Sustainable production of sophorolipid biosurfactants using renewable cellulose-derived feedstocks

Authors: Msanne, Joseph; Ashby, Richard - Rick; Harron, Andrew; Czerhoniak, Alexis

Submitted to: Journal of Surfactants and Detergents
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: The large-scale production of bioproducts to replace petroleum products using fermentation remains challenging due to high costs associated with cell growth, harvesting, and purification. A few microorganisms, such as the yeast Pseudohyphozyma bogoriensis, can naturally produce a high value class of chemicals known as sophorolipids that are useful surfactants for many applications. The availability of yeast genetic data allowed us to predict that it may be viable when grown on media derived from agricultural waste products, while simultaneously converting these low value wastes to valuable sophorolipids. To validate these findings, renewable organic carbon substrates, easily obtained from biomass, were tested in this study. Results confirmed the uptake of these substrates, in addition to abundant production of sophorolipid biosurfactants with important physico-chemical properties. The ability to grow this yeast on extracts from low value agricultural waste has the potential to greatly increase productivity and yield, as well as improve process costs and add value to agricultural residues.

Technical Abstract: Glycolipids produced and secreted by oleaginous yeasts are renewable and eco-friendly compounds with important physico-chemical properties, and multiple biological and industrial applications. The large-scale production of these compounds has been limited by high production costs and low yields. The sophorolipid-producing yeast Pseudohyphozyma bogoriensis may possess the ability to grow in fermentation systems using carbon substrates deriving from inexpensive lignocellulosic biomass, while simultaneously secreting high value biomaterials. In this study, comparative analyses between different cellulose-derived carbon sources including glucose, cellobiose, and sodium carboxymethyl cellulose confirmed the ability of P. bogoriensis to grow and accumulate glycolipids using these substrates. On a dry weight basis, the highest yields of about 4% (w/w) glycolipids were obtained when cellobiose was supplemented at 10 g/L in shake-flask fermentations. When the unconventional carbon substrate sodium carboxymethyl cellulose was supplemented, cultures exhibited a lower glycolipid yield of 0.3% (w/w), but the dry weight was higher compared to other substrates. Analytical analyses using various chromatography methods confirmed the chemical profiles, whereas both monoacetylated and diacetylated sophorolipid forms with C22 long-chain hydroxy fatty acid were identified in all glycolipid extracts. Surface tension (ST) and critical micelle concentration (CMC) measurements showed that glycolipids produced on cellulose-derived substrates exhibited similar or even superior physical and surfactant properties compared with glucose. Furthermore, availability of the yeast genome sequences facilitated the identification of putative genes that may be involved in cellulose hydrolysis (e.g., cellulase-like). Information on genomic and metabolic pathways is a prerequisite for trait improvement towards increasing the production of high value biomaterials.