Showing papers in "Applied Microbiology and Biotechnology in 2012"

CHO cells in biotechnology for production of recombinant proteins: current state and further potential.

Abstract: Recombinant Chinese hamster ovary cells (rCHO) cells have been the most commonly used mammalian host for large-scale commercial production of therapeutic proteins. Recent advances in cell culture technology for rCHO cells have achieved significant improvement in protein production leading to titer of more than 10 g/L to meet the huge demand from market needs. This achievement is associated with progression in the establishment of high and stable producer and the optimization of culture process including media development. In this review article, we focus on current strategies and achievements in cell line development, mainly in vector engineering and cell engineering, for high and stable protein production in rCHO cells. The approaches that manipulate various DNA elements for gene targeting by site-specific integration and cis-acting elements to augment and stabilize gene expression are reviewed here. The genetic modulation strategy by “direct” cell engineering with growth-promoting and/or productivity-enhancing factors and omics-based approaches involved in transcriptomics, proteomics, and metabolomics to pursue cell engineering are also presented.

Synthesis and assembly of fungal melanin

Abstract: Melanin is a unique pigment with myriad functions that is found in all biological kingdoms. It is multifunctional, providing defense against environmental stresses such as ultraviolet (UV) light, oxidizing agents and ionizing radiation. Melanin contributes to the ability of fungi to survive in harsh environments. In addition, it plays a role in fungal pathogenesis. Melanin is an amorphous polymer that is produced by one of two synthetic pathways. Fungi may synthesize melanin from endogenous substrate via a 1,8-dihydroxynaphthalene (DHN) intermediate. Alternatively, some fungi produce melanin from l-3,4-dihydroxyphenylalanine (l-dopa). The detailed chemical structure of melanin is not known. However, microscopic studies show that it has an overall granular structure. In fungi, melanin granules are localized to the cell wall where they are likely cross-linked to polysaccharides. Recent studies suggest the fungal melanin may be synthesized in internal vesicles akin to mammalian melanosomes and transported to the cell wall. Potential applications of melanin take advantage of melanin's radioprotective properties and propensity to bind to a variety of substances.

Role of nanotechnology in agriculture with special reference to management of insect pests

Abstract: Nanotechnology is a promising field of interdisciplinary research. It opens up a wide array of opportunities in various fields like medicine, pharmaceuticals, electronics and agriculture. The potential uses and benefits of nanotechnology are enormous. These include insect pests management through the formulations of nanomaterials-based pesticides and insecticides, enhancement of agricultural productivity using bio-conjugated nanoparticles (encapsulation) for slow release of nutrients and water, nanoparticle-mediated gene or DNA transfer in plants for the development of insect pest-resistant varieties and use of nanomaterials for preparation of different kind of biosensors, which would be useful in remote sensing devices required for precision farming. Traditional strategies like integrated pest management used in agriculture are insufficient, and application of chemical pesticides like DDT have adverse effects on animals and human beings apart from the decline in soil fertility. Therefore, nanotechnology would provide green and efficient alternatives for the management of insect pests in agriculture without harming the nature. This review is focused on traditional strategies used for the management of insect pests, limitations of use of chemical pesticides and potential of nanomaterials in insect pest management as modern approaches of nanotechnology.

Microalgal carbohydrates: an overview of the factors influencing carbohydrates production, and of main bioconversion technologies for production of biofuels.

Abstract: Microalgal biomass seems to be a promising feedstock for biofuel generation. Microalgae have relative high photosynthetic efficiencies, high growth rates, and some species can thrive in brackish water or seawater and wastewater from the food- and agro-industrial sector. Today, the main interest in research is the cultivation of microalgae for lipids production to generate biodiesel. However, there are several other biological or thermochemical conversion technologies, in which microalgal biomass could be used as substrate. However, the high protein content or the low carbohydrate content of the majority of the microalgal species might be a constraint for their possible use in these technologies. Moreover, in the majority of biomass conversion technologies, carbohydrates are the main substrate for production of biofuels. Nevertheless, microalgae biomass composition could be manipulated by several cultivation techniques, such as nutrient starvation or other stressed environmental conditions, which cause the microalgae to accumulate carbohydrates. This paper attempts to give a general overview of techniques that can be used for increasing the microalgal biomass carbohydrate content. In addition, biomass conversion technologies, related to the conversion of carbohydrates into biofuels are discussed.

