The biotechnological potential of piezophiles

Microorganisms that prefer high-pressure conditions are termed piezophiles (previously termed barophiles). The molecular basis of piezophily is now being investigated extensively focusing on aspects of gene regulation and the function of certain proteins in deep-sea isolates. Little attention has been paid, however, to the potential biotechnological applications of piezophiles compared with other extremophiles. Based on the fundamental knowledge available, we will try to answer the following questions: How can we exploit the biotechnological potential of piezophiles? What can be understood by the application of high-pressure in biological systems?     

The yeast Kluyveromyces marxianus and its biotechnological potential

Strains belonging to the yeast species Kluyveromyces marxianus have been isolated from a great variety of habitats, which results in a high metabolic diversity and a substantial degree of intraspecific polymorphism. As a consequence, several different biotechnological applications have been investigated with this yeast: production of enzymes (beta-galactosidase, beta-glucosidase, inulinase, and polygalacturonases, among others), of single-cell protein, of aroma compounds, and of ethanol (including high-temperature and simultaneous saccharification-fermentation processes); reduction of lactose content in food products; production of bioingredients from cheese-whey; bioremediation; as an anticholesterolemic agent; and as a host for heterologous protein production. Compared to its congener and model organism, Kluyveromyces lactis, the accumulated knowledge on K. marxianus is much smaller and spread over a number of different strains. Although there is no publicly available genome sequence for this species, 20% of the CBS 712 strain genome was randomly sequenced (Llorente et al. in FEBS Lett 487:71-75, 2000). In spite of these facts, K. marxianus can envisage a great biotechnological future because of some of its qualities, such as a broad substrate spectrum, thermotolerance, high growth rates, and less tendency to ferment when exposed to sugar excess, when compared to K. lactis. To increase our knowledge on the biology of this species and to enable the potential applications to be converted into industrial practice, a more systematic approach, including the careful choice of (a) reference strain(s) by the scientific community, would certainly be of great value.     

The biotechnological use and potential of plant pathogenic smut fungi

Plant pathogens of the family Ustilaginaceae parasitise mainly on grasses and cause smut disease. Among the best characterised members of this family are the covered smut fungus Ustilago hordei colonising barley and oat as well as the head smut Sporisorium reilianum and the corn smut Ustilago maydis, both infecting maize. Over the past years, U. maydis in particular has matured into a model system for diverse topics like plant–pathogen interaction, cellular transport processes or DNA repair. Consequently, a broad set of genetic, molecular and system biological methods has been established. This set currently serves as a strong foundation to improve existing and establish novel biotechnological applications. Here, we review four promising aspects covering different fields of applied science: (1) synthesis of secondary metabolites produced at fermenter level. (2) Lipases and other hydrolytic enzymes with potential roles in biocatalytic processes. (3) Degradation of ligno-cellulosic plant materials for biomass conversion. (4) Protein expression based on unconventional secretion, a novel approach inspired by basic research on mRNA transport. Thus, plant pathogenic Ustilaginaceae offer a great potential for future biotechnological applications by combining basic research and applied science.     

Mineral-microbe interactions: biotechnological potential of bioweathering

Mineral-microbe interaction has been a key factor shaping the lithosphere of our planet since the Precambrian. Detailed investigation has been mainly focused on the role of bioweathering in biomining processes, leading to the selection of highly efficient microbial inoculants for the recovery of metals. Here we expand this scenario, presenting additional applications of bacteria and fungi in mineral dissolution, a process with novel biotechnological potential that has been poorly investigated. The ability of microorganisms to trigger soil formation and to sustain plant establishment and growth are suggested as invaluable tools to counteract the expansion of arid lands and to increase crop productivity. Furthermore, interesting exploitations of mineral weathering microbes are represented by biorestoration and bioremediation technologies, innovative and competitive solutions characterized by economical and environmental advantages. Overall, in the future the study and application of the metabolic properties of microbial communities capable of weathering can represent a driving force in the expanding sector of environmental biotechnology.     

The biotechnological potential of anaerobic fungi on fiber degradation and methane production

Anaerobic fungi (phylum Neocallimastigomycota), an early branching family of fungi, are commonly encountered in the digestive tract of mammalian herbivores. To date, isolates from ten described genera have been reported, and several novel taxonomic groupings are detected using culture-independent molecular methods. Anaerobic fungi are recognized as playing key roles in the decomposition of lignocellulose (up to 50% of the ingested and untreated lignocellulose), with their physical penetration and extracellular enzymatical secretion of an unbiased diverse repertoire of cell-wall-degrading enzymes. The secreted cell-wall-degrading enzymes of anaerobic fungi include both free enzymes and extracellular multi-enzyme complexes called cellulosomes, both of which have potential as fiber degraders in industries. In addition, anaerobic fungi can provide large amounts of substrates such as hydrogen, formate, and acetate for their co-cultured methanogens. Consequently, large amounts of methane can be produced. And thus, it is promising to use the co-culture of anaerobic fungi and methanogens in the biogas process to intensify the biogas yield owing to the efficient and robust degradation of recalcitrant biomass by anaerobic fungi and improved methane production from co-cultures of anaerobic fungi and methanogens.     

