Effect of Sludge Concentration and Crude Glycerol Matrix as a Substrate on the Production of Single-Cell Oil by Oleaginous Yeast Yarrowia lipolytica SKY7

Abstract

The disposal of excess crude glycerol produced by the booming biodiesel industry and wastewater sludge solid waste has become a severe problem, and alternate routes of use and valorization of these waste byproducts are needed. The use of cheaply available wastewater sludge solids in fermentation media is very much desirable to reduce the cost of production. The strains of Yarrowia lipolytica can assimilate a wide array of waste substrates, such as crude glycerol, waste cooking oil, starch wastewater, and cellulosic. This study optimized the concentration of wastewater sludge solids (5-35 g/L) to be used with crude glycerol in fermentation media to produce microbial oil as feedstock for biodiesel production. The results indicated that 20 g/L of sludge solids with 40 g/L of crude glycerol resulted in highest lipid content of 29.35% in 96 h. Further, assuming wet extraction of lipids, it was found that at least 11.2% or higher lipid content is required for this process to have an overall positive net solid waste reduction. Insignificant inhibition was observed by the crude glycerol used in this study as compared to pure glycerol, which proves it to be an adequate source of carbon substrate for lipid production.

Isopropanol biosynthesis from crude glycerol using fatty acid precursors via engineered oleaginous yeast Yarrowia lipolytica

“…6 a). This is also consistent with a previous report on the growth adaptation of the Y. lipolytica strain to crude glycerol [ 25 ]. The maximum yield of 470 mg/L isopropanol was obtained after the strain was cultured in medium with crude glycerol as a carbon source for 48 h. However, as in the control group, the production of isopropanol was not observed in the basic YP medium without crude glycerol.…”

Microbial lipid and biodiesel production from municipal sludge fortified with crude glycerol medium using pH-based fed-batch strategy

“…The fermentation was started with 2020 g/L SS of washed sludge and crude glycerol (10.08(10.08 g/L FFA with 5.785.78 g/L glycerol) at 00 h with no addition of trace elements and nitrogen. The selection of 2020 g/L SS for YL cultivation was based on study conducted by Ram, Tyagi and Drogui [16]. During YL fermentation, pH continuously decreases due to secretion of organic acids in the medium and alkaline pH is required to adjust the pH.…”

Screening the Lipid Production Potential of Oleaginous Yeast Yarrowia lipolytica under Wood Hydrolysates

“…The relatively lower growth rates achieved in more concentrated substrate concentrations could be related to conditions such as decreased air transfer and the density of the media slowing the propagation of the yeast. In a study with glycerol consumption, maximum kinetic coefficients were estimated as a specific growth rate of 0.043, a lipid production rate of 0.09, and a glycerol consumption rate of 0.05 per hour for Y. lipolytica, which decreased after 40 h on 10 g/L of pure glycerol [66]. The relatively lower growth rates achieved in more concentrated substrate concentrations could be related to conditions such as decreased air transfer and the density of the media slowing the propagation of the yeast.…”