MALDI-TOF MS in microbiological diagnostics—identification of microorganisms and beyond (mini review)

Abstract: Few developments in microbiological diagnostics have had such a rapid impact on species level identification of microorganisms as matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Conventional differentiation methods rely on biochemical criteria and require additional pre-testing and lengthy incubation procedures. In comparison, MALDI-TOF MS can identify bacteria and yeast within minutes directly from colonies grown on culture plates. This radically new, methodically simple approach profoundly reduces the cost of consumables and time spent on diagnostics. The reliability and accuracy of the method have been demonstrated in numerous studies and different systems are already commercially available. Novel applications of the system besides microbial species level identification are also being explored. This includes identification of pathogens from positive blood cultures or directly from patient samples, such as urine. Currently, intriguing MALDI-TOF MS developments are being made regarding the phenotypic detection of certain antibiotic resistance mechanisms, e.g., β-lactamases and carbapenemases. This mini review provides an overview of the literature in the field and also includes our own data and experiences gathered from over 4 years of routine MALDI-TOF MS use in a university hospital’s microbiological diagnostics facility.

Microbial steroid transformations: current state and prospects

Abstract: Studies of steroid modifications catalyzed by microbial whole cells represent a well-established research area in white biotechnology. Still, advances over the last decade in genetic and metabolic engineering, whole-cell biocatalysis in non-conventional media, and process monitoring raised research in this field to a new level. This review summarizes the data on microbial steroid conversion obtained since 2003. The key reactions of structural steroid functionalization by microorganisms are highlighted including sterol side-chain degradation, hydroxylation at various positions of the steroid core, and redox reactions. We also describe methods for enhancement of bioprocess productivity, selectivity of target reactions, and application of microbial transformations for production of valuable pharmaceutical ingredients and precursors. Challenges and prospects of whole-cell biocatalysis applications in steroid industry are discussed.

Industrial biotechnology of Pseudomonas putida and related species

Abstract: Since their discovery many decades ago, Pseudomonas putida and related subspecies have been intensively studied with regard to their potential application in industrial biotechnology. Today, these Gram-negative soil bacteria, traditionally known as well-performing xenobiotic degraders, are becoming efficient cell factories for various products of industrial relevance including a full range of unnatural chemicals. This development is strongly driven by systems biotechnology, integrating systems metabolic engineering approaches with novel concepts from bioprocess engineering, including novel reactor designs and renewable feedstocks.

Review of research on Dendrobium, a prized folk medicine.

Abstract: Medicinal plants of the Dendrobium genus are highly prized, and hence, methodologies have been developed to authenticate Dendrobium drugs from its adulterants. Many bioactive constituents of Dendrobium species have been identified. The macromolecules included lectins; the enzymes chalcone synthase, sucrose synthase, and cytokinin oxidase; and polysaccharides. The polysaccharides display immunomodulatory and hepatoprotective activities. Alkaloids exhibit antioxidant, anticancer, and neuroprotective activities. Other compounds manifest antioxidant, anticancer, and immunomodulatory.

Shuttling happens: soluble flavin mediators of extracellular electron transfer in Shewanella.

