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Research Webzine of the KAIST College of Engineering since 2014

Spring 2025 Vol. 24
Sustainability

Biodiesel production from oil-producing microorganisms by using various economical sources

July 27, 2023   hit 95

Biodiesel production from oil-producing microorganisms by using various economical sources

 

Biodiesel is produced from the cultivation of an oil-producing microorganism, Cryptococcus sp., using low-cost reusable sources.

 

Article  |  Spring 2015

 

 

Fuel depletion is recognized as a serious issue, and a number of studies have been conducted to address this problem. One promising approach is to produce biodiesel by extracting lipids from oleaginous (oil-producing) microorganisms.

Biodiesel has usually been produced from food-based sources such as soybean oil, palm oil, or corn oil. In fact, some of the major advantages of using microorganisms are their properties of rapid growth and high cell density, which indicate that a larger amount of biodiesel can be produced in a shorter period of time. There are several demerits, however, in that organic substrates should be continuously supplied for cultivation and the cost is excessively expensive especially when applied on a large scale. To overcome these fatal drawbacks, Prof. Jong-in Han’s lab used low-cost organic substrates such as cellulosic biomass, activated sludge, and food waste.

In the process, cultivation cost can be minimized by using low cost feed stocks or other reusable sources. Then, they are pretreated using proven methods, such as acid-based catalytic reactions, hydrodynamic cavitation, and ultrasonic treatment, to enhance the cultivation efficiency. For the experiment, Cryptococcus sp. was selected among various oleaginous microorganisms due to its outstanding features: high lipid content (53%) and high lipid quality (71%). After the cultivation, an impressive amount of lipid was extracted and harvested. Finally, biodiesel was produced through esterification, which is the conversion process from lipid to biodiesel.

Prof. Han’s research group expressed great confidence and excitement about the potential for successful biodiesel production through this method. Once the optimal cultivation conditions for maximum growth rate and lipid contents are obtained and developed on a large scale, it will ultimately have a huge impact on the economy and the environment.

The overall system of biodiesel production from oleaginous microorganisms
Microscopic image of an oleaginous microorganism, Cryptococcus sp. (B) Lipid body of Cryptococcus sp. stained with Nile Red.

[ Images from Prof. Han’s group ]
Additional information:  http://ebtel.kaist.ac.kr/