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Beneficial Lactic Acid Bacteria
Published in K. Balamurugan, U. Prithika, Pocket Guide to Bacterial Infections, 2019
The other substances produced by LAB are mannitol, sorbitol, tagatose, and xylitol used as sweeteners in food industry. Mannitol is a six-carbon sugar alcohol synthesized by bacteria from fructose using mannitol dehydrogenase (Patra et al. 2009; Papagianni 2012). The research revealed that one-third of fructose could be replaced with glucose, maltose, galactose, mannose, raffinose, or starch with glucoamylase, and two-thirds of fructose could be replaced with sucrose for mannitol production (Saha and Nakamura 2003). Tagatose is an isomer of fructose showing prebiotic effect and antioxidant activity, and it can be used for control of diabetes and obesity. D-tagatose can be produced from D-galactose by L-arabinose isomerase (araA) (Chouayekh et al. 2007; Patra et al. 2009). Sorbitol is another six-carbon sugar alcohol produced by catalytic hydrogenation of glucose, with applications in the food and pharmaceutical industries. Only a few organisms are able to synthesize sorbitol. LAB strains are often subjected to metabolic engineering to achieve sorbitol hyperexpression (Patra et al. 2009; Papagianni 2012). Xylitol is a five-carbon sugar alcohol produced by reduction of xylose. LAB have not been reported to produce xylitol naturally, but recombinant strains with xylose reductase were able to generate this compound (Papagianni 2012). Bacteriocins are considered in the separate chapter.
Hypersensitivity and Allergic Fungal Manifestations: Diagnostic Approaches
Published in Johan A. Maertens, Kieren A. Marr, Diagnosis of Fungal Infections, 2007
A. alterncita, a member of the Deuteromycetes class, is one of the most important allergenic fungi, and Alt a 1 is the most frequently recognized allergen, binding to IgE in more than 80% of asthmatic patients with Alternaria allergy. A sensitive two-site ELISA has been recently developed for measurement of the major A. alternata allergen Alt a 1 with a detection limit lower than 0.5 ng/mL and a practical working range of 0.5 to 50 ng/mL (42). A specific double monoclonal antibody based assay was developed for Alt a 1 by Portnoy et al. with a sensitivity of 0.2 μg/mL (43). Various isoelectric variants and isoforms of Alt a 1 have also been reported (5,44). Saenz-de-Santamaria et al. recently reported phosphatase and esterase activities in Alt a 1 (45). Other Alternaria allergens identified include a heat-stable glycoprotein allergen of 31 kDa, a 53-kDa aldehyde dehydrogenase (ALDH), a 22-kDa allergen, and an 11-kDa ribosomal P2 protein. Schneider et al. recently reported that NADP-dependent mannitol dehydrogenase (Alt a 8) is an important fungal allergen of A. alternata (46). In IgE-ELISA and immunoblots, mannitol dehydrogenase (MtDH) is recognized by 41% of A. alternata-alleigic patients. In vivo immunoreactivity of the recombinant MtDH was verified by SPT (46). Portnoy et al. reported a double monoclonal antibody-based assay for the 70-kD Alternaria allergen GP70 that was sensitive to GP70 concentrations as low as 0.2 μg/mL and was highly specific for the allergen (47).
Marine-Based Carbohydrates as a Valuable Resource for Nutraceuticals and Biotechnological Application
Published in Se-Kwon Kim, Marine Biochemistry, 2023
Rajni Kumari, V. Vivekanand, Nidhi Pareek
Macroalgae are of three types, green, brown, and red algae, among them brown and red algae have been reported as having the highest content of carbohydrates. However, research is going on to develop a suitable process at large scale for producing biofuels by utilizing carbohydrates from these algae. Brown algae, including Laminaria, Alaria, and Saccorhiza have stored food material in the form of mannitol and laminarin and can grow meters in length (Nobe et al., 2003; Adams et al., 2009; Horn et al., 2000). Brown algae may have a high content of mannitol and laminarin—for example, Laminaria hyperborea has 25% mannitol and 30% laminarin as dry weight. This high content of carbohydrate in brown algae makes it a potential source for the generation of liquid fuel such as ethanol. The concentration of mannitol and laminarin in any seaweed varies throughout the year (Jensen and Haug, 1956). These storage sugars can be easily extracted from brown algae under low pH and high temperature (Percival and McDowell, 1967). Laminarin can be hydrolyzed enzymatically by laminaranase and cellulase into its glucose monomer by use of many microorganisms during fermentation. Mannitol is a sugar alcohol which has to be first oxidized to fructose by the enzyme mannitol dehydrogenase and then hydrolyzed into its monomer. The oxidation of mannitol requires oxygen; thus many microorganisms are unable to hydrolyze it anaerobically (Van Dijken and Scheffers, 1986). Various hydrolysis treatments such as dilute acid thermal, dilute alkaline thermal, and enzymatic can be used to hydrolyze complex sugars like mannitol, laminarin, cellulose, etc., to simple sugars mannose, glucose, and galactose and are further followed by fermentation to ethanol production. Two types of fermentation techniques, separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) can be utilized for the production of ethanol from sugar in the presence of microorganisms (Offei et al., 2018).
Efficiency of Bacillus subtilis metabolism of sugar alcohols governs its probiotic effect against cariogenic Streptococcus mutans
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2020
Danielle Duanis-Assaf, Doron Steinberg, Moshe Shemesh
Further investigating the regulatory profiles of the key metabolic enzymes in the tested bacteria led us to the assumption that B. subtilis cells express those genes (at least at a basal level) even prior to their exposure to the sugars. Notably, even though there was major induction in the expression of the genes gutB and mtlD in S. mutans even after 3–6 h, the cells started to grow in minimal media with addition of sorbitol or mannitol at a very low rate which is correlated to the findings by Dills and Seno [48]. The growth of S. mutans cells in TY medium containing sorbitol or mannitol is maybe due to sucrose derivatives, which has been found in GCMS analysis of the medium (Table S1), and may not be related to the presence of the sugar alcohols. These results support the findings of Brown and Wittenberger [49] who demonstrated that sorbitol or mannitol dehydrogenase activities are almost completely absent in S. mutans cells grown in a mixture of sorbitol or mannitol and another carbon source. Moreover, the sorbitol transport by S. mutans is mediated by the phosphotransferase system that could be inhibited by glucose residues, which disables the sorbitol uptake [48,50,51].