Abstract: The genus Shewanella contains Gram negative γ-proteobacteria capable of reducing a wide range of substrates, including insoluble metals and carbon electrodes. The utilization of insoluble respiratory substrates by bacteria requires a strategy that is quite different from a traditional respiratory strategy because the cell cannot take up the substrate. Electrons generated by cellular metabolism instead must be transported outside the cell, and perhaps beyond, in order to reduce an insoluble substrate. The primary focus of research in model organisms such as Shewanella has been the mechanisms underlying respiration of insoluble substrates. Electrons travel from the menaquinone pool in the cytoplasmic membrane to the surface of the bacterial cell through a series of proteins collectively described as the Mtr pathway. This review will focus on respiratory electron transfer from the surface of the bacterial cell to extracellular substrates. Shewanella sp. secrete redox-active flavin compounds able to transfer electrons between the cell surface and substrate in a cyclic fashion—a process termed electron shuttling. The production and secretion of flavins as well as the mechanisms of cell-mediated reduction will be discussed with emphasis on the experimental evidence for a shuttle-based mechanism. The ability to reduce extracellular substrates has sparked interest in using Shewanella sp. for applications in bioremediation, bioenergy, and synthetic biology.

Peculiarities of brown-rot fungi and biochemical Fenton reaction with regard to their potential as a model for bioprocessing biomass

Abstract: This work reviews the brown-rot fungal biochemical mechanism involved in the biodegradation of lignified plant cell walls. This mechanism has been acquired as an apparent alternative to the energetically expensive apparatus of lignocellulose breakdown employed by white-rot fungi. The mechanism relies, at least in the incipient stage of decay, on the oxidative cleavage of glycosidic bonds in cellulose and hemicellulose and the oxidative modification and arrangement of lignin upon attack by highly destructive oxygen reactive species such as the hydroxyl radical generated non-enzymatically via Fenton chemistry $$ ({\text{F}}{{\text{e}}^{{{3} + }}} + {{\text{H}}_{{2}}}{{\text{O}}_{{2}}} \to {\text{F}}{{\text{e}}^{{{2} + }}} + \cdot {\text{OH}}{{ + }^{ - }}{\text{OH}}) $$ . Modifications in the lignocellulose macrocomponents associated with this non-enzymatic attack are believed to aid in the selective, near-complete removal of polysaccharides by an incomplete cellulase suite and without causing substantial lignin removal. Utilization of this process could provide the key to making the production of biofuel and renewable chemicals from lignocellulose biomass more cost-effective and energy efficient. This review highlights the unique features of the brown-rot fungal non-enzymatic, mediated Fenton reaction mechanism, the modifications to the major plant cell wall macrocomponents, and the implications and opportunities for biomass processing for biofuels and chemicals.

Mannanases: microbial sources, production, properties and potential biotechnological applications

Abstract: Mannans are the major constituents of the hemicellulose fraction in softwoods and show widespread distribution in plant tissues. The major mannan-degrading enzymes are β-mannanases, β-mannosidases and β-glucosidases. In addition to these, other enzymes such as α-galactosidases and acetyl mannan esterases, are required to remove the side chain substituents. The mannanases are known to be produced by a variety of bacteria, fungi, actinomycetes, plants and animals. Microbial mannanases are mainly extracellular and can act in wide range of pH and temperature because of which they have found applications in pulp and paper, pharmaceutical, food, feed, oil and textile industries. This review summarizes the studies on mannanases reported in recent years in terms of important microbial sources, production conditions, enzyme properties, heterologous expression and potential industrial applications.

Protein secretion in Pichia pastoris and advances in protein production.

Abstract: Yeast expression systems have been successfully used for over 20 years for the production of recombinant proteins. With the growing interest in recombinant protein expression for various uses, yeast expression systems, such as the popular Pichia pastoris, are becoming increasingly important. Although P. pastoris has been successfully used in the production of many secreted and intracellular recombinant proteins, there is still room for improvement of this expression system. In particular, secretion of recombinant proteins is still one of the main reasons for using P. pastoris. Therefore, endoplasmic reticulum protein folding, correct glycosylation, vesicular transport to the plasma membrane, gene dosage, secretion signal sequences, and secretome studies are important considerations for improved recombinant protein production.

