Biotechnological applications of hydrogenases

Hydrogenases have found use in a variety of biotechnological applications, including biohydrogen production, wastewater treatment, the prevention of microbial-induced corrosion and the generation and regeneration of NADP cofactors. In the future, advances in genome mining and screening techniques are likely to identify new hydrogenases for novel applications.     

Biotechnological applications of peroxidases

Peroxidases are widely distributed in nature. Reduction of peroxides at the expense of electron donating substrates, make peroxidases useful in a number of biotechnological applications. Enzymes such as lignin peroxidase and manganese peroxidase, both associated with lignin degradation, may be successfully used for biopulping and biobleaching in the paper industry, and can produce oxidative breakdown of synthetic azo dyes. Oxidative polymerization of phenols and aromatic amines conducted by horseradish peroxidase (HRP) in water and water-miscible organic solvents, may lead to new types of aromatic polymers. Site directed mutagenesis of HRP has been used to improve the enantioselectivity of arylmethylsulfide oxidations. Peroxidase has a potential for soil detoxification, while HRP as well as soybean and turnip peroxidases have been applied for the bioremediation of wastewater contaminated with phenols, cresols, and chlorinated phenols. Peroxidase based biosensors have found use in analytical systems for determination of hydrogen peroxide and organic hydroperoxides, while co-immobilized with a hydrogen peroxide producing enzyme, they can be used for determination of glucose, alcohols, glutamate and choline. Peroxidase has also been used for practical analytical applications in diagnostic kits, such as quantitation of uric acid, glucose, cholesterol, lactose, and so on. Enzyme linked immunorbent assay (ELISA) tests on which peroxidase is probably the most common enzyme used for labeling an antibody, are a simple and reliable way of detecting toxins, pathogens, cancer risk in bladder and prostate, and many other analytes. Directed evolution methods, appear to be a valuable alternative to engineer new catalyst forms of plant peroxidases from different sources to overcome problems of stability and to increase thermal resistance.     

Biotechnological applications of microbial bioconversions

Modern research has focused on the microbial transformation of a huge variety of organic compounds to obtain compounds of therapeutic and/or industrial interest. Microbial transformation is a useful tool for producing new compounds, as a consequence of the variety of reactions for natural products. This article describes the production of many important compounds by biotransformation. Emphasis is placed on reporting the metabolites that may be of special interest to the pharmaceutical and biotechnological industries, as well as the practical aspects of this work in the field of microbial transformations.     

Haloalkane dehalogenases: Biotechnological applications

Haloalkane dehalogenases (EC 3.8.1.5, HLDs) are α/β-hydrolases which act to cleave carbon-halogen bonds. Due to their unique catalytic mechanism, broad substrate specificity and high robustness, the members of this enzyme family have been employed in several practical applications: (i) biocatalytic preparation of optically pure building-blocks for organic synthesis; (ii) recycling of by-products from chemical processes; (iii) bioremediation of toxic environmental pollutants; (iv) decontamination of warfare agents; (v) biosensing of environmental pollutants; and (vi) protein tagging for cell imaging and protein analysis. This review discusses the application of HLDs in the context of the biochemical properties of individual enzymes. Further extension of HLD uses within the field of biotechnology will require currently limiting factors – such as low expression, product inhibition, insufficient enzyme selectivity, low affinity and catalytic efficiency towards selected substrates, and instability in the presence of organic co-solvents – to be overcome. We propose that strategies based on protein engineering and isolation of novel HLDs from extremophilic microorganisms may offer solutions.     

Biotechnological production and applications of pullulan

Pullulan is a unique biopolymer with many useful traits and hundreds of patented applications. However, despite the fact that pullulan has been in commercial production for more than 25 years, few of these potential uses have been widely adopted. In large part this may be due to the relatively high price of pullulan. Nevertheless, the last few years have seen a resurgence in interest in pullulan, particularly for higher-value health and pharmaceutical applications.Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable     

