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Triacylglycerols (TAGs) can be modified to increase the absorption of fatty acids, prevent obesity, and treat fat malabsorption disorders and metabolic diseases. Medium-long-medium (MLM)-type TAGs, which contain medium-chain fatty acids in the sn-1 and sn-3 positions of the glycerol backbone and a long-chain fatty acid in the sn-2 position, show particularly interesting nutritional characteristics. This study aimed to synthesize MLM-type TAGs by enzymatic acidolysis of grape seed oil with medium-chain capric acid (C10:0) in associated packed bed reactors. The reaction was carried out during 120 H, at 45 °C, using lipase from Rhizomucor miehei (Lipozyme® RM IM). The residence time distribution of reagents in the reactor was quantified to evaluate the reactor behavior and to diagnose the existence of preferential paths. The reaction progress was monitored by analyzing TAG composition and, at the steady state (after 48 H of reaction), the incorporation degree achieved a value of 39.91 ± 2.77%. To enhance the capric acid incorporation, an acidolysis reaction in associated packed bed reactors was performed. The results showed a good operational stability of the biocatalyst, revealing values of half-life 209.64 H, 235.63 H of packed bed and associated packed bed reactor, respectively, and a deactivation coefficient 0.0061 H-1 .

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Solid-state cultivation (SSC) is microbial growth on solid supports under limited water conditions. Citric acid is a microbial aerobic metabolic product with several industrial applications, with production potential that can be obtained by SSF. Several wastes from agro-industries are used in SSF, such as sugarcane bagasse and vinasse. Cultures of mixed fungi or co-cultures are used in this SSF in order to complement the inoculum's xylanolytic enzymes for action on the lignocellulosic material (bagasse). Thus, this study aims to evaluate the effect of inoculum (Aspergillus niger and Trichoderma reesei consortium) in the production of citric acid from sugarcane bagasse impregnated with vinasse using bench packed-bed reactors (PBR). The results show the importance of T. reesei and A. niger in inoculum at a ratio of 50:50 and 25:75, suggesting the use of solid support due to the complementation of the hydrolytic enzymes. The highest concentration of citric acid, approximately 1000 mg L-1, was obtained for 100 mm of bed height in 48 and 72 h, with maximum glucose yield in citric acid (2.2 mg citric acid mg glucose-1). kLa indicates that maintaining solid moisture and liquid film thickness is important to keep the oxygen transfer in SSC.

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Solar-driven photocatalysis is a promising water-cleaning and energy-producing technology that addresses some of the most urgent engineering problems of the twenty-first century: universal access to potable water, use of renewable energy, and mitigation of CO2 emissions. In this work, we aim at improving the efficiency of solar-driven photocatalysis by studying a novel reactor design based on microfluidic principles using 3D-printable geometries. The printed reactors had a dimensional accuracy of 97%, at a cost of less than $1 per piece. They were packed with 1.0-mm glass and steel beads coated with ZnO synthesised by a sol-gel routine, resulting in a bed with 46.6% void fraction (reaction volume of ca. 840 µL and equivalent flow diameter of 580 µm) and a specific surface area of 3200 m2 m-3. Photocatalytic experiments, under sunlight-level UV-A irradiation, showed that reactors packed with steel supports had apparent reaction rates ca. 75% higher than those packed with glass supports for the degradation of an aqueous solution of acetaminophen; however, they were strongly deactivated after the first use suggesting poor fixation. Glass supports showed no measurable deactivation after three consecutive uses. The apparent first-order reaction rate constants were between 1.9 and 9.5 × 10-4 s-1, ca. ten times faster than observed for conventional slurry reactors. The mass transfer was shown to be efficient (Sh > 7.7) despite the catalyst being immobilised onto fixed substrates. Finally, the proposed reactor design has the merit of a straightforward scaling out by sizing the irradiation window according to design specifications, as exemplified in the paper.

