Classification system for immobilization techniques

Biotechnological processes call for an overall process optimization. One of the major possibilities of optimizing biotechnological processes lies in immobilization technologies, which may increase productivities and product concentrations. This paper gives a systematic approach to the various immobilization techniques reported in literature. The most important levels of influence on overall process performance are considered within a classification system by three criteria: Substrates and products flow pattern criterion, catalyst criterion and apparatus criterion. Some important immobilization systems are discussed, and the classification system is applied to these examples.     

Microalgae as multi-functional options in modern agriculture: current trends,prospects and challenges

Algae are a group of ubiquitous photosynthetic organisms comprising eukaryotic green algae and Gram-negative prokaryotic cyanobacteria, which have immense potential as a bioresource for various industries related to biofuels, pharmaceuticals, nutraceuticals and feed. This fascinating group of organisms also has applications in modern agriculture through facilitating increased nutrient availability, maintaining the organic carbon and fertility of soil, and enhancing plant growth and crop yields, as a result of stimulation of soil microbial activity. Several cyanobacteria provide nitrogen fertilization through biological nitrogen fixation and through enzymatic activities related to interconversions and mobilization of different forms of nitrogen. Both green algae and cyanobacteria are involved in the production of metabolites such as growth hormones, polysaccharides, antimicrobial compounds, etc., which play an important role in the colonization of plants and proliferation of microbial and eukaryotic communities in soil. Currently, the development of consortia of cyanobacteria with bacteria or fungi or microalgae or their biofilms has widened their scope of utilization. Development of integrated wastewater treatment and biomass production systems is an emerging technology, which exploits the nutrient sequestering potential of microalgae and its valorisation. This review focuses on prospects and challenges of application of microalgae in various areas of agriculture, including crop production, protection and natural resource management. An overview of the recent advances, novel technologies developed, their commercialization status and future directions are also included.     

Stabilization of thymidine phosphorylase from Escherichia coli by immobilization and post immobilization techniques

Homodimeric thymidine phosphorylase from Escherichia coli (TP, E.C. 2.4.2.4) was immobilized on solid support with the aim to have a stable and recyclable biocatalyst for nucleoside synthesis. Immobilization by ionic adsorption on amine-functionalized agarose and Sepabeads^® resulted in a very high activity recovery (>85%). To prevent undesirable leakage of immobilized enzyme away from the support, the ionic preparations were cross-linked with aldehyde dextran (MW 20 kDa) and the influence of the dextran oxidation degree on the resulting biocatalyst activity was evaluated. Although in all cases the percentage of expressed activity after immobilization drastically decreased (≤25%), this procedure allowed to obtain an active catalyst which resulted up to 6-fold and 3-fold more stable than the soluble (non immobilized) enzyme and the just adsorbed (non cross-linked) counterpart, respectively, at pH 10 and 37 °C. No release of the enzyme from the support could be observed. Covalent immobilization on aldehyde or epoxy supports was generally detrimental for enzyme activity. Optimal TP preparation, achieved by immobilization onto Sepabeads^® coated with polyethyleneimine and cross-linked, was successfully used for the one-pot synthesis of 5-fluoro-2′-deoxyuridine starting from 2′-deoxyuridine or thymidine (20 mM) and 5-fluorouracil (10 mM). In both cases, the reaction proceeded at the same rate (3 μmol min⁻¹) affording 62% conversion in 1 h.     

Microalgae potential as a biogas source: current status,restraints and future trends

In recent years, the world energy demands have had a recurrent increase. For this reason the alternative to the fossil fuel resources are trend topics in investigation. Microalgae have been extensively studied as a source of biofuels and as one of the most promising alternatives in this new framework. One of the possibilities of obtaining renewable energy from microalgae is biogas production using anaerobic digestion process. This process is considered a significant component for biofuels and waste management, since represent an opportunity for energy generation using different wastewater products; also, the economic viability of microalgae liquid biofuel production could be improved. However, the anaerobic digestion of microalgae biomass is still not optimized because of the numerous technical limitations such as the microalgae characteristics, low carbon:nitrogen ratio, ammonia toxicity and even salinity. The present review summarizes and compares information concerning to anaerobic digestion of microalgal biomass and future directions for research. Besides, specific operational factors and potential inhibitory parameters of the process are analyzed and compared. Additionally, the paper covers the state or art concerning in methane production enhancement from algal biomass.     

