Concomitant Production of Lipids and Carotenoids in Rhodosporidium toruloides under Osmotic Stress Using Response Surface Methodology

Abstract

As a replacement to existing fossil fuels, biofuels, have proven their worth; however, their widespread use is limited due to inconsistent yields, higher costs and poor productivity. An oleaginous yeast, Rhodosporidium toruloides has been reported to accumulate substantial amounts of lipids (that can be converted to biofuels) and therefore, it was selected for study and optimization. Apart from lipids, R. toruloides is also reported to produce carotene that can be used as a therapeutic agent. In this study, the culture medium was statistically modeled and optimized for concomitant production of lipids and carotenoids and for improving and maximizing the productivity of lipids as well as carotenes. The two metabolites were expressed differentially in the growth cycle of the organism. Culture medium components were simultaneously varied at five different levels using statistical modeling employing response surface methodology (RSM). Osmotic stress was introduced in order to simulate saline conditions and optimize the carotenoid as well as lipid production process, to be used in conditions with high salt contents. We observed a 10% (w/v) increase in carotenoid production in initial experiments under osmotic stress due to high salt concentration, while the increase in lipid synthesis was not pronounced. In this study, we demonstrate 36.2% (w/v) lipid production and 27.2% (w/v) carotenoid production, under osmotic stress with high salt concentrations, for the first time.

A synthetic biology approach to transform Yarrowia lipolytica into a competitive biotechnological producer of β‐carotene

“…This work shows the enormous potential of Y. lipolytica to produce β-carotene in an economically feasible manner, not only by the high titer achieved but also due to the co-production of high amount of lipids, which can be used as fuels or chemicals (Singh et al, 2016).…”

“…This work shows the enormous potential of Y. lipolytica to produce β‐carotene in an economically feasible manner, not only by the high titer achieved but also due to the co‐production of high amount of lipids, which can be used as fuels or chemicals (Singh et al, ). Moreover, the process can be further improved not only by strain engineering and bioreactor condition optimization but also by the use of low cost carbon sources such as starch or lignocellulosic materials.…”

Genome-scale model of Rhodotorula toruloides metabolism

“…Carotenoid production in yeast has been shown to depend on cultivation conditions (Dias, Silva, Freitas, 310 Reis, & da Silva, 2016;Singh et al, 2016) with yields of 0.28 mg/g having been achieved in fed-batch cultivation of R. toruloides (Dias, Sousa, Caldeira, Reis, & Lopes da Silva, 2015). R. toruloides produces a number of carotenoids including torularhodin, torulene, γ-carotene and β-carotene.…”

Challenges in lipid production from lignocellulosic biomass using Rhodosporidium sp.; A look at the role of lignocellulosic inhibitors

“…This parameter is critical when selecting or optimizing the composition of the fermentation broth. Likewise, Singh et al . evaluated the production of lipids in R. toruloides under conditions of osmotic stress by the addition of NaCl.…”