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Three heterotrophic microalgae identified as Scenedesmus sp. Y5, Scenedesmus sp. Y7 and Chorellasp. Y9 were isolated and screened from natural water based on biomass yield and lipid productivity. Fatty acids’ composition analysis showed that both Y5 and Y7 mainly contained C16:0, C18:1 (n - 9), C18:2 (n - 6) and C18:3 (n - 3) and Y9 mainly contained C16:0, C18:0 and C18:2 (n - 6), suggesting that these microalgae can be ideal feedstock for biodiesel. Considering the specific growth rate and lipid productivity, the culture conditions were optimized for Scenedesmus sp. Y5, Scenedesmus sp. Y7 and Chorellasp. Y9. Based on the optimization of cultural conditions, all of these three microalgae were tested in fed-batch fermentation, and their biomass productivities were 4.960 g·L-1·d-1, 5.907 g·L-1·d-1 and 4.038 g·L-1
Interactions between the light-harvesting subunits
and the non-covalently bound photopigments attribute considerably to the
spectral properties of photosynthetic bacteria light-harvesting complexes. In
our previous studies, we have constructed a novel Rhodobacter sphaeroides expression system. In the present study,
we focus on the spectral properties of LH2 when heterologously express LH2 with β-subunit- GFP fusion protein in Rb. sphaeroides. Near infra-red
spectrum of LH2 remained nearly unchanged as measured by spectroscopy.
Fluorescence spectrum suggested that the LH2 with β-subunit-GFP fusion protein complexes still possessed normal
activity in energy transfer. However, photopigments contents were
significantly decreased to a very low level in the LH2
with β-subunit-GFP fusion protein
complexes compared to that of LH2. FT-IR spectra indicated that interactions
between photopigments and LH2 α/β- subunits appeared not to be changed.
It was concluded that the LH2 spectral properties exhibited very similar even
when heterologously expressed LH2 b-subunit
fusion protein in Rb. sphaeroides.
Our present study may supply a new insight into better understand the interactions
between light-harvesting subunits and photopigments and bacterial photosynthesis
and promote the development of the novel Rb.
sphaeroides expression system.