China
Africa
Explore chapters and articles related to this topic
Microbial Biofilms
Published in Bakrudeen Ali Ahmed Abdul, Microbial Biofilms, 2020
Muhsin Jamal, Sayed Muhammad Ata Ullah Shah Bukhari, Sana Raza, Liloma Shah, Redaina, Noor-ul-ain Ali, Saadia Andleeb
Biofilms have adverse effects on human activity, and numerous strategies are used for the prevention and removal of biofilm. Traditionally, chemical and physical approaches like chlorination, ultraviolet disinfection, and flushing are used for controlling and removing biofilms. However, due to the lack of both effectiveness and safety of these stratifies, the concerns still persist (Srinivasan et al. 2008). In the late twentieth century, researchers tried to prove through experimentation that several naturally occurring compounds have antimicrobial characteristics (Cowan 1999). However, antibiofilm activities have been accredited to numerous natural substances like diverse essential oil (EO), plant extracts, and honey, and such properties are investigated expansively. Phages are supposed to be the largest group of microbes in the environment having antibacterial activity irrespective of their resistance (Pires et al. 2011). Quorum sensing (QS) plays a crucial role in the formation of biofilm, and QS inhibition is a hopeful approach for preventing biofilms (Ueda and Wood 2009). Nanotechnology is also a promising tool for control and prevention of biofilm, e.g., silver nanoparticles (AgNPs) (Kalishwaralal et al. 2010). Bacteriocins are antimicrobial peptides produced by prokaryotes which are commonly used against closely related bacterial species having a role in controlling bacterial biofilms (Hetrick et al. 2009). In this chapter, we have discussed biofilms in detail, such as biofilm formation, properties, biodiversity, and several current managements for the control of biofilms.
Biofilm Formation in the Food Industry
Published in Moayad N. Khalaf, Michael Olegovich Smirnov, Porteen Kannan, A. K. Haghi, Environmental Technology and Engineering Techniques, 2020
Quorum sensing plays an important role in biofilm formation. Quorum sensing is a cell-to-cell communication process that enables bacteria to secrete special signals in response to changes in the cell density of the surrounding microbial community. The quorum sensing can be turned “off” with a few bacteria in the environment. When the number of bacteria reaches a certain threshold, the activation of the corresponding genes are expressed in cells, and as more signal molecules release, it can lead to bacteria secreting toxins, biofilm formation, and bioluminescence with the quorum sensing “on.”5○ Quorum sensing regulates the whole stages of biofilm formation, which activates certain genes in the bacteria to secrete the extracellular matrix, such as EPS and protein, and gradually a full biofilm structure is formed, in which the bacteria have drug resistance. The normal operation of a quorum-sensing system requires the participation of signal molecules, and different types of bacteria secrete different signal molecules, such as AHL secreted by Gram-negative bacteria, AIP secreted by Grampositive bacteria, and AI-2 secreted both by Gram-negative and Gram-positive bacteria.5○ The regulation of biofilm formation is complex and involves several regulatory mechanisms. AI-2 and LuxS act as a regulator of biofilm formation and LPS synthesis in sessile bacterial cells.5
Biological Agents
Published in Katarzyna Majchrzycka, Małgorzata Okrasa, Justyna Szulc, Respiratory Protection Against Hazardous Biological Agents, 2020
The communication of microorganisms is referred to as quorum sensing. It is a system that controls specific genes in response to population density. The signalling molecules produced by microorganisms as part of quorum sensing are autoinducers and pheromones. When the threshold concentration of these compounds is exceeded (which indicates that the population of microorganisms has reached a sufficient size, i.e. a quorum), a coordinated change in gene expression occurs, which is necessary for effective cooperation of the entire population [Wu et al. 2001]. The process of communication between microorganisms increases their chances of survival in the environmental niches occupied by them; it is also important for taking over new territories and adapting to changes in environmental conditions [Miller 2001; Waters 2005]. This phenomenon also seems to be crucial in the formation and development of infections, pathogenesis of chronic diseases and creation of biofilms [Driscoll 2007; Irie 2008; Suleman 2014].
Bacilli as sources of agrobiotechnology: recent advances and future directions
Published in Green Chemistry Letters and Reviews, 2021
Zerihun T. Dame, Mahfuz Rahman, Tofazzal Islam
Quorum sensing (QS) is a process by which bacteria communicate. It involves detection and mounting of response to extracellular signaling molecules (autoinducers) through secretion of antibiotics, biofilm formation, and production of virulence factors. It allows bacteria to share information about cell density and adjust gene expression accordingly. This process enables bacteria to express energetically expensive processes as a collective only when the impact of those processes on the environment or a host will be maximized. Among the many traits controlled through quorum sensing, one is the expression of virulence factors by pathogenic bacteria (168). This communication process among the cells involves the production, detection, and response to extracellular signaling molecules. As bacterial population density increases, extracellular signaling molecules or autoinducers (AIs) accumulate in the environment. It helps them monitoring the information and track changes in their cell numbers leading to gene expression. The QS controls genes that dictates beneficial activities when performed by groups of bacteria in synchrony. The processes that are controlled by QS include bioluminescence, sporulation, competence, antibiotic production, biofilm formation, and secretions related to virulence factor.
Bacteriocin production and inhibition of Bacillus subtilis by Lactobacillus paracasei HD1.7 in an indirect coculture system
Published in Preparative Biochemistry & Biotechnology, 2021
Yanxin Ren, Yan Zhang, Xinglin Li, Dongni Gao, Yanyang Sun, Wenxiang Ping, Jingping Ge
Quorum sensing is a form of cell-to-cell communication that is controlled by the bacterial community density. Many life processes of microorganisms are controlled by QS, such as biofilm formation,[7] stress response,[8] regulation of virulence factors[9,10] and Lactobacillus bacteriocin synthesis.[11–13]