Metabolomics of Microbial Biofilms
Chaminda Jayampath Seneviratne in Microbial Biofilms, 2017
A major portion of the EPS is composed of exopolysaccharides, which complicates the extraction as well as the analysis of EPS. Some of these exopolysaccharides are in the form of homopolysaccharides, while most of them are heteropolysaccharides composed of a mixture of neutral and charge residues. The most well-known exopolysaccharides present inside biofilms are alginate, cellulose and poly-N-acetyl glucosamine (PNAG). Alginate is an exopolysaccharide of relatively high molecular mass (104–106 g/mL) occurring in brown algae and certain bacterial strains. Its presence in bacteria Azotobacter vinelandii and Pseudomonas aeruginosa has been studied extensively. It consists of the uronic acid residues β-d-mannuronate (M) and its C-5 epimer, α-l-guluronate (G). The functional properties of alginate strongly correlate with its composition (M/G ratio) and with the uronic acid sequence. The mechanical properties of alginate gels can vary depending on the amount of guluronic acid present in the polymer. Alginate is involved both in microcolony formation in the early stages of biofilm development, and in providing mechanical stability to the biofilms [96,97].
Marine Biopolymers
Se-Kwon Kim in Marine Biochemistry, 2023
Alginate is the constructed polymer for seaweed and bacteria and is found in the cell wall. It may contribute to the strength of seaweed in respond to the flow and wave of seawater in the tidal areas. Although many species of brown algae exist, up to 40% in dry weight, the industry uses the most abundant species, including Ascophyllum nodosum, Macrocystis pyrifera, Laminaria hyperborea, Laminaria digitata, Laminaria japonica, and Sargassum. Ascophyllum is found in the cold waters of Northern Hemisphere and grows in the eulittoral zone. Macrocystis pyrifera, distributed in Baja California, is the largest brown seaweed with the holdfast fixed in the bottom of the sea and rising to the surface water. The length of this seaweed can get up to 20 meters. Laminaria hyperborea is located in the cold water, in the mid-sublittoral zone. They have a strong stipe and can survive to 15 years. Laminaria digitata and Laminaria japonica grow in the cold water, mainly in Japan and China. Laminaria japonica is mainly used for food and only the surplus production is used for alginate (McHugh, 2003). Located in tropical areas, Sargassum is used for alginate production but not much because of the poor quality of alginate. In bacteria, alginate is produced with a more defined chemical structure and so that changes the properties of alginate. Azotobacter and Pseudomonas are used for obtaining the bacteria alginate, which get more interest in biomedical applications for controlled structure by bacteria modification and are tailor-made for meeting the specific application (Hay et al., 2013).
Vector Technology of Relevance to Nitrogen Fixation Research*
Peter M. Gresshoff in Molecular Biology of Symbiotic Nitrogen Fixation, 2018
Another useful application of pKT230 has been demonstrated by Kennedy and Robson.195 The K. pneumoniae nifA gene and flanking portions of the nifB and nifL genes were cloned into pKT230 to produce plasmid pCK1. Its introduction into regulatory mutants of Azotobacter resulted in restoration of the Nif phenotype. Elimination of pCK1 by introducing pKT248 (Sm,Cm) proved that the complementation was actually due to a trans effect of the cloned nifA gene product, indicating the existence of a nifA-like gene in Azotobacter. A similar construct was able to activate the R. meliloti p1 symbiotic promoter in E. coli.196
Alginate-based matrix tablets for drug delivery
Published in Expert Opinion on Drug Delivery, 2023
Natalia Veronica, Paul Wan Sia Heng, Celine Valeria Liew
Alginate is a naturally occurring anionic polysaccharide, primarily extracted from marine brown algae of the Phaeophyceae family, particularly Ascophyllum nodosum, Laminaria hyperborea, and Macrocystis pyrifera. Alternatively, alginate can also be obtained from bacterial sources including Azotobacter sp. and Pseudomonas sp [1]. Structurally, alginate consists of a mixture of β-(1→4)-D-mannuronic acid (M) and α-(1→4)-L-guluronic acid (G) residues. These acid residues are arranged as homogeneous blocks (comprising either acid residue alone – MM or GG blocks) interspersed by heteropolymeric blocks made of random alternating units of mannuronic and guluronic acid (MG or GM blocks) [2]. Alginate is available as free acid (alginic acid) or salt derivatives whereby sodium alginate is the most common form. Additionally, alginate can be modified through physical, chemical, and biological methods. Alginate comes in various grades of different molecular weights, sources, compositions, and sequences of polymer blocks [3,4].
Evaluation of the acute and 28-day sub-acute intravenous toxicity of α-l -guluronic acid (ALG; G2013) in mice
Published in Drug and Chemical Toxicology, 2022
Ahmad Mahdian-Shakib, Mohammad Sadegh Hashemzadeh, Ali Anissian, Mona Oraei, Abbas Mirshafiey
Although the synthetic polymers, ceramics, and metal alloys were applied extensively for drug discovery, the use of biomaterials is of interest (Huebsch and Mooney 2009, Williams 2009). Some of the important advantages of biomaterials over the synthetic polymers are their: higher bioavailability, biodistribution, higher adsorption rate, easy production in large scale as well as low toxic effects on vital organs (Huebsch and Mooney 2009, Williams 2009). Alginate is an anionic polymer, which is obtained from bacterial species such as Azotobacter and Pseudomonas as well as seaweed (Nazeri et al.2017). The alginate is mainly comprised of α-l-guluronic acid (ALG) and, β-d-mannuronic acid (BDM) monomers and widely used in biomedical industries due to its biocompatibility, low toxicity, relatively low costs, and mild gelation (obtained by addition of divalent cations such as Ca2+ to alginate) (Nazeri et al.2017). Indeed, the linear copolymer blocks consisting of (1,4)-linked BDM (M) and ALG (G) residues contribute to the principal structure of the alginate (Fundueanu et al.1999, Nazeri et al.2017). Recently, it has been shown that the ALG (G2013, patented (DE-102016113017.6)) can exert remarkable anti-inflammatory and immunomodulatory effects (Afraei et al.2015). The therapeutic effects of this drug on inflammatory diseases have been evaluated in different preclinical studies (Mirshafiey and Rehm 2009, Afraei et al.2015, Mirshafiey et al.2016). Previously, we observed that the ALG can potentially modulate experimental autoimmune encephalomyelitis (EAE) (Afraei et al.2015). Our results showed that the ALG can inhibit the production of NO species (Mirshafiey et al.2016), as a key player in MS pathogenesis and various inflammatory disorders, and reduce its serum levels both in treatment and prevention groups compared to the control group (Smith and Lassmann 2002). Furthermore, the inflammatory indices such as demyelination, neuronal degeneration infiltration of inflammatory cells, and perivascular cuffing in the brain and cerebellum in EAE mice those received ALG i.p. were significantly milder than the control group (Afraei et al.2015). Further investigations showed that ALG can act as a modulator of TLR4 signaling pathway by reducing the expression levels of IRAK1 and TRAF6 and thereby can partially inhibit the inflammatory responses (Hajivalili et al.2015).
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