Agitation Conditions Research Articles

Quartz bleaching by phosphoric acid: An investigation on the relationship between Fe rejection rate and colour response

Advances in high-tech industries have led to increasing the demand for highly pure quartz. Research on the beneficiation of quartz has been conducted to meet market requirements by different processes including hydrometallurgical ones. Even though phosphoric acid (PA) has a capacity to complex iron, and therefore has the potential to bleach quartz, this reagent has not attracted sufficient attention. This study was conducted to investigate the relationship between Fe remaining in concentrate by PA bleaching and colour responses of quartz ore sample employing Box-Behnken Design, a common designs of Response Surface Methodology. Effects of bleaching parameters (PA concentration 0–2 M, temperature 65–95 °C, bleaching time 45–180 min.) were investigated in agitated pulp condition at 400 rpm. The efficiency of the process was determined by colorimetric analysis and chemical analysis (ICP-MS). Experimental results revealed that the linear effects of bleaching parameters on Fe removal by PA were statistically significant. The lowest Fe remaining in concentrate, 79 ppm, was observed in two different conditions tested at the highest initial PA concentration (2 M) at 95 °C, over 90 min, and at 85 °C, over 180 min of bleaching. The increase in acidity resulted in the higher Fe rejection rate and the lower yellowness. Significant improvements in whiteness and yellowness were obtained by PA bleaching, whereas redness could not be improved considerably. This finding has been attributed to the presence of free dark coloured particles, and the resistance of redness source minerals like hematite to react with PA ions.

Self-Assembled, Dilution-Responsive Hydrogels for Enhanced Thermal Stability of Insulin Biopharmaceuticals.

Biotherapeutics currently dominate the landscape of new drugs because of their exceptional potency and selectivity. Yet, the intricate molecular structures that give rise to these beneficial qualities also render them unstable in formulation. Hydrogels have shown potential as stabilizing excipients for biotherapeutic drugs, providing protection against harsh thermal conditions experienced during distribution and storage. In this work, we report the utilization of a cellulose-based supramolecular hydrogel formed from polymer–nanoparticle (PNP) interactions to encapsulate and stabilize insulin, an important biotherapeutic used widely to treat diabetes. Encapsulation of insulin in these hydrogels prevents insulin aggregation and maintains insulin bioactivity through stressed aging conditions of elevated temperature and continuous agitation for over 28 days. Further, insulin can be easily recovered by dilution of these hydrogels for administration at the point of care. This supramolecular hydrogel system shows promise as a stabilizing excipient to reduce the cold chain dependence of insulin and other biotherapeutics.

First report on the production of phytotoxic metabolites by Mycoleptodiscus indicus under optimized conditions of submerged fermentation

ABSTRACT An alternative to controlling weeds resistant to conventional herbicides is the isolation of new active principles. Fungi can produce phytotoxic metabolites that may be used in the development of new herbicides. The objectives of this study were: (1) isolate, select, and identify a fungus producer of phytotoxic metabolites and (2) optimize the culture conditions of this fungus in a low-cost culture medium, with the aim of increasing the phytotoxic effects of their metabolites in weeds and commercial plants. Fungi were isolated from the leaves of Conyza sp. with disease symptoms and selected according to the production of phytotoxic metabolites in solid and submerged fermentation in a low-cost culture medium. A Plackett–Burman Design and Central Composite Rotational Design were used to optimize the conditions of temperature, agitation, pH, and concentrations of glucose and yeast extract in submerged fermentation. The phytotoxic metabolites produced under optimal conditions were tested on 10 commercial plants and weeds that are difficult to control. Of the nine fungi isolated, Mycoleptodiscus indicus UFSM54 produced higher leaf lesions. The production of phytotoxic metabolites was optimized when the fungus was cultivated at 35°C, 50 rpm, and 1.5 g L−1 of glucose in submerged fermentation. The metabolites of M. indicus caused severe phytotoxic effects on germination and seedling growth, and enhanced lesion development on detached plant leaves. The present study is the first to report on the production of phytotoxic metabolites by M. indicus, a potential producer of bioherbicides.

