Biotechnologically relevant enzymes from Thermus thermophilus

. Enzymes produced by Thermus thermophilus are of considerable biotechnological interest. This review covers industrial applications of several protein products of this thermophilic bacterium that are functional under extreme conditions. The purification of proteins from T. thermophilus using either conventional methods or in the light of the cloning of their genes and expression in mesophilic microorganisms is discussed. Enzymes that biodegrade proteins, polysaccharides or key enzymes that are involved in amino acid metabolism, protein folding or in other fundamental biological processes such as DNA replication, DNA repair, and RNA maturation, with potential use in different biotechnological processes are reviewed as well.     

Modulation of α-chymotrypsin specificity induced by pyridoxal

Summary Chymotrypsin catalyses the hydrolysis of the D-isomers of aromatic amino acids and of glycine methyl esters provided that pyridoxal is present. The corresponding L-isomers still behave as substrates for the enzyme even if pyridoxal decreases the rate of their hydrolysis. This change of enzyme stereospecificity should be taken into account in biotechnological processes.     

Biosynthesis of cis,cis-Muconic Acid and Its Aromatic Precursors,Catechol and Protocatechuic Acid,from Renewable Feedstocks by Saccharomyces cerevisiae

Adipic acid is a high-value compound used primarily as a precursor for the synthesis of nylon, coatings, and plastics. Today it is produced mainly in chemical processes from petrochemicals like benzene. Because of the strong environmental impact of the production processes and the dependence on fossil resources, biotechnological production processes would provide an interesting alternative. Here we describe the first engineered Saccharomyces cerevisiae strain expressing a heterologous biosynthetic pathway converting the intermediate 3-dehydroshikimate of the aromatic amino acid biosynthesis pathway via protocatechuic acid and catechol into cis,cis-muconic acid, which can be chemically dehydrogenated to adipic acid. The pathway consists of three heterologous microbial enzymes, 3-dehydroshikimate dehydratase, protocatechuic acid decarboxylase composed of three different subunits, and catechol 1,2-dioxygenase. For each heterologous reaction step, we analyzed several potential candidates for their expression and activity in yeast to compose a functional cis,cis-muconic acid synthesis pathway. Carbon flow into the heterologous pathway was optimized by increasing the flux through selected steps of the common aromatic amino acid biosynthesis pathway and by blocking the conversion of 3-dehydroshikimate into shikimate. The recombinant yeast cells finally produced about 1.56 mg/liter cis,cis-muconic acid.     

Multi-omics approach to study the growth efficiency and amino acid metabolism in <Emphasis Type="Italic">Lactococcus lactis</Emphasis> at various specific growth rates

Background  

Lactococcus lactis is recognised as a safe (GRAS) microorganism and has hence gained interest in numerous biotechnological approaches. As it is fastidious for several amino acids, optimization of processes which involve this organism requires a thorough understanding of its metabolic regulations during multisubstrate growth.     

Amino acids production focusing on fermentation technologies – A review

Amino acids are attractive and promising biochemicals with market capacity requirements constantly increasing. Their applicability ranges from animal feed additives, flavour enhancers and ingredients in cosmetic to specialty nutrients in pharmaceutical and medical fields.This review gives an overview of the processes applied for amino acids production and points out the main advantages and disadvantages of each.Due to the advances made in the genetic engineering techniques, the biotechnological processes, and in particular the fermentation with the aid of strains such as Corynebacterium glutamicum or Escherichia coli, play a significant role in the industrial production of amino acids. Despite the numerous advantages of the fermentative amino acids production, the process still needs significant improvements leading to increased productivity and reduction of the production costs.Although the production processes of amino acids have been extensively investigated in previous studies, a comprehensive overview of the developments in bioprocess technology has not been reported yet. This review states the importance of the fermentation process for industrial amino acids production, underlining the strengths and the weaknesses of the process. Moreover, the potential of innovative approaches utilizing macro and microalgae or bacteria are presented.     