Diol production byAeromonas hydrophila: Comparison of different immobilization techniques

Summary Techniques for immobilizing intact cells ofAeromonas hydrophila by cross-linking, attachment to an inorganic matrix, or entrapment in a polymeric gel are compared. Cells immobilized on a titanium (IV) hydroxide matrix were suitable for producing butane 2,3-diol from starch, whereas cells entrapped in polyacrylamide were a better catalyst for producing the diol from glucose.     

Antigen retrieval techniques: current perspectives.

Development of the antigen retrieval (AR) technique, a simple method of boiling archival paraffin-embedded tissue sections in water to enhance the signal of immunohistochemistry (IHC), was the fruit of pioneering efforts guided by the philosophy of rendering IHC applicable to routine formalin-fixed, paraffin-embedded tissues for wide application of IHC in research and clinical pathology. On the basis of thousands of articles and many reviews, a book has recently been published that summarizes basic principles for practice and further development of the AR technique. Major topics with respect to several critical issues, such as the definition, application, technical principles, and further studies of the AR technique, are highlighted in this article. In particular, a further application of the heat-induced retrieval approach for sufficient extraction of nucleic acids in addition to proteins, and standardization of routine IHC based on the AR technique in terms of a test battery approach, are also addressed. Furthermore, understanding the mechanism of the AR technique may shed light on facilitating the development of molecular morphology.     

A perspective on microarrays: current applications,pitfalls, and potential uses

With advances in robotics, computational capabilities, and the fabrication of high quality glass slides coinciding with increased genomic information being available on public databases, microarray technology is increasingly being used in laboratories around the world. In fact, fields as varied as: toxicology, evolutionary biology, drug development and production, disease characterization, diagnostics development, cellular physiology and stress responses, and forensics have benefiting from its use. However, for many researchers not familiar with microarrays, current articles and reviews often address neither the fundamental principles behind the technology nor the proper designing of experiments. Although, microarray technology is relatively simple, conceptually, its practice does require careful planning and detailed understanding of the limitations inherently present. Without these considerations, it can be exceedingly difficult to ascertain valuable information from microarray data. Therefore, this text aims to outline key features in microarray technology, paying particular attention to current applications as outlined in recent publications, experimental design, statistical methods, and potential uses. Furthermore, this review is not meant to be comprehensive, but rather substantive; highlighting important concepts and detailing steps necessary to conduct and interpret microarray experiments. Collectively, the information included in this text will highlight the versatility of microarray technology and provide a glimpse of what the future may hold.     

Proteomic analysis of synovial fluid: current and potential uses to improve clinical outcomes

Introduction: Synovial fluid (SF) is in close proximity to tissues which are primarily altered during articular disease and has significant potential to better understand the underlying disease pathogeneses of articular pathologies and biomarker discovery. Although development of mass spectrometry-based methods has allowed faster and higher sensitivity techniques, interrogation of the SF proteome has been hindered by its large protein concentration dynamic range, impeding quantification of lower abundant proteins.

Areas covered: Recent advances have developed methodologies to reduce the large protein concentration dynamic range of SF and subsequently allow deeper exploration of the SF proteome. This review concentrates on methods to overcome biofluid complexity, mass spectrometry proteomics methodologies, extracellular vesicles proteomics and the application of advances within the field in clinical disease, including osteoarthritis, rheumatoid arthritis, spondyloarthritis and juvenile arthritis. A narrative review was conducted with articles searched using PubMed, 1991–2018.

Expert opinion: The SF proteomics field faces various challenges, including the requirement for rigorous and standardised methods of sample collection/storage, the sensitivity and specificity of proteomic assays, techniques to combat the large protein concentration dynamic range and comprehensive data analysis to reduce falsely identified markers. Additionally, there are challenges in developing multi ‘omic’ integration techniques, with computational integration enhancing analysis.     

Proteomics: current techniques and potential applications to lung disease

Proteomics aims to study the whole protein content of a biological sample in one set of experiments. Such an approach has the potential value to acquire an understanding of the complex responses of an organism to a stimulus. The large vascular and air space surface area of the lung expose it to a multitude of stimuli that can trigger a variety of responses by many different cell types. This complexity makes the lung a promising, but also challenging, target for proteomics. Important steps made in the last decade have increased the potential value of the results of proteomics studies for the clinical scientist. Advances in protein separation and staining techniques have improved protein identification to include the least abundant proteins. The evolution in mass spectrometry has led to the identification of a large part of the proteins of interest rather than just describing changes in patterns of protein spots. Protein profiling techniques allow the rapid comparison of complex samples and the direct investigation of tissue specimens. In addition, proteomics has been complemented by the analysis of posttranslational modifications and techniques for the quantitative comparison of different proteomes. These methodologies have made the application of proteomics on the study of specific diseases or biological processes under clinically relevant conditions possible. The quantity of data that is acquired with these new techniques places new challenges on data processing and analysis. This article provides a brief review of the most promising proteomics methods and some of their applications to pulmonary research.     