Rheology and Catastrophic Phase Inversion of Emulsions in the Presence of Starch Nanoparticles

Emulsions stabilized by solid nanoparticles, referred to as Pickering emulsions, are becoming increasingly important in applications as they are free of surfactants. However, the bulk properties and stability of Pickering emulsions are far from being well understood. In this work, the rheological behavior and catastrophic phase inversion of emulsions in the presence of starch nanoparticles were studied using in-situ measurements of viscosity and electrical conductivity. The aqueous phase consisting of starch nanoparticles was added sequentially in increments of 5% vol. to the oil phase under agitation condition to prepare the emulsions. The emulsions were water-in-oil (W/O) type at low to moderate concentrations of aqueous phase. At a certain critical volume fraction of aqueous phase, catastrophic phase inversion of W/O emulsion to oil-in-water (O/W) emulsion took place accompanied a sharp jump in the electrical conductivity and a sharp drop in the emulsion viscosity. The W/O emulsions were nearly Newtonian at low concentrations of aqueous phase. At high concentrations of aqueous phase, prior to phase inversion, the W/O emulsions exhibited a shear-thickening behavior. The O/W emulsions produced after phase inversion were shear-thinning in nature. The comparison of the experimental viscosity data with the predictions of emulsion viscosity model revealed only partial coverage of droplet surfaces with nanoparticles. With the increase in the concentration of starch nanoparticles (SNPs) in the aqueous phase of the emulsions, the phase inversion of W/O emulsion to O/W emulsion was delayed to higher volume fraction of aqueous phase. Thus SNPs imparted some stability to W/O emulsions against coalescence and phase inversion.

Improvement of carotenoids production from Rhodotorula glutinis CCT-2186

Abstract Rhodotorula strains can produce industrial valuable bioproducts. In this work, the production of carotenoids, and lipids by Rhodotorula glutinis using different nitrogen sources was evaluated. Two statistical experimental designs were applied to improve carotenoid production: a first 25−1 fractional factorial design evaluating the influence of independent variables pH, nitrogen source, glucose, KH2PO4 and MgSO4 concentration; a second 22 central factorial design to optimize the effect of pH and nitrogen sources. After the optimization using two statistical designs, a culture mediium composed of (in g/L) glucose (10), asparagine (10), NH4NO3 (4), KH2PO4 (0.52), MgSO4 (0.52) was found as the best for the production of carotenoids at a pH 5 and 30 °C. The best bioprocess was scaled-up to a 5 L stirred-tank bioreactor. The change to a bioreactor allowed to improve aeration and agitation conditions, and consequently, increasing the production yields (m/v) in, approximately, 25.83 %, 11.88 %, 24.50 % and 10.32 % for β-carotene, torularhodin, torulene and lipids, respectively. The combined supplementation of the culture media with both organic (asparagine) and inorganic nitrogen (ammonium nitrate) sources was primordial for enhancing the carotenogenesis. R. glutinis are very efficient in the production of valuable carotenoids and lipids, presenting high potential of yeast for the industrial production of more sustainable cosmetic, pharmaceutical, and food products.

D eterminação da taxa de resfriamento de diferentes meios de extração de calor e a influência sobre a dureza do aço ABNT 8620

Cooling rate of steel from its austenitic temperature influences the microstructure and resulting mechanical properties. The study on cooling media rates is still poor in the literature, making it necessary to study it. In the present work, heat extractions were carried out on SAE 8620 steel from its austenitization temperature, in moderately and severely agitated water, brine and air media. From the cooling curves, it was verified that the agitation of the heat extraction medium has an influence on their severity, and that the stirred brine and water severely extracted heat in the same time interval, with different cooling rates, being water the largest one, with a maximum cooling rate of 221,25 ° C/s at a temperature of approximately 180 °C. On the other hand, the hardness obtained for the most severe media, despite being close, the severely stirred brine made it possible to obtain a higher average hardness, which was 60,2 HRC. The present work was therefore possible to obtain satisfactorily the cooling curves and rates for air, water and brine when subjected to conditions of moderate and severe agitation, to be used in heat treatments by continuous cooling.