Simulation and control of fermentation complex systems

The paper deals with biotechnological complex systems with focus onto fermentation processes. Discontinuous, semicontinuous and continuous fermentation processes are discussed. Mathematical model of continuous biotechnological process for ethanol production is introduced and verified.     

Eco-Efficiency Analysis of biotechnological processes

For almost 50 years now, biotechnological production processes have been used for industrial production of amino acids. Market development has been particularly dynamic for the flavor-enhancer glutamate and the animal feed amino acids l-lysine, l-threonine, and l-tryptophan, which are produced by fermentation processes using high-performance strains of Corynebacterium glutamicum and Escherichia coli from sugar sources such as molasses, sucrose, or glucose. But the market for amino acids in synthesis is also becoming increasingly important, with annual growth rates of 5–7%. The use of enzymes and whole cell biocatalysts has proven particularly valuable in production of both proteinogenic and nonproteinogenic l-amino acids, d-amino acids, and enantiomerically pure amino acid derivatives, which are of great interest as building blocks for active ingredients that are applied as pharmaceuticals, cosmetics, and agricultural products. Nutrition and health will continue to be the driving forces for exploiting the potential of microorganisms, and possibly also of suitable plants, to arrive at even more efficient processes for amino acid production.     

Enzymatic reactions in biotechnology (48th Bach lecture)]

The paper is the 48th Bach Lecture presented under the same title. It covers the biochemical mechanisms of the biogenesis of microbial biosynthetic products, role of acetyl-CoA, function of the succinate-glycine cycle, reactions of the hexose-monophosphate pathway of carbon metabolism. The reversible action of hydrolases in enzymatic catalysis and degradation of xenobiotics are discussed. The data on redox reactions are pooled. Such modern biotechnological processes as epoxidation, synthesis of acrylamide and some monomers involved in chemical syntheses of polymers, synthesis of oligosaccharide and fluorine-containing amino acids are considered. Promising commercial applications of biocatalysis are discussed.     

The expression,secretion and activity of the aspartic protease MpAPr1 in Metschnikowia pulcherrima IWBT Y1123

Journal of Industrial Microbiology & Biotechnology - Protease-secreting yeasts have broad biotechnological potential for application to various industrial processes, including winemaking....     

Enhancement of biomolecule transport by electroporation: a review of theory and practical application to transformation of Corynebacterium glutamicum

Selective and reversible permeabilization of the cell wall permeability barrier is the focus for many biotechnological applications. In this article, the basic principles for reversible membrane permeabilization, based on biological, chemical, and physical methods are reviewed. Emphasis is given to electroporation (electropermeabilization) which tends to be the most popular method for membrane permeabilization and for introduction of foreign molecules into the cells. The applications of this method in industrial processes as well as the critical factors and parameters which affect the success of this approach are discussed. The different strategies developed throughout the years for increased transformation efficiencies of the industrially important amino acid-overproducing bacterium Corynebacterium glutamicum, are also summarized.     

Exploring the bioprospecting and biotechnological potential of white-rot and anaerobic Neocallimastigomycota fungi: peptidases,esterases, and lignocellulolytic enzymes

Fungi constitute an invaluable natural resource for scientific research, owing to their diversity; they offer a promising alternative for bioprospecting, thus contributing to biotechnological advances. For a long time, extensive information has been exploited and fungal products have been tested as a source of natural compounds. In this context, enzyme production remains a field of interest, since it offers an efficient alternative to the hazardous processes of chemical transformations. Owing to their vast biodiversity and peculiar biochemical characteristics, two fungal categories, white-rot and anaerobic Neocallimastigomycota, have gathered considerable attention for biotechnological applications. These fungi are known for their ability to depolymerize complex molecular structures and are used in degradation of lignocellulosic biomass, improvement of animal feed digestibility, biogas and bioethanol production, and various other applications. However, there are only limited reports that describe proteolytic enzymes and esterases in these fungi and their synergistic action with lignocellulolytic enzymes on degradation of complex polymers. Thus, in this minireview, we focus on the importance of these organisms in enzyme technology, their bioprospecting, possibility of integration of their enzyme repertoire, and their prospects for future biotechnological innovation.