Endomyocardial biopsy: its history,techniques and current indications

Endomyocardial biopsy has found wide application as a diagnostic tool in the practice of cardiology and is of great clinical use in selected cardiac disorders. It is indispensable in the management of cardiac transplant recipients and has become increasingly valuable in the diagnosis of myocarditis and certain cardiomyopathies. Technical difficulties have been overcome, and the procedure is straightforward and of low risk in experienced hands. It is hoped that advances in endomyocardial biopsy will lead to a greater ability of physicians to diagnose and treat cardiac disease.     

Enhanced production techniques,properties and uses of coenzyme Q10

Coenzyme Q10 (CoQ10) is an essential component of the respiratory chain which produces ATP. It is formed from the conjugation of a benzoquinone ring with a hydrophobic isoprenoid chain. Efforts on the production of CoQ10 by microorganisms focus on the development of potent strains by conventional mutagenesis and metabolic engineering especially in Escherichia coli, analysis and modification of the key metabolic pathways and optimization of fermentation strategies. CoQ10 has excellent antioxidant properties and is beneficial in the treatment of several human diseases. The present review covers the current strategies used to improve and/or engineer CoQ10 production in microbes, the yields obtained in light of the current knowledge on the biosynthesis of this molecule. It also highlights the medical effects of CoQ10.     

Microalgae production: technical and economic evaluations

A review of the various literature data for large-scale algae production costs is described. Costs were updated and recomputed in order to compare the different schemes. Total production costs of a nonprocessed biomass range from US$0.15 to US$4.0 kg(-1), according to various authors. Process performance hypotheses and proposed technologies are analyzed to explain these variations. A cost analysis for a tubular bioreactor system is then presented that shows that, assuming a productivity of 60 tons/ha yr, production costs would range from FF24 to FF29 kg(-1) for such a system. Operating costs as well as fixed charges account for approximately 50% of the cost. Parametric sensitivity of these costs is then analyzed: If productivity would be 30, 45, or 90 tons/ha yr, total cost would be around FF48, FF33 and FF19 kg(-1). Advantages and disadvantages of the proposed tubular technology are finally discussed.     

Principles,techniques, and applications of biocatalyst immobilization for industrial application

Immobilization is one of the most effective and powerful tools used in industry, which has been studied and improved since the last century. Various immobilization techniques and support materials have been used on both laboratory and industrial scale. Each immobilization technique is applicable for a specific production mostly depending on the cost and sensibility of process. Compared to free biocatalyst systems, immobilization techniques often offer better stability, increased activity and selectivity, higher resistance, improved separation and purification, reuse of enzymes, and consequently more efficient process. Recently, many reviews have been published about immobilization systems; however, most of them have focused on a specific application or not emphasized in details. This review focuses on most commonly used techniques in industry with many recent applications including using bioreactor systems for industrial production. It is also aimed to emphasize the advantages and disadvantages of the immobilization techniques and how these systems improve process productivity compared to non-immobilized systems.     

Biofiltering of aquaculture effluents by halophytic plants: Basic principles,current uses and future perspectives

Halophytes comprise a promising group of plants for different applications due to their special physiological characteristics and biochemical composition. Their ability to grow in salt-affected habitats makes them useful for recycling the nutrient-containing effluents from saline aquacultures. The potential of different halophytes for nutrient uptake and remediation has been investigated in several laboratory and field studies and the application of natural and constructed wetlands. Various factors influence the filtration capacity of a halophyte biofilter for aquaculture effluents, such as salinity, flooding, nutrient level, root characteristics and technical applications. Those effects studied so far are characterized and those in need of further study are outlined. Technical aspects in artificial wetlands such as water flow direction, water level, hydraulic retention time and hydraulic loading rate, influence the transformation of the nutrients within the wetland and their uptake by the plants. Open as well as re-circulating systems are considered. Because soil processes are lacking, the application of hydroponic culture shifts the importance of nutrient removal toward plant uptake. This is important when besides the pure nutrient removal the recycling of the nutrients become a focus in terms of sustainability. The economic feasibility, including different utilization possibilities, of selected halophytes with filtering capacities is delineated. The economic attractiveness of a halophytic biofilter can also be upgraded by the use of salt-tolerant species with a commercial value. Modularized versions of waste water treatments by plants in temperate and tropic regions could help to reduce the nutrient load in the bodies of water and to recycle the nutrients. More effort is needed to determine the specific nutrient removal mechanisms within different types of wetlands planted with halophytes and to point out appropriate halophyte species and wetland conditions for different applications.     

