Microbial Biofilms: Current Research and Practical Implications
Caister Academic Press
Adamas University, Kolkata, India
vi + 236
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Biofilms are classic examples of microbial communities that persist collectively in a self-synthesized matrix and challenge the concept of prokaryotes as isolated organisms. Microbial biofilms are extremely robust in terms of resistance to various chemicals and antimicrobials and are relevant in more than half of infectious diseases globally. In addition microbial biofilms have numerous industrial applications such as their use in bioremediation, electricity generation and wastewater treatment. The importance of biofilms cannot be understated and work in this field will continue to grow in the future.
This concise volume is written by highly qualified scientists working on various aspects of biofilms. Under the expert guidance of the editor, respected leaders in their fields present detailed reviews of various aspects of biofilms with a focus on mechanisms of biofilm formation, techniques to study microbial biofilms and applications of biofilms. The book is topical and up-to-date in terms of content and developments in the field. Topics of note include: formation and development of biofilms, novel techniques to study biofilms, biofilm formation in clinical situations, host immune response, application of biofilms in electricity generation, wastewater treatment and bioremediation.
Aimed at research scientists, advanced students and other professionals, this informative and up-to-date book is an invaluable and timely review on current research in biofilms and is an essential acquisition for anyone involved in this area of biology.
Table of contents
1. Molecular Mechanisms of Biofilm Development and Biofilm Dispersal in Gram-Positive Bacteria
Öykü İrigül-Sönmez, Öznur Pehlivan and Ayten Yazgan-Karataş
In nature, majority of bacteria live together in large complex sessile communities termed as biofilms. Within biofilm community, compared with their planktonic state, the physiological behavior of biofilm members is deeply altered, leading to gaining resistance to various environmental stresses, such as desiccation, antimicrobial agents and host immune response. As final stage of biofilm maturation, biofilm dispersal is also accepted as a critical step in bacterial lifestyle allowing dissemination of bacteria from the original site of infection in the host or the environment and increasing virulence of pathogenic bacteria. Biofilm formation and dispersal is under the control of complex regulatory mechanism that involves the coordination of various signaling messengers and molecular effectors. In this chapter, we review and summarize recent findings in the factors and regulatory pathways controlling the biofilm formation and dispersal in a range of Gram-positive bacteria, including some members of Bacillus and Staphylococcus aureus.
2. Mechanism of Biofilm Formation in Gram-Negative Bacteria
Ulrich Vasconcelos, Palashpriya Das, Diogo Simas Bernardes Dias, Tarcísio Tárcio Correa Bonifácio, Ray Ravilly Alves Arruda, Bianca Teixeira Morais de Oliveira and Thiago Gonçalves Cavalcanti
Biofilms consist of one or more microbial species of microbes living in close association. Mixed species biofilms are more predominant in the environment. Though biofilm imparts various advantages to its producer, huge economic losses are encountered because of biofilm formation and has been described with special emphasis on Pseudomonas aeruginosa. However, recent studies on human microbiota imply that biofilm formation helps in maintenance of human health as well so it is wholly not harmful only. While physicochemical factors like temperature, oxygen, light, compounds like antibiotics etc. can affect the process of biofilm formation, this process also involves various genes. The interplay of the genes and the resultant products in various conditions together result in biofilm formation in different microorganisms. Since the first models on understandings of biofilms were evaluated in Gram-negative bacteria, the present review summarizes all parameters that might be affecting this preferred form of microbial sustenance in different Gram-negative bacteria.
