|
Author
Alegre, Francesca
|
Abstract
Background: The increasing global demand for oils and fats has led to a search for unusual sources which do not contribute to deforestation and water consumption. Microbial production of lipids, particularly from yeasts, appears to be an attractive solution to this problem, particularly in those countries with restricted supplies o lipids form natural sources. Over the last decades, numerous research efforts have focused on the implementation of alternative feedstocks for the production of lipids. However, the microbial growth characteristics and bioprocessing challenges are making its commercialization difficult due to their high production costs which enables them to compete with conventional lipids. Therefore, strategies are required to reduce the production costs of SCOs and to increase the productivity. With the aim of reducing costs in the production of microbial lipids, here we have analyzed a set of by-products from the agro-food industry to implement it in this process. Additionally, we have investigated the best bioreactor conditions to optimize the process of lipid production using those by-products.
From bibliography research, we have seen that Oleaginous microorganisms are able to convert carbon sources into storage lipids as intracellular lipid droplets, also known as single cell oils (SCOs), which are produced in the stationary phase under nitrogen limitation with simultaneous excess of carbon source and oxygen limitation. Following this statement, we have focused in prepare our culture conditions with nitrogen limitation, high quantities of by-product and oxygen limitations.
Yarrowia lypolytica, which is one of the most studied oleaginous yeasts, has been chosen as organism in this study. The study was divided in preliminary research to understand Y.lipolytica behavior under defined medium, followed by a study in shake-flask using a variety of by-products and finishing with a study in the scale-up to obtain the best conditions for lipid production in 10L bioreactor.
Results: The values obtained indicate variation of lipid production depending on the carbon and nitrogen source used, however obtaining high biomass quantity but not as high lipid content as expected. According to oxygen effect on lipid production, it is deduced that limiting conditions of oxygen decreases biomass growth and increases lipid synthesis. When scaling up with the by-product, higher biomass content was obtained, mostly due to the increase in oxygen in the medium, however lipid content decrease and with the study carried on, we were not able to reproduce the shake-flask conditions in the scale up.
Conclusions: With the research done, we were able to understand Yarrowia lipolytica behavior under different conditions and estimate the best for the scale-up. However, further research should be done to optimize the production and continue trying different feedstocks.
|
|
