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Synthesis of Pullulan
Published in Shakeel Ahmed, Aisverya Soundararajan, Pullulan, 2020
Pullulan is synthesized by A. pullulans (formally known as pullan pullularia). The organism (A. pullulans) involved is ubiquitous in nature and is found in soil, lake water, on the surface of latex paint files, synthetic plastic materials, used cosmetic, and foods such as cereals, fruits, cheese, tomato, etc. This organism forms a black pigment (melanin), so it is also called “black yeast.” Different synthesis routes for the preparation of pullulan have been proposed by several researchers [6, 19]. In 1981, Catley reported that up to 7% maltotetraose subunits were detected; this is the main reason why, currently and frequently in the literature, the term “pullulan” is used for both the “polymaltotriose” produced by A. pullulans and the polysaccharide varieties. Catley proposed that a lipid is used as a carrier to take out pullulan outside of plasmalemma. Rho et al. proposed two pathways; one allowed direct conversion of glucose, whereas in the second pathway, an identified precursor is used [26].
The level of aquatic yeast as a possible indicator of microbiological quality of urban recreational water reservoirs
Published in Urban Water Journal, 2023
Magdalena Dzikowiec, Katarzyna Góralska, Ewa Brzeziańska-Lasota
In our research in pond S water, we also found ‘black yeast’ from the Exophiala genus, which is known to form biofilms in water systems. The genus Exophiala shows high tolerance to adverse factors: temperature, pH, salt concentration, etc. Although most species of the genus Exophiala do not show pathogenic potential, some species (e.g. Exophiala dermatitidis isolated in our studies) are responsible for phaeohyphomycosis, mycetoma, respiratory and CNS infections, and is especially dangerous in cystic fibrosis patients. Exophiala was often isolated from groundwater, tap water, fountains and due to its potential pathogenicity should be monitored as standard (Novak Babiˇc et al. 2016; Biedunkiewicz and Schulz 2012; Modrzewska, Bartnicka, and Blaszkowska 2019). The presence of potentially pathogenic species Exophiala dermatitidis in our studies indicates that such monitoring should also include bathing areas.