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Since COVID-19 pandemic, indoor air quality control has become a priority, and the development of air purification devices effective for disinfecting airborne viruses and bacteria is of outmost relevance. In this work, a photocatalytic device for the removal of airborne microorganisms is presented. It is an annular reactor filled with TiO2-coated glass rings and irradiated internally and externally by UV-A lamps. B. subtilis spores and vegetative cells have been employed as model biological pollutants. Three types of assays with aerosolized bacterial suspensions were performed to evaluate distinct purification processes: filtration, photocatalytic inactivation in the air phase, and photocatalytic inactivation over the TiO2-coated rings. The radiation distribution inside the reactor was analysed by performing Monte Carlo simulations of photon absorption in the photocatalytic bed. Complete removal of a high load of microorganisms in the air stream could be achieved in 1 h. Nevertheless, inactivation of retained bacteria in the reactor bed required longer irradiation periods: after 8 h under internal and external irradiation, the initial concentration of retained spores and vegetative cells was reduced by 68% and 99%, respectively. Efficiency parameters were also calculated to evaluate the influence of the irradiation conditions on the photocatalytic inactivation of bacteria attached at the coated rings.

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Lipases CAL-B, TLL, and RML were used in the synthesis of free fatty acids of grape seed oil as heterogeneous substrate. The best enzyme was used to optimize the reaction variables temperature, enzyme content, and molar ratio of water:oil in batch reactions using experimental planning. The ideal conditions to produce free fatty acids using pure RML were 45 °C, 12:1 substrate molar ratio, and 15% enzyme, resulting in 66% of oil hydrolysis and a productivity of 0.54 mol L-1 min-1 in 4 h of reaction at 180 rpm. Repeated batches of reaction were performed testing the operational stability of RML, results showing that this enzyme could be used for at least 20 cycles keeping more than 80% of its initial activity, suggesting its potential use in industrial processes. The synthesis of free fatty acids was then evaluated in continuous reactions using packed-bed reactor (PBR). The highest productivity in the continuous process was 6.85 mol L-1 min-1, using only RML, showing an operational stability higher than 80% of its initial conversion capacity after 11 days of operation, at a flow rate of 0.13 mL min-1 at 45 °C. We evaluated the use of this hydrolyzed oil as substrate for lactone bioproduction using Galactomyces geotrichum UFMG-CM-Y3276, G. geotrichum UFMG-CM-Y3558, and Geotrichum klebahnii UFMG-CM-Y3014 screened for their oil-hydrolysis ability. Volatile compounds were qualitatively identified in GC-MS as γ-octalactone and γ-nonalactone.

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Here, we have assessed the use of one packed bed or two packed bed reactors in series in which Burkholderia cepacia lipase (BCL) was immobilized on protic ionic liquid (PIL)-modified silica and used as a biocatalyst for the transesterification of crude coconut oil. Reaction parameters including volumetric flow, temperature, and molar ratio were evaluated. The conversion of transesterification reaction products (ethyl esters) was determined using gas chromatography and the quantities of intermediate products (diglyceride and monoglyceride [MG]) were assessed using high-performance liquid chromatography. Packed bed reactors in series produced ethyl esters with the greatest efficiency, achieving 65.27% conversion after 96 H at a volumetric flow rate of 0.50 mL Min-1 at 40 °C and a 1:9 molar ratio of oil to ethanol. Further, within the first 24 H of the reaction, increased MG (54.5%) production was observed. Molecular docking analyses were performed to evaluate the catalytic step of coconut oil transesterification in the presence of BCL. Molecular docking analysis showed that triglycerides have a higher affinity energy (-5.7 kcal mol-1 ) than the smallest MG (-6.0 kcal mol-1 ), therefore, BCL catalyzes the conversion of triglycerides rather than MG, which is consistent with experimental results.

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This study investigated the synthesis of 2-ethylhexyl oleate catalyzed by Candida antarctica lipase immobilized on magnetic poly(styrene-co-divinylbenzene) particles in a continuous packed-bed bioreactor. Runs were carried out in a solvent-free system at 50 °C. The performance of the reactor was evaluated for substrates composed by oleic acid and 2-ethylhexanol at five molar ratios (1:4-4:1), determining its operation limits in terms of substrate flow rate. The system performance was quantified for three different flow rates corresponding to space-time between 3 and 12 h. For each condition, the influence of the space-time in the ester formation, esterification yield and productivity was determined. The molar ratio of acid-to-alcohol interfered, in a remarkable way, in the formation of 2-ethylhexyl oleate and the best performance was attained for substrate at equimolar ratio running at 12 h space-time. Under this condition, average 2-ethylhexyl oleate concentration was 471.65 ± 2.98 g L-1 which corresponded to ester productivity of 23.16 ± 0.49 mmol g-1 L-1 h-1. This strategy also gave high biocatalyst operational stability, revealing a half-life time of 2063 h. A model based on the ping-pong Bi-Bi mechanism was developed to describe the kinetics of the esterification reaction and validated using experimental data. The goodness of fit of the model was satisfactory (R2 = 0.9310-0.9952).

