In this study, the impacts of nitrogen loading rates on microalgal
communities and intracellular storage compounds in a chemostat
enrichment system were investigated. The chemostat was operated at a
constant dilution rate of 0.5 d-1 with different nitrogen loading rates
of 10, 20, 32.5, 42 and 63 mgN.l-1.d-1. The cultures with the lowest
nitrogen loading rates showed nitrogen fixation capacity. Diverse
microalgal communities were observed for nitrogen loading rates of 10
and 20 mgN.l-1.d-1. Chlorella sorokiniana and Chlorella vulgaris were
dominant species at nitrogen loading rates of 42 and 32.5 mgN.l-1.d-1,
respectively. Different species of Arthrospira platensis, Chlorella sp.,
Rhopalodia coexisted under the light-limited condition at NLR of 63
mgN.l-1.d-1. Lipids accumulation overtook starch accumulation at all
nitrogen loading rates. mgN.l-1.d-1. Lipids accumulation overtook starch
accumulation at all nitrogen loading rates. Specifically, the
concentration of lipids in the enriched species cells, Chlorella
sorokiniana was 4.2 times higher than the amount of accumulated starch.
The results demonstrate that the approximately balanced addition of
nutrients and light in chemostat enrichment culture could be an
important trait to enrich a potential lipid production organism.