Identification of Green Alga Chlorella vulgaris Isolated from Freshwater and Improvement Biodiesel Productivity via UV Irradiation

  • Gomaa, Mohamed A. (Genetic and Genetic Engineering Department, Faculty of Agriculture, Benha University) ;
  • Refaat, Mohamed H. (Genetic and Genetic Engineering Department, Faculty of Agriculture, Benha University) ;
  • Salim, Tamer M. (Genetic and Genetic Engineering Department, Faculty of Agriculture, Benha University) ;
  • El-Sayed, Abo El-Khair B. (Algal Biotechnology Unit, National Research Centre) ;
  • Bekhit, Makhlouf M. (Genetic and Genetic Engineering Department, Faculty of Agriculture, Benha University)
  • Received : 2018.12.26
  • Accepted : 2019.04.29
  • Published : 2019.09.28


Chlorella vulgaris was isolated from the Nile River, Qalubia Governorate, Egypt, for possible use in biodiesel production. BG-II nutrient growth media was used for isolation and laboratory growth. Identification was performed via 18S rRNA gene amplification, followed by sequencing. The alga was exposed to UV-C (254 nm) for 15, 30, and 45 s to improve dry weight accumulation and to increase the oil production. Daily measurements of dry weight ($g{\cdot}l^{-1}$) were performed; oil content and volumetric lipid productivity were also determined. UV-C exposure led to an increase in the volumetric lipid productivity by 27, 27.3, and $32.4mg{\cdot}l^{-1}{\cdot}d^{-1}$ with 15, 30, and 45 s, respectively, as compared with the control, which resulted in $18mg{\cdot}l^{-1}{\cdot}d^{-1}$. Of the examined mutants, the one with the highest productivity was re-irradiated by UV-C (254 nm) for 15, 30, 45, and 60 s. For 15 s of exposure time, the oil content increased to 34%, while it was 31% at 30 s; further, it decreased to 22% at 45 and 60 s exposures. The fatty acid methyl ester profile was 82.22% in the first mutant at 45 s, compared with the wild strain that contained a total of 66.01% of FAs. Furthermore, the highest levels of polyunsaturated fatty acid methyl ester were observed in the mutant exposed for 45 s, and it reached 11.41%, which reduced the cetane number to 71.3.


Chlorella vulgaris;18S rRNA gene;UV irradiation;fatty acid;fuel properties


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