Abstract:Many bacteria biosynthesize structurally diverse exopolysaccharides (EPS) and excrete them into their surrounding environment. The EPS functional features have found many applications in industries such as cosmetics and pharmaceutics. In particular, some EPS produced by marine bacteria are composed of uronic acids, neutral sugars, and N-acetylhexosamines, and may also bear some functional sulfate groups. This suggests that they can share common structural features with glycosaminoglycans (GAG) like the two EPS… Show more
“…The EPS yield was higher in strain PQQ-42 (0.36 g l −1 ) than in strain PQQ-44 (0.15 g l −1 ), which confirmed the results observed by scanning electron microscopy. These EPS production values are similar to those obtained with other marine bacteria 42,43 .Figure 5Exopolysaccharide production in strains PQQ-42 and PQQ-44. Uranyl acetate staining of strains PQQ-42 ( a ) and PQQ-44 ( b ) as observed by transmission electron microscopy.…”
The Alteromonas stellipolaris strains PQQ-42 and PQQ-44, previously isolated from a fish hatchery, have been selected on the basis of their strong quorum quenching (QQ) activity, as well as their ability to reduce Vibrio-induced mortality on the coral Oculina patagonica. In this study, the genome sequences of both strains were determined and analyzed in order to identify the mechanism responsible for QQ activity. Both PQQ-42 and PQQ-44 were found to degrade a wide range of N-acylhomoserine lactone (AHL) QS signals, possibly due to the presence of an aac gene which encodes an AHL amidohydrolase. In addition, the different colony morphologies exhibited by the strains could be related to the differences observed in genes encoding cell wall biosynthesis and exopolysaccharide (EPS) production. The PQQ-42 strain produces more EPS (0.36 g l−1) than the PQQ-44 strain (0.15 g l−1), whose chemical compositions also differ. Remarkably, PQQ-44 EPS contains large amounts of fucose, a sugar used in high-value biotechnological applications. Furthermore, the genome of strain PQQ-42 contained a large non-ribosomal peptide synthase (NRPS) cluster with a previously unknown genetic structure. The synthesis of enzymes and other bioactive compounds were also identified, indicating that PQQ-42 and PQQ-44 could have biotechnological applications.
“…The EPS yield was higher in strain PQQ-42 (0.36 g l −1 ) than in strain PQQ-44 (0.15 g l −1 ), which confirmed the results observed by scanning electron microscopy. These EPS production values are similar to those obtained with other marine bacteria 42,43 .Figure 5Exopolysaccharide production in strains PQQ-42 and PQQ-44. Uranyl acetate staining of strains PQQ-42 ( a ) and PQQ-44 ( b ) as observed by transmission electron microscopy.…”
The Alteromonas stellipolaris strains PQQ-42 and PQQ-44, previously isolated from a fish hatchery, have been selected on the basis of their strong quorum quenching (QQ) activity, as well as their ability to reduce Vibrio-induced mortality on the coral Oculina patagonica. In this study, the genome sequences of both strains were determined and analyzed in order to identify the mechanism responsible for QQ activity. Both PQQ-42 and PQQ-44 were found to degrade a wide range of N-acylhomoserine lactone (AHL) QS signals, possibly due to the presence of an aac gene which encodes an AHL amidohydrolase. In addition, the different colony morphologies exhibited by the strains could be related to the differences observed in genes encoding cell wall biosynthesis and exopolysaccharide (EPS) production. The PQQ-42 strain produces more EPS (0.36 g l−1) than the PQQ-44 strain (0.15 g l−1), whose chemical compositions also differ. Remarkably, PQQ-44 EPS contains large amounts of fucose, a sugar used in high-value biotechnological applications. Furthermore, the genome of strain PQQ-42 contained a large non-ribosomal peptide synthase (NRPS) cluster with a previously unknown genetic structure. The synthesis of enzymes and other bioactive compounds were also identified, indicating that PQQ-42 and PQQ-44 could have biotechnological applications.
“…In contrast to the EPS produced by Alteromonas and Pseudoalteromonas species, the HE800 EPS produced by Vibrio diabolicus is a linear non-sulfated polysaccharide composed only of uronic acids (GlcA) and N-acetyl hexosamines: N-acetyl-glucosamine (GlcNAc) and N-acetyl-galactosamine (GalNAc) [16,17]. A recent study reported by Delbarre-Ladrat et al [18] put forward that general traits of the EPS composition were specific to the bacterial genera with Alteromonas and Pseudoalteromonas species mainly producing EPS rich in neutral sugars and uronic acids with some substituents, such as sulfates, and Vibrio species synthesizing EPS composed of uronic acids and hexosamines.…”
Bacteria have developed a unique strategy to survive in extreme environmental conditions through the synthesis of an extracellular polymeric matrix conferring upon the cells a protective microenvironment. The main structural component of this complex network constitutes high-molecular weight hydrophilic macromolecules, namely exopolysaccharides (EPS). EPS composition with the presence of particular chemical features may closely be related to the specific conditions in which bacteria evolve. Deep-sea hydrothermal vent bacteria have already been shown to produce EPS rich in hexosamines and uronic acids, frequently bearing some sulfate groups. Such a particular composition ensures interesting functional properties, including biological activities mimicking those known for glycosaminoglycans (GAG). The aim of the present study was to go further into the exploration of the deep-sea hydrothermal vent IFREMER (French Research Institute for Exploitation of the Sea) collection of bacteria to discover new strains able to excrete EPS endowed with GAG-like structural features. After the screening of our whole collection containing 692 strains, 38 bacteria have been selected for EPS production at the laboratory scale. EPS-producing strains were identified according to 16S rDNA phylogeny. Chemical characterization of the obtained EPS highlighted their high chemical diversity with the presence of atypical compositional patterns. These EPS constitute potential bioactives for a number of biomedical applications, including regenerative medicines and cancer treatment.
“…The marine environment and in particular extreme habitats, such as deep-sea hydrothermal vents constitute a potential resource of unknown bacteria that can synthesize EPS with unique structures (Delbarre-Ladrat, Sinquin, Lebellenger, Zykwinska, & Colliec-Jouault, 2014;Delbarre-Ladrat, Leyva Salas, Sinquin, Zykwinska, & Colliec-Jouault, 2017).…”
Polysaccharides have attracted much attention due to their interesting physico-chemical and also biological properties that are explored in food, cosmetic and pharmaceutical industries. GY785 exopolysaccharide (EPS) presenting an unusual structure is secreted by the deep-sea hydrothermal bacterium, Alteromonas infernus. Low-molecular weight (LMW) derivatives obtained by chemical depolymerization of the native high molecular weight (HMW) EPS were previously shown to exhibit biological properties similar to glycosaminoglycans (GAG). In the present study, in order to generate well defined derivatives with a better control of the depolymerization, an enzymatic approach was applied for the first time. Various commercially available enzymes were firstly screened for their depolymerizing activities, however none of them was able to degrade the polysaccharide. Enzymatic assays performed with A. infernus protein extracts have shown that the bacterium produces by itself endogenous enzymes able to depolymerize its own EPS. The oligosaccharides released by the enzymes were analyzed and their structures allowed to assess that the protein extract contains several depolymerizing activities.
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