Batik Dye Decolorization by Immobilized Biomass of Aspergillus sp

The rapidity of the batik industry in the Former Residence of Banyumas raises problems. Wastewater that discharged into upstream causes accumulation in downstream up to empties into the sea, so does not only threatens the river ecosystem but also has the potential to cause problems in the mangrove ecosystem in Segara Anakan (the downstream area of the Citanduy River which is very close to the downstream area of the Serayu River Basin). The strategy of batik wastewater management in an effort not to pollute the environment is offered. This study tried indigosol blue batik dye which are often used in the batik industry by using immobilization of the pure fungi biomass compared to biomass which was induced with tannic acid. Combination between incubation time and shaking treatment in immobilization of pure Aspergillus sp. biomass that capable to decolorize indigosol blue batik dye were also done. Data of degradation percentage was analyzed using spectrophotometry. The decolorization result of comparison between biomass of Aspergillus sp. with or without the addition of tannic acid under agitated treatment conditions at 24, 48, 72 hours were 54.7, 75.8, 77.4% and 78.8, 84, 80.1%, respectively. While the result of treatment under static conditions were 65.4, 86.3, 73.7% and 79.2, 78.6, 68.2, respectively. The next experiment is showed that 48th hour on static treatment have the highest decolorization percentage up to 67.1%. The pH was measured before and after treatment. The pH after treatment were decrease both in static and shaking treatment, and also in control treatment both in static and saker treatment. Based on the results of the research, the fact is the use of immobilization biomass of Aspergillus sp. in the form of alginate beads can be used for decolorization application in the environment.

Thermodynamic and Kinetic Pathways to Agitated and Spontaneous Emulsification.

Emulsification of an oil (dodecane and diesel fuel) in salinized water was studied under turbulent and agitation-free conditions in the presence of a mixture of an ionic and a nonionic surfactant. The properties of the air-water and the oil-water interfaces were investigated using the methods of du-Nouy ring, drop resonance vibrometry, and Langmuir film balance that allowed pinpointing the relevance of certain interfacial properties in emulsification. Estimation of the droplet size and its distribution from the nanometer-to-micrometer range was carried out with optical microscopy, acoustic attenuation spectroscopy, and continuous hydrodynamic flow fractionation. These measurements provided the platform for the comparison of the emulsion droplet size with those predicted from the fluctuation of the dynamic stress in the turbulent water via a capillary hydrodynamic model. While such a comparison was reasonably meaningful for micron size emulsion droplets, production of nanometer size droplets was beyond such a rudimentary expectation. We thus carried out systematic investigations into other factors that contribute to emulsification under both agitated and agitation-free conditions. An important finding of these studies is that the infusion of air bubbles that profoundly enhance the hydrodynamic fluctuation produces mainly submicroscopic emulsion droplets, while a fluctuation inhibiting water-soluble polymer has the opposite effect. Furthermore, while a hydrophilic polymer dissolved in water enhances the ripening of the droplets with time, hydrophobic polymer in oil thwarts aging, plausibly by osmotic backpressure and interfacial stiffening, which, upon compression, acts against surface tension, thereby decreasing the chemical potential of the trapped oil molecules inside the droplet. These effects are similarly observed in spontaneous emulsifications, that is, when a layer of oil containing the additives is deposited upon the surface of the aqueous phase in the absence of any external work input.

Bioproduction of α-terpineol and R-(+)-limonene derivatives by terpene-tolerant ascomycete fungus as a potential contribution to the citrus value chain.

