Exploring sugarcane vinasse for sustainable lipid production applied to biodiesel generation by Rhodotorula glutinis R4

D. DANIELA MAZA; J. MAXIMILIANO BARROS; MANUEL J. AYBAR; SILVANA C. VIÑARTA

Chapadmalal, Prov. Buenos Aires

Congreso; XVIII Reunión Anual de SAMIGE; 2023

SAMIGE

Oleaginous yeasts such as Rhodotorula spp. efficiently accumulate ~50-70% (w/w) ofneutral lipid storage, mainly in the form of triglycerides, under specific growth conditions.These microbial oils offer a viable alternative to vegetable oils for biodiesel production.Vinasse is a highly polluting by-product generated from the bioethanol production processfrom sugarcane. For each liter of alcohol produced, between 13 and 15 L of vinasse aregenerated and pose a significant environmental challenge. It is crucial to explorealternatives to generate value-added products.The main objective of this study was to obtain lipids suitable for biodiesel production bythe oleaginous yeast R. glutinis R4, using vinasse sourced from the sugarcane-alcoholindustry in Tucumán as a substrate.Vinasse, obtained from a Tucumán distillery, was utilized to formulate the culture media.The growth and lipid production of R. glutinis R4 were evaluated in diluted vinasse (10%and 25%, v/v), supplemented with glucose (40 g/L) as the sole carbon source. Additionally,growth was assessed in 10% vinasse with added glucose (40 g/L) and yeast extract (3 g/L),and in 10% vinasse with crude glycerol (40 g/L)- a biodiesel industry by-product- as the solecarbon source. GMY culture medium with glucose (40 g/L) was utilized as a control.Cultures were incubated at 25°C, 250 rpm for 168 h. Growth, cellular biomass and lipidproduction were monitored at different culture times. Fatty acid profiles of lipids producedby R4 were analyzed using GC-MS, and biodiesel quality parameters were estimated.The results revealed the capacity of R. glutinis R4 for growth and intracellular lipidssynthesis using 10% and 25% diluted vinasse as substrate, with glucose as the sole carbonsource. No significant differences were observed in cell biomass between the two evaluatedconditions. However, in the case of 10% diluted vinasse, lipid accumulation was higher, withlipids constituting 88% of the cell biomass after 96 h. Additionally, 10% diluted vinassesupplemented with glucose and yeast extract, or crude glycerol were also evaluated. In bothconditions, the growth, lipid production (5.1 -5.9 g/L), and lipid accumulation (40%) exhibitedby R4 was comparable to those achieved in the GMY control medium (7 g/L of lipids;48.6%). The fatty acid profile of the microbial oils obtained from R4 revealed the presenceof long-chain fatty acids similar to those found in vegetable oils, with a high content (~80%)of palmitic (C16:0) and oleic (C18:1) acids, which are suitable for biodiesel synthesis.Biodiesel quality parameters complied with the established by international biodieselstandards.Vinasse and crude glycerol could be considered for formulating culture media in thedesign of processes for sustainable microbial oil production by R. glutinis R4, enabling thevalorization of these wastes. R4 emerges as a promising strain for alternative oil sourcesfor various biotechnological applications.