Agitation Conditions Research Articles

Bryozoan fauna of the Lake Valley Formation (Mississippian), New Mexico

AbstractTen bryozoan species are described from the Andrecito and Tierra Blanca members of the Lake Valley Formation (Mississippian) of Sierra County, New Mexico, USA. One genus, with one species, is new—a cystoporate,Cystomeson sierraensisn. gen. n. sp. The bryozoans indicate quieter and deeper conditions in the Andrecito Member and more agitated and shallower conditions in the Tierra Blanca Member. The species identified in this study are endemic to North America, whereas at the generic level, the composition is rather cosmopolitan.UUID:http://zoobank.org/fc354A60-1fbc-4e41-8b9b-bbfd65e59a71

Production and sequential optimization of Bacillus subtilis MF467279 pullulanase by statistical experimental designs and evaluation of its desizing efficiency

Abstract In our search for a pullulanase production from unconventional sources, Bacillus subtilis MF467279 was isolated from the desert plant species Salsola imbricate, that collected from Tur Sinai, Egypt. The optimization of pullulanase enzyme was performed in three stages. First, the two level Plackett-Burman design to screen the medium constituents that significantly affect the enzyme production. Secondly experiment was important for optimization of the most effective constituents using central composite design (CCD). In the third experiment Two–factor–five–level central composite design (CCD) was applied to identify the best initial pH and agitation (rpm) conditions. A maximal enzyme activity of 75.13 U/ml was more than 4.53-folds the activity obtained using the basal medium. Application of partially purified pullulanase enzyme signified that, the fraction contained mixture of pullulanase and amylase was effectively improved the desizing process of fabrics even at lowest dose as indicated from violet scale scale (TEGEWA), weight loss and Scanning Electron Microscopy (SEM).

Automatic procedures for the synthesis of difficult peptides using oxyma as activating reagent: A comparative study on the use of bases and on different deprotection and agitation conditions

Solid-Phase Peptide Synthesis (SPPS) is a rapid and efficient methodology for the chemical synthesis of peptides and small proteins. However, the assembly of peptide sequences classified as “difficult” poses severe synthetic problems in SPPS for the occurrence of extensive aggregation of growing peptide chains which often leads to synthesis failure. In this framework, we have investigated the impact of different synthetic procedures on the yield and final purity of three well-known “difficult peptides” prepared using oxyma as additive for the coupling steps. In particular, we have comparatively investigated the use of piperidine and morpholine/DBU as deprotection reagents, the addition of DIPEA, collidine and N-methylmorpholine as bases to the coupling reagent. Moreover, the effect of different agitation modalities during the acylation reactions has been investigated. Data obtained represent a step forward in optimizing strategies for the synthesis of “difficult peptides”.

Agitation impacts fermentation performance as well as carbon and nitrogen metabolism inSaccharomyces cerevisiaeunder winemaking conditions

Background and Aims Under industrial conditions, fermenting juice is normally not mechanically agitated; thermodynamic forces will lead to some rotating motion of the medium. At laboratory scale, research aims to mimic industrial conditions using a standardised synthetic grape juice‐like medium. The level of agitation applied, however, to fermentations differs between the studies. In this study, we investigated the influence of agitation speed on fermentation parameters, including fermentation kinetics, yeast cell production and volatile aroma production. Methods and Results These parameters were evaluated during fermentations under different agitation conditions. Agitation speed was found to significantly influence all the parameters monitored. In the evaluated conditions, a speed of 80 rpm was optimal for the production of fermentative aromas (lead to the highest production) while guaranteeing the complete and rapid fermentation and limiting the production of off‐flavours. Fermentation of a Chardonnay grape juice in 50 L tanks confirmed the results, and the panellists described the wine produced by the stirred fermentation as sweeter but it is likely that the panellists meant softer because the wines were dry. Conclusions Agitation is an important parameter to control during fermentation under laboratory conditions. The data also suggest that the type and strength of agitation in commercial fermentations may have a more significant impact than previously thought. Significance of the Study This study demonstrates that researchers must take into account the importance of agitation during their studies. Similarly, winemakers might consider constant agitation of their tanks.