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Biodecolorization and biodegradation of azo dyes are a challenge due to their recalcitrance and the characteristics of textile effluents. This study presents the use of Halomonas sp. in the decolorization of azo dyes Reactive Black 5 (RB5), Remazol Brilliant Violet 5R (RV5), and Reactive Orange 16 (RO16) under high alkalinity and salinity conditions. Firstly, the effect of air supply, pH, salinity and dye concentration was evaluated. Halomonas sp. was able to remove above 84% of all dyes in a wide range of pH (6-11) and salt concentrations (2-10%). The decolorization efficiency of RB5, RV5, and RO16 was found to be ≥ 90% after 24, 13 and 3 h, respectively, at 50 mg L-1 of dyes. The process was monitored by HPLC-DAD, finding a reduction of dyes along the time. Further, Halomonas sp. was immobilized in volcanic rocks and used in a packed bed reactor for 72 days, achieving a removal rate of 3.48, 5.73, and 8.52 mg L-1 h-1, for RB5, RV5 and RO16, respectively, at 11.8 h. The study has confirmed the potential of Halomonas sp. to decolorize azo dyes under high salinity and alkalinity conditions and opened a scope for future research in the treatment of textile effluents.

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The main objective of this study is the degradation of a synthetic solution of atrazine by a modified vermiculite catalyzed ozonation, in a rotating packed bed (RPB) reactor. A 0.5 L RPB reactor was used to perform the experiments, using a Central Composite Design (CCD) response surface to construct the quadratic model based on the factors: pH, catalyst concentration and reactor rotation frequency. The response variable was the removal of the organic load measured in terms of Chemical Oxygen Demand (COD). After the complete quadratic model was constructed through the response surface, the COD degradation process had an optimal removal of 41% under the following conditions: pH 8.0, rotation of 1150 rpm and catalyst concentration 0.66 g L-1.

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This work describes the continuous synthesis of ethyl esters via enzymatic catalysis on a packed-bed continuous reactor, using mixtures of immobilized lipases (combi-lipases) of Candida antarctica (CALB), Thermomyces lanuginosus (TLL), and Rhizomucor miehei (RML). The influence of the addition of glass beads to the reactor bed, evaluation of the use of different solvents, and flow rate on reaction conditions was studied. All experiments were conducted using the best combination of lipases according to the fatty acid composition of the waste oil (combi-lipase composition: 40% of TLL, 35% of CALB, and 25% of RML) and soybean oil (combi-lipase composition: 22.5% of TLL, 50% of CALB, and 27.5% of RML). The best general reaction conditions were found to be using tert-butanol as solvent, and the flow rate of 0.08 mL min-1 . The combi-lipase reactors operating at steady state for over 30 days (720 h), kept conversion yields of ∼50%, with average productivity of 1.94 gethyl estersgsubstrate-1 h-1 , regardless of the type of oil in use. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:952-959, 2018.

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The anaerobic treatment of raw vinasse in a combined system consisting in two methanogenic reactors, up-flow anaerobic sludge blanket (UASB) + anaerobic packed bed reactors (APBR), was evaluated. The organic loading rate (OLR) was varied, and the best condition for the combined system was 12.5 kg COD m-3day-1 with averages of 0.289 m3 CH4 kg COD r-1for the UASB reactor and 4.4 kg COD m-3day-1 with 0.207 m3 CH4 kg COD r-1 for APBR. The OLR played a major role in the emission of H2S conducting to relatively stable quality of biogas emitted from the APBR, with H2S concentrations <10 mg L-1. The importance of the sulphate to COD ratio was demonstrated as a result of the low biogas quality recorded at the lowest ratio. It was possible to develop a proper anaerobic digestion of raw vinasse through the combined system with COD removal efficiency of 86.7% and higher CH4 and a lower H2S content in biogas.

