Effects of cultivation conditions on the production of soluble algal products (SAPs) of Scenedesmus sp. LX1

During growth microalgal cells release soluble algal products (SAPs), which may be associated with negative effects on microalgal cultivation, including inhibiting microalgal growth, inducing bacterial growth, etc. In this study, the SAP production characteristics of Scenedesmus sp. LX1 under different light intensities, cultivation temperatures and initial pH were investigated. Under the cultivation conditions which were adverse to microalgal growth, including low light intensity (1000 lx), low temperature (15 °C) and extreme pH (5 or 11), microalgal cells tended to release more SAPs. At the end of cultivation, the concentration of SAP changed in the range of 4.9-14.3 mg DOC L− 1, with the SAP production yield per cell of 0.5-4 pg DOC cell− 1 except under the initial pH of 5. SAP production rate of Scenedesmus sp. LX1 increased with microalgal growth rate, but was limited by algal density. During growth, the major constitutes of SAPs changed from growth-associated products into non-growth-associated products gradually.