Physical structure variations of bacterial cellulose produced by different Komagataeibacter xylinus strains and carbon sources in static and agitated conditions

The morphology, crystallinity, crystallite size, and production yield of bacterial cellulose (BC) produced with six different carbon sources (glucose, fructose, lactose, maltitol, sucralose, and xylitol) in static and agitated fermentation conditions by five strains of Komagataeibacter xylinus (KX, TISTR 086, 428, 975, and 1011) which are locally available, were studied. In static condition, the BC pellicle was formed as a membrane sheet at the medium surface exposed to air, while in agitated condition, the spherical or asterisk-like shape BC particles were obtained in the culture media. The XRD and FT-IR analyses found no significant differences in the cellulose crystallinity, crystallite size or polymorphic distribution within the carbon sources. However, changes in crystallinity and mass fraction of the Iα allomorph were observed in BC produced from the different bacterial strains and incubation conditions. The BC samples produced by the same bacterial strain with the varying culture conditions showed the alteration of physical properties more clearly than the BC samples prepared by the opposite situation. These findings suggested that the strains of bacteria and fermentation conditions strongly affected on the physical structures of BC.

Effects of Agitating Culture Condition on the Growth, Metabolic and Carotenoid Profiles of Lemna paucicostata

The effects of agitating culture conditions on the growth, metabolic and carotenoid profiles of Lemna paucicostata were investigated in this study using gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry. Lemna paucicostata cultivated under static and agitating conditions showed no significant difference in total plant growth. Various alcohols, amino acids, fatty acids, organic acids, sugars, and phenolic compounds were identified in the sample. The higher relative yields of ferulic acid and GABA were obtained under the agitating condition on day 28, whereas that of coumaric acid was higher under the static condition on day 42. Significantly higher relative yields of antheraxanthin and lutein were achieved under agitation condition than static condition on day 42. In addition, fucoxanthinol was identified for the first time in L. paucicostata culture. The results of this study suggest that static and agitating culture conditions, as well as optimal harvest timing, should be selected according to the target products including ferulic acid, GABA, coumaric acid, antheraxanthin and lutein in L. paucicostata culture.

Influence of the Processing Parameters on the Characteristics of Spherical Bacterial Cellulose

Bacterial Cellulose (BC) biosynthesized under agitated conditions can produce hydrogels with spherical shapes and the processing parameters govern this formation of BC hydrogels. The variations of these parameters cause different results in the formation of spherical BC and it is relevant to evaluate these effects. Carbon source, inoculum concentration, volume of the culture medium, stirring speed and incubation temperature were the processing parameters evaluated in this work. Therefore, the results obtained were characterized in terms of dry mass production, water uptake and sphericity of the spherical BC. To do so, Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were employed as tools for morphological and chemical evaluations. Among the parameters analyzed, the carbon source had the greatest effect on the production of dry mass and water uptake. Glycerol had the greatest growing rate, generating a higher dry mass production with spherical and homogeneous bodies with excellent water absorption indexes. Furthermore, the morphological analysis of BC revealed a typical structure, with high crystallinity index and the presence of typical functional groups. These results indicate a path for the optimized and controlled production of spherical BC, allowing it to be used in many applications, such as enzyme immobilization, water treatment, bone regeneration, spherical cancer model, as adsorption agent and drug delivery.

Forced fluid fluctuations in cylindrical reservoirs under vertical excitation

The shell and shell structures containing various types of liquid fillers can be exposed to intense dynamic effects during the exploitation. In order to analyze the strength of structures in these conditions, it is necessary to take into account nonlinear phenomena in fluid motion, since the application of linear equations does not provide an adequate assessment for the determination of the pressure and amplitude of the splashing. In this paper, a study of fluid fluctuations in a rigid cylindrical reservoir partially filled with the liquid under condition of vertical agitation has been carried out. The systems of differential equations that correspond to the linear and nonlinear formulation of the problem are presented. The fluid is believed to be perfect and incompressible, and its movement induced by external influences is non-vortex. Under these conditions there is a velocity potential that satisfies the Laplace equation. The conditions of non-leakage on the wetted surfaces of the shell are chosen as the boundary conditions for solving the boundary value problem. The kinematic and static conditions are specified on a free surface. The static condition consists in the equality of pressure on the liquid surface with atmospheric pressure. The pressure is determined from the Cauchy-Lagrange integral. In this case the linearization of the Cauchy-Lagrange integral leads to the linear formulation of the problem. Quadratic components are taken into account for the nonlinear formulation. To formulate the kinematic condition an additional unknown function describing the motion of the free surface is introduced. The kinematic condition is the equality of the liquid velocity described by the velocity potential and the velocity of the free surface itself. If there is a vertical agitation, an additional acceleration will be present. Therefore for the linear formulation we obtain a system of unbounded differential equations, each of which is the equation of Mathieu. This allows us to investigate the phenomena of parametric resonance. When analyzing differential equations which occur in case of a nonlinear problem, it has been found that the solutions of such equations depend essentially on the initial conditions. The phase portraits of a dynamic system with indication of resonances are presented. A numerical analysis of the differential equation corresponding to nonlinear formulation has been carried out.