The aims of this article were to select fungal species with high tolerance and high growth rate in mediums supplemented with limonene and citrus essential oils (CEOs), and to test the bioconversion capability of the chosen isolates for the bioproduction of aroma compounds. Based on the use of predictive mycology, 21 of 29 isolates were selected after assaying R-(+)-limonene and CEO tolerance (10gl-1 ). With a dendrogram divisive coefficient of 0·937, the subcluster two with isolates Aspergillus niger LBM 055, Penicillium sp. LBM 150, Penicillium sp. LBM 151 and Penicillium sp. LBM 154 gathered the highest tolerance and mycelia growth speed. Ultrastructural analysis indicated that culture media containing limonene had no visible toxic activity that could promote morphological changes in the fungal cell wall. The biomass of A. niger LBM055 was distinctive in liquid media supplemented with R-(+)-limonene (0·57±0·07g) and it was selected to prove bioconversion capacity, under static and agitated conditions, and converted up to 98% of limonene, yielding a wide variety of products that were quantified by GC-FID. It was obtained at molecular weights less than limonene (64-100%), between limonene and α-terpineol (12-72%) and greater than α-terpineol (2-48%). Aspergillus niger LBM 055, Penicillium sp. LBM 150, Penicillium sp. LBM 151 and Penicillium sp. LBM 154 showed to the highest tolerance and growth rate in mediums supplemented with R-(+)-limonene and orange and lemon essential oils. Particularly, A. niger LBM055, showed limonene bioconversion capability and produced different molecular weights compounds such us α-terpineol. Different bioproducts can be obtained by changing operative condition with the same fungus, and this bioprocess aspect is a significant approach to be adopted on industrial scale leading to the creation of new natural flavours and fragrance compositions.

Clove Oil (Syzygium aromaticum L.) Activity against Alicyclobacillus acidoterrestris Biofilm on Technical Surfaces.

Acidotermophilic bacteria Alicyclobacillus acidoterrestris is one of the main contaminants in the fruit industry forming biofilms which are difficult to remove from the production line by conventional methods. An alternative approach aims for the use of essential oils to prevent Alicyclobacillus biofilm development. The effect of clove essential oil on A. acidoterrestris biofilms on glass and polyvinyl chloride surfaces under static and agitated culture conditions was investigated by atomic force microscopy and the plate count method. The medium-flow and the type of technical surface significantly influenced A. acidoterrestris biofilm. The PVC was colonized in a greater extent comparing to glass. Clove essential oil in 0.05% (v/v) caused 25.1–65.0% reduction of biofilms on the technical surfaces along with substantial changes in their morphology by a decrease in the biofilm: height, surface roughness, and surface area difference. The oil also induced alteration in individual bacterial cells length and visible increase of their roughness. Clove essential oil seems to release EPS from biofilm and thus induce detachment of bacteria from the surface. Due to anti-A. acidoterrestris biofilm activity, the clove oil may be used in the juice industry to hinder a development of A. acidoterrestris biofilms on production surfaces.

Turpentine oil: a novel and natural bridging liquid for agglomeration of coal fines of high ash coals

ABSTRACT Oil agglomeration is an effective way to demineralize high ash coals as compared to froth flotation and density gradient separation. In this process, the choice of bridging liquid is critical with respect to economics and efficiency. Herein, we report turpentine oil as a potential bridging liquid which is demonstrably efficient in coal demineralization at lower concentration (10 vol.%) compared to literature (20–25 vol.%) without inclusion of surfactants, which enhances economic viability. We chose two high ash coals of Indian origin, with 26% and 34% ash. A varied range of particle sizes were examined along with pH, type of electrolytes, agitation conditions and oil dosages. Both coals (200 mesh) demonstrated approximately 50% reduction in ash content at pH 7, which is an improvement over previously known reports on Indian coals. Chemical structural resemblance between primary components of turpentine oil and predominant π-delocalized aromatic structure of high rank coals could be the reason behind improved adsorption of oil. Our work thus demonstrated the utilization of a natural oil which can be dried easily, readily available and cheap in a significantly demanding commercial process like coal beneficiation. This is expected to deliver a substantial performance and cost improvement over incumbent known bridging liquids.

Extended release pellets prepared by hot melt extrusion technique for abuse deterrent potential: Category-1 in-vitro evaluation.