Fungal chitinases: diversity, mechanistic properties and biotechnological potential

Abstract: Chitin derivatives, chitosan and substituted chito-oligosaccharides have a wide spectrum of applications ranging from medicine to cosmetics and dietary supplements. With advancing knowledge about the substrate-binding properties of chitinases, enzyme-based production of these biotechnologically relevant sugars from biological resources is becoming increasingly interesting. Fungi have high numbers of glycoside hydrolase family 18 chitinases with different substrate-binding site architectures. As presented in this review, the large diversity of fungal chitinases is an interesting starting point for protein engineering. In this review, recent data about the architecture of the substrate-binding clefts of fungal chitinases, in connection with their hydrolytic and transglycolytic abilities, and the development of chitinase inhibitors are summarized. Furthermore, the biological functions of chitinases, chitin and chitosan utilization by fungi, and the effects of these aspects on biotechnological applications, including protein overexpression and autolysis during industrial processes, are discussed in this review.

Intestinal microbiota associated with differential feed conversion efficiency in chickens.

Abstract: Analysis of model systems, for example in mice, has shown that the microbiota in the gastrointestinal tract can play an important role in the efficiency of energy extraction from diets. The study reported here aimed to determine whether there are correlations between gastrointestinal tract microbiota population structure and energy use in chickens. Efficiency in converting food into muscle mass has a significant impact on the intensive animal production industries, where feed represents the major portion of production costs. Despite extensive breeding and selection efforts, there are still large differences in the growth performance of animals fed identical diets and reared under the same conditions. Variability in growth performance presents management difficulties and causes economic loss. An understanding of possible microbiota drivers of these differences has potentially important benefits for industry. In this study, differences in cecal and jejunal microbiota between broiler chickens with extreme feed conversion capabilities were analysed in order to identify candidate bacteria that may influence growth performance. The jejunal microbiota was largely dominated by lactobacilli (over 99% of jejunal sequences) and showed no difference between the birds with high and low feed conversion ratios. The cecal microbial community displayed higher diversity, and 24 unclassified bacterial species were found to be significantly (<0.05) differentially abundant between high and low performing birds. Such differentially abundant bacteria represent target populations that could potentially be modified with prebiotics and probiotics in order to improve animal growth performance.

Stability and inhibition of anaerobic processes caused by insufficiency or excess of ammonia nitrogen

Abstract: Ammonia increases buffer capacity of methanogenic medium in mesophilic anaerobic reactor thus increasing the stability of anaerobic digestion process. Optimal ammonia concentration ensures sufficient buffer capacity while not inhibiting the process. It was found out in this paper that this optimum depends on the quality of anaerobic sludge under investigation. The optimal concentrations for methanogens were 2.1, 2.6 and 3.1 g/L of ammonia nitrogen in dependence on inoculum origin. High ammonia nitrogen concentration (4.0 g/L) inhibited methane production, while low ammonia nitrogen concentration (0.5 g/L) caused low methane yield, loss of biomass (as VSS) and loss of the aceticlastic methanogenic activity. It was found out that negative effect of low ammonia nitrogen concentration on biomass is caused not only by low buffer capacity but also by insufficiency of nitrogen as nutrient. It was also found out that anaerobic sludge with higher ammonia nitrogen concentration (4.2 g/L) tolerates even concentration of volatile fatty acids (160 mmol/L) which causes inhibition of the process with low ammonia nitrogen concentration (0.2 g/L).

Potential uses of spent mushroom substrate and its associated lignocellulosic enzymes

Abstract: Mushroom industries generate a virtually in-exhaustible supply of a co-product called spent mushroom substrate (SMS). This is the unutilised substrate and the mushroom mycelium left after harvesting of mushrooms. As the mushroom industry is steadily growing, the volume of SMS generated annually is increasing. In recent years, the mushroom industry has faced challenges in storing and disposing the SMS. The obvious solution is to explore new applications of SMS. There has been considerable discussion recently about the potentials of using SMS for production of value-added products. One of them is production of lignocellulosic enzymes such as laccase, xylanase, lignin peroxidase, cellulase and hemicellulase. This paper reviews scientific research and practical applications of SMS as a readily available and cheap source of enzymes for bioremediation, animal feed and energy feedstock.