Microalgae wastewater treatment: Biological and technological approaches

Current global environmental issues raise unavoidable challenges for our use of natural resources. Supplying the human population with clean water is becoming a global problem. Numerous organic and inorganic impurities in municipal, industrial, and agricultural waters, ranging from microplastics to high nutrient loads and heavy metals, endanger our nutrition and health. The development of efficient wastewater treatment technologies and circular economic approaches is thus becoming increasingly important. The biomass production of microalgae using industrial wastewater offers the possibility of recycling industrial residues to create new sources of raw materials for energy and material use. This review discusses algae‐based wastewater treatment technologies with a special focus on industrial wastewater sources, the potential of non‐conventional extremophilic (thermophilic, acidophilic, and psychrophilic) microalgae, and industrial algae‐wastewater treatment concepts that have already been put into practice.     

Satellite-based monitoring of tropical seagrass vegetation: current techniques and future developments

Decline of seagrasses has been documented in many parts of the world. Reduction in water clarity, through increased turbidity and increased nutrient concentrations, is considered to be the primary cause of seagrass loss. Recent studies have indicated the need for new methods that will enable early detection of decline in seagrass extent and productivity, over large areas. In this review of current literature on coastal remote sensing, we examine the ability of remote sensing to serve as an information provider for seagrass monitoring. Remote sensing offers the potential to map the extent of seagrass cover and monitor changes in these with high accuracy for shallow waters. The accuracy of mapping seagrasses in deeper waters is unclear. Recent advances in sensor technology and radiometric transfer modelling have resulted in the ability to map suspended sediment, sea surface temperature and below-surface irradiance. It is therefore potentially possible to monitor the factors that cause the decline in seagrass status. When the latest products in remote sensing are linked to seagrass production models, it may serve as an early-warning system for seagrass decline and ultimately allow a better management of these susceptible ecosystems.     

MINOTAURUS: microorganism and enzyme immobilization: novel techniques and approaches for upgraded remediation of underground-, wastewater and soil

The European project MINOTAURUS aims to deliver innovative bio-processes to eliminate emerging and classic organic pollutants. These bio-processes are all based on the concept of immobilization of biocatalysts (microorganisms and enzymes) and encompass bioaugmentation, enzyme technology, rhizoremediation with halophytes, and a bioelectrochemical remediation process. The immobilization-based technologies are applied to engineered ex situ and natural systems in situ for the bioremediation of groundwater, wastewater and soil. The selection and application of modern physico-chemical, biological and ecotoxicological monitoring tools combined with a rational understanding of engineering, enzymology and microbial physiology is a pertinent approach to open the black-box of the selected technologies. Reliable process-monitoring constitutes the basis for developing and refining biodegradation kinetics models, which in turn will improve the predictability of performances to be achieved with our technologies. A key strength of MINOTAURUS is the possibility of direct implementation of our technologies at five European reference sites that are confronted with pollutants (two technologies will be tested on-site starting from the first year). We will deliver not only a set of tools, techniques, and processes, which will enhance the ability of our communities to respond to the challenges of organic pollutants but also frameworks for structuring and making evidence-based decisions for the most sustainable and appropriate bioremediation measures. The MINOTAURUS consortium includes fifteen partners from eight European countries. Eight research & education institutions, five SMEs covering the whole chain of our bioremediation approaches (production, and monitoring of biocatalysts, bioremediation and engineering), one large end-user operating wastewater treatment plants and one environmental agency work together with the support of an advisory board mainly consisting of environmental decision-makers.     

A comparative study of protein immobilization techniques for optical immunosensors.

This paper presents the results of a study of a number of antibody immobilization techniques for application to optical immunosensors. In particular, well-known methods such as covalent binding and physical adsorption have been extended to the Langmiur-Blodgett method in an attempt to improve the density and possibly the uniformity of orientation of monoclonal antibodies on an optical surface. The surface density of active immobilized antibodies was determined from enzyme immunoassay and their thickness and refractive index were deduced from ellipsometry. It is shown that, although high surface densities (500 ng/cm2) of antibody can be obtained, the major obstacle to the detection of low concentrations of antigens or haptens is the non-specific binding of foreign molecules to the sensing surface.