The objective of the present study was to develop extended-release (ER) hot-melt extruded (HME) abuse-deterrent pellets of acetaminophen, a model drug, by utilizing high molecular weight polyethylene oxide (PEO) and gelling agents (xanthan gum, guar gum, and gellan gum). The HME pellets were evaluated for their abuse-deterrence (AD) potential by Category-1 laboratory in-vitro evaluation parameters, including particle size reduction (PSR), small volume extraction, dissolution, viscosity, syringeability, and injectability. Further, the pellets were investigated for resistance to physical (crushing) and thermal (oven and microwave) manipulation to evaluate the strength of the AD properties. Physical manipulation studies demonstrated that the pellets were intact, extremely hard, and resistant to PSR and manipulation to bypass ER properties. Dissolution of all intact and physically manipulated pellets led to complete drug release within 8h, and resistance to dose-dumping in 40% ethanol was observed. The drug extraction was <50% in 10mL of ingestible and non-ingestible solvents under static, agitation, and thermal manipulation conditions with an incubation time of 30min. The PEO/xanthan gum-based formulation showed higher viscosity, syringe and injection forces, and lower syringeable volume in all manipulation conditions compared with plain PEO pellets. These findings supported the AD potential of PEO and xanthan gum pellets against intravenous abuse.

Advances in human mesenchymal stromal cell-based therapies - Towards an integrated biological and engineering approach.

Recent advances of stem cell-based therapies in clinical trials have raised the need for large-scale manufacturing platforms that can supply clinically relevant doses to meet an increasing demand. Promising results have been reported using stirred-tank bioreactors, where human Mesenchymal Stromal Cells (hMSCs) were cultured in suspension on microcarriers (MCs), although the formation of microcarrier-cell-aggregates might still limit mass transfer and determine a heterogeneous distribution of hMSCs. A variety of MCs, bioreactor-impeller configurations, and agitation conditions have been established in an attempt to overcome the trade-off of ensuring good suspension while keeping the stresses to a minimum. While understanding and controlling the fluid flow environment of bioreactors has been initially under-appreciated, it has recently gained in popularity in the mission of providing ideal culture environments across different scales. This review article aims to provide a comprehensive overview of how rigorous engineering characterisation studies improved the outcome of biological process development and scale-up efforts. Reconciling these two disciplines is crucial to propose tailored bioprocessing solutions that can provide improved growth environments across a range of scales for the allogeneic cell therapies of the future.

Dead biomass of Morganella morganii acts as an efficient adsorbent to remove Pb(II) from aqueous solution in different aeration–agitation and pH conditions

Lead (Pb) removal from industrial effluent using physicochemical methods, though efficient, poses economic and environmental challenges due to high cost and generation of toxic wastes as by-products. Biosorption using dead microbial biomass, on the other hand, offers economic feasibility and environmental safety, but its application is limited because it relies on specific pH and agitation conditions. To address these issues, we used wastewater of a drain containing effluent from nineteen industries and isolated Pb-tolerant strains of Morganella morganii (ND1 and ND2). We demonstrated that the dead biomass of M. morganii ND1 and ND2 maintains a high biosorption potential at pH ranging from 3 to 5 in both shaking (89.96–89.99 mg/g) and static conditions (89.99–84.05 mg/g). Adsorption of Pb(II) from M. morganii ND1 and ND2 follows pseudo-second-order kinetic model and chemisorption as a dominant underlying mechanism in aqueous media. Fourier-transform infrared spectroscopic analyses of dead biomass before and after Pb(II) biosorption revealed the involvement of phosphoryl, hydroxyl, amide, carbonyl, and phosphate functional groups during biosorption. We demonstrated the potential of M. morganii ND1 and ND2 in developing a cost-effective biosorption technology for removing Pb in industrially relevant pH, and both agitation and static conditions.