Lactic acid bacteria producing B-group vitamins: a great potential for functional cereals products.

Abstract: Wheat contains various essential nutrients including the B group of vitamins. However, B group vitamins, normally present in cereals-derived products, are easily removed or destroyed during milling, food processing or cooking. Lactic acid bacteria (LAB) are widely used as starter cultures for the fermentation of a large variety of foods and can improve the safety, shelf life, nutritional value, flavor and overall quality of the fermented products. In this regard, the identification and application of strains delivering health-promoting compounds is a fascinating field. Besides their key role in food fermentations, several LAB found in the gastrointestinal tract of humans and animals are commercially used as probiotics and possess generally recognized as safe status. LAB are usually auxotrophic for several vitamins although certain strains of LAB have the capability to synthesize water-soluble vitamins such as those included in the B group. In recent years, a number of biotechnological processes have been explored to perform a more economical and sustainable vitamin production than that obtained via chemical synthesis. This review article will briefly report the current knowledge on lactic acid bacteria synthesis of vitamins B2, B11 and B12 and the potential strategies to increase B-group vitamin content in cereals-based products, where vitamins-producing LAB have been leading to the elaboration of novel fermented functional foods. In addition, the use of genetic strategies to increase vitamin production or to create novel vitamin-producing strains will be also discussed.

Paracetamol in the environment and its degradation by microorganisms

Abstract: Paracetamol (4'-hydroxyacetanilide, N-acetyl-p-aminophenol, acetaminophen, and paracetamol) is a widely used over-the-counter analgesic and antipyretic drug. Paracetamol and structural analogs are ubiquitous in the natural environment and easily accumulate in aquatic environment, which have been detected in surface waters, wastewater, and drinking water throughout the world. Paracetamol wastewater is mainly treated by chemical oxidation processes. Although these chemical methods may be available for treating these pollutants, the harsh reaction conditions, the generation of secondary pollutants, and the high operational cost associated with these methods have often made them not a desirable choice. Biodegradation of paracetamol is being considered as an environmentally friendly and low-cost option. The goal of this review is to provide an outline of the current knowledge of biodegradation of paracetamol in the occurrence, degrading bacteria, and proposed metabolic/biodegrading pathways, enzymes and possible intermediates. The comprehensive understanding of the metabolic pathways and enzyme systems involved in the utilization of paracetamol means will be helpful for optimizing and allowing rational design of biodegradation systems for paracetamol-contaminated wastewater.

Endophytic fungi: novel sources of anticancer lead molecules

Abstract: Cancer is a major killer disease all over the world and more than six million new cases are reported every year. Nature is an attractive source of new therapeutic compounds, as a tremendous chemical diversity is found in millions of species of plants, animals, and microorganisms. Plant-derived compounds have played an important role in the development of several clinically useful anti-cancer agents. These include vinblastine, vincristine, camptothecin, podophyllotoxin, and taxol. Production of a plant-based natural drug is always not up to the desired level. It is produced at a specific developmental stage or under specific environmental condition, stress, or nutrient availability; the plants may be very slow growing taking several years to attain a suitable growth phase for product accumulation and extraction. Considering the limitations associated with the productivity and vulnerability of plant species as sources of novel metabolites, microorganisms serve as the ultimate, readily renewable, and inexhaustible source of novel structures bearing pharmaceutical potential. Endophytes, the microorganisms that reside in the tissues of living plants, are relatively unstudied and offer potential sources of novel natural products for exploitation in medicine, agriculture and the pharmaceutical industry. They develop special mechanisms to penetrate inside the host tissue, residing in mutualistic association and their biotransformation abilities opens a new platform for synthesis of novel secondary metabolites. They produce metabolites to compete with the epiphytes and also with the plant pathogens to maintain a critical balance between fungal virulence and plant defense. It is therefore necessary that the relationship between the plants and endophytes during the accumulation of these secondary metabolites is studied. Insights from such research would provide alternative methods of natural product drug discovery which could be reliable, economical, and environmentally safe.

