chapter  13
24 Pages

Biofilms: A Summarized Account and Control Strategies

WithKanavillil Nandakumar, Kurissery R. Sreekumari

CONTENTS 13.1 Introduction ............................................................................................. 266

13.1.1 History ........................................................................................ 266 13.1.2 Biofilm Extracellular Polymeric Substances ......................... 266 13.1.3 Growth of Biofilms ................................................................... 267 13.1.4 Nature and Formation of Biofilms......................................... 268 13.1.5 Beneficial and Detrimental Roles of Biofilms....................... 269

13.2 Control Techniques ................................................................................ 270 13.2.1 Surfaces That Resist Biofilm Formation ................................ 270 13.2.2 Possibilities of Biological=Molecular Biological

Intervention of Biofilm Formation ......................................... 271 13.2.3 Antifouling Coatings ................................................................ 273

13.2.3.1 Toxic Coatings .......................................................... 273 13.2.3.2 Nontoxic Foul-Release Coatings ........................... 273

13.2.4 Treatment with Biocides .......................................................... 274 13.2.5 Treatment with Antibiotics ..................................................... 276 13.2.6 Other Recent Developments in Nontoxic Methods ............ 278

13.2.6.1 Electrochemical Methods........................................ 278 13.2.6.2 Irradiation Techniques ............................................ 278

13.2.7 Physical and Mechanical Methods......................................... 279 13.3 Summary and Conclusions ................................................................... 280 Acknowledgments ............................................................................................. 281 References ........................................................................................................... 282

13.1.1 History

The preference of marine bacteria to grow on surfaces was first mentioned by ZoBell [1]. Subsequently, this aspect was extended to freshwater ecosystems and a variety of microbial ecosystems such as the surfaces of eukaryotic tissues [2]. Early era of biofilm studies, i.e., until late 1980s, perceived biofilms as simple sheath-or slab-like structures on surfaces [3]. Modern era of biofilm studies began with the use of environmental scanning electron microscope and confocal laser scanning microscope, which significantly enhanced our understanding of the biofilm architecture. Biofilms are now described as a complex boundary layer community with bunches of mushroom-like structures and water channels running in between [4]. This revelation resolved the perturbing question of how nutrients and oxygen are supplied in biofilms. The supply of nutrients and removal of waste products help biofilms grow in thickness and complexity [5]. The vertical profiling of the nutrient and oxygen concentrations in biofilms showed that they decrease from the surface to the interior. The species distribution showed colonization of anaerobic forms in the interior portion of biofilms, whereas aerobic forms occupied the outer surface.