The potential of microalgal biomass production for biotechnological purposes using wastewater resources

The utilization of microalgae for wastewater treatment represents an attractive opportunity for wastewater valorization through the use of the produced biomass. Five strains of microalgae were isolated from municipal wastewater and grown in autoclaved and non-autoclaved effluent at 30 °C and 150 μmol photons m^?2 s^?1 to study biomass production, nutrient removal, and the biochemical composition of the biomass. All strains reached high biomass productivity (35.6 to 54.2 mg dry weight L^?1 day^?1) within 4 days of batch culturing. In this period, ammonium-N and phosphate were reduced by more than 60 and 90 %, respectively. The high growth rate (0.57 to 1.06 day^?1) ensured a rapid removal of nutrients and thereby a short retention time. By the fourth day of cultivation, the algal biomass contained 32 % protein, but only 11 % lipids and 18 % carbohydrates. It was found that the biomass was a suitable raw material for biogas production by anaerobic digestion. Biodigestion of obtained biomass was simulated by employing the Aspen HYSYS modeling software, resulting in methane yields comparable to those found in the literature. The elemental analysis of the algal biomass showed very low concentrations of pollutants, demonstrating the potential of use of the digestate from biodigestion as a bio-fertilizer.     

Underground metabolism: network-level perspective and biotechnological potential

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Methanol,a potential feedstock for biotechnological processes

A wide variety of bacteria and yeasts is able to grow in inexpensive synthetic media with methanol as the sole or major source of carbon and energy. This is due to the presence of a few unique enzymes which enable these organisms to generate metabolic energy and synthesize cell constituents from this one-carbon substrate. In the chemical industry there is currently much interest in the production of fuels and chemicals from methanol. As a feedstock for industrial fermentations methanol is also attractive because of its low cost, ease of handling and abundant availability. In many countries methanol-utilizing microbes are being studied and their potential utility in biotechnological processes is explored. These studies are aimed at making use of their characteristic properties, exploiting known organisms and new strains for improving existing processes and developing novel products.     

A perspective on the biotechnological potential of extremophiles.

It is well recognized that many environments considered by man to be extreme are colonized by microorganisms which are specifically adapted to these ecological niches. A diverse range of bacteria, cyanobacteria, algae and yeasts have been isolated from such habitats and it is now widely accepted that these microorganisms provide a valuable resource not only for exploitation in novel biotechnological processes but also as models for investigating how biomolecules are stabilized when subjected to extreme conditions. This short review summarizes our current state of knowledge of this unique group of microorganisms and their enzymes, and attempts to identify their future biotechnological potential.     

Extremophile Microalgae: the potential for biotechnological application

Microalgae are photosynthetic microorganisms that use sunlight as an energy source, and convert water, carbon dioxide, and inorganic salts into algal biomass. The isolation and selection of microalgae, which allow one to obtain large amounts of biomass and valuable compounds, is a prerequisite for their successful industrial production. This work provides an overview of extremophile algae, where their ability to grow under harsh conditions and the corresponding accumulation of metabolites are addressed. Emphasis is placed on the high-value products of some prominent algae. Moreover, the most recent applications of these microorganisms and their potential exploitation in the context of astrobiology are taken into account.     

Unnatural amino acids: production and biotechnological potential

World Journal of Microbiology and Biotechnology - Selenium (Se) is one of the essential trace elements in the human body, and Se-enriched lactic acid bacteria (LAB) can improve the biological...     

Haloarchaea: worth exploring for their biotechnological potential

Halophilic archaea are unique microorganisms adapted to survive under high salt conditions and biomolecules produced by them may possess unusual properties. Haloarchaeal metabolites are stable at high salt and temperature conditions that are useful for industrial applications. Proteins and enzymes of this group of archaea are functional under salt concentrations at which bacterial counterparts fail to be active. Such properties makes haloarchaeal enzymes suitable for salt-based applications and their use under dehydrating conditions. For example, bacteriorhodopsin or the purple membrane protein present in halophilic archaea has the most recognizable applications in photoelectric devices, artificial retinas, holograms etc. Haloarchaea are also useful for bioremediation of polluted hypersaline areas. Polyhydroxyalkanoates and exopolysccharides produced by these microorganisms are biodegradable and have the potential to replace commercial non-degradable plastics and polymers. Moreover, halophilic archaea have excellent potential to be used as drug delivery systems and for nanobiotechnology by virtue of their gas vesicles and S-layer glycoproteins. Despite of possible applications of halophilic archaea, laboratory-to-industrial transition of these potential candidates is yet to be established.     