3. Existing and Novel Techniques to Study Biofilms
Bacterial biofilms are aggregates of microorganisms in which cells adhere to each other and also to a solid surface or an animal host cavity (oral cavity in humans and rats and nasal cavities in non-human hosts). Biofilms also commonly occur on the surface of in-dwelling devices in humans, on dentures and medical devices and sutures etc. placed inside the body. The complex composition of bacterial biofilms with EPS (extracellular polymeric substance) includes proteins, polysaccharides, extracellular DNA, peptidoglycan, lipids and phospholipids. These substances play a role in the initial adhesion of bacteria to a surface and maintenance of the biofilm structure. This chapter describes various traditional and novel techniques are available for studying structures of bacterial biofilms, their analysis and quantification. The methods vary in their approach and include colorimetric and fluorescence-based methods to evaluate and quantify biofilm matrix and viability, direct imaging using different types of microscopy, as well as molecular approaches including omics studies and are described in terms of methodology and application.
4. Mechanisms of Biofilm Formation in Clinically Used Biomaterials
John-Jairo Aguilera-Correa, Jaime Esteban and David Romera-García
Medical-device infections are associated with high morbidity and exhibits robustness typically due to formation of biofilms on the device surface and surrounding tissues. Biofilms are complex communities composed of microorganisms embedded in secreted polysaccharide matrix which commonly display high resistance against the host immune system and antimicrobial therapy and can lead to a systemic infection or device failure leading to high costs in the healthcare. Frequently isolated agents in medical devices include bacteria such as Staphylococcus aureus and Pseudomonas aeruginosa and fungi represented mainly by Candida. In this chapter, we provide an overview of the current types of clinically used biomaterials, explore the major strategies and mechanisms developed by microorganisms to colonize devices, initial forces that are responsible for the interaction among the membranes of the microorganisms and the biomaterial surface and conditioning layer and regulatory systems that govern biofilm dispersal, expression of virulence factors and immune response evasion.
5. Bacterial Biofilms and Host Immune Response
Pradeep Kumar Singh, Vivek Kumar Yadav, Deepmala Sharma, Vishnu Agarwal and Vandan Nagar
The biofilm includes a group of microbial cells which stick together and remain attached to a surface. Biofilm-associated microbial cells secrete extra-cellular polymeric substances and are embedded in this slimy matrix. Components of the extracellular polymeric substance have a specific role in the development of biofilm. Biofilms are the product of the microbial developmental process which involves different stages, including initial attachment, irreversible attachment, maturation, and dispersion. In many cases, the biofilm mode of microbial growth contributes to antibiotic resistance and escape from the host immune system. Device-associated microbial colonisation plays a vital role in the biofilm-related infections, and a large amount of money is being used for the eradication of microbial growth from these devices. Biofilm interacts with the different components of the host immune system and may contribute to the stimulation or suppression of immune response. Different immune cells, including neutrophils, macrophages, T Cells, and B-cells, generate a specific response against biofilms.
6. Application of Biofilms in Electricity Generation, Wastewater Treatment and Bioremediation
Akash Mitra and Arindam Mitra
Bacteria residing in biofilm mode are considered detrimental due to their enhanced ability of resistance towards chemicals, antibiotics and immune defenses but biofilms can be harnessed for beneficial processes such as wastewater treatment, bioremediation and electricity generation. In wastewater reactor systems, biofilms are grown and immobilized to enhance the rate of degradation of contaminants in wastewater and can be advantageous to a number of removal mechanisms such as biodegradation and biomineralization. Biofilm based bioremediation utilizes metabolic capacity of microbes in biofilms to degrade harmful pollutants and the process is considered cost-effective, reliable and widely used in industry. In microbial fuel cells, biofilms are deposited on electroconductive surfaces such as anode and cathode and during electron transfer, chemical energy is converted into usable electrical energy which can then be harvested by appropriate electronic devices. Microbial Fuel Cells are a promising sustainable technology that can reduce the dependency on fossil fuels and will be used more in the future. Here we discuss recent studies on applications of biofilms in microbial fuel cells, wastewater treatment and bioremediation.
How to buy this book
(EAN: 9781912530328 9781912530335 Subjects: [bacteriology] [environmental microbiology] [medical microbiology] [microbiology] [molecular microbiology] )