Current Prospects on Production of Microbial Lipid and Other Value-Added Products Using Crude Glycerol Obtained from Biodiesel Industries Bijaya K. Uprety 1 & Balaji Venkatesagowda 2 & Sudip K. Rakshit 1,2,3 # Springer Science+Business Media, LLC 2017 Abstract Production of microbial lipids using crude glycerol from the biodiesel industry is reviewed in this paper. Approximately 10 wt.% of crude glycerol is obtained for every batch of biodiesel. The crude glycerol accumulated contains various impurities and hence cannot be used for any commercial applications without further purification. Its conversion via bio- logical and chemical routes into valuable products has been studied by different researchers. Varieties of fungal, yeasts, and algal species have been used to produce microbial lipids from crude glycerol. However, research focus on screening a robust industrial oleaginous strain capable of doing this is still on-go- ing. Due to its chemical similarity to vegetable oils, microbial lipids are considered a potential renewable feedstock for biodie- sel production and for applications in food and pharmaceutical industries. Its conversion to polyols and subsequently to biobased polymers is also being explored. The rising price of vegetable oils, increasing energy demands, growing environ- mental concerns, and availability of crude glycerol as a cheap carbon substrate result in considerable potential for the applica- tion of these processes in the future. Keywords Crude glycerol . Microbial oil . Biodiesel industry . Oleaginous microbes . Value-added products . Commercial application of microbial lipid Introduction There has been considerable research focus on the conversion of biomass to biofuels and chemicals. It addresses various issues related to climate change mitigation and the use of fossil re- sources. Some of the problems associated with the use of non- renewable fossil resources include its fluctuating prices, depletion of reserves, production of greenhouse gases, and geo-political wars [1–3]. Biodiesel is a renewable clean form of energy which can contribute to the alternate energy mix of the future. Conventionally, biodiesel is obtained by transesterification of vegetable oils. Approximately 10 wt.% of glycerol is pro- duced as a by-product during this process. The glycerol ob- tained during the biodiesel production process is also known as crude glycerol [2]. It contains various types of impurities and has low commercial value without purification. Pure glyc- erol has numerous applications in varieties of sectors includ- ing pharmaceutical, food, and cosmetic industries [3–5]. However, with the rapid rise in biodiesel production, and the resultant glut in crude glycerol, the prices of both forms of glycerol (crude and pure) have decreased considerably [3, 6]. Many medium- and small-scale industries have already started treating the crude glycerol as a waste and incur a cost for its disposal. Thus, utilization of crude glycerol to produce various value-added products with commercial value has become quite imperative, both from an economical and an environ- mental point of view [7]. Conversion of crude glycerol into commercial products will add revenue to the existing biodiesel producers. Also, this will help manage crude glycerol in an environmentally friendly way. As a result, different studies focusing on the chemical and biological conversion of crude glycerol into various products has been carried out [3, 8–14]. Among the various alternative options available, bioconver- sion of crude glycerol to microbial lipids (single cell oils or microbial oils) is a focus of research recently. * Sudip K. Rakshit srakshit@lakeheadu.ca 1 Department of Biotechnology, Lakehead University, Thunder Bay, ON, Canada 2 Biorefining Research Institute, Lakehead University, Thunder Bay, ON, Canada 3 Department of Chemical Engineering, Lakehead University, Thunder Bay, ON, Canada Bioenerg. Res. DOI 10.1007/s12155-017-9857-0