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This study reports the immobilization of a ß-CGTase on glutaraldehyde pre-activated silica and its use to production of cyclodextrins in batch and continuous reactions. We were able to modulate the cyclodextrin production (α-, ß- and γ-CD) by immobilization and changing the reaction conditions. In batch reactions, the immobilized enzyme reached to maximum productions of 4.9mgmL-1 of α-CD, 3.6mgmL-1 of ß-CD and 3.5mgmL-1 of γ-CD at different conditions of temperature, pH and reaction time. In continuous reactor, varying the residence time and pH it was possible to produce at pH 4.0 and 141min of residence time preferentially γ-CD (0.75 and 3.36mgmL-1 of α- and γ-CD, respectively), or at pH 8.0 and 4.81min α- and ß-CDs (3.44 and 3.51mgmL-1).

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The transesterification of coconut oil with ethanol catalyzed by Burkholderia cepacia lipase immobilized on polysiloxane-polyvinyl alcohol was performed in a continuous flow. The experimental design consisted of a two-stage packed-bed reactor incorporating a column with cationic resin (Lewatit GF 202) to remove the glycerol formed as by-product and the reactor performance was quantified for three different flow rates corresponding to space-times from 10 to 14 h. The influence of space-time on the ethyl ester (FAEE) concentrations, yields and productivities was determined. The reactor operation was demonstrated for space-time of 14 h attaining FAEE concentrations of 58.5 ± 0.87 wt%, FAEE yields of 97.3 ± 1.9 % and productivities of 41.6  ± 1.0 mgester g medium (-1)  h(-1). Biodiesel purified samples showed average kinematic viscosity values of 5.5 ± 0.3 mm(2) s(-1) that meet the criteria established by the American National Standard ASTM (D6751). The immobilized lipase was found to be stable regarding its morphological and catalytic characteristics, showing half-life time (t 1/2) around 1540 h. The continuous packed-bed reactor connected in series with simultaneous glycerol removal has a great potential to attain high level of transesterification yields, raising biodiesel productivity.

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Se llevaron a cabo procesos de biodesulfurización de dos carbones colombianos ricos en azufre ("Mina Vieja" y "Vampiro"), en reactores de lecho empacado a nivel de erlenmeyer, utilizando un consorcio de Acidithiobacillus ferrooxidans (ATCC 23270) y Acidithiobacillus thiooxidans (ATCC 15494), evaluando la adición de cisteína a la solución lixiviante. Los ensayos fueron monitoreados por medidas de hierro en solución, pH y potencial redox. Adicionalmente, se hicieron análisis mineralógicos por difracción de rayos X (DRX) antes y después de los experimentos. Los ensayos sin adición de cisteína alcanzaron una oxidación de pirita de 45.3% y 57.9% para "Mina Vieja" y "Vampiro" respectivamente. Cuando se adicionó cisteína, la oxidación aumentó en 14.9% para "Mina Vieja" y 6.4% para "Vampiro". Por otra parte, todos los ensayos evidenciaron remoción de caolinita, debido a su interacción con el ácido sulfúrico del medio. Con base en los resultados obtenidos, los componentes del carbón influenciaron tanto crecimiento bacteriano como la eficiencia de la cisteína sobre el grado de pirita oxidada.

Biodesulphurization processes of a two sulphur-rich coals from Colombia ("Mina Vieja" y "Vampiro") were carried out at packed-bed reactors at erlenmeyer level, using a consortium of Acidithiobacillus ferrooxidans (ATCC 23270) and Acidithiobacillus thiooxidans (ATCC 15494). Cysteine addition were evaluated. The assays were monitored by measurements of iron content, pH, and redox potential. X-ray diffraction (XRD) were used to establish the mineralogy before and after the process. The assays without cysteine respectively reached a pyrite oxidation of 45.3% ("Mina Vieja") and 57.9% ("Vampiro") after 38 days. Cysteine addition improved pyrite oxidation by 14.9% ("Mina Vieja") and 6.4% ("Vampiro"). On the other hand, all the assays removed kaolinite by interaction with sulphuric acid of the media. In base to the results, coal compounds influence bacterial growth and affects the efficiency of cysteine over pyrite oxidation.