Immobilized metal ion affinity chromatography: a review on its applications

Abstract: After 35 years of development, immobilized metal ion affinity chromatography (IMAC) has evolved into a popular protein purification technique. This review starts with a discussion of its mechanism and advantages. It continues with its applications which include the purification of histidine-tagged proteins, natural metal-binding proteins, and antibodies. IMAC used in conjunction with mass spectroscopy for phosphoprotein fractionation and proteomics is also covered. Finally, this review addresses the developments, limitations, and considerations of IMAC in the biopharmaceutical industry.

Sialic acid metabolism and sialyltransferases: natural functions and applications.

Abstract: Sialic acids are a family of negatively charged monosaccharides which are commonly presented as the terminal residues in glycans of the glycoconjugates on eukaryotic cell surface or as components of capsular polysaccharides or lipooligosaccharides of some pathogenic bacteria. Due to their important biological and pathological functions, the biosynthesis, activation, transfer, breaking down, and recycle of sialic acids are attracting increasing attention. The understanding of the sialic acid metabolism in eukaryotes and bacteria leads to the development of metabolic engineering approaches for elucidating the important functions of sialic acid in mammalian systems and for large-scale production of sialosides using engineered bacterial cells. As the key enzymes in biosynthesis of sialylated structures, sialyltransferases have been continuously identified from various sources and characterized. Protein crystal structures of seven sialyltransferases have been reported. Wild-type sialyltransferases and their mutants have been applied with or without other sialoside biosynthetic enzymes for producing complex sialic acid-containing oligosaccharides and glycoconjugates. This mini-review focuses on current understanding and applications of sialic acid metabolism and sialyltransferases.

Agar degradation by microorganisms and agar-degrading enzymes

Abstract: Agar is a mixture of heterogeneous galactans, mainly composed of 3,6-anhydro-l-galactoses (or l-galactose-6-sulfates) d-galactoses and l-galactoses (routinely in the forms of 3,6-anhydro-l-galactoses or l-galactose-6-sulfates) alternately linked by β-(1,4) and α-(1,3) linkages. It is a major component of the cell walls of red algae and has been used in a variety of laboratory and industrial applications, owing to its jellifying properties. Many microorganisms that can hydrolyze and metabolize agar as a carbon and energy source have been identified in seawater and marine sediments. Agarolytic microorganisms commonly produce agarases, which catalyze the hydrolysis of agar. Numerous agarases have been identified in microorganisms of various genera. They are classified according to their cleavage pattern into three types—α-agarase, β-agarase, and β-porphyranase. Although, in a broad sense, many other agarases are involved in complete hydrolysis of agar, most of those identified are β-agarases. In this article we review agarolytic microorganisms and their agar-hydrolyzing systems, covering β-agarases as well as α-agarases, α-neoagarobiose hydrolases, and β-porphyranases, with emphasis on the recent discoveries. We also present an overview of the biochemical and structural characteristics of the various types of agarases. Further, we summarize and compare the agar-hydrolyzing systems of two specific microorganisms: Gram-negative Saccharophagus degradans 2–40 and Gram-positive Streptomyces coelicolor A3(2). We conclude with a brief discussion of the importance of agarases and their possible future application in producing oligosaccharides with various nutraceutical activities and in sustainably generating stock chemicals for biorefinement and bioenergy.

The immunomodulatory effects of lactic acid bacteria for improving immune functions and benefits

Abstract: Probiotics have a number of beneficial health effects in humans and animals, such as reducing lactose intolerance symptoms and enhancing the bioavailability of nutrients. Probiotics help regulate intestinal microflora and immunomodulatory properties. Probiotics also decrease the prevalence of allergies in susceptible individuals, inhibit the inflammatory responses in the gut, and have antagonistic effects against intestinal and food-borne pathogens. Bacteria typically colonize the intestinal tract first and then reinforce the host defense systems by inducing generalized mucosal immune responses, including modulation of DC/NK interaction, a balanced T-helper cell response, self-limited inflammatory response, and the secretion of polymeric IgA. A lot of reports showed that lactic acid bacteria (LAB) as Lactobacillus and Bifidobacterium and their fermented products are effective at enhancing innate and adaptive immunity, prevent gastric mucosal lesion development, alleviate allergies, and put up defense against intestinal pathogen infection. In this review paper, we compared the influence of immunomodulatory effects on the function and efficacy of lactobacillus products with different strains. We also discuss the beneficial effects of several LAB strain and its derivative products for human immunity and related diseases.