Optimization of extraction conditions of volatile compounds from pequi peel (Caryocar brasiliense Camb.) using HS-SPME

The pequi is a native specie from the Brazilian Cerrado that has great economic importance for the population of the region. The pericarp is considered an agroindustrial residue despite corresponding to approximately 80% of the total fruit mass. Informations about the chemical composition of pericarp would allow better utilization of this portion of the fruit. The objective of this study was to identify the best conditions of agitation, extraction time and extraction temperature to maximize the extraction of volatile organic compounds present in pequi pericarp (Caryocar brasiliense Camb.) using two types of solid phase microextraction fibers. The extraction of the volatile compounds was using the headspace solid-phase microextraction method with subsequent separation and identification by CG-MS. Polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber was statistically more efficient than divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber. The both fibers enabled the extraction and identification of 35 compounds, mainly terpenes (65.71%) and esters (14.29%). An increase in the extraction temperature and time allowed greater extraction of volatile compounds by both fibers. However, in relation to agitation, the best condition for using DVB/CAR/PDMS was 100 rpm, while agitation was not necessary for an efficient extraction using the PDMS/DVB fiber.

Inoculant production of Pisolithus sp. in submerged culture under agitation

Ectomycorrhizal fungi inoculation can increase the sustainability of planted forests hence the inoculant production should be optimized. The objective of this study was to determine the agitation speed and time of growth for maximum production of mycelium of D216 isolate of Pisolithus sp. The treatments were established by factorial 6x3, being six agitation conditions and three different times (days) of growth. The kinds of agitation used were: Without agitation, gentle manual agitation every two days and orbital agitation speed of 50, 100, 200 and 250 rpm. The times of growth were 14, 21 and 28 days. The mycelium mass was generally single and remained on the surface of the culture medium when grown without agitation or with manual agitation. Spherical mass units formed under agitation and grew submerged. The dry mass production of mycelium of D216 isolate was higher when grown under agitation of 200 rpm, followed by 250 and 100 rpm. For all agitation system, the production of mycelium did not increase after 14 days. The maximum production of mycelium dry mass of D216 isolate of Pisolithus sp. was obtained in the agitation speed of 200 rpm for 14 days. The elevation of the agitation to 250 rpm decreased the mycelium dry mass production of Pisolithus sp. In the absence or in lower agitation speeds, the mycelium dry mass was minimal. Using the ideal speed for maximum mycelium production and adjusting other growing conditions can decrease the risk of contamination, the production time and cost of the inoculant and encourage the use of this biotechnology. Key words: Ectomycorrhizal fungi, inoculation, mycorrhiza, planted forests.

Rehydration of food powders: Interplay between physical properties and process conditions

Dehydrated food powders with poor dissolution or dispersion can dramatically compromise food processing, with consequences for the final product quality and consumer experience. In this study, the reconstitution performance of maltodextrin powders with different moisture content and molecular weight, has been determined by varying the processing conditions, including agitation speed, liquid temperature, powder addition rate and mode of addition to the liquid surface.In particular, the inter-relationship between the glass transition temperature (Tg) of the powder, its moisture content and the liquid temperature (TL) is highlighted. When TL ≥ Tg, the individual maltodextrin granules tend to swell, restricting further dispersion and rehydration. It has been shown that higher liquid temperatures reduce the dispersion of food powders containing high molecular weight carbohydrates. Increasing the rate of powder addition to the liquid surface under low agitation conditions has been shown to result in faster reconstitution of low-molecular weight maltodextrins, whilst, on the other hand, the corresponding reconstitution rates of high-molecular weight maltodextrins are reduced.On the basis of this work and a previous study [X.Y. Ong, S.E. Taylor and M. Ramaioli, Pouring of Grains onto Liquid Surfaces: Dispersion or Lump Formation? Langmuir (2019) 1115011156] an improved, yet simple, approach to improve powder dispersion in a liquid is also demonstrated, by optimizing the distribution of the powder on the liquid surface. This approach avoids powder grains accumulating as heterogeneous lumps on the liquid surface and has been applied herein to a wide range of food powders.

Development of a scale-up strategy for Chinese hamster ovary cell culture processes using the kL a ratio as a direct indicator of gas stripping conditions.