     

A new cold-adapted β-D-galactosidase from the Antarctic Arthrobacter sp. 32c - gene cloning, overexpression, purification and properties

Background  

The development of a new cold-active β-D-galactosidases and microorganisms that efficiently ferment lactose is of high biotechnological interest, particularly for lactose removal in milk and dairy products at low temperatures and for cheese whey bioremediation processes with simultaneous bio-ethanol production.     

Impacts of economic strategies on biotechnological developments

The traditional basis of the processing technologies is profit generation from the transformation of either raw materials or intermediates, using know-how and energy, into marketable products. However, the establishment of both regional economic communities and raw material producer cartels has distorted and even invalidated the economic evaluation of processes in strict economic terms. Essentially, individual countries and regions are moving towards a state of economic protectionism based on specific strategic policies. Such policies are most evident and effective in the agricultural and energy sectors. Biotechnology is intimately linked with both these sectors and major biotechnological ventures have failed as a result of strategic economic changes. This paper examines the basis for the economic evaluation of novel biotechnological processes and seeks to identify politico-economic scenarios that will permit successful establishment of biotechnological processing ventures.     

Yeast flocculation and its biotechnological relevance

Adhesion properties of microorganisms are crucial for many essential biological processes such as sexual reproduction, tissue or substrate invasion, biofilm formation and others. Most, if not all microbial adhesion phenotypes are controlled by factors such as nutrient availability or the presence of pheromones. One particular form of controlled cellular adhesion that occurs in liquid environments is a process of asexual aggregation of cells which is also referred to as flocculation. This process has been the subject of significant scientific and biotechnological interest because of its relevance for many industrial fermentation processes. Specifically adjusted flocculation properties of industrial microorganisms could indeed lead to significant improvements in the processing of biotechnological fermentation products such as foods, biofuels and industrially produced peptides. This review briefly summarises our current scientific knowledge on the regulation of flocculation-related phenotypes, their importance for different biotechnological industries, and possible future applications for microorganisms with improved flocculation properties.     

Microbial CO conversions with applications in synthesis gas purification and bio-desulfurization

Recent advances in the field of microbial physiology demonstrate that carbon monoxide is a readily used substrate by a wide variety of anaerobic micro-organisms, and may be employed in novel biotechnological processes for production of bulk and fine chemicals or in biological treatment of waste streams. Synthesis gas produced from fossil fuels or biomass is rich in hydrogen and carbon monoxide. Conversion of carbon monoxide to hydrogen allows use of synthesis gas in existing hydrogen utilizing processes and is interesting in view of a transition from hydrogen production from fossil fuels to sustainable (CO2-neutral) biomass. The conversion of CO with H2O to CO2 and H2 is catalyzed by a rapidly increasing group of micro-organisms. Hydrogen is a preferred electron donor in biotechnological desulfurization ofwastewaters and flue gases. Additionally, CO is a good alternative electron donor considering the recent isolation of a CO oxidizing, sulfate reducing bacterium. Here we review CO utilization by various anaerobic micro-organisms and their possible role in biotechnological processes, with a focus on hydrogen production and bio-desulfurization.     

Metabolic pathways and biotechnological production of l-cysteine

l-Cysteine is an important amino acid both biologically and commercially. Although most amino acids are commercially produced by fermentation, cysteine is mainly produced by protein hydrolysis. However, synthetic or biotechnological products have been preferred in the market. Biotechnological processes for cysteine production, both enzymatic and fermentative processes, are discussed. Enzymatic process, the asymmetric hydrolysis of dl-2-amino-Δ²-thiazoline-4-carboxylic acid to l-cysteine, has been developed and industrialized. The l-cysteine biosynthetic pathways of Escherichia coli and Corynebacterium glutamicum, which are used in many amino acid production processes, are also described. These two bacteria have basically same l-cysteine biosynthetic pathways. l-Cysteine-degrading enzymes and l-cysteine-exporting proteins both in E. coli and C. glutamicum are also described. In conclusion, for the effective fermentative production of l-cysteine directly from glucose, the combination of enhancing biosynthetic activity, weakening the degradation pathway, and exploiting the export system seems to be effective.     