The plant strengthening root endophyte Piriformospora indica: potential application and the biology behind.

Abstract: The successful conversion of plant production systems from conventional resource-exhausting to sustainable strategies depends on knowledge-based management of environmental factors. Root-inhabiting fungi came more and more into focus because their hyphae connect in ideal manner resources and challenges of the surrounding with the plant. A paradigm for such root endophytes is presented by the basidiomycete Piriformospora indica. This fungus possesses a broad host spectrum and positively affects different aspects of plant performance. This so far unique combination of attributes makes P. indica and its close relatives among the Sebacinales very interesting tools for cultivation of various crops. This review will outline the different aspects required to apply this root endophyte in agri- and horticulture concerning plant growth, plant nutrition and plant defence or tolerance thereby explaining what is known about the biological basis for the observed effects. Open questions and challenges for successful inoculum production and application will be discussed.

Recent advances in technology supporting biopharmaceutical production from mammalian cells.

Abstract: The demand for production of glycoproteins from mammalian cell culture continues with an increased number of approvals as biopharmaceuticals for the treatment of unmet medical needs. This is particularly the case for humanized monoclonal antibodies which are the largest and fastest growing class of therapeutic pharmaceuticals. This demand has fostered efforts to improve the efficiency of production as well as to address the quality of the final product. Chinese hamster ovary cells are the predominant hosts for stable transfection and high efficiency production on a large scale. Specific productivity of recombinant glycoproteins from these cells can be expected to be above 50 pg/cell/day giving rise to culture systems with titers of around 5 g/L if appropriate fed-batch systems are employed. Cell engineering can delay the onset of programmed cell death to ensure prolonged maintenance of productive viable cells. The clinical efficacy and quality of the final product can be improved by strategic metabolic engineering. The best example of this is the targeted production of afucosylated antibodies with enhanced antibody-dependent cell cytotoxicity, an important function for use in cancer therapies. The development of culture media from non-animal sources continues and is important to ensure products of consistent quality and without the potential danger of contamination. Process efficiencies may also be improved by employing disposable bioreactors with the associated minimization of downtime. Finally, advances in downstream processing are needed to handle the increased supply of product from the bioreactor but maintaining the high purity demanded of these biopharmaceuticals.

Conversion of CO2 into biomass by microalgae: how realistic a contribution may it be to significant CO2 removal?

Abstract: Microalgae have been proposed as a CO2 removal option to contribute to climate change avoidance and problems coming from the use of fossil fuels. However, even though microalgae can be used to fix CO2 from air or flue gases, they do not permit long-term CO2 storage because they are easily decomposed. On the other hand, microalgae can contribute to an enhancement in human sustainability by producing biofuels as an alternative to fossil fuels in addition to the production of other useful chemicals and commodities. Moreover, microalgae can contribute to enhancing the sustainability of waste treatment processes, reducing the energy consumed, and improving the recycling of nutrients contained within them. This paper reviews the potential contribution of these processes and the existing knowledge in these areas.