FTIR Spectral and Microarchitectural Analysis of Cellulose Produced by Lactococcus lactis Under Agitated Condition

FTIR Spectral and Microarchitectural Analysis of Cellulose Produced by Lactococcus lactis Under Agitated Condition

Conditional Function of Autoaggregative Protein Cah and Common cah Mutations in Shiga Toxin-Producing Escherichia coli.

Cah is a calcium-binding autotransporter protein involved in autoaggregation and biofilm formation. Although cah is widespread in Shiga toxin-producing Escherichia coli (STEC), we detected mutations in cah at a frequency of 31.3% in this pathogen. In STEC O157:H7 supershedder strain SS17, a large deletion results in a smaller coding sequence, encoding a protein lacking the C-terminal 71 amino acids compared with Cah in STEC O157:H7 strain EDL933. We examined the function of Cah in biofilm formation and host colonization to better understand the selective pressures for cah mutations. EDL933-Cah played a conditional role in biofilm formation in vitro: it enhanced E. coli DH5α biofilm formation on glass surfaces under agitated culture conditions that prevented autoaggregation but inhibited biofilm formation under hydrostatic conditions that facilitated autoaggregation. This function appeared to be strain dependent since Cah-mediated biofilm formation was diminished when an EDL933 cah gene was expressed in SS17. Deletion of cah in EDL933 enhanced bacterial attachment to spinach leaves and altered the adherence pattern of EDL933 to bovine recto-anal junction squamous epithelial (RSE) cells. In contrast, in trans expression of EDL933 cah in SS17 increased its attachment to leaf surfaces, and in DH5α, it enhanced its adherence to RSE cells. Hence, the ecological function of Cah appears to be modulated by environmental conditions and other bacterial strain-specific properties. Considering the prevalence of cah in STEC and its role in attachment and biofilm formation, cah mutations might be selected in ecological niches in which inactivation of Cah would result in an increased fitness in STEC during colonization of plants or animal hosts.IMPORTANCE Shiga toxin-producing Escherichia coli (STEC) harbors genes encoding diverse adhesins, and many of these are known to play an important role in bacterial attachment and host colonization. We demonstrated here that the autotransporter protein Cah confers on E. coli DH5α cells a strong autoaggregative phenotype that is inversely correlated with its ability to form biofilms and plays a strain-specific role in plant and animal colonization by STEC. Although cah is widespread in the STEC population, we detected a mutation rate of 31.3% in cah, which is similar to that reported for rpoS and fimH The formation of cell aggregates due to increased bacterium-to-bacterium interactions may be disadvantageous to bacterial populations under conditions that favor a planktonic state in STEC. Therefore, a loss-of-function mutation in cah is likely a selective trait in STEC when autoaggregative properties become detrimental to bacterial cells and may contribute to the adaptability of STEC to fluctuating environments.

3D aggregate culture improves metabolic maturation of human pluripotent stem cell derived cardiomyocytes