Biotechnological applications of bioluminescence and chemiluminescence

Recent progress in molecular biology has made available several biotechnological tools that take advantage of the high detectability and rapidity of bioluminescence and chemiluminescence spectroscopy. These developments provide inroads to in vitro and in vivo continuous monitoring of biological processes (e.g. gene expression, protein-protein interaction and disease progression), with clinical, diagnostic and drug discovery applications. Furthermore, combining luminescent enzymes or photoproteins with biospecific recognition elements at the genetic level has led to the development of ultrasensitive and selective bioanalytical tools, such as recombinant whole-cell biosensors, immunoassays and nucleic acid hybridization assays. The high detectability of the luminescence analytical signal makes it appropriate for miniaturized bioanalytical devices (e.g. microarrays, microfluidic devices and high-density-well microtiter plates) for the high-throughput screening of genes and proteins in small sample volumes.     

Spectrofluorometric analytical applications of cyclodextrins

Cyclodextrins (CDs) are a family of cyclic oligosaccharides composed of α‐(1,4)‐linked glucopyranose subunits. The most important feature of CDs is their ability to form inclusion complexes (host–guest complexes) with a very wide range of solid, liquid and gaseous compounds by a molecular complexation. During the last decade, a considerable number of research papers has been focused on the use of CDs to enhance fluorescence intensity of different analytes and to develop CD‐induced spectrofluorimetric method. In this review, the various spectrofluorimetric methods based on host–inclusion complex are presented. Copyright © 2013 John Wiley & Sons, Ltd.     

Biotechnological production and applications of statins

Statins are a group of extremely successful drugs that lower cholesterol levels in blood; decreasing the risk of heath attack or stroke. In recent years, statins have also been reported to have other biological activities and numerous potential therapeutic uses. Natural statins are lovastatin and compactin, while pravastatin is derived from the latter by biotransformation. Simvastatin, the second leading statin in the market, is a lovastatin semisynthetic derivative. Lovastatin is mainly produced by Aspergillus terreus strains, and compactin by Penicillium citrinum. Lovastatin and compactin are produced industrially by liquid submerged fermentation, but can also be produced by the emerging technology of solid-state fermentation, that displays some advantages. Advances in the biochemistry and genetics of lovastatin have allowed the development of new methods for the production of simvastatin. This lovastatin derivative can be efficiently synthesized from monacolin J (lovastatin without the side chain) by a process that uses the Aspergillus terreus enzyme acyltransferase LovD. In a different approach, A. terreus was engineered, using combinational biosynthesis on gene lovF, so that the resulting hybrid polyketide synthase is able to in vivo synthesize 2,2-dimethylbutyrate (the side chain of simvastatin). The resulting transformant strains can produce simvastatin (instead of lovastatin) by direct fermentation.     

Biotechnological production and applications of phytases

Phytases decompose phytate, which is the primary storage form of phosphate in plants. More than 10 years ago, the first commercial phytase product became available on the market. It offered to help farmers reduce phosphorus excretion of monogastric animals by replacing inorganic phosphates by microbial phytase in the animal diet. Phytase application can reduce phosphorus excretion by up to 50%, a feat that would contribute significantly toward environmental protection. Furthermore, phytase supplementation leads to improved availability of minerals and trace elements. In addition to its major application in animal nutrition, phytase is also used for processing of human food. Research in this field focuses on better mineral absorption and technical improvement of food processing. All commercial phytase preparations contain microbial enzymes produced by fermentation. A wide variety of phytases were discovered and characterized in the last 10 years. Initial steps to produce phytase in transgenic plants were also undertaken. A crucial role for its commercial success relates to the formulation of the enzyme solution delivered from fermentation. For liquid enzyme products, a long shelf life is achieved by the addition of stabilizing agents. More comfortable for many customers is the use of dry enzyme preparations. Different formulation technologies are used to produce enzyme powders that retain enzyme activity, are stable in application, resistant against high temperatures, dust-free, and easy to handle.     

