Conversion of cellulosic materials into glycolipid biosurfactants, mannosylerythritol lipids, by Pseudozyma spp. under SHF and SSF processes

Abstract

BackgroundMannosylerythritol lipids (MEL) are glycolipids with unique biosurfactant properties and are produced by Pseudozyma spp. from different substrates, preferably vegetable oils, but also sugars, glycerol or hydrocarbons. However, solvent intensive downstream processing and the relatively high prices of raw materials currently used for MEL production are drawbacks in its sustainable commercial deployment. The present work aims to demonstrate MEL production from cellulosic materials and investigate the requirements and consequences of combining commercial cellulolytic enzymes and Pseudozyma spp. under separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes.ResultsMEL was produced from cellulosic substrates, Avicel® as reference (>99% cellulose) and hydrothermally pretreated wheat straw, using commercial cellulolytic enzymes (Celluclast 1.5 L® and Novozyme 188®) and Pseudozyma antarctica PYCC 5048T or Pseudozyma aphidis PYCC 5535T. The strategies included SHF, SSF and fed-batch SSF with pre-hydrolysis. While SSF was isothermal at 28°C, in SHF and fed-batch SSF, yeast fermentation was preceded by an enzymatic (pre-)hydrolysis step at 50°C for 48 h. Pseudozyma antarctica showed the highest MEL yields from both cellulosic substrates, reaching titres of 4.0 and 1.4 g/l by SHF of Avicel® and wheat straw (40 g/l glucan), respectively, using enzymes at low dosage (3.6 and 8.5 FPU/gglucan at 28°C and 50°C, respectively) with prior dialysis. Higher MEL titres were obtained by fed-batch SSF with pre-hydrolysis, reaching 4.5 and 2.5 g/l from Avicel® and wheat straw (80 g/l glucan), respectively.ConclusionsThis work reports for the first time MEL production from cellulosic materials. The process was successfully performed through SHF, SSF or Fed-batch SSF, requiring, for maximal performance, dialysed commercial cellulolytic enzymes. The use of inexpensive lignocellulosic substrates associated to straightforward downstream processing from sugary broths is expected to have a great impact in the economy of MEL production for the biosurfactant market, inasmuch as low enzyme dosage is sufficient for good systems performance.

Production and characterization of a new glycolipid, mannosylerythritol lipid, from waste cooking oil biotransformation by Pseudozyma aphidis ZJUDM34

“…Though MELs and their properties have been documented for several decades, they gained more and more attention only in recent years because of their interesting application possibilities in the biochemical and pharmaceutical industries. Up to date, researches have shown that MELs are mainly produced by anamorphic basidiomycetous yeasts, Pseudozyma spp., as relatively high quantities, and fungi, Ustilago maydis , as relatively low quantities (Faria et al, ), which is with regard to the substrate, fermentation condition, and downstream processing.…”

Hydrolysis of olive mill waste to enhance rhamnolipids and surfactin production

“…For example, Ma et al (2014) and Konishi et al (2015) used enzymatically and chemically hydrolysed corncob residue to produce up to 42.1 and 49.2 g/L of sophorolipids, respectively. Marin et al (2015) obtained surfactin from hydrolysed sisal pulp, while Faria et al (2014) produced up to 2.5 g/L of mannosylerythritol lipids by using enzymatically hydrolysed wheat straw.…”

Pseudozyma Priming Influences Expression of Genes Involved in Metabolic Pathways and Immunity in Zebrafish Larvae

“…Our results from using a GF model demonstrate that an increase in transcript levels of metabolism-related genes correlates with the presence of the yeast in the environment. Interestingly, all species of the genus Pseudozyma produce mannosylerythritol (MEL) as an essential hydrophobic glycolipid with biosurfactant properties (93), which acts as an immunomodulatory and antitumor agent. Its anti-inflammatory activity is mediated through various pathways involving some of the proteins encoded by the genes that we found to be upregulated following yeast exposure (19,94,95).…”