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Exopolysaccharide Production from Marine Bacteria and Its Applications
Published in Se-Kwon Kim, Marine Biochemistry, 2023
Prashakha J. Shukla, Shivang B. Vhora, Ankita G. Murnal, Unnati B. Yagnik, Maheshwari Patadiya
The first step of biofilm formation is the adsorption of nutrients to the surface. Initial attachment starts with the diverse group of specific and nonspecific microbial communities that adheres to the primary surface. These adhered microbial communities initiate cell differentiation, proliferation and EPSs synthesis, which results in mature biofilm formation (Chakraborty et al., 2016). Initial attachment can be reversible, but at the final stage of EPSs synthesis, the attachment is irreversible. Bacteria may reversibly attach to a surface using surface-associated nutrients (Wolfaardt et al., 1999). A biochemical interaction between the organisms and the surrounding surface environment is made by the production of EPSs. Secretions of exoenzymes are important in the cycling of organic and inorganic materials. This EPS-containing hydrated layer increases the cellular uptake of small molecules for energy and biomass (Decho et al., 1995; Manca et al., 1996). Biofilm formation helps the organisms with nutrient transportation and horizontal gene transfer (Caron, 1987). Changes in physical environmental conditions affect the stability of EPSs (Boyle and Reade, 1983).
Macromolecular Absorption From The Digestive Tract In Young Vertebrates
Published in Károly Baintner, Intestinal Absorption of Macromolecules and Immune Transmission from Mother to Young, 2019
I discuss separately N-acetyls-hexosaminidase, an enzyme occuring in the distal intestine with an optimum between pH 4.0 and 4.5.738 It occurs in both soluble and particle-bound form in mucosal homogenates. The activity was demonstrated in granules attached to the internal surface of ACS vesicles. After releasing the granules from the membrane in 10 mM CaCl2 solution, they were resolved by gel filtration to N-acetyl-hexosaminidase and to a filamentous protein (“ligatin”), which attaches the enzyme to the membrane.610,1209 The enzyme has both N-acetyl-β-glucosidase and N-acetyl-β-galactosidase activities, but it differs from TV-acetyl-neuraminidase, which splits alpha-glycosidic bonds.1262 N-acetyl-hexosamin-idase is an exoenzyme. It splits hexosamines from the end of carbohydrate chains and disappears at closure time together with the vacuolated cells.742, 738
Role of Bacteria in Blood Infections
Published in K. Balamurugan, U. Prithika, Pocket Guide to Bacterial Infections, 2019
Kannan Balaji, Gnanasekaran JebaMercy, K. Balamurugan
The pathogenesis of P. aeruginosa starts from adherence to epithelial cells using adhesins and exoenzyme S. An exotoxin A causes tissue necrosis followed by phospholipase C, which is a hemolysin. The exoenzyme S causes resistance to macrophages by disrupting the normal cytoskeletal organization and destruction of immunoglobulin G and A (Kalifa et al., 2011).
Nanoparticle carrier co-delivery of complementary antibiofilm drugs abrogates dual species cariogenic biofilm formation in vitro
Published in Journal of Oral Microbiology, 2022
Guilherme Roncari Rocha, Kenneth R. Sims, Baixue Xiao, Marlise I. Klein, Danielle S.W. Benoit
Streptococcus mutans is widely credited with the development of dental caries. This species is acidogenic and aciduric [7] and encodes exoenzymes glucosyltransferases (Gtfs) that synthesize EPS (e.g. glucans) when sucrose is available [8]. S. mutans synthesizes the majority of EPS within dental biofilms [8]. Gtfs are also components of the salivary pellicle and foment adhesion and accumulation of several microorganisms [9], including Candida albicans that provides an abundance of binding sites for Gtfs produced by S. mutans [10]. C. albicans is the most commonly detected fungus on human mucosal surfaces and co-adheres with S. mutans and also commensal species [11], assisting biofilm formation [12–14] when proper sugar resources are available in the diet [15]. C. albicans is acidogenic, aciduric, and produces secreted aspartyl proteases [16]. These exoenzymes can degrade collagen within the dentin. Moreover, the symbiotic interactions between S. mutans and C. albicans increase acid production and extracellular glucan formation, enabling the assembly of a dense and abundant matrix rich in EPS [10,17] under acidic conditions, further increasing cariogenicity of biofilms [16].
Alternative approaches to treat bacterial infections: targeting quorum-sensing
Published in Expert Review of Anti-infective Therapy, 2020
Pipat Piewngam, Janice Chiou, Priyanka Chatterjee, Michael Otto
Quorum-sensing (QS) is a way of cell-cell communication that describes the ability of bacteria to sense the bacterial cell density and respond with gene expression changes to adapt to the changing environmental conditions that arise as a consequence of the increased number of bacteria and decreased availability of nutrients [3]. This type of regulation occurs in both pathogenic and nonpathogenic species, but QS systems of pathogens have been in the focus of investigation because they frequently control virulence determinants [4,5]. The biological purpose of QS regulation of virulence factors is believed to be due to the fact that in the beginning of an infection the production of QS-controlled pro-inflammatory toxins would alert immune defenses, while during progressed infection such immune evasion factors become increasingly necessary for bacterial survival. Furthermore, bacteria that have established an infection need degradative exoenzymes to acquire nutrient sources; and thus, such enzymes are also often QS-controlled [6,7].
Stenotrophomonas maltophilia – a low-grade pathogen with numerous virulence factors
Published in Infectious Diseases, 2019
Angelina Trifonova, Tanya Strateva
The gelatinase production of S. maltophilia is an important biochemical characteristic of the species (over 85% of the strains are producers). Although in other bacteria the enzyme participates in biofilm formation, host tissue degradation, and avoidance of immune response by inactivating the complement system [29], data on its role as a virulence factor in S. maltophilia are scarce [1,6]. A case of ecthyma gangrenosum due to bacteraemia with S. maltophilia was reported in a patient with leukaemia [17]. The exoenzyme profile of the isolate included both gelatinase and elastase. One of the functions of elastase is degradation of the elastic lamina of blood vessels facilitating release of bacterial cells into subcutaneous tissue [17]. A study of clinical S. maltophilia isolates established that elastase activity is dependent on incubation time and temperature (all tested strains demonstrate elastin hydrolysis at 30 °C after 72 h). According to the authors, previous results showing a low prevalence of the enzyme, are due to absence of standard methodology in laboratory practice [30].