The superfamily of thaumatin-like proteins: its origin, evolution, and expression towards biological function

Thaumatin-like proteins (TLPs) are the products of a large, highly complex gene family involved in host defence and a wide range of developmental processes in fungi, plants, and animals. Despite their dramatic diversification in organisms, TLPs appear to have originated in early eukaryotes and share a well-defined TLP domain. Nonetheless, determination of the roles of individual members of the TLP superfamily remains largely undone. This review summarizes recent advances made in elucidating the varied TLP activities related to host resistance to pathogens and other physiological processes. Also discussed is the current state of knowledge on the origins and types of TLPs, regulation of gene expression, and potential biotechnological applications for TLPs.     

Industrial production of amino acids by coryneform bacteria

In the 1950s Corynebacterium glutamicum was found to be a very efficient producer of L-glutamic acid. Since this time biotechnological processes with bacteria of the species Corynebacterium developed to be among the most important in terms of tonnage and economical value. L-Glutamic acid and L-lysine are bulk products nowadays. L-Valine, L-isoleucine, L-threonine, L-aspartic acid and L-alanine are among other amino acids produced by Corynebacteria. Applications range from feed to food and pharmaceutical products. The growing market for amino acids produced with Corynebacteria led to significant improvements in bioprocess and downstream technology as well as in molecular biology. During the last decade big efforts were made to increase the productivity and to decrease the production costs. This review gives an overview of the world market for amino acids produced by Corynebacteria. Significant improvements in bioprocess technology, i.e. repeated fed batch or continuous production are summarised. Bioprocess technology itself was improved furthermore by application of more sophisticated feeding and automatisation strategies. Even though several amino acids developed towards commodities in the last decade, side aspects of the production process like sterility or detection of contaminants still have increasing relevance. Finally one focus of this review is on recent developments in downstream technology.     

Secretion of amino acids by bacteria: Physiology and mechanism

Abstract: Although representing a common property of microorganisms and being widely used for biotechnological purposes, solute secretion has been relatively poorly studied in terms of biochemistry. In this review, various examples of metabolite secretion processes by bacteria are discussed with the emphasis on the mechanisms of amino acid secretion by coryneform bacteria. Among the metabolic concepts which may be applied to explain the physiological meaning of metabolite secretion, mainly two concepts are dealt with, i.e. the so-called 'overflow metabolism' on the one hand and the situation where non-metabolizable intermediates are accumulated and finally secreted on the other. In the central part of this review, the different concepts are discussed which have been put forward to mechanistically explain amino acid secretion under particular metabolic conditions and in particular strains of bacteria, i.e. secretion mediated (i) by diffusion, (ii) by the participation of amino acid uptake systems, and (iii) by the use of specific secretion systems. These concepts are then applied to amino acid secretion in Corynebacterium glutamicum , and emplified by detailed studies on the mechanism and regulation of the secretion of lysine, isoleucine and glutamate by C. glutamicum .     

Computational studies on a new cationic peroxidase isoenzyme from artichoke leaves

Previously we presented the purification, biochemical characterization, and cloning of a cationic peroxidase isoenzyme (CysPrx) from artichoke (Cynara cardunculus subsp scolymus (L.) Hegi) leaves. The protein was shown to have some interesting properties, suggesting that CysPrx could be a considered as a potential candidate for industrial application. In addition, from the CysPrx sequence, two full-lengh cDNAs: CysPrx1 and CysPrx2, differing for three amino acids, were isolated. A three-dimensional model was predicted from CysPrx1 by homology modeling, using two different computational tools. Herein we discuss the roles of particular amino acid residues and structural motifs or regions of both deduced sequences with the aim to find new understandings between the new plant peroxidase isoenzymes and their physiological substrates. Additionally, the obtained information may lead to new methods for improving the stability of the enzyme in several processes of biotechnological interest for peroxidase applications.