Biotechnological applications of acetic acid bacteria

The acetic acid bacteria (AAB) have important roles in food and beverage production, as well as in the bioproduction of industrial chemicals. In recent years, there have been major advances in understanding their taxonomy, molecular biology, and physiology, and in methods for their isolation and identification. AAB are obligate aerobes that oxidize sugars, sugar alcohols, and ethanol with the production of acetic acid as the major end product. This special type of metabolism differentiates them from all other bacteria. Recently, the AAB taxonomy has been strongly rearranged as new techniques using 16S rRNA sequence analysis have been introduced. Currently, the AAB are classified in ten genera in the family Acetobacteriaceae. AAB can not only play a positive role in the production of selected foods and beverages, but they can also spoil other foods and beverages. AAB occur in sugar- and alcohol-enriched environments. The difficulty of cultivation of AAB on semisolid media in the past resulted in poor knowledge of the species present in industrial processes. The first step of acetic acid production is the conversion of ethanol from a carbohydrate carried out by yeasts, and the second step is the oxidation of ethanol to acetic acid carried out by AAB. Vinegar is traditionally the product of acetous fermentation of natural alcoholic substrates. Depending on the substrate, vinegars can be classified as fruit, starch, or spirit substrate vinegars. Although a variety of bacteria can produce acetic acid, mostly members of Acetobacter, Gluconacetobacter, and Gluconobacter are used commercially. Industrial vinegar manufacturing processes fall into three main categories: slow processes, quick processes, and submerged processes. AAB also play an important role in cocoa production, which represents a significant means of income for some countries. Microbial cellulose, produced by AAB, possesses some excellent physical properties and has potential for many applications. Other products of biotransformations by AAB or their enzymes include 2-keto-L-gulonic acid, which is used for the production of vitamin C; D-tagatose, which is used as a bulking agent in food and a noncalorific sweetener; and shikimate, which is a key intermediate for a large number of antibiotics. Recently, for the first time, a pathogenic acetic acid bacterium was described, representing the newest and tenth genus of AAB.     

Biotechnological applications of occlusion bodies of Baculoviruses

Applied Microbiology and Biotechnology - The ability of Baculoviruses to hyper-express very late genes as polyhedrin, the major component of occlusion bodies (OBs) or polyhedra, has allowed the...     

Biotechnological applications of research on animal pigmentation

The implications of primary research on pigmentation for the colour manipulation of animal species of economic importance, and the facilitation of specific processes in biotechnology are discussed. Pigment technologists, especially poultry and fish nutritionists, are concerned with achieving the often specific type and degree of coloration demanded by consumers of various products (notably egg yolk, eggshell, broiler skin and salmon flesh). In most instances involving melanin (pelage, plumage and integument) and porphyrin (eggshell) pigments, the desired coloration is achieved through the use of alternate alleles at gene loci controlling the characters of interest. In contrast, coloration involving carotenoids is controlled primarily through pigment supplementation in the diet. The difference between carotenoids and other pigments involves the strict dietary origin of the former. Factors other than pigment availability, such as body condition, hormonal status and genetic constitution, also affect coloration. Although day-old chicks can be sexed by visual inspection of their genitalia, matings resulting in sex-associated phenotypes are in wide use. The genetic markers involved affect the colour of the plumage. The cloning of genes involved in pigmentation offers the prospect of deciphering the genetic control of animal pigmentation and modifying it to meet specific pigmentation needs.     

Biotechnological applications of plant cells in culture

For many workers, the most exciting recent advances in the realm of plant cell biotechnology, center on results obtained from experiments concerned with the genetic engineering of plant cells. Various groups of workers have managed to introduce new genetic material into plant cells, using Ti-plasmids (or modified Ti-plasmids) from Agrobacterium tumefaciens. This genetic material has been expressed (with varying degrees of efficiency), in each case. Thus the way may possibly be coming clear to produce plant cell cultures, or whole plants with entirely new or novel properties. Other areas in which progress has been made, are in the design of media conditions to promote secondary product formation, and in ways of immobilizing plant cells and enzymes, to achieve efficient secondary product formation.     