A yeast lysis mutant: potential biotechnological applications

The conditional yeast lysis mutant cly8 was studied for potential biotechnological applications. The strain stops to grow immediately after a shift to elevated temperatures ( > 30°C). Cell viability (colony forming capacity) decreases at 37°C at a rate depending on the composition of the medium. However, at the elevated temperature cells still consume glucose and incorporate [¹⁴C]leucine into cell material. With decreasing viability the mutant cells become leaky for small, predominantly cytoplasmic components such as leucine or uridine but not for vacuolar storage products like arginine. No trichloroacetic acid-precipitable material could be detected in the medium after the shift to the elevated temperature indicating that leakiness was restricted to low molecular weight compounds. On acetate medium mutant cells became permeable only after prolonged incubation at 37°C but could be used for the oxidation of exogenous NADH. In comparison to the wild type the mutant also produced more glycerol. When the mutant cells were immobilized, glycerol production was in the same range at room temperature and at 28°C and could be maintained for several days.     

The biotechnological potential of fibrinolytic enzymes in the dissolution of endogenous blood thrombi

Formation of endogenous thrombi in blood vessels is one of the leading causes of death in our modern life. According to data provided by the World Health Organization (WHO) in 2000, heart diseases are responsible for 29% of the total mortality rate in the world. For this, a tremendous amount of research has been done in the area of prevention and treatment of these diseases. The classical therapy of these thrombi relies upon the use of antiplatelets, anticoagulants, or even surgeries. Relatively recently, the fibrinolytic enzymes produced by microorganisms, snakes, earthworms, insects, plants, and other organisms are being successfully used in the treatment of blood clots, especially with regard to the direct dissolving action on fibrin in tandem with less cost and side effects in comparison with the first‐generation thrombolytic agents, streptokinase and urokinase. Furthermore, recombinant DNA technology has succeeded in improving and decreasing the undesirable effects of the first generation of enzymes. Recombinant PAs or rt‐PAs like alteplase, retelase, saruplase, tenecteplase, lanoteplase, and desmoteplase became available in the drug markets with advantages of less binding loci with PAI‐1 to avoid degradation while providing faster and more complete reperfusion in a greater number of patients with less risk of bleeding and intracranial hemorrhage. This review is the first to cover all the natural and recombinant thrombolytic agents used in enzyme therapy. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:656–672, 2014     

The biotechnological potential of marine bacteria in the novel lineage of Pseudomonas pertucinogena

Marine habitats represent a prolific source for molecules of biotechnological interest. In particular, marine bacteria have attracted attention and were successfully exploited for industrial applications. Recently, a group of Pseudomonas species isolated from extreme habitats or living in association with algae or sponges were clustered in the newly established Pseudomonas pertucinogena lineage. Remarkably for the predominantly terrestrial genus Pseudomonas, more than half (9) of currently 16 species within this lineage were isolated from marine or saline habitats. Unlike other Pseudomonas species, they seem to have in common a highly specialized metabolism. Furthermore, the marine members apparently possess the capacity to produce biomolecules of biotechnological interest (e.g. dehalogenases, polyester hydrolases, transaminases). Here, we summarize the knowledge regarding the enzymatic endowment of the marine Pseudomonas pertucinogena bacteria and report on a genomic analysis focusing on the presence of genes encoding esterases, dehalogenases, transaminases and secondary metabolites including carbon storage compounds.     

Diversity and biotechnological potential of the sponge-associated microbial consortia

Sponges are well known to harbor diverse microbes and represent a significant source of bioactive natural compounds derived from the marine environment. Recent studies of the microbial communities of marine sponges have uncovered previously undescribed species and an array of new chemical compounds. In contrast to natural compounds, studies on enzymes with biotechnological potential from microbes associated with sponges are rare although enzymes with novel activities that have potential medical and biotechnological applications have been identified from sponges and microbes associated with sponges. Both bacteria and fungi have been isolated from a wide range of marine sponge, but the diversity and symbiotic relationship of bacteria has been studied to a greater extent than that of fungi isolated from sponges. Molecular methods (e.g., rDNA, DGGE, and FISH) have revealed a great diversity of the unculturable bacteria and archaea. Metagenomic approaches have identified interesting metabolic pathways responsible for the production of natural compounds and may provide a new avenue to explore the microbial diversity and biotechnological potential of marine sponges. In addition, other eukaryotic organisms such as diatoms and unicellular algae from marine sponges are also being described using these molecular techniques. Many natural compounds derived from sponges are suspected to be of bacterial origin, but only a few studies have provided convincing evidence for symbiotic producers in sponges. Microbes in sponges exist in different associations with sponges including the true symbiosis. Fungi derived from marine sponges represent the single most prolific source of diverse bioactive marine fungal compounds found to date. There is a developing interest in determining the true diversity of fungi present in marine sponges and the nature of the association. Molecular methods will allow scientists to more accurately identify fungal species and determine actual diversity of sponge-associated fungi. This is especially important as greater cooperation between bacteriologists, mycologists, natural product chemists, and bioengineers is needed to provide a well-coordinated effort in studying the diversity, ecology, physiology, and association between bacteria, fungi, and other organisms present in marine sponges.     

Progress in Arabidopsis starch research and potential biotechnological applications

For the past decade, Arabidopsis has been the model higher plant of choice. Research into leaf starch metabolism has demonstrated that Arabidopsis is a useful system in which to make fundamental discoveries about both starch biosynthesis and starch degradation. This review describes recent discoveries in these fields and illustrates how such discoveries might be applied in the green biotechnology sector to improve and diversify our starch crops.