Breeding of high lipid producing strain of Geotrichum robustum by ion beam implantation 

Yuanyuan Cao^{1, 2} · Jianming Yao*¹· Jun Li³ · Xiangsong Chen³ · Jinyong Wu³

¹Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, PR China
²College of Life Science, Anhui Agricultural University, PR China
³Anhui Academy of Recycling Economical and Technical Engineering, PR China

*Corresponding author: yy721@hotmail.com

Financial support: Director Foundation of Institute of Plasma, Chinese Academy of Sciences (No. 095GZ1156X).

Keywords: fatty acids, Geotrichum robustum, high lipid producing strain, ion beam implantation.

To obtain an industrial strain with high lipid yield, the wild strain G0 of Geotrichum robustum was mutated by means of nitrogen ions implantation. Mutagenic effects of strain G0 by low energy N⁺ ion implantation were studied. The experimental results indicated that the survival rate curve took a “saddle” shape, and the positive mutation rate was increased to 22.00% at the dose of nitrogen ions 2.0 x 10¹⁵ ions/cm² when the survival rate was 28.60%. By repeated screening, a high lipid producing strain G9 was obtained. The biomass, lipid content and lipid yield of the mutant can reach 40.25 g/L, 71.14% and 28.63 g/L after cultured in a 5L fermenter for 8 days, increasing by 52.81%, 68.82% and 157.93% to those of wild strain, respectively. Analysis results on fatty acids composition and relative content by gas chromatography and mass spectrometry showed that the lipid in strain G9 was mainly composed of 16-carbon and 18-carbon fatty acids, including 37.360% oleic acid, 23.631% palmitic acid, 4.458% linoleic acid and 26.465% stearic acid. Such compositional features were quite similar to plant oil. Geotrichum robustum strain G9 may be an ideal high lipid producing strain for biodiesel production.