Efficient surface modification of biomaterial to prevent biofilm formation and the attachment of microorganisms

Abstract: Biomaterials play a fundamental role in disease management and the improvement of health care. In recent years, there has been a significant growth in the diversity, function, and number of biomaterials used worldwide. Yet, attachment of pathogenic microorganisms onto biomaterial surfaces remains a significant challenge that substantially undermines their clinical applicability, limiting the advancement of these systems. The emergence and escalating pervasiveness of antibiotic-resistant bacterial strains makes the management of biomaterial-associated nosocomial infections increasingly difficult. The conventional post-operative treatment of implant-caused infections using systemic antibiotics is often marginally effective, further accelerating the extent of antimicrobial resistance. Methods by which the initial stages of bacterial attachment and biofilm formation can be restricted or prevented are therefore sought. The surface modification of biomaterials has the potential to alleviate pathogenic biofouling, therefore preventing the need for conventional antibiotics to be applied.

Culture-independent methods for studying environmental microorganisms: methods, application, and perspective.

Abstract: Since the application of molecular methods, culture-independent methods (CIMs) have been developed to study microbial communities from various environments. In the past 20 years, several methods based on the direct amplification and analyses of the small subunit ribosomal RNA gene have been developed to directly study environmental microorganisms. These methods include denaturing/temperature gradient gel electrophoresis, single-strand-conformation polymorphism, restriction fragment length polymorphism, terminal restriction fragment length polymorphism, and quantitative polymerase chain reaction (PCR). Similarly, non-PCR-based molecular techniques, such as microarray and fluorescence in situ hybridization have also been adopted. In recent years, several novel fields of investigation such as metagenomics, metatranscriptomics, metaproteomics, and single-cell genomics were developed, largely propelled by the innovation and application of next-generation sequencing methods. Several single-cell-based technologies such as Raman microspectroscopy and nano-scale secondary ion mass spectrometry are also increasingly used in the fields of microbial ecology and environmental microbiology. The application of these methods has revolutionized microbiology by allowing scientists to directly analyze natural microbial communities in situ, including their genes, transcripts, proteins, and metabolites and how their interactions impact their distribution patterns. In this review, we present an up-to-date review on different CIMs and their applications, our focuses are on the comparison of different CIMs and their application in the analyses of microbial diversities and communities.

Alginate beads provide a beneficial physical barrier against native microorganisms in wastewater treated with immobilized bacteria and microalgae

Abstract: When the freshwater microalga Chlorella sorokiniana and the plant growth-promoting bacterium Azospirillum brasilense were deployed as free suspensions in unsterile, municipal wastewater for tertiary wastewater treatment, their population was significantly lower compared with their populations in sterile wastewater. At the same time, the numbers of natural microfauna and wastewater bacteria increased. Immobilization of C. sorokiniana and A. brasilense in small (2-4 mm in diameter), polymer Ca-alginate beads significantly enhanced their populations when these beads were suspended in normal wastewater. All microbial populations within and on the surface of the beads were evaluated by quantitative fluorescence in situ hybridization combined with scanning electron microscopy and direct measurements. Submerging immobilizing beads in wastewater created the following sequence of events: (a) a biofilm composed of wastewater bacteria and A. brasilense was created on the surface of the beads, (b) the bead inhibited penetration of outside organisms into the beads, (c) the bead inhibited liberation of the immobilized microorganisms into the wastewater, and (d) permitted an uninterrupted reduction of ammonium and phosphorus from the wastewater. This study demonstrated that wastewater microbial populations are responsible for decreasing populations of biological agents used for wastewater treatment and immobilization in alginate beads provided a protective environment for these agents to carry out uninterrupted tertiary wastewater treatment.

Microbial production of itaconic acid: developing a stable platform for high product concentrations

Abstract: Biotechnologically produced itaconic acid (IA) is a promising organic acid with a wide range of applications and the potential to open up new application fields in the area of polymer chemistry, pharmacy, and agriculture. In this study, a systematic process optimization was performed with an own isolated strain of Aspergillus terreus and transferred from a 250-mL to a 15-L scale. An IA concentration of 86.2 g/L was achieved within 7 days with an overall productivity of 0.51 g/(L h), a maximum productivity of 1.2 g/(L h), and a yield of 86 mol%. A cultivation of other well-known A. terreus strains with the developed process showed no significant differences. Based on this, a process is developed providing a high final IA concentration independent of the used strain combined with high reproducibility.