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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
A marine bacterium Alteromonas infernus was reported to secrete branched acidic heteropolysaccharide EPS having an HMW. Its monosaccharide repeating units are composed of galacturonic, glucuronic acid, galactose and glucose substituted with a sulfate group (Roger et al., 2004). Alteromonas strain 1644 possessed the ability to produce two different kinds of EPSs that differ in their viscosity and concentration of ions, making their separation difficult due to their gelling nature (Poli et al., 2010). The tertiary structure and characteristics of EPSs mainly depend on the presence of hydroxyl and carboxyl groups. Microbial exopolymers are available either in dissolved form or as aggregates in a gel-like slime matrix. Figure 18.5 indicates the EPSs structure of psychrotolerant Pseudoalteromonas sp. SM9913 isolated from the deep sea of Antarctica at a depth of 1855 m. It contains a linear simple arrangement of α-1,6 glucose with an elevated degree of acetylation (Qin et al., 2007).
Macro and Micro Algal Impact on Marine Ecosystem
Published in Gokare A. Ravishankar, Ranga Rao Ambati, Handbook of Algal Technologies and Phytochemicals, 2019
According to Engel et al. (2004), not all organic particles in the ocean originate from cellular debris. In recent years, extracellular polysaccharide particles described as Transparent Exopolymeric Substances (TEP) have gained a lot of attention in the field of limnology (Passow 2002). TEP possess a surface reactive nature and hence support coagulation processes that increase the formation of large aggregates (marine snow) (Engel 2000, Passow 2002). This in turn enhances carbon pumping to the deep ocean (Asper et al. 1992).
Saccharomyces cerevisiae
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Brunella Posteraro, Gianluigi Quaranta, Patrizia Posteraro, Maurizio Sanguinetti
Both in the commensal and pathogenic states, fungal organisms form a multicellular biofilm that anchors cells to biotic or abiotic surfaces, which include host tissues, indwelling catheters, implants, and other devices in the clinical setting,37 and surfaces of plants, stagnant pools and pipelines, food products, and food-contact surfaces in the natural setting.38 Biofilm growth is often associated with the production of self-gathered exopolymeric substances (exopolysaccharides, proteins, and exoDNA) forming an extracellular matrix (ECM) that bind the sessile community together, thereby protecting microbes within the biofilm against potentially harmful external factors. These factors causing biofilm detachment enable microbes to spread and colonize other regions of the substrate, thereby resulting in the environmental contamination (Figure 48.4).
Influence of abiotic conditions on the biofouling formation of flagellated microalgae culture
Published in Biofouling, 2022
Lucía García-Abad, Lorenzo López-Rosales, María del Carmen Cerón-García, Marta Fernández-García, Francisco García-Camacho, Emilio Molina-Grima
The amount of adhered cells was inversely proportional to the biomass concentration (Figure 4B), which implies that the greater the cell concentration, the lower the adhesion (Supporting Information Figure S1), in accordance with that reported by Soriano-Jerez et al. (2021). The cell adhesion behaviour, as a function of the N/P ratio, was similar at the four irradiance levels studied (Figure 4B), with the number of adhered cells decreasing as the amount of phosphate present in the medium decreased. The same trend occurred for the EPS concentration adhered to the surfaces (Figure 4C). The concentration decreased as the N/P ratio increased, in the same way as Magaletti et al. (2004) reported in their studies. The highest adhered EPS concentration occurred at an irradiance level of 100 μE·m−2·s−1 (Figure 3C), after which the concentration began to decline. The amount of protein excreted into the medium rose with increased irradiance (Thrane et al. 2016). Nevertheless, at irradiances above the saturation level, the EPS concentration synthetized by the cells and excreted into the medium was lower (Clément-Larosière et al. 2014), leading to less EPS adhering to the surface and, consequently, less cell adhesion. The amount of biofilm that forms, mainly due to exopolymeric substances, is affected by the conditions in which the culture finds itself (Shen et al. 2016).
Exploring the anti-caries properties of baicalin against Streptococcus mutans: an in vitro study
Published in Biofouling, 2021
Arval Viji Elango, Sahana Vasudevan, Karthi Shanmugam, Adline Princy Solomon, Prasanna Neelakantan
Colonisation of the teeth by S. mutans is aided by its ability to form firmly adherent biofilms. These exopolymeric matrix-rich biofilms offer substantial resistance and tolerance to antimicrobial agents, and is produce by the bacterium from the dietary sugars available for its consumption (Koo et al. 2010). The metabolism of these sugars results in acid production, and a subsequent drop in pH, leading to tooth demineralisation. Notably, this pathogenic bacterium has evolved tolerance mechanisms to thrive in the acidic environment created by them (Matsui and Cvitkovitch 2010), while inhibiting the generally acid-sensitive commensals, thereby causing and maintaining dysbiosis within the oral microbiome (Kaur et al. 2015). Bacterial adherence, biofilm formation, acid production and acid tolerance in S. mutans are marked virulence phenotypes that are regulated by interconnected networks (Shanmugam et al. 2020). Targeting these systems will inhibit the expression of these virulence phenotypes and provide an alternative method to prevent caries (Buzalaf et al. 2011).
Biofilm and Quorum Sensing inhibitors: the road so far
Published in Expert Opinion on Therapeutic Patents, 2020
Simone Carradori, Noemi Di Giacomo, Martina Lobefalo, Grazia Luisi, Cristina Campestre, Francesca Sisto
Bacterial biofilms are ordered and structured aggregates described as ubiquitous forms of microbial communities occurring at solid-liquid, solid-air, liquid-liquid and liquid-air interfaces in different ecosystems. Their detection on mucosal linings of various organs, medical devices and wounds stimulated the researches toward these survival strategies employed by bacteria. Over 80% human infections can be related to biofilm presence [1]. They can consist of single microbial cells or co-cultures (10–15% of the total volume) embedded into a highly hydrated and self-produced exopolymeric matrix including microbial biopolymers (polysaccharides, proteins and glycoproteins, nucleic acids, lipids) as key components [2]. Polysaccharides, usually produced as structural elements of the bacterial cell wall and virulence factors, depend on the genetic profile of microorganisms involved and can be released into media (exopolysaccharides, EPS) [3]. The mechanism of resistance to antimicrobials and immune response in biofilm-related infections is different from plasmids, transposons and mutations [4], being strictly connected to (i) physical/chemical diffusion barriers for penetration; (ii) stress response activation; (iii) non-canonical growth and shape of the microorganisms; (iv) active metabolic resistance related to bacterial stringent response; and (v) emergence of new phenotypes (biofilm-related) as subpopulation of dormant cells (persisters). Genetically nonresistant planktonic cells can be killed by antibiotics, whereas when they grow up into a biofilm can be 1000 time more resistant to the same therapeutic arsenal [5].