Abstract
Brewers’ spent grain (BSG) accounts for 85% of the total amount of by-products generated by the brewing industries. BSG is a lignocellulosic biomass that is rich in proteins, lipids, minerals, and vitamins. In the present study, BSG was subjected to pretreatment by two different methods (microwave assisted alkaline pretreatment and organosolv) and was evaluated for the liberation of glucose and xylose during enzymatic saccharification trials. The highest amount of glucose (46.45 ± 1.43 g/L) and xylose (25.15 ± 1.36 g/L) were observed after enzymatic saccharification of the organosolv pretreated BSG. The glucose and xylose yield for the microwave assisted alkaline pretreated BSG were 34.86 ± 1.27 g/L and 16.54 ± 2.1 g/L, respectively. The hydrolysates from the organosolv pretreated BSG were used as substrate for the cultivation of the oleaginous yeast Rhodosporidium toruloides, aiming to produce microbial lipids. The yeast synthesized as high as 18.44 ± 0.96 g/L of cell dry weight and 10.41 ± 0.34 g/L lipids (lipid content of 56.45 ± 0.76%) when cultivated on BSG hydrolysate with a C/N ratio of 500. The cell dry weight, total lipid concentration and lipid content were higher compared to the results obtained when grown on synthetic media containing glucose, xylose or mixture of glucose and xylose. To the best of our knowledge, this is the first report using hydrolysates of organosolv pretreated BSG for the growth and lipid production of oleaginous yeast in literature. The lipid profile of this oleaginous yeast showed similar fatty acid contents to vegetable oils, which can result in good biodiesel properties of the produced biodiesel.
Highlights
Nowadays, the most significant challenge for researchers, environmentalists, and stakeholders is to clean our environment as it is rapidly deteriorating as a consequence of increasing demand of land, water, food, and energy [1]
We studied the growth and the lipid accumulation of the oleaginous yeast Rhodosporidium toruloides, a yeast capable of co-utilizing xylose and glucose, when using Brewers’ spent grain (BSG) as medium
BSG is mainly composed of cellulose, hemicellulose and lignin along with considerable amounts of proteins and lipids and its composition varies depending on the applied brewing techniques [19]
Summary
The most significant challenge for researchers, environmentalists, and stakeholders is to clean our environment as it is rapidly deteriorating as a consequence of increasing demand of land, water, food, and energy [1]. Increasing public concerns about global warming and green-house gas emissions attributed to the use of fossil fuels have attracted the attention to these issues which are considered as a grand challenge in the 21st century [2]. Apart from the environmental concerns raised by using fossil resources for energy production, import of fossil fuels is negatively impacting domestic economies due to supply insecurity. For any developed and developing nation it is crucial to uphold economical and sustainable growth with the utilization of domestic and renewable sources of energy so that the import of oils can be reduced [3]. Utilization of edible sources as raw materials for biofuels production can directly compete with human foods and has been criticized [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
