Economic Production Process Research Articles

Culture Medium Development for Microbial-Derived Surfactants Production-An Overview.

Surfactants are compounds that can reduce the surface tension between two different phases or the interfacial tension of the liquid between water and oil, possessing both hydrophilic and hydrophobic moieties. Biosurfactants have traits that have proven to be advantageous over synthetic surfactants, but these compounds do not compete economically with synthetic surfactants. Different alternatives increase the yield of biosurfactants; development of an economical production process and the usage of cheaper substrates during process have been employed. One of the solutions relies on the suitable formulation of a production medium by including alternative raw materials sourced from agro-wastes, hydrocarbons, or by-products of a process might help in boosting the biosurfactant production. Since the nutritional factors required will be different among microorganisms, the establishment of a suitable formulation for biosurfactant production will be challenging. The present review describes various nutrients and elements considered in the formulation of a production medium with an approach focusing on the macronutrient (carbon, nitrogen source, and C/N ratio), minerals, vitamins, metabolic regulators, and salinity levels which may aid in the study of biosurfactant production in the future.

Metabolome- and genome-scale model analyses for engineering of Aureobasidium pullulans to enhance polymalic acid and malic acid production from sugarcane molasses

BackgroundPolymalic acid (PMA) is a water-soluble biopolymer with many attractive properties for food and pharmaceutical applications mainly produced by the yeast-like fungus Aureobasidium pullulans. Acid hydrolysis of PMA, resulting in release of the monomer l-malic acid (MA), which is widely used in the food and chemical industry, is a competitive process for producing bio-based platform chemicals.ResultsIn this study, the production of PMA and MA from sucrose and sugarcane molasses by A. pullulans was studied in shake flasks and bioreactors. Comparative metabolome analysis of sucrose- and glucose-based fermentation identified 81 intracellular metabolites and demonstrated that pyruvate from the glycolysis pathway may be a key metabolite affecting PMA synthesis. In silico simulation of a genome-scale metabolic model (iZX637) further verified that pyruvate carboxylase (pyc) via the reductive tricarboxylic acid cycle strengthened carbon flux for PMA synthesis. Therefore, an engineered strain, FJ-PYC, was constructed by overexpressing the pyc gene, which increased the PMA titer by 15.1% compared with that from the wild-type strain in a 5-L stirred-tank fermentor. Sugarcane molasses can be used as an economical substrate without any pretreatment or nutrient supplementation. Using fed-batch fermentation of FJ-PYC, we obtained the highest PMA titers (81.5, 94.2 g/L of MA after hydrolysis) in 140 h with a corresponding MA yield of 0.62 g/g and productivity of 0.67 g/L h.ConclusionsWe showed that integrated metabolome- and genome-scale model analyses were an effective approach for engineering the metabolic node for PMA synthesis, and also developed an economical and green process for PMA and MA production from renewable biomass feedstocks.

Bridge inspection practices and bridge management programs in China, Japan, Korea, and U.S.

The present study reviews bridge inspection practices and bridge management programs in China, Japan, Korea, and U.S. Bridges play an essential role in transportation systems and in the economic production process. Transportation agencies should maintain bridges in acceptable conditions to provide a desirable level of service to the public within limited budgets. In addition, a number of bridges are aging rapidly in these four countries. Fortunately, since several countries have experienced deteriorated bridges due to aging, the countries considered in this study have already developed comprehensive bridge management system (BMS) and bridge inspection practices. Therefore, the goal of this paper is to search for and synthesize useful knowledge on BMSs and bridge inspection practices of the four countries. Finally, recommendations that will serve as guidance to transportation agencies for potential enhancements to BMS and bridge inspections are presented.

External effects in the maritime sector leading to new economic perspectives.

Our present economic system is facing some real challenges. It is a so-called linear system like “take-make-use-lose”. Sustainable economic development requires valuing (environmental) resources correctly and factoring them into production and consumption decisions. Having a focus on the economic production process, external effects do not seem to fit in the linear system. So-called external effects are not included in economic models, business decisions etc. External effects like the Sustainable Development goals and legal actions in court are of growing importance for economic developments ranging from port development to design of ships and logistics. The distinction Economic Capital, Social Capital and Natural Capital is helpful in creating consciousness about the concept of circular economy. Nature provides tools, systems and knowledge from 3.8 billion years of evolution that will enable us to enter and develop new circular economic developments, to develop real "green ports”; to combine divergent functions in a smart way.

