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Über dieses Buch

This book review series presents current trends in modern biotechnology. The aim is to cover all aspects of this interdisciplinary technology where knowledge, methods and expertise are required from chemistry, biochemistry, microbiology, genetics, chemical engineering and computer science. Volumes are organized topically and provide a comprehensive discussion of developments in the respective field over the past 3-5 years. The series also discusses new discoveries and applications. Special volumes are dedicated to selected topics which focus on new biotechnological products and new processes for their synthesis and purification. In general, special volumes are edited by well-known guest editors. The series editor and publisher will however always be pleased to receive suggestions and supplementary information. Manuscripts are accepted in English.

Inhaltsverzeichnis

Frontmatter

Investigation of Microbial Biofilm Structure by Laser Scanning Microscopy

Abstract
Microbial bioaggregates and biofilms are hydrated three-dimensional structures of cells and extracellular polymeric substances (EPS). Microbial communities associated with interfaces and the samples thereof may come from natural, technical, and medical habitats. For imaging such complex microbial communities confocal laser scanning microscopy (CLSM) is the method of choice. CLSM allows flexible mounting and noninvasive three-dimensional sectioning of hydrated, living, as well as fixed samples. For this purpose a broad range of objective lenses is available having different working distance and resolution. By means of CLSM the signals detected may originate from reflection, autofluorescence, reporter genes/fluorescence proteins, fluorochromes binding to specific targets, or other probes conjugated with fluorochromes. Recorded datasets can be used not only for visualization but also for semiquantitative analysis. As a result CLSM represents a very useful tool for imaging of microbiological samples in combination with other analytical techniques.
Graphical Abstract
Thomas R. Neu, John R. Lawrence

Modeling of Biofilm Systems: A Review

Abstract
The modeling of biochemical processes in biofilms is more complex compared to those in suspended biomass due to the existence of substrate gradients. The diffusion and reaction of substrates within the biofilms were simulated in 1D models in the 1970s. The quality of these simulation results was later improved by consideration of mass transfer at the bulk/biofilm interface and detachment of biomass from the surface. Furthermore, modeling of species distribution along the axis perpendicular to the substratum helped to simulate productivity and long-term behavior in multispecies biofilms. Multidimensional models that were able to give a realistic prediction of the surface structure of biofilms were published in the 1990s. The 2D or 3D representation of the distribution of the species in a matrix of extracellular polymeric substances (EPS) helped predict the behavior of multispecies biofilm systems. The influence of shear forces on such 2D or 3D biofilm structures was included by solving the Navier–Stokes equation for the liquid phase above the biofilm. More recently, the interaction between the fluid and biofilm structures was addressed more seriously by no longer considering the biofilm structures as being rigid. The latter approach opened a new door, enabling one to describe biofilms as viscoelastic systems that are not only able to grow and produce but also be deformed or even dislodged if external forces are applied.
Graphical Abstract
Harald Horn, Susanne Lackner

Biofilm Architecture

Abstract
Microbial biofilms are complex self-organized communities of microbial cells that provide protective environments for the cells that inhabit the biofilm, enabling them to respond efficiently to challenges. The enhanced resistance and altered metabolism of the cells in the biofilm makes biofilms potentially very useful in chemical production processes, including the production of pharmaceuticals and biofuels. Synthetic biofilms in which the composition and architecture of the biofilm is controlled by the designer could help in harnessing this potential. In this chapter we discuss biofilm architecture, how it can be created by natural or artificial means, and how it affects biofilm function.
Graphical Abstract
Jochen J. Schuster, Gerard H. Markx

Engineered Cell–Cell Communication and Its Applications

Abstract
Over the past several decades, biologists have become more appreciative of the fundamental role of intercellular communication in natural systems spanning prokaryotic biofilms to eukaryotic developmental systems and neurological networks. From an engineering perspective, the use of cell–cell communication provides an opportunity to engineer more complex and robust functions using cellular components. Indeed, this strategy has been adopted in synthetic biology in the creation of diverse gene circuits that program spatiotemporal dynamics in one or multiple populations. Gene circuits such as these may offer insights regarding basic biological questions and motifs or serve as a basis for novel applications.
Graphical Abstract
Stephen Payne, Lingchong You

