Biosensors in biotechnology and medicine

The work is a review of the state-of-art of research in the field of biological sensors. The enzymatic and immune biosensors are described. Problems concerning application of microorganisms as biosensors have been reported in detail. The use of luminescent bacteria and luciferase sensors is under discussion. The principles of operation of fibrous-optic and semiconducting biosensors are stated.     

Effects of high oxygen concentrations on microbial biosensor signals. Hyperoxygenation by means of perfluorodecalin

Amperometric biosensors register oxygen depletion in response to analyte catabolism, and thus are limited by the availability of dissolved oxygen. Microbial sensors containing immobilized cells of Gluconobacter oxydans were hyperoxygenated to 400% of control levels and the effects on sensor responses to glucose were determined. Oxygenated perfluorodecalin (a completely fluorinated organic substance) was as effective in hyperoxygenation as direct sparging with O2, increasing sensor base medium oxygen concentrations from 9.3 to 37 mg/l. Hyperoxygenation enhanced maximal biosensor response amplitudes, particularly at high cell loading densities. Maximal response rates were also improved, although less dramatically. Results suggest that hyperoxygenation may be a new general approach for modulating biosensor responses.     

Biocatalysis, biodegradation and bioinformatics

Biocatalysis, biodegradation and bioinformatics are prominent scientific fields in industrial microbiology and biotechnology. This paper describes developments in these fields with a focus on the role of David T Gibson as a researcher and mentor. He has pioneered studies on the mechanisms by which aerobic microorganisms transform aromatic hydrocarbons. In addition, his research has served as a model for further investigations into bacterial atrazine and dichloromethane catabolism described here. Microbial catabolism research requires information on organic chemistry, microorganisms, metabolic pathways, catabolic genes, and enzymes. These information needs are now being met more comprehensively by development of the University of Minnesota Biocatalysis/Biodegradation Database.     

Subdural effusions in children. Pathophysiology and treatment

Pyrolysis mass spectrometry is a data rich analysis technique now becoming widely applied in microbiology. Data analysis is a key step in the exploitation of the technique and the application of neural network analysis to pyrolysis mass spectrometric data offers new opportunities for classification, identification and inter-strain comparison of microorganisms in biotechnology and clinical microbiology. The use of a supervised neural network for the identification of members of a streptomycete species-group is described.     

生物传感器的研究现状和发展趋势

生物传感器是发展生物技术必不可少的一种先进的检测与监控元件,具有广阔的发展前景,是传感器的一个重要研究方面.本文综述了生物传感器的结构特点、基本原理以及研究现状,探讨了生物传感器的发展趋势.     

Biotechnology/materials: The growing interface

The biotechnology/materials interaction dates back 3.5 billion years, yet today offers novel challenges for human creativity. The materials cycle practiced by microorganisms is compared to that recently practiced by humans. The processes of the biotechnology materials cycle are biogenesis, bioleaching, biofouling, biocorrosion, biodeterioration, and bioaccumulation. Each process is examined for mechanisms, scale of effect, and opportunity for creative human intervention or utilization. More than 50 of our metallic elements are bio-processed in nature. A like number of biogenic materials have been identified, with some at production rates of trillions of kg per annum (p.a.). Microorganisms can substitute for energy, capital, and labor. Over the eons, microorganisms have gained special attributes that now offer creative humans a new era of partnership in materials processing.     

The simplicity of complex MACs

The development of mammalian artificial chromosomes (MACs) would be useful for biotechnology and biomedicine, including their use in functional genomics, transgenic animals and gene therapy. By analogy to large cloning systems in microorganisms, MACs may be engineered using endogenous chromosomal elements such as the yeast-based artificial chromosomes (YACs), or exogenous extra-chromosomal components derived from viruses and other cellular parasites such as the bacterial-based artificial chromosomes (BACs) and p1 artificial chromosomes (PACs).     

Conducting polymers and the bioanalytical sciences: new tools for biomolecular communication. A review

This review covers the evolution of conducting polymers and their use in the bioanalytical sciences. It is the controlled dynamic behaviour of these unique materials that enables such diverse and high-level performance to be achieved. The construction and application of conducting polymers for use as biosensors are the particular emphasis of this paper. Biocompatibility is briefly discussed.     

