Accumulation characteristics of soluble algal products (SAP) by a freshwater microalga Scenedesmus sp. LX1 during batch cultivation for biofuel production

Abstract

Algae cultivation is the essential basis for microalgal biofuel production. Soluble algal products (SAP) are significant obstacle to large-scale, high-cell-density cultivation processes. SAP accumulation during batch cultivation of Scenedesmus sp. LX1 (a unique strain accumulating lipid substantially while growing fast under low-nutrient conditions) with different initial nitrogen concentrations (7.4–34.0mgNL−1) was investigated. The SAP content varied in the range of 3.4–17.4mgDOCL−1 at stationary phase, with average yield per cell of 0.5–2.5pgDOCcell−1. High SAP accumulation up to 15.2–17.4mgDOCL−1 were observed with initial nitrogen above 20.2mgNL−1. The maximum SAP production rate per unit culture volume (rSAP) was 2.6mgDOC(Ld)−1 and that per cell (νSAP) was 1.5pgDOC(celld)−1. The rSAP increased with cell growth rate and decreased with cell density linearly. The SAP accumulation was majorly due to the release of growth-associated products.