Prospects for pretreatment methods of lignocellulosic waste biomass for biogas enhancement: opportunities and challenges

ABSTRACTLignocellulose biomass/lignocellulosic waste biomass (LCB/LCWB) represents the largest renewable pool for potentially fermentable carbohydrates, which provides a good solution for bioenergy production. Although it is assumed to have a lower theoretical yield for biogas than waste material made of sugar or starch, it is free from the problems associated with other generations of biofuels. An inexpensive and efficient pretreatment method of LCB/LCWB is highly desired to achieve an economical biogas production process. This paper reviews the conventional, advanced and infant (i.e. under development) pretreatment methods that have been studied for enhancement of biogas production. In addition to various pretreatment methods, this article also reviews further aspects of the conventional, advanced and infant methods (nanotechnolgy) for pretreatment of LCB/LCWB. Thus, the article provides systematic technological strategies and new pretreatment approaches for sustainable bioprocessing of LCB/LCWB into value-added product.

EMPLOYEE BENEFITS AS ONE OF FACTORS OF WORK MOTIVATION

Behind a successful company there are several factors which affect its activities and performance. These are various economic issues, production processes, capital and people- employees. The human resources of a company largely depend on how the company is able to respond to challenges of the market. Employers are recently trying to take care of their employees much more than just rewarding them with a salary. They provide them a variety of employee benefits with which they try to motivate them to better perform. The aim of the paper is to describe the system of benefits provided by companies in general. The first part of paper contains a general framework of the issue and the second part describes the current situation of providing benefits in Slovakia and abroad, specifically in the United States. The paper highlights the differences in understanding of importance of benefits in each country. The final part of the paper contains research about opinions of students of the University of Žilina about providing benefits at the workplace.

Batch and semicontinuous production of l-ascorbyl oleate catalyzed by CALB immobilized onto Purolite® MN102

l-Ascorbyl oleate is recognized as efficient liposoluble antioxidant and biosurfactant which can be synthesized by using immobilized lipases as catalysts in organic media. However, development of economical production process is still a challenge, particularly in (semi)continuous systems. Hereby, we present application of novel immobilized lipase preparation, lipase B from Candida antarctica hydrophobically adsorbed onto styrene divinylbenzene based support, for the synthesis of l-ascorbyl oleate in batch bioreactor (BB) and fluidized bed bioreactor (FBB) with recirculation of reaction medium. Reaction kinetics was described by Ping Pong bi bi mechanism with low acyl donor inhibition. Considerably higher reaction rates (∼40%) were accomplished in FBB. Hydrodynamic study revealed that reaction is kinetically controlled and unhindered external and internal mass transfer was enabled in both systems. However, much higher shear stress occurred in BB (10.46Pa) comparing to FBB (5×10−2Pa). After 12 consecutive reaction cycles lasting 24h, 23.13g of product per gram of biocatalyst was synthesized in a FBB. Within this study, usage of new immobilized enzyme in semicontinuous system enabled high reaction rates and satisfying operational stability in the synthesis of l-ascorbyl oleate, offering good prospect for further process development.

Orientation imaging of macro-sized polysilicon grains on wafers using spatially resolved acoustic spectroscopy

Due to its economical production process polysilicon, or multicrystalline silicon, is widely used to produce solar cell wafers. However, the conversion efficiencies are often lower than equivalent monocrystalline or thin film cells, with the structure and orientation of the silicon grains strongly linked to the efficiency. We present a non-destructive laser ultrasonic inspection technique, capable of characterising large (52×76mm2) photocell's microstructure - measurement times, sample surface preparation and system upgrades for silicon scanning are discussed. This system, known as spatially resolved acoustic spectroscopy (SRAS) could be used to optimise the polysilicon wafer production process and potentially improve efficiency.

Efficient de novo synthesis of resveratrol by metabolically engineered Escherichia coli.