Polishable and renewable DNA hybridization biosensors

Routine applications of DNA hybridization biosensors are often restricted by the need for regenerating the single-stranded (ss) probe for subsequent reuse. This note reports on a viable alternative to prolonged thermal or chemical regeneration schemes through the mechanical polishing of oligonucleotide-bulk-modified carbon composite electrodes. The surface of these biocomposite hybridization biosensors can be renewed rapidly and reproducibly by a simple extrusion/polishing protocol. The immobilized probe retains its hybridization activity on confinement in the interior of the carbon paste matrix, with the use of fresh surfaces erasing memory effects and restoring the original target response, to allow numerous hybridization/measurement cycles. We expect that such reusable nucleic acid modified composite electrodes can be designed for a wide variety of biosensing applications.     

Inversin, a novel gene in the vertebrate left-right axis pathway, is partially deleted in the inv mouse

A DNA fragment containing the recA gene of Gluconobacter oxydans was isolated and further characterized for its nucleotide sequence and ability to functionally complement various recA mutations. When expressed in an Escherichia coli recA host, the G. oxydans recA protein could efficiently function in homologous recombination and DNA damage repair. The recA gene's nucleotide sequence analysis revealed a protein of 344 amino acids with a molecular mass of 38 kDa. We observed an E. coli-like LexA repressor-binding site in the G. oxydans recA gene promoter region, suggesting that a LexA-like mediated response system may exist in G. oxydans. The expression of G. oxydans recA in E. coli RR1, a recA+ strain, surprisingly caused a remarkable reduction of the host wild-type recA gene function, whereas the expression of both Serratia marcescens recA and Pseudomonas aeruginosa recA gene caused only a slight inhibitory effect on function of the host wild-type recA gene product. Compared with the E. coli RecA protein, the identity of the amino acid sequence of G. oxydans RecA protein is much lower than those RecA proteins of both S. marcescens and Pseudomonas aeruginosa. This result suggests that the expression of another wild-type RecA could interfere with host wild-type recA gene's function, and the extent of such an interference is possibly correlated to the identity of the amino acid sequence between the two classes of RecA protein.     

An Integrated Biotechnological Approach to Gold Processing - An Indian Experience

Abstract

The role of biotechnology in different facets of gold extraction metallurgy is illustrated with respect to biogenesis of gold ore deposits, biobenefication, bioliberation and bioenvironmental control. The use and commerical potential of this technology are discussed with reference to the mining and processing of Hutti gold ores. A microbial survey of the Hutti gold mines revealed the ubiquitous presence of various autotrophic and heterotrophic bacteria, fungi and yeast of relevance in gold processing. The possible roles played by different indigenous microorganisms in the formation, conversion and transport of gold along with various associated minerals have been brought out. Similarly, the role of Thiobacillus ferrooxidans in the flotation beneficiation of gold-bearing sulphides and in enhancing gold recovery from refractory sulphide ores and concentrates has been demonstrated. Direct gold solubilization could be achieved by Bacillus spp. Various fungi and yeast were found to be useful in the biosorption of gold and other base metals from cyanide effluents. It could thus show that biotechnology could be beneficially utilized in different stages of precious metal processing spanning from mining to waste disposal.     

