Efficient Production of Scleroglucan by Sclerotium rolfsii and Insights Into Molecular Weight Modification by High-Pressure Homogenization.

Weizhu Zeng,Jingwen Zhou,Shiqin Yu,Junyi Wang,Xiaoyu Shan

doi:10.3389/fbioe.2021.748213

Weizhu Zeng, Jingwen Zhou + Show 3 more

Open Access

https://doi.org/10.3389/fbioe.2021.748213

Copy DOI

Abstract

Scleroglucan is a non-ionic water-soluble polysaccharide, and has been widely used in the petroleum, food, medicine and cosmetics industries. Currently, scleroglucan is mainly produced by Sclerotium rolfsii. A higher level of scleroglucan (42.0 g/L) was previously obtained with S. rolfsii WSH-G01. However, the production of scleroglucan was reduced despite a higher glucose concentration remaining. Additionally, the molecular weight of scleroglucan was large, thus restricted its application. In this study, by adjusting the state of seeds inoculated, the degradation issue of scleroglucan during the fermentation process was solved. By comparing different fed-batch strategies, 66.6 g/L of scleroglucan was harvested by a two-dose fed-batch mode, with 53.3% glucose conversion ratio. To modify the molecular weight of scleroglucan, a combination method with HCl and high-pressure homogenization treatment was established. Finally, scleroglucan with molecular weight of 4.61 × 105 Da was obtained. The developed approaches provide references for the biosynthesis and molecular weight modification of polysaccharides.

Highlights

Scleroglucan is a microbial exopolysaccharide, and is a typical β-glucan (Bai et al, 2021; Valdez et al, 2021)
42.0 g/L of scleroglucan was produced by S. rolfsii WSH-G01, and further enhancement of scleroglucan production was difficult
The expression of β-glucanases and β-1,3-glucanases was initially considered to be the main reason for this phenomenon, as studies have reported that S. rolfsii can express some glucanohydrolases that degrade scleroglucan into glucose, providing energy to maintain basic cell growth and metabolism (Bateman, 1972; Martin et al, 2007)

Summary

Introduction

Scleroglucan is a microbial exopolysaccharide, and is a typical β-glucan (Bai et al, 2021; Valdez et al, 2021). Scleroglucan is reported to have a higher molecular weight (Tan et al, 2019; Elsehemy et al, 2020) Due to these outstanding properties of a unique chemical structure and higher molecular weight, scleroglucan has significant advantages in terms of water solubility, biocompatibility, pseudoplasticity, resistance to hydrolysis, salt tolerance, moisture retention and viscosity stability (Barcelos et al, 2020; Song et al, 2020). It has been applied in the petroleum, food, medicine and cosmetics industries (Giavasis, 2014; Li et al, 2020c)

Methods

Results

Conclusion