TITLE:
Improvement of Medium Composition and Utilization of Mixotrophic Cultivation for Green and Blue Green Microalgae towards Biodiesel Production
AUTHORS:
Seham M. Hamed, Gerd Klöck
KEYWORDS:
Green Microalgae; Cyanobacteria; Mixotrophy; Lipid Productivity; Biomass; Biodiesel; Photobioreactor
JOURNAL NAME:
Advances in Microbiology,
Vol.4 No.3,
February
19,
2014
ABSTRACT:
A possible source of biological material for the
production of biodiesel is represented by microalgae, in particular by their
lipid content. The aim of the present work was to optimize culture medium
composition for improving growth and lipid content of green microalgae Chlorella
sorokiniana, Scenedesmus acuminatus and blue green Cyanobacterium
aponicum. Lipids were quantitatively determined by spectrofluorometric
method using Nile red flurometric stain. Initially, the effect of two different
medium types, Bold’s and optimized culture medium (OCM), four types of carbon source
(glucose and sodium acetate, molasses, glycerol, control) and four nitrogen concentrations
(100%, -75%, -50%, -25%) on the enhancement of biomass and lipid content and
lipid productivity were studied; indeed, optimized culture medium significantly
improved growth, CDW for three microalgae, beside increasing lipid content and
lipid productivity for S. acuminatus and C. aponicum by 7.5 and 5
folds respectively at 25th day compared to Bold’s
medium. Moreover, 25% nitrogen deficient medium significantly increased lipid
content and lipid productivity for both C. sorokiniana and C. aponicum at 2nd week of re-propagation to 10.6 and 2.6 folds over control
(100% nitrogen). While S. acuminatus recorded the significant lipid content & productivity at 2nd week
under recommended nitrogen dose in medium (100% N) by 4.4 folds over 25% deficient
medium. Meanwhile 0.3% glycerol medium enhanced CDW, lipid content of S.
acuminatus to 1.68 gL-1. While C.
sorokiniana and C. aponicum recorded significant CDW under 0.3%
acetate medium 1.37 and 0.76 gL-1. C. aponicum exhibited no growth under glycerol medium. The highest lipid
content and lipid productivity were obtained under glycerol medium for C. sorokiniana and S. acuminatus (64.3
and 52.8 mg·g·gǃ·dǃ).