Protein translocation into and across the chloroplastic envelope membranes

A revolution has occurred in the attitude of biologists toward their intellectual property rights. What today is patentable and highly profitable was, 20 years ago, unpatentable and given away for nothing. The history of this revolution began in the early 1960s when we made the first effort to have self-duplicating cell strains patented. The application was denied because patent law at that time did not include living matter. Because of the demand for our normal human diploid cell strain, WI-38, by NIH grantees, NIH support was provided to distribute WI-38 gratis to hundreds of recipients. These included vaccine and cell manufacturers who profited enormously from the direct sale of WI-38 or its use as a substrate for many human virus vaccines. When federal support for the distribution of WI-38 ended, but demand did not, I continued to distribute it for costs similar to those made by the American Type Culture Collection. When I took the first initiative and asked NIH to have the then unique question of title to a self-duplicating system resolved, they sent an accountant who accused me of theft of government property. I replied with a lawsuit that, after six years of litigation, we won with an out-of-court settlement. During these six years the United States Supreme Court ruled that living matter could be patented. Also, the biotechnology industry was launched by biologists who, like me, started companies using cells or microorganisms developed with federal support. This use of intellectual property rights by the nascent biotechnology industry was ultimately embraced by the entire biological community and by a directive from the President of the United States. This revolution has now evolved to the point where government biologists themselves may profit from research in federal laboratories, and the NIH itself aggressively seeks private commercial alliances. Universities have also pursued similar alliances to the extent that today the distinction between a research university and a commercial organization is only in the eyes of the Internal Revenue Service.     

Cocoa fermentations conducted with a defined microbial cocktail inoculum

Cocoa fermentations were performed in wooden boxes under the following four experimental regimens: beans naturally fermented with wild microflora; aseptically prepared beans with no inoculum; and beans inoculated with a defined cocktail containing microorganisms at a suitable concentration either at zero time or by using phased additions at appropriate times. The cocktail used consisted of a yeast, Saccharomyces cerevisiae var. chevalieri, two lactic acid bacterial species, Lactobacillus lactis and Lactobacillus plantarum, and two acetic acid bacterial species, Acetobacter aceti and Gluconobacter oxydans subsp. suboxydans. The parameters measured were cell counts (for yeasts, filamentous fungi, lactic acid bacteria, acetic acid bacteria, and spore formers, including reisolation and identification of all residual cell types), sugar, ethanol, acetic acid, and lactic acid contents (and contents of other organic acids), pH, and temperature. A cut test for bean quality and a sensorial analysis of chocolate made from the beans were also performed. The natural fermentation mimicked exactly the conditions in 800-kg boxes on farms. The aseptic box remained largely free of microflora throughout the study, and no significant biochemical changes occurred. With the zero-time inoculum the fermentation was almost identical to the natural fermentation. The fermentation with the phased-addition inoculum was similar, but many changes in parameters were slower and less pronounced, which led to a slightly poorer end product. The data show that the nearly 50 common species of microorganisms found in natural fermentations can be replaced by a judicious selection and concentration of members of each physiological group. This is the first report of successful use of a defined, mixed starter culture in such a complex fermentation, and it should lead to chocolate of more reliable and better quality.     

Bacterial biosensors for monitoring toxic metals

Biosensors utilize biological components to provide selectivity for monitoring compounds of environmental, clinical and industrial importance. A number of biosensors based on bacteria have recently been developed for monitoring toxic metals in the environment. The advantages and disadvantages of these types of biosensors are discussed.     

Environmental Biotechnology in Water and Wastewater Treatment

Environmental biotechnology “manages microbial communities to provide services to society.” The key services today include detoxifying contaminated water and soil to reclaim lost resources and converting diffuse energy in biomass to forms easily used by society. Two timely examples are the reduction of oxidized water contaminants (e.g., nitrate, perchlorate, selenate, and chlorinated solvents) and the production of methane, hydrogen, and electricity. The key science underlying environmental biotechnology is microbial ecology, which has advanced rapidly in the past 20 or so years through the proliferation of new genomics-based techniques to characterize the communities’ structure and function. The genomic methods provide detailed information that helps us understand what aspects of the microbial community need to be managed to ensure that it provides the desired service. Often, we achieve the management goals through partnering the microorganisms with modern materials and physical/chemical processes. The membrane biofilm reactor and microbial fuel cells offer excellent examples of exciting new technologies that come directly from this kind of partnering.     

