A novel approach for the production and purification of mannosylerythritol lipids (MEL) by Pseudozyma tsukubaensis using cassava wastewater as substrate

Abstract

P. tsukubaensis is a yeast-like microorganism that synthesized the biosurfactant mannosylerythritol lipids-B (MEL-B). Production cost can be one of the drawbacks of biosurfactants production. Therefore the development of efficient and cost effective purification strategies and the use of by-products in the culture medium could serve as important strategies to reduce overall process cost. The aim of this work was to evaluate the production of MEL using cassava wastewater, a hydrophilic medium composed of a low-cost substrate which is a by-product of cassava processing, followed by foam fractionation and ultrafiltration of MEL. Cassava wastewater proved to be a feasible culture medium for P. tsukubaensis and MEL-B production as the yield (1.26 g L) was similar to that reported by others using water-soluble carbon sources (up to 2 g/L). Interestingly ultrafiltration with 100 KDa MWCO memabranes (using 20 mL centrifugal devices) led to the purification of MEL-B in one step since ≈ 80% of MEL was recovered, while more than 95% of proteins were found in the permeate. The scale up of the ultrafiltration (up to 500 mL) using a cross flow filtration unit led to very similar results. Overall the ultrafiltration led to a threefold increase in MEL purity in terms of protein (at both scales). The chemical characterisation by NMR confirmed the production of MEL-B homologue and also the production of a second stereoisomer ≈ 9%, while the CG-MS and MALDI-TOFMS analysis confirmed the main fatty acids within the structure of MEL-B (C8:0 and 12:0 and C8:0 and C14:1). Therefore, the process developed here was found to be a good alterntative to the conventional production of MEL which uses synthetic culture medium, solvent extraction (ethyl acetate) and column chromatography (silica) for its purification.

Fungal biosurfactants, from nature to biotechnological product: bioprospection, production and potential applications

“…sorghi [ 82 ], Pseudozyma spp. [ 28 ] and Schizonella melanogramma (MEL-A and -B) [ 89 ] are also described as MEL producers. As far as we known, the highest MEL (165 gL −1 ) production was obtained in batch-fed cultivation of Pseudozyma aphidis [ 90 ].…”

“…The combination of energy sources, such as carbohydrates and lipids in culture medium, has been commonly reported [ 229 , 230 ]. In this context, several sources of carbon can be used in culture media such as glucose, sucrose [ 231 ], xylose [ 227 ], inulin [ 131 ], cassava wastewater [ 28 ], cane molasses [ 232 ], soy molasses [ 233 ], glycerol [ 234 ] and hydrolyzates from restaurant food waste [ 235 ]. Additionally, lipid sources, such as refined vegetable oils and residual food frying oils [ 71 , 208 , 230 , 236 ], wastewater from the oil industry [ 186 , 237 ], motor oil [ 151 ] and animal fat [ 44 , 238 ], have also been used.…”

“…In addition, the use of agro-industrial waste, non-conventional substrates and the optimization of bioprocess parameters through statistical designs have also been shown as a tool to enhance the viability of the production of these biomolecules [ 26 , 27 ]. Downstream processing steps are also constantly being improved to ensure greater yields and better performance and to elucidate structural variants of these molecule [ 28 , 29 ].…”

Microbial biosurfactants: A broad analysis of properties, applications, biosynthesis, and techno‐economical assessment of rhamnolipid production

“…• Fast, one-step recovery • High level of purity • Avoids end-product inhibition or product degradation as a result of product aggregation 85 7-8.5% 86 11-13% (for surfactin) 84 5% (for surfactin) 87 20% (for MEL) 88…”

Agro-Industrial Residues Utilization for Surfactin Production: Cassava Wastewater

“…Regarding surfactin production, the culture medium represents ≈ 30% total production cost. Thus, some agro-industrial residues have been investigated as alternative culture medium such as olive mill waste, brewery wastewaters, sugarcane and beet molasses, whey, cassava wastewater, etc [3]. In this sense, the cassava processing industry generates ≈ 300 liters of cassava wastewater/ton of cassava, residue which currently has not industrial application.…”