Herein, we described a scale-up strategy focused on the dissolved carbon dioxide concentration (dCO2 ) during fed-batch cultivation of Chinese hamster ovary cells. A fed-batch culture process for a 2000-L scale stainless steel (SS) bioreactor was scaled-up from similarly shaped 200-L scale bioreactors based on power input per unit volume (P/V). However, during the 2000-L fed-batch culture, the dCO2 was higher compared with the 200-L scale bioreactor. Therefore, we developed an alternative approach by evaluating the kL a values of O2 (kL a[O2 ]) and CO2 [kL a(CO2 )] in the SS bioreactors as a scale-up factor for dCO2 reduction. The kL a ratios [kL a(CO2 )/kL a(O2 )] were different between the 200-L and 2000-L bioreactors under the same P/V condition. When the agitation conditions were changed, the kL a ratio of the 2000-L scale bioreactor became similar and the P/V value become smaller compared with those of the 200-L SS bioreactor. The dCO2 trends in fed-batch cultures performed in 2000-L scale bioreactors under the modified agitation conditions were similar to the control. This kL a ratio method was used for process development in single-use bioreactors (SUBs) with shapes different from those of the SS bioreactor. The kL a ratios for the SUBs were evaluated and conditions that provided kL a ratios similar to the 200-L scale SS bioreactors were determined. The cell culture performance and product quality at the end of the cultivation process were comparable for all tested SUBs. Therefore, we concluded that the kL a ratio is a powerful scale-up factor useful to control dCO2 during fed-batch cultures.

Polymorphic A\u03b242 fibrils adopt similar secondary structure but differ in cross-strand side chain stacking interactions within the same \u03b2-sheet

Formation of polymorphic amyloid fibrils is a common feature in neurodegenerative diseases involving protein aggregation. In Alzheimer’s disease, different fibril structures may be associated with different clinical sub-types. Structural basis of fibril polymorphism is thus important for understanding the role of amyloid fibrils in the pathogenesis and progression of these diseases. Here we studied two types of Aβ42 fibrils prepared under quiescent and agitated conditions. Quiescent Aβ42 fibrils adopt a long and twisted morphology, while agitated fibrils are short and straight, forming large bundles via lateral association. EPR studies of these two types of Aβ42 fibrils show that the secondary structure is similar in both fibril polymorphs. At the same time, agitated Aβ42 fibrils show stronger interactions between spin labels across the full range of the Aβ42 sequence, suggesting a more tightly packed structure. Our data suggest that cross-strand side chain packing interactions within the same β-sheet may play a critical role in the formation of polymorphic fibrils.

Enrichment and characterization of a bilge microbial consortium with oil in water-emulsions breaking ability for oily wastewater treatment

Oily bilge wastewater is one of the main sources of hydrocarbons pollution in marine environments due to accidental or clandestine discharges. The main technical challenge for its effective treatment is the presence of stable oil-in-water (O/W) emulsions. In this work we are reporting an enriched microbial consortium from bilge wastewater with remarkable ability to demulsify oil in water emulsions. The consortium showed emulsion-breaking ratios up to 72.6% in the exponential growth phase, while the values range from 11.9 to 8.5% in stationary phase. A positive association was observed between demulsifying ability and microbial adhesion to hydrocarbons, as well as between cell concentration and demulsifying ability. Also, an interesting ability to demulsify under different temperatures, conditions of agitation, and bilge emulsions from different vessels was observed. The Bacterial and Archaeal composition was analyzed by 16S rRNA gene amplicon lllumina sequencing analyses, revealing an assemblage composed of bacterial types highly related to well characterized bacterial isolates and also to non-yet cultured bacterial types previously detected in marine and sediment samples. Hydrocarbonoclastic microbial types such as Marinobacter, Flavobacteriaceae, Alcanivorax and Gammaproteobacteria PYR10d3 were found in high relative abundance (27.0%-11.1%) and types of marine oligotrophs and surfactant degraders such as Thallasospira, Parvibaculum, Novospirillum, Shewanella algae, and Opitutae were in a group of middle predominance (1.7-3.5%). The microbial consortium reported has promising potential for the biological demulsification of bilge wastewater and other oily wastewaters.