(675a) Microbial Oil Production by Oleaginous Fungi and Yeasts Using the Hydrolysate From the Dilute Sulfuric Acid Pretreatment of Wheat Straw

Microbial oil production by oleaginous fungi and yeasts using the
hydrolysate from the dilute sulfuric acid pretreatment of wheat straw

Xiaochen Yu, Jijiao
Zeng, Yubin Zheng and Shulin Chen

Department of
Biological Systems Engineering,
Washington State University,

Abstract

Taking
into account the fundamental problems around the world: hunger, the lack of
energy and the deterioration of the environment, biodiesel production from
lignocellulosic biomass has increasingly attracted much attention, since it
decreases the potential to spark conflicts between food and energy issues by
using non-starch, non-food biomass, and additionally it emits less green house
gas to the environment than conventional fossil fuels. Generally lignocellulosic
biomass is firstly hydrolyzed either chemically or biologically to fermentable
sugars derived from cellulose and hemicellulose, which will be then converted to
single cell oil by oleaginous microorganisms, as the feedstock for biodiesel
production. Our work comprehensively explores the use of the hydrolysate from
the dilute sulfuric acid pretreatment of wheat straw for microbial oil
production. In this study, we investigated the performance of the oleaginous
yeast and fungi on both detoxified and non-detoxified hydrolysate. The results showed
that all the strains could use the hydrolysate to produce lipids and
detoxification of the hydrolysate was not necessary for optimal cell growth and
lipid production by the fungus and yeast strains. Among all the tested strains,
the yeast Cryptococcus curvatus and
the fungus Mortierella isabellina
achieved 34% and 50% lipid content respectively on the non-detoxified
hydrolysate with up to 20% lipid yield. The overall mass balance shown in Fig.1
indicated that lipid yield using the hydrolysate
from dilute sulfuric acid pretreatment of wheat straw was 4.7 g lipids/
100 g initial dry biomass. Our finding is quite significant as (1) it
elucidates the feasibility of microbial oil production from lignocellulosic
materials and suggests an alternative strategy for biodiesel production, (2) it
provides the possibilities for the further scale-up and demonstration, which
will accelerate the development of biodiesel production towards the
commercialization, (3) it simplifies the hydrolysate fermentation process and
could probably reduce the cost since the detoxification step is not required.

Fig. 1. The overall mass balance of
converting lignocellulosic biomass into lipids