Resveratrol has been the subject of numerous scientific investigations due to its health-promoting activities against a variety of diseases. However, developing feasible and efficient microbial processes remains challenging owing to the requirement of supplementing expensive phenylpropanoic precursors. Here, various metabolic engineering strategies were developed for efficient de novo biosynthesis of resveratrol. A recombinant malonate assimilation pathway from Rhizobium trifolii was introduced to increase the supply of the key precursor malonyl-CoA and simultaneously, the clustered regularly interspaced short palindromic repeats interference system was explored to down-regulate fatty acid biosynthesis pathway to inactivate the malonyl-CoA consumption pathway. Down-regulation of fabD, fabH, fabB, fabF, fabI increased resveratrol production by 80.2, 195.6, 170.3, 216.5 and 123.7%, respectively. Furthermore, the combined effect of these genetic perturbations was investigated, which increased the resveratrol titer to 188.1mg/L. Moreover, the efficiency of this synthetic pathway was improved by optimizing the expression level of the rate-limiting enzyme TAL based on reducing mRNA structure of 5' region. This further increased the final resveratrol titer to 304.5mg/L. The study described here paves the way to the development of a simple and economical process for microbial production of resveratrol.

Bio-immobilization of dark fermentative bacteria for enhancing continuous hydrogen production from cornstalk hydrolysate

Mycelia pellets were employed as biological carrier in a continuous stirred tank reactor to reduce biomass washout and enhance hydrogen production from cornstalk hydrolysate. Hydraulic retention time (HRT) and influent substrate concentration played critical roles on hydrogen production of the bioreactor. The maximum hydrogen production rate of 14.2mmol H2L−1h−1 was obtained at optimized HRT of 6h and influent concentration of 20g/L, 2.6 times higher than the counterpart without mycelia pellets. With excellent immobilization ability, biomass accumulated in the reactor and reached 1.6g/L under the optimum conditions. Upon further energy conversion analysis, continuous hydrogen production with mycelia pellets gave the maximum energy conversion efficiency of 17.8%. These results indicate mycelia pellet is an ideal biological carrier to improve biomass retention capacity of the reactor and enhance hydrogen recovery efficiency from lignocellulosic biomass, and meanwhile provides a new direction for economic and efficient hydrogen production process.

Amylase Production from Thermophilic Bacillus sp. BCC 021-50 Isolated from a Marine Environment

The high cost of fermentation media is one of the technical barriers in amylase production from microbial sources. Amylase is used in several industrial processes or industries, for example, in the food industry, the saccharification of starchy materials, and in the detergent and textile industry. In this study, marine microorganisms were isolated to identify unique amylase-producing microbes in starch agar medium. More than 50 bacterial strains with positive amylase activity, isolated from marine water and soil, were screened for amylase production in starch agar medium. Bacillus sp. BCC 021-50 was found to be the best amylase-producing strain in starch agar medium and under submerged fermentation conditions. Next, fermentation conditions were optimized for bacterial growth and enzyme production. The highest amylase concentration of 5211 U/mL was obtained after 36 h of incubation at 50 °C, pH 8.0, using 20 g/L molasses as an energy source and 10 g/L peptone as a nitrogen source. From an application perspective, crude amylase was characterized in terms of temperature and pH. Maximum amylase activity was noted at 70 °C and pH 7.50. However, our results show clear advantages for enzyme stability in alkaline pH, high-temperature, and stability in the presence of surfactant, oxidizing, and bleaching agents. This research contributes towards the development of an economical amylase production process using agro-industrial residues.

Fluidized Bed Production of Surface Functionalized Powders for Solid Oxide Fuel Cell Cathodes

Surface functionalized powders were produced using the novel technique of fluidized bed chemical vapor deposition. Test structures of SOFC cathodes were fabricated from coated and uncoated powder samples, using standard screen printing and sintering techniques. Electrochemical impedance spectroscopy showed the surface functionalized powers to outperform uncoated cathode powder, in all cases, in the temperature range of 600 C to 800 C. Fluidized bed chemical vapor deposition is shown to be an effective and economical process for production of high performance SOFC cathode materials.

Solvent recovery and deacidification by organic solvent nanofiltration: Experimental investigation and mass transfer modeling

Non-edible oils, waste oils and animal fats are promising feedstocks for more economic and ecological production processes. However, the composition of these low-quality oils, especially the content of free fatty acids, strongly fluctuates requiring the development of flexible process concepts. Therefore, this study investigates the potential of organic solvent nanofiltration for important applications in the oleochemical industry. It is shown that an efficient recovery of non-polar extraction solvents is possible for a wide range of low-quality oils. Commercially available PDMS-based membranes enable high solvent fluxes and rejection of triglyceride and fatty acids. In deacidification experiments, high selective separation of free fatty acids from triglycerides for long-chain as well as medium-chain oils is achieved by using polar solvents and available polyimide-based membranes. The amount of solvent, which is added to the low-quality oils, is identified as crucial parameter for separation efficiency. Membrane performance is accurately described by a (reduced) solution-diffusion model with imperfections, for which mass transfer of solvents and fatty acids is described by the convective contribution, while mass transfer of triglycerides is described by the diffusive contribution.