Three-dimensional (3D) cultures of human pluripotent stem cell derived cardiomyocytes (hPSC-CMs) hold great promise for drug discovery, providing a better approximation to the in vivo physiology over standard two-dimensional (2D) monolayer cultures. However, the transition of CM differentiation protocols from 2D to 3D cultures is not straightforward. In this work, we relied on the aggregation of hPSC-derived cardiac progenitors and their culture under agitated conditions to generate highly pure cardiomyocyte aggregates. Whole-transcriptome analysis and 13 C-metabolic flux analysis allowed to demonstrate at both molecular and fluxome levels that such 3D culture environment enhances metabolic maturation of hiPSC-CMs. When compared to 2D, 3D cultures of hiPSC-CMs displayed down-regulation of genes involved in glycolysis and lipid biosynthesis and increased expression of genes involved in OXPHOS. Accordingly, 3D cultures of hiPSC-CMs had lower fluxes through glycolysis and fatty acid synthesis and increased TCA-cycle activity. Importantly, we demonstrated that the 3D culture environment reproducibly improved both CM purity and metabolic maturation across different hPSC lines, thereby providing a robust strategy to derive enriched hPSC-CMs with metabolic features closer to that of adult CMs.

Underestimated effects of sediments on enhanced startup performance of biofilm systems for polluted source water pretreatment.

In order to evaluate the enhancement mechanisms of enhanced startup performance in biofilm systems for polluted source water pretreatment, three lab-scale reactors with elastic stereo media (ESM) were operated under different enhanced sediment and hydraulic agitation conditions. It is interesting to found the previously underestimated or overlooked effects of sediment on the enhancement of pollutants removal performance and enrichment of functional bacteria in biofilm systems. The maximum NH4+-N removal rate of 0.35mg L-1 h-1 in sediment enhanced condition was 2.19 times of that in control reactor. Sediment contributed to 42.0-56.5% of NH4+-N removal and 15.4-41.2% of total nitrogen removal in different reactors under different operation conditions. The enhanced hydraulic agitation with sediment further improved the operation performance and accumulation of functional bacteria. Generally, Proteobacteria (48.9-52.1%), Bacteroidetes (18.9-20.8%) and Actinobacteria (15.7-18.5%) were dominant in both sediment and ESM bioiflm at phylum level. The potentially functional bacteria found in sediment and ESM biofilm samples with some functional bacteria mainly presented in sediment samples only (e.g., Genera Bacillus and Lactococcus of Firmicutes phylum) may commonly contribute to the removal of nitrogen and organics.

Ultrasound assisted photocatalytic oxidative desulfurization of model diesel fuel

ABSTRACTUltrasound assisted photocatalytic oxidation technology is an efficient and gentle technology to remove the organic sulfur from diesel. The influence parameters of catalytic oxidation phase include catalyst dosage, reaction temperature, oxidation time, hydrogen peroxide to diesel fuel ratio and time of the extraction process. Furthermore, the comparison of the results under two conditions of ultrasound irradiation and mechanical agitation are also specially examined. The obtained results indicate that under the optimal condition, ultrasound assisted oxidative desulfurization (UAOD) is more efficient for sulfur removal which the desulfurization degree can be reached 99.47%.

Use of rice husk in waste cooking oil pretreatment

ABSTRACTSince industrial wastes are increasing, the development of studies to find ways for their use is urgent. Waste cooking oil is an important source for the production of biodiesel, one of the main biofuels in Brazil. However, during cooking, the oil undergoes conditions that change its properties and decrease its quality, such as its acidity value. Current research treats waste cooking oil by the adsorption process using rice husk, an agro-industrial waste, and activated carbon to compare results. The potential of the adsorbents to remove free fatty acids in waste cooking oil has been investigated by the batch technique, evaluating different operating conditions of temperature, adsorbent mass and agitation. Adsorbents were characterized by nitrogen physisorption, scanning electron microscope, energy-dispersive spectroscopy and X-ray diffraction. The maximum result obtained for activated carbon at acidity reduction was 63%, using 22.4°C, 169.64 rpm and 3.39 g of adsorbent mass. Already, using the rice husk the percentage of removal was the same, 63% using 22.4°C, 80.36 rpm and 1.61 g of adsorbent, however in shorter times. The results prove that the application of the rice husk for this purpose is advantageous, for being a low-cost material, available on a large scale and that provide results similar to activated carbon.

Optimization of Bacillus subtilis natto growth parameters in glycerol-based medium for vitamin K (Menaquinone-7) production in biofilm reactors.

