Abstract
Pullulan, with its excellent characteristics of film-forming, water solubility, and biodegradability, is attracting more and more attention in agricultural products preservation. However, high pullulan production cost largely restricts its widely application due to its low production. In order to improve pullulan production by Aureobasidium pullulans NCPS2016, the medium was optimized using single factor experiment and response surface methodology. Based on the single factor experiments, the contents of soybean meal hydrolysates (SMHs), (NH4)2SO4, and K2HPO4·3H2O were considered to be main factors influencing the extracellular polysaccharide (EPS) production, and were further optimized by Box–Behnken design. The optimal content of SMHs of 7.71 g/L, (NH4)2SO4 of 0.35 g/L, and K2HPO4·3H2O of 8.83 g/L were defined. Finally, EPS production of 59.8 g/L was obtained, 39% higher in comparison with the production in the basal medium. The purified EPS produced by NCPS2016 was confirmed to be pullulan. This is the first time fructose is reported to be the optimal carbon source for pullulan production by Aureobasidium pullulans, which is of great significance for the further study of the mechanism of the synthesis of pullulan by NCPS2016. Also, the results here have laid a foundation for reducing the industrial production cost of pullulan.
Highlights
Pullulan is a kind of extracellular water-soluble polysaccharide secreted by Aureobasidium spp., which is a linear macromolecule linked by α-(1,6) glycosidic linkages of maltotriose repeating units [1,2]
That internal transcribed spacers sequence (ITS) sequence of NCPS2016 was similar to those phylogenetically related to Aureobasidium spp., and the ITS sequence of NCPS2016
A pullulan-producing strain was confirmed by morphological analysis and phylogenetic analysis, and it was named by A. pullulans NCPS2016
Summary
Pullulan is a kind of extracellular water-soluble polysaccharide secreted by Aureobasidium spp., which is a linear macromolecule linked by α-(1,6) glycosidic linkages of maltotriose repeating units [1,2].The unique structure of pullulan makes it highly water soluble and biodegradable, so that it is a functional biological macromolecule with great development values and application prospects [3].Pullulan has been widely applied in food processing and preservation in recent years [4], and it is considered as a new kind of material for food preservation because of its fine film-forming property [5].Pullulan coating has been applied to protect perishable agricultural products especially susceptible to mechanical injury including vegetables, sea foods, and fruits. Pullulan is a kind of extracellular water-soluble polysaccharide secreted by Aureobasidium spp., which is a linear macromolecule linked by α-(1,6) glycosidic linkages of maltotriose repeating units [1,2]. The unique structure of pullulan makes it highly water soluble and biodegradable, so that it is a functional biological macromolecule with great development values and application prospects [3]. Pullulan has been widely applied in food processing and preservation in recent years [4], and it is considered as a new kind of material for food preservation because of its fine film-forming property [5]. Pullulan coating has been applied to protect perishable agricultural products especially susceptible to mechanical injury including vegetables, sea foods, and fruits. The pullulan coated peppers show less changes in color, weight loss, Molecules 2018, 23, 1334; doi:10.3390/molecules23061334 www.mdpi.com/journal/molecules
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