Biotechnological applications of Listeria's sophisticated infection strategies

Listeria monocytogenes is a Gram‐positive bacterium that is able to survive both in the environment and to invade and multiply within eukaryotic cells. Currently L. monocytogenes represents one of the most well‐studied and characterized microorganisms in bacterial pathogenesis. A hallmark of L. monocytogenes virulence is its ability to breach bodily barriers such as the intestinal epithelium, the blood–brain barrier as well as the placental barrier to cause severe systemic disease. Curiously, this theme is repeated at the level of the interaction between the individual cell and the bacterium where its virulence factors contribute to the ability of the bacteria to breach cellular barriers. L. monocytogenes is a model to study metabolic requirements of bacteria growing in an intracellular environment, modulation of signalling pathways in the infected cell and interactions with cellular defences involving innate and adaptive immunity. Technical advances such as the creation of LISTERIA‐susceptible mouse strains, had added interest in the study of the natural pathogenesis of the disease via oral infection. The use of attenuated strains of L. monocytogenes as vaccines has gained considerable interest because they can be used to express heterologous antigens as well as to somatically deliver recombinant DNA to eukaryotic cells. A novel vaccine concept, the use of non‐viable but metabolically active bacteria to induced immunoprotective responses, has been developed with L. monocytogenes. In this mini‐review, we review the strategies used by L. monocytogenes to subvert the cellular functions at different stages of the infection cycle in the host and examine how these properties are being exploited in biotechnological and clinical applications.     

Biotechnological applications and potentialities of halophilic microorganisms

Halophilic microorganisms are found as normal inhabitants of highly saline environments and thus are considered extremophiles. They are mainly represented, but not exclusively, by the halobacteria (extremely halophilic aerobic Archaea), the moderate halophiles (Bacteria and some methanogens) and several eukaryotic algae. These extremophilic microorganisms are already used for some biotechnological processes, for example halobacteria are used for the production of bacteriorhodopsin, and the alga Dunaliella is used in the commercial production of -carotene. Several other present or potential applications of halophiles are reviewed, including the production of polymers (polyhydroxyalcanoates and polysaccharides), enzymes, and compatible solutes, and the use of these extremophiles in enhanced oil recovery, cancer detection, drug screening and the biodegradation of residues and toxic compounds.The authors are with the Departamento de Microbiología y Parasitología, Universidad de Sevilla, 41012 Sevilla, Spain     

Biotechnological production of lutein and its applications

Lutein is an antioxidant that has gathered increasing attention due to its potential role in preventing or ameliorating age-related macular degeneration. Currently, it is produced from marigold oleoresin, but continuous reports of lutein-producing microalgae pose the question if those microorganisms can become an alternative source. Several microalgae have higher lutein contents than most marigold cultivars and have been shown to yield productivities hundreds of times higher than marigold crops on a per square meter basis. Microalgae and marigold are opposite alternatives in the use of resources such as land and labor and the prevalence of one or the other could change in the future as the lutein demand rises and if labor or land becomes more restricted or expensive in the producing countries. The potential of microalgae as a lutein source is analyzed and compared to marigold. It is suggested that, in the current state of the art, microalgae could compete with marigold even without counting on any of the improvements in microalgal technology that can be expected in the near future.     

Biotechnological production of erythritol and its applications

Erythritol, a four-carbon polyol, is a biological sweetener with applications in food and pharmaceutical industries. It is also used as a functional sugar substitute in special foods for people with diabetes and obesity because of its unique nutritional properties. Erythritol is produced by microbial methods using mostly osmophilic yeasts and has been produced commercially using mutant strains of Aureobasidium sp. and Pseudozyma tsukubaensis. Due to the high yield and productivity in the industrial scale of production, erythritol serves as an inexpensive starting material for the production of other sugars. This review focuses on the approaches for the efficient erythritol production, strategies used to enhance erythritol productivity in microbes, and the potential biotechnological applications of erythritol.     

Biotechnological applications of penicillin acylases: state-of-the-art

This review describes the most recent developments in the biotechnological applications of penicillin acylases. This group of enzymes is involved mainly in the industrial production of 6-aminopenicillanic acid and the synthesis of semisynthetic beta-lactam antibiotics. In addition, penicillin acylases can also be employed in other useful biotransformations, such as peptide synthesis and the resolution of racemic mixtures of chiral compounds. Particular emphasis is placed on advances in detection of new enzyme specificities towards other natural penicillins, enzyme immobilization, and optimization of enzyme-catalyzed hydrolysis and synthesis in the presence of organic solvents.