Application of Biofilm Bioreactors in White Biotechnology

Abstract
The production of valuable compounds in industrial biotechnology is commonly done by cultivation of suspended cells or use of (immobilized) enzymes rather than using microorganisms in an immobilized state. Within the field of wastewater as well as odor treatment the application of immobilized cells is a proven technique. The cells are entrapped in a matrix of extracellular polymeric compounds produced by themselves. The surface-associated agglomerate of encapsulated cells is termed biofilm. In comparison to common immobilization techniques, toxic effects of compounds used for cell entrapment may be neglected. Although the economic impact of biofilm processes used for the production of valuable compounds is negligible, many prospective approaches were examined in the laboratory and on a pilot scale. This review gives an overview of biofilm reactors applied to the production of valuable compounds. Moreover, the characteristics of the utilized materials are discussed with respect to support of surface-attached microbial growth.
K. Muffler, M. Lakatos, C. Schlegel, D. Strieth, S. Kuhne, R. Ulber

Ecological Roles and Biotechnological Applications of Marine and Intertidal Microbial Biofilms

Abstract
This review is a retrospective of ecological effects of bioactivities produced by biofilms of surface-dwelling marine/intertidal microbes as well as of the industrial and environmental biotechnologies developed exploiting the knowledge of biofilm formation. Some examples of significant interest pertaining to the ecological aspects of biofilm-forming species belonging to the Roseobacter clade include autochthonous bacteria from turbot larvae-rearing units with potential application as a probiotic as well as production of tropodithietic acid and indigoidine. Species of the Pseudoalteromonas genus are important examples of successful surface colonizers through elaboration of the AlpP protein and antimicrobial agents possessing broad-spectrum antagonistic activity against medical and environmental isolates. Further examples of significance comprise antiprotozoan activity of Pseudoalteromonas tunicata elicited by violacein, inhibition of fungal colonization, antifouling activities, inhibition of algal spore germination, and 2-n-pentyl-4-quinolinol production. Nitrous oxide, an important greenhouse gas, emanates from surface-attached microbial activity of marine animals. Marine and intertidal biofilms have been applied in the biotechnological production of violacein, phenylnannolones, and exopolysaccharides from marine and tropical intertidal environments. More examples of importance encompass production of protease, cellulase, and xylanase, melanin, and riboflavin. Antifouling activity of Bacillus sp. and application of anammox bacterial biofilms in bioremediation are described. Marine biofilms have been used as anodes and cathodes in microbial fuel cells. Some of the reaction vessels for biofilm cultivation reviewed are roller bottle, rotating disc bioreactor, polymethylmethacrylate conico-cylindrical flask, fixed bed reactor, artificial microbial mats, packed-bed bioreactors, and the Tanaka photobioreactor.
Graphical Abstract
Sayani Mitra, Barindra Sana, Joydeep Mukherjee

Novel Materials for Biofilm Reactors and their Characterization

Abstract
The application of adherently growing microorganisms for biotechnological production processes is established, but it is still a niche technology with only a small economic impact. However, novel approaches are under development for new types of biofilm reactors. In this context, increasingly more microstructured metal surfaces are being investigated, and they show positive effects on the bacterial growth and the biofilm establishment. However, for comparison of the data, the different surface materials have to correspond in their different characteristics, such as wettability and chemical composition. Also, new materials, such as plastic composite supports, were developed. To understand the interaction between these new materials and the biofilm-producing microorganisms, different surface science methods have to be applied to reveal a detailed knowledge of the surface characteristics. In conclusion, microstructured surfaces show a high potential for enhanced biofilm growth, probably accompanied by an enhanced productivity of the microorganisms.
Graphical Abstract
C. Müller-Renno, S. Buhl, N. Davoudi, J. C. Aurich, S. Ripperger, R. Ulber, K. Muffler, Ch. Ziegler

Microsensors and Microscale Gradients in Biofilms

Abstract
Understanding the limiting factors and mechanisms of biofilm processes requires the direct measurement of microscale gradients using the appropriate tools. Microscale measurements can provide mechanistic information that cannot be obtained from bulk-scale measurements. Among the most used and trusted tools in microscale biofilm research are microsensors. The goal of this chapter is to introduce microsensor technology along with several examples to illustrate microscale processes in biofilms that are usually absent in bulk. We define a microsensor for biofilm research as a needle-type sensor with tip diameter of a few microns and a length up to several hundred microns. Microsensors can be used noninvasively to monitor in situ biofilm processes. Both optical and electrochemical microsensors can be used for biofilm applications. Because of newly discovered biofilm processes, the design and use of microsensors require customization and carefully designed experiments. In this chapter we present several examples describing the use of microsensors (1) in environmental biofilms, (2) in medical biofilms, and (3) in biofilms for energy and bioproducts. Microsensors can be the most useful if the measured profiles are integrated into the study of overall biofilm processes.
Graphical Abstract
Haluk Beyenal, Jerome Babauta

Backmatter

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