Downstream Process Synthesis for Microbial Steroids.

Systematic and holistic process development, considering upstream and downstream processing simultaneously, is crucial for designing effective and economical production processes. Based on a multiphasic fermentation process, where oil is added to improve substrate solubility, a systematic approach for the purification of microbial steroids is presented. The design methodology incorporates expert knowledge in the form of heuristics to generate different downstream processing alternatives for processing the complex, multiphasic fermentation broth, and recovering the target steroid precursor androst-4-ene-3,17-dione (androstenedione; AD). The resulting alternative tree of different purification techniques is evaluated using scouting experiments to check the performance of each technique. Purification steps such as extraction, adsorption-desorption, and precipitation seem most promising and have been investigated in detail. Each process step selected is optimized and connected to a process route for recovering AD.

Metabolic engineering of Clostridium tyrobutyricum for enhanced butyric acid production from glucose and xylose

Clostridium tyrobutyricum is a promising microorganism for butyric acid production. However, its ability to utilize xylose, the second most abundant sugar found in lignocellulosic biomass, is severely impaired by glucose-mediated carbon catabolite repression (CCR). In this study, CCR in C. tyrobutyricum was eliminated by overexpressing three heterologous xylose catabolism genes (xylT, xylA and xlyB) cloned from C. acetobutylicum. Compared to the parental strain, the engineered strain Ct-pTBA produced more butyric acid (37.8g/L vs. 19.4g/L) from glucose and xylose simultaneously, at a higher xylose utilization rate (1.28g/L·h vs. 0.16g/L·h) and efficiency (94.3% vs. 13.8%), resulting in a higher butyrate productivity (0.53g/L·h vs. 0.26g/L·h) and yield (0.32g/g vs. 0.28g/g). When the initial total sugar concentration was ~120g/L, both glucose and xylose utilization rates increased with increasing their respective concentration or ratio in the co-substrates but the total sugar utilization rate remained almost unchanged in the fermentation at pH 6.0. Decreasing the pH to 5.0 significantly decreased sugar utilization rates and butyrate productivity, but the effect was more pronounced for xylose than glucose. The addition of benzyl viologen (BV) as an artificial electron carrier facilitated the re-assimilation of acetate and increased butyrate production to a final titer of 46.4g/L, yield of 0.43g/g sugar consumed, productivity of 0.87g/L·h, and acid purity of 98.3% in free-cell batch fermentation, which were the highest ever reported for butyric acid fermentation. The engineered strain with BV addition thus can provide an economical process for butyric acid production from lignocellulosic biomass.

Core tenets of the theory of ecologically unequal exchange

In this article, core tenets and claims of the theory of ecologically unequal exchange (EUE) are synthesized. EUE theory postulates a net flow of natural resources from peripheral developing to core industrialized countries through international trade, a situation which undermines the development of the periphery while enhancing that of the core. The key claims and EUE mechanisms are categorized and discussed under three topics: 1) the structure of the capitalist world-economy, 2) monetary valuation, and 3) equity and justice. The treadmill logic of capitalism in which capital extracts ecological resources and release waste in an endless pursuit of profits creates an expansionary dynamic which draws peripheral countries into exploitative market relations. This peripheralization is supported by 'free trade' economic policies, while nation-states and other political-economic institutions such as the WTO and IMF provide the regulations which ensure proper functioning of the system. Monetary valuation caps it by obscuring the inverse relationship between thermodynamics and economics, in which low-entropy energy and materials indispensable in economic production processes are lowly priced while processed goods which have dissipated most of their matter-energy are highly priced, ensuring that biophysical resources and profits accumulates in the industrialized Northern countries. This EUE framework is applied to the EU's Raw Materials Initiative from the vantage point of policy as implicit theory. By challenging mainstream policies and their underlying theories, the EUE perspective demonstrates that alternatives to neoliberal policy prescriptions exist and policy can play a crucial role in bringing about the necessary structural changes.Key words: ecologically unequal exchange, environmental justice, EU, capitalism, free trade, policy

Production and Properties of a Thermostable, pH-Stable Exo-Polygalacturonase Using Aureobasidium pullulans Isolated from Saharan Soil of Algeria Grown on Tomato Pomace.

