Biofilm matrix

About: Biofilm matrix is a research topic. Over the lifetime, 1589 publications have been published within this topic receiving 110140 citations.

Introduction to biofilms

Abstract: In the seventeenth century, a dry-goods merchant named Antonie van Leeuwenhoek first observed “animalcules” swarming on living and dead matter. Leeuwenhoek’s curiosity and inventiveness were remarkable; he discovered these “animalcules” in the tartar on his own teeth and even after meticulous cleansing, the remaining opaque deposits isolated between his teeth were still “as thick as if it were batter”. These deposits contained a mat of various forms of “animalcules” that we now know were the bacteria of dental plaque. It is reasonable to suggest that this early study of dental plaque was the first documented evidence of the existence of microbial biofilms. Today, we generally define such biofilms as microbial communities adhered to a substratum and encased within an extracellular polymeric substance (EPS) produced by the microbial cells themselves. Biofilms may form on a wide variety of surfaces, including natural aquatic systems living tissues, indwelling medical devices and industrial/potable water system piping. The vast majority of microbes grow as biofilms in aqueous environments. These biofilms can be benign or pathogenic, releasing harmful products and toxins, which become encased within the biofilm matrix. Biofilm formation is a phenomenon that occurs in both natural and man-made environments under diverse conditions, occurring on most moist surfaces, plant roots and nearly every living animal. Biofilms may exist as beneficial epithilic communities in rivers and streams, wastewater treatment plant trickling beds or in the alimentary canal of mammals. Given the prevalence of biofilms in natural environments, it is not surprising that these growth forms are responsible for infection in humans and animals. In humans, biofilms have been linked with numerous conditions and equally in animals equivalent infections may occur.

Microbiologically-Synthesized Nanoparticles and Their Role in Silencing the Biofilm Signaling Cascade.

Abstract: The emergence of bacterial resistance to antibiotics has led to the search for alternate antimicrobial treatment strategies. Engineered nanoparticles (NPs) for efficient penetration into a living system have become more common in the world of health and hygiene. The use of microbial enzymes/proteins as a potential reducing agent for synthesizing NPs has increased rapidly in comparison to physical and chemical methods. It is a fast, environmentally safe, and cost-effective approach. Among the biogenic sources, fungi and bacteria are preferred not only for their ability to produce a higher titer of reductase enzyme to convert the ionic forms into their nano forms, but also for their convenience in cultivating and regulating the size and morphology of the synthesized NPs, which can effectively reduce the cost for large-scale manufacturing. Effective penetration through exopolysaccharides of a biofilm matrix enables the NPs to inhibit the bacterial growth. Biofilm is the consortia of sessile groups of microbial cells that are able to adhere to biotic and abiotic surfaces with the help extracellular polymeric substances and glycocalyx. These biofilms cause various chronic diseases and lead to biofouling on medical devices and implants. The NPs penetrate the biofilm and affect the quorum-sensing gene cascades and thereby hamper the cell-to-cell communication mechanism, which inhibits biofilm synthesis. This review focuses on the microbial nano-techniques that were used to produce various metallic and non-metallic nanoparticles and their "signal jamming effects" to inhibit biofilm formation. Detailed analysis and discussion is given to their interactions with various types of signal molecules and the genes responsible for the development of biofilm.

Resilience of planktonic and biofilm cultures to supercritical CO2

Abstract: Supercritical CO2 has been shown to act as a disinfectant against microorganisms. These organisms have most often been tested in vegetative or spore form. Since biofilm organisms are typically more resilient to physical, chemical, and biological stresses than the same organisms in planktonic form, they are often con- sidered more difficult to eradicate. It is therefore hypothesized that supercritical CO2 (SC-CO2) induced inactivation of biofilm organisms would be less effective than against planktonic (suspended) growth cultures of the same organism. Six-day old biofilm cultures as well as suspended planktonic cultures of Bacillus mojavensis were exposed to flowing SC-CO2 at 136 atm and 35 ◦ C for 19 min and slowly depres- surized after treatment. After SC-CO2 exposure, B. mojavensis samples were analyzed for total and viable cells. Suspended cultures revealed a 3 log10 reduction while biofilm cultures showed a 1 log10 reduction in viable cell numbers. These data demonstrate that biofilm cultures of B. mojavensis are more resilient to SC-CO2 than suspended planktonic communities. It is hypothesized that the small reduction in the viability of biofilm microorganisms reflects the protective effects of extracellular polymeric substances (EPS) which make up the biofilm matrix, which offer mass transport resistance, a large surface area, and a number of functional groups for interaction with and immobilization of CO2. The resistance of biofilm suggests that higher pressures, longer durations of SC-CO2 exposure, and a quicker depressurization rate may be required to eradicate biofilms during the sterilization of heat-sensitive materials in medical and industrial applications. However, the observed resilience of biofilms to SC-CO2 is particularly promis- ing for the prospective application of subsurface biofilms in the subsurface geologic sequestration of