Recent Developments in the Bioprocessing of Minerals

Microorganisms are finding increasing use in minerals engineering. Goals include both enhancement of mineral engineering operations and remediation of mineral industry wastes. Some of the applications, such as biologically assisted leaching of sulfide ores and biooxidation of refractory sulfide gold ores. are established commercial processes. Others, such as the use of organisms for the removal of heavy metal ions from dilute aqueous streams, are nearing commercial application. Other uses of microorganisms are potentially possible. These include use of microorganisms in leaching non-sulfide ores, the flocculation or flotation of minerals and remediation of toxic chemicals discharged from mineral engineering operations. Genetic engineering of microorganisms and adaptation of existing strains are important potential tools in many of these applications, as is also the identification of new, novel and useful organisms.     

Bone resorption caused by three periodontal pathogens in vivo in mice is mediated in part by prostaglandin

Gingival inflammation, bacterial infection, alveolar bone destruction, and subsequent tooth loss are characteristic features of periodontal disease, but the precise mechanisms of bone loss are poorly understood. Most animal models of the disease require injury to gingival tissues or teeth, and the effects of microorganisms are thus complicated by host responses to tissue destruction. To determine whether three putative periodontal pathogens, Porphyromonas gingivalis, Campylobacter rectus, and Fusobacterium nucleatum, could cause localized bone resorption in vivo in the absence of tissue injury, we injected live or heat-killed preparations of these microorganisms into the subcutaneous tissues overlying the calvaria of normal mice once daily for 6 days and then examined the bones histologically. We found that all three microorganisms (both live and heat killed) stimulated bone resorption and that the strain of F. nucleatum used appeared to be the strongest inducer of osteoclast activity. Treatment of the mice concomitantly with indomethacin reduced but did not completely inhibit bone resorption by these microorganisms, suggesting that their effects were mediated, in part, by arachidonic acid metabolites (e.g., prostaglandins). Our findings indicate that these potential pathogens can stimulate bone resorption locally when placed beside a bone surface in vivo in the absence of prior tissue injury and support a role for them in the pathogenesis of bone loss around teeth in periodontitis.     

Thyroid hormone stimulates progesterone release from human luteal cells by generating a proteinaceous factor

Specifications are the regulatory and legal standards that a product must meet to be suitable for use in humans. Specifications evolve in parallel with drug development and are refined prior to marketing authorization and, in some cases, after marketing. Recent changes in regulatory procedures for biotechnology-derived protein products have placed much emphasis on the use of characterization and final product specifications to provide assurance of overall quality of these products. In addition, harmonized guidelines for the testing and specifications for biotechnology products have been developed through the International Conference on Harmonization process. The availability of sensitive, quantitative, and specific analytical methods for characterization has made this possible, thus providing regulatory flexibility in the development of biotechnology-derived protein products. Further refinement of these analytical tools will undoubtedly enhance this regulatory flexibility.     

Heme compounds as iron sources for nonpathogenic Rhizobium bacteria

Many animal-pathogenic bacteria can use heme compounds as iron sources. Like these microorganisms, rhizobium strains interact with host organisms where heme compounds are available. Results presented in this paper indicate that the use of hemoglobin as an iron source is not restricted to animal-pathogenic microorganisms. We also demonstrate that heme, hemoglobin, and leghemoglobin can act as iron sources under iron-depleted conditions for Rhizobium meliloti 242. Analysis of iron acquisition mutant strains indicates that siderophore-, heme-, hemoglobin-, and leghemoglobin-mediated iron transport systems expressed by R. meliloti 242 share at least one component.     

O2 sensitive L-lactate biosensors with enzyme membranes based on L-lactate-2-monooxygenase and L-lactate-oxidase with electroanalytic comparison

O2-sensitive biosensors using oxidase membranes have acquired considerable electro-analytical importance. Since some of these O2-converting enzymes also produce H2O2, the use of additive reagents for the O2-free breakdown of the H2O2 in the second reaction has repeatedly been reported. In contrast to L-lactate oxidase, L-lactate-2-monooxygenase converts its substrate without producing H2O2. Employing reference sera, tests with L-lactate showed that bioelectrochemical membrane electrodes with H2O2-producing enzymes of high purity, require no additive reagents to ensure reliable analysis. Continuous measurements with citrated blood using the principle of intermediate carrier analysis are demonstrated.