Menaquinone-7 (MK-7) is the key form of vitamin K used as a dietary supplement and its production revolves around Bacillus subtilis natto. Current fermentation strategies, which suggest static fermentations without aeration and agitation, can be problematic for large scale MK-7 production due to biofilm formation. The use of biofilm reactors, therefore, is proposed in the present study, which could utilize both agitation and aeration without interrupting MK-7 secretion. In this study, biofilm reactors were constructed using the selected plastic composite support (PCS) and B. subtilis natto strain for MK-7 production. Using response surface methodology (RSM), optimum growth parameters including temperature, pH, and agitation were determined in a glycerol-based medium. Results were presented in a statistical model (R 2 = 0.90), leading to optimum growth conditions of temperature (35°C), agitation (200rpm) and pH (6.58). Model-predicted MK-7 concentration was validated and MK-7 concentration of 12.09mg/L was produced in the biofilm reactor. The obtained concentration was 58% higher as compared to the suspended-cell culture (7.67mg/L). The results of this study will provide a critical step towards improved industrial scale production of MK-7.

Thermal and Rheological Properties of Crude Tall Oil for Use in Biodiesel Production

The primary objective of this work was to investigate the thermal and rheological properties of crude tall oil (CTO), a low-cost by-product from the Kraft pulping process, as a potential feedstock for biodiesel production. Adequate knowledge of CTO properties is a prerequisite for the optimal design of a cost-effective biodiesel process and related processing equipment. The study revealed the correlation between the physicochemical properties, thermal, and rheological behavior of CTO. It was established that the trans/esterification temperature for CTO was greater than the temperature at which viscosity of CTO entered a steady-state. This information is useful in the selection of appropriate agitation conditions for optimal biodiesel production from CTO. The point of interception of storage modulus (G′) and loss modulus (G′′) determined the glass transition temperature (40 °C) of CTO that strongly correlated with its melting point (35.3 °C). The flow pattern of CTO was modeled as a non-Newtonian fluid. Furthermore, due to the high content of fatty acids (FA) in CTO, it is recommended to first reduce the FA level by acid catalyzed methanolysis prior to alkali treatment, or alternatively apply a one-step heterogeneous or enzymatic trans/esterification of CTO for high-yield biodiesel production.

Optimization and mechanisms for biodecoloration of a mixture of dyes by Trichosporon akiyoshidainum HP 2023

ABSTRACTTrichosporon akiyoshidainum HP2023 is a basidiomycetous yeast isolated from Las Yungas rainforest (Tucumán, Argentina) and selected based on its outstanding textile-dye-decolorizing ability. In this work, the decolorization process was optimized using Reactive Black 5 as dye model. Lactose and urea were chosen as carbon and nitrogen sources through a one-at-time approach. Afterwards, factorial designs were employed for medium optimization, leading to the formulation of a simpler optimized medium which contains in g L−1: lactose 10, yeast extract 1, urea 0.5, KH2PO4 1 and MgSO4 1. Temperature and agitation conditions were also optimized. The optimized medium and incubation conditions for dye removal were extrapolated to other dyes individually and a mixture of them. Dye removal process happened through both biosorption and biodegradation mechanisms, depending primarily on the dye structure. A positive relation between initial inoculum and dye removal rate and a negative relation between initial dye concentration and final dye removal percentages were found. Under optimized conditions, T. akiyoshidainum HP2023 was able to completely remove a mixture of dyes up to a concentration of 300 mg L−1, a concentration much higher than those expected in real effluents.

