Lipid recovery from wet oleaginous microbial biomass for biofuel production: A critical review

Abstract

h i g h l i g h t sChallenges in industrial lipid extraction processes were illustrated. Lipid recovery from wet biomass was critically reviewed in the context of biofuel productions. Cell wall disruption technologies were critically reviewed and compared. a b s t r a c tBiological lipids derived from oleaginous microorganisms are promising precursors for renewable biofuel productions. Direct lipid extraction from wet cell-biomass is favored because it eliminates the need for costly dehydration. However, the development of a practical and scalable process for extracting lipids from wet cell-biomass is far from ready to be commercialized, instead, requiring intensive research and development to understand the lipid accessibility, mechanisms in mass transfer and establish robust lipid extraction approaches that are practical for industrial applications. This paper aims to present a critical review on lipid recovery in the context of biofuel productions with special attention to cell disruption and lipid mass transfer to support extraction from wet biomass.

Lipids from yeasts and fungi: physiology, production and analytical considerations

“…; Dong et al . ). At pilot‐scale operations (production of SCO in 150‐L batch bioreactors using Apiotrichum curvatum ATCC 20509 in trials in which sweet rennet whey had been employed as substrate) various mechanical methods had been considered as the most appropriate ones for SCO extraction; thus, steam explosion, liquid shear (homogenization) and solid shear (bead milling) methods with or without simultaneous solvent extraction have been successfully employed on wet yeast biomass (Davies ).…”

“…In order to perform extraction of the microbial synthesized lipids, a nonpolar solvent is usually necessary in which most of the lipid compounds would be reasonably soluble (Davies 1988;Hammond and Glatz 1988;Dong et al 2016). On the other hand, the presence of a more polar solvent inside the extracting blend of solvents (i.e.…”

“…However, in most of the cases, the methods of extraction of storage lipid are not effective when they are employed in wet biomass (i.e. the one that had not been previously freeze-or thermally dried) Dong et al 2016). Therefore, in order to proceed with the extraction of cellular lipid from the recovered and wet microbial mass, various solutions have been proposed; they involve repeated and lengthy extractions with (mostly) several blends of chloroform and methanol, treatments with successions of alcohols and nonpolar solvents and several types of pretreatments of the microbial mass in order for disruption of the cell wall to be (partially or completely) achieved followed by or performed simultaneously with solvent extraction (for reviews see Hammond and Glatz 1988;Dong et al 2016).…”

“…the one that had not been previously freeze-or thermally dried) Dong et al 2016). Therefore, in order to proceed with the extraction of cellular lipid from the recovered and wet microbial mass, various solutions have been proposed; they involve repeated and lengthy extractions with (mostly) several blends of chloroform and methanol, treatments with successions of alcohols and nonpolar solvents and several types of pretreatments of the microbial mass in order for disruption of the cell wall to be (partially or completely) achieved followed by or performed simultaneously with solvent extraction (for reviews see Hammond and Glatz 1988;Dong et al 2016). As far as the pretreatment of the wet microbial mass is concerned, before or simultaneously with the recovery of the microbial lipids, several types of operations have been proposed including but not limited to high-pressure homogenization (this method is currently used in large-scale operations in order highvalue protein to be recovered), steam explosion, bead milling, pulse electric field, ultrasound, osmotic shock, microwave-induced heating, subcritical water hydrolysis, supercritical fluid extraction, enzymatic hydrolysis, autolysis, chemical hydrolysis, employment of hydroxyl radicals that are generated from semiconductors (TiO 2 ) under UV-light irradiation and that can function as strong nonselective cell surface attackers, autoclaving at T = 120°C for variable time applications, etc.…”

“…As far as the pretreatment of the wet microbial mass is concerned, before or simultaneously with the recovery of the microbial lipids, several types of operations have been proposed including but not limited to high-pressure homogenization (this method is currently used in large-scale operations in order highvalue protein to be recovered), steam explosion, bead milling, pulse electric field, ultrasound, osmotic shock, microwave-induced heating, subcritical water hydrolysis, supercritical fluid extraction, enzymatic hydrolysis, autolysis, chemical hydrolysis, employment of hydroxyl radicals that are generated from semiconductors (TiO 2 ) under UV-light irradiation and that can function as strong nonselective cell surface attackers, autoclaving at T = 120°C for variable time applications, etc. (for critical reviews see Davies 1988;Hammond and Glatz 1988;Wang et al 2012;Dong et al 2016). At pilot-scale operations (production of SCO in 150-L batch bioreactors using Apiotrichum curvatum ATCC 20509 in trials in which sweet rennet whey had been employed as substrate) various mechanical methods had been considered as the most appropriate ones for SCO extraction; thus, steam explosion, liquid shear (homogenization) and solid shear (bead milling) methods with or without simultaneous solvent extraction have been successfully employed on wet yeast biomass (Davies 1988).…”