Polygalacturonase is a valuable biocatalyst for several industrial applications. Production of polygalacturonase using the Aureobasidium pullulans stain isolated from Saharan soil of Algeria was investigated. Its capacity to produce polygalacturonase was assessed under submerged culture using tomato pomace as an abundant agro-industrial substrate. Optimization of the medium components, which enhance polygalacturonase activity of the strain Aureobasidium pullulans, was achieved with the aid of response surface methodology. The composition of the optimized medium was as follows: tomato pomace 40 g/L, lactose 1.84 g/L, CaCl20.09 g/L and pH 5.16. Practical validation of the optimum medium provided polygalacturonase activity of 22.05 U/mL, which was 5-fold higher than in unoptimized conditions. Batch cultivation in a 20 L bioreactor performed with the optimal nutrients and conditions resulted in a high polygalacturonase content (25.75 U/mL). The enzyme showed stability over a range of temperature (5–90 °C) with an optimum temperature of 60 °C with pH 5.0, exhibiting 100% residual activity after 1h at 60 °C. This enzyme was stable at a broad pH range (5.0–10). The enzyme proved to be an exo-polygalacturonase, releasing galacturonic acid by hydrolysis of polygalacturonic acid. Moreover, the exo-polygalacturonase was able to enhance the clarification of both apple and citrus juice. As a result, an economical polygalacturonase production process was defined and proposed using an industrial food by-product.

Dealing with endogeneity in data envelopment analysis applications

Although the presence of the endogeneity is frequently observed in economic production processes, it tends to be overlooked when practitioners apply data envelopment analysis (DEA). In this paper we deal with this issue in two ways. First, we provide a simple statistical heuristic procedure that enables practitioners to identify the presence of endogeneity in an empirical application. Second, we propose the use of an instrumental input DEA (II-DEA) as a potential tool to address this problem and thus improve DEA estimations. A Monte Carlo experiment confirms that the proposed II-DEA approach outperforms standard DEA in finite samples under the presence of high positive endogeneity. To illustrate our theoretical findings, we perform an empirical application on the education sector.

Stepwise modular pathway engineering of Escherichia coli for efficient one-step production of (2S)-pinocembrin

Developing efficient microbial processes to produce flavonoids has been a metabolic engineering goal over the past decade due to their important functions. Previously, the de novo production of the main flavonoid precursor (2S)-pinocembrin was achieved. However, low productivity and two separate fermentation steps made it inappropriate for industrial scale low-cost production. Here, a stepwise modular engineering approach was introduced to systematically identify and eliminate metabolic pathway bottlenecks. The overall pathway was firstly divided into four modules and analysis then revealed that efficient conversion of l-phenylalanine to (2S)-pinocembrin is the major limiting factor. Therefore, the pathway from l-phenylalanine to (2S)-pinocembrin was re-cast into three modules to alleviate this bottleneck by modifying both the gene copy number and promoter strength. Furthermore, the expression of the rate-limiting enzyme PAL was found to be correlated with 5′ region of mRNA structure. The efficiency of the synthetic pathway was then improved by customizing the PAL expression level based on modification of the mRNA secondary structure. Fed-batch cultivation of engineered strains in a 3-L fermentor resulted in a final (2S)-pinocembrin production of 432.4mg/L. The results presented here pave the way for the development of an economical and simple process for microbial production of flavonoids.

A novel process for obtaining phenylpropanoic acid precursor using Escherichia coli with a constitutive expression system.

Phenylpropanoids are widely used in food supplements, pharmaceuticals, and cosmetics with diverse benefits to human health. Trans-cinnamic acid or p-coumaric acid is usually used as the starting precursor to produce phenylpropanoids. Synthetic bioengineering of microbial cell factories offers a sustainable and flexible alternative method for obtaining these compounds. In this study, a constitutive expression system consisting of Rhodotorula glutinis phenylalanine/tyrosine ammonia lyase was developed to produce a phenylpropanoic acid precursor in Escherichia coli. To improve trans-cinnamic acid and p-coumaric acid production, BioBrick optimization was investigated, causing a 7.2- and 14.2-fold increase in the yield of these compounds, respectively. The optimum strain was capable of de novo producing 78.81 mg/L of trans-cinnamic acid and 34.67 mg/L of p-coumaric acid in a shake flask culture. The work presented here paves the way for the development of a sustainable and economical process for microbial production of a phenylpropanoic acid precursor.