Parameters for MDBK cell growth on microcarriers and BoHV-1 virus production

Bovine herpes virus 1 (BoHV-1) is an important veterinary agent , which causes infectious bovine rhinotra-cheitis. This disease affects the respiratory tract or genitals, causing weight loss, reduced milk production and abor-tion. Several vaccines against BoHV-1 have been developed. In this paper, we study the parameters for MDBK growth on microcarriers (Cytodex 1) and for BoHV-1 virus production. The cell culture attached to microcarriers is an effi-cient method to enlarge the surface of cell growth and for large-scale cell production. Our studies reveal that MDBK adhered to MCs in 30 minutes and that initial agitation of culture did not influence on the efficiency of adhesion or cell growth. In our experiments, we detected no relevant influence of agitation on initial cell adhesion of MDBK to MCs. The maximum cell yield was similar to all initial conditions of agitation studied. The maximum yield obtained in culture started with 15, 20 and 30 cells / MC, was respectively.8.7 x105, 9.3 x105 and 9.8 x105 cells / ml . The cellular distribution on the MCs at the beginning of the culture was more heterogeneous in higher initial densities. After three medium exchanges during MDBK cell culture, the increase in the final yield was 100% higher than that from culture performed without medium change (0.93 x 106 cells / mL). Replacing 50% of the culture medium with fresh medium after 24 hours of growth, the concentration of glucose (5 mM) and glutamine (1.8 mM) were almost completely res-tored. In these studies, BoHV-1 infections of MDBK were performed after 48, 72 and 86 hours with daily exchanges of 50% of the medium. The increase in viral titer was proportional to the number of viable cells present at the time of infection. The best result of BoHV-1 production was achieved when the infection was performed from 86 hours of cell culture, reaching about 3.7 x108 (TCID50/ml) after 24-48 hours of infection, being on average four times higher when compared to the culture in which the infection was performed with 48 hours of culture and approximately 2 times greater than the crop whose infection occurred after 72 hours of culture. The best yields are obtained when viral infections were performed on cultures with higher cell densities. The best result for the production of BoHV-1 occur-red with 10 MOI, 48 hours after infection, which yield was 24 and 41% superior to the MOI 0.1 and 1, respectively.

Elucidation of insulin assembly at acidic and neutral pH: Characterization of low molecular weight oligomers.

Deficiency in insulin secretion and function that characterize type 2 diabetes often requires administration of extraneous insulin, leading to injection-site amyloidosis. Insulin aggregation at neutral pH is not well understood. Although oligomer formation is believed to play an important role, insulin oligomers have not been fully characterized yet. Here, we elucidate similarities and differences between in vitro insulin aggregation at acidic and neutral pH for a range of insulin concentrations (2.5-100 μM) by using kinetic thioflavin T fluorescence, circular dichroism, atomic force and electron microscopy imaging. Importantly, we characterize the size distribution of insulin oligomers at different assembly stages by the application of covalent cross-linking and gel electrophoresis. Our results show that at the earliest assembly stage, oligomers comprise up to 40% and 70% of soluble insulin at acidic and neutral pH, respectively. While the highest oligomer order increases with insulin concentration at acidic pH, the opposite tendency is observed at neutral pH, where oligomers up to heptamers are formed in 10 μM insulin. These findings suggest that oligomers may be on- and off-pathway assemblies for insulin at acidic and neutral pH, respectively. Agitation, which is required to induce insulin aggregation at neutral pH, is shown to increase fibril formation rate and fibrillar mass both by an order of magnitude. Insulin incubated under agitated conditions at neutral pH rapidly aggregates into large micrometer-sized aggregates, which may be of physiological relevance and provides insight into injection-site amyloidosis and toxic pulmonary aggregates induced by administration of extraneous insulin.

2-Arachidonoylglycerol metabolism is differently modulated by oligomeric and fibrillar conformations of amyloid beta in synaptic terminals

Alzheimer’s disease (AD) is the most prevalent disorder of senile dementia mainly characterized by amyloid-beta peptide (Aβ) deposits in the brain. Cannabinoids are relevant to AD as they exert several beneficial effects in many models of this disease. Still, whether the endocannabinoid system is either up- or down-regulated in AD has not yet been fully elucidated. Thus, the aim of the present paper was to analyze endocannabinoid 2-arachidonoylglycerol (2-AG) metabolism in cerebral cortex synaptosomes incubated with Aβ oligomers or fibrils. These Aβ conformations were obtained by “aging” the 1-40 fragment of the peptide under different agitation and time conditions. A diminished availability of 2-AG resulting from a significant decrease in diacylglycerol lipase (DAGL) activity was observed in the presence of large Aβ1-40 oligomers along with synaptosomal membrane damage, as judged by transmission electron microscopy and LDH release. Conversely, a high availability of 2-AG resulting from an increase in DAGL and lysophosphatidic acid phosphohydrolase activities occurred in the presence of Aβ1-40 fibrils although synaptosomal membrane disruption was also observed. Interestingly, neither synaptosomal mitochondrial viability assayed by MTT reduction nor membrane lipid peroxidation assayed by TBARS formation measurements were altered by Aβ1-40 oligomers or fibrils. These results show a differential effect of Aβ1-40 peptide on 2-AG metabolism depending on its conformation.