Table1_Efficient pH and dissolved CO2 conditions for indoor and outdoor cultures of green alga Parachlorella.docx

Efficient pH and dissolved CO2 conditions for indoor (50–450 mL scale) and outdoor (100–500 L scale) culture of a green alga BX1.5 strain that can produce useful intracellular lipids and extracellular polysaccharides were investigated for the first time in Parachlorella sp. The cultures harvested under 26 different conditions were analysed for pH, dissolved CO2 concentration, and the biomass of extracellular polysaccharides. The BX1.5 strain could thrive in a wide range of initial medium pH ranging from 3 to 11 and produced valuable lipids such as C16:0, C18:2, and C18:3 under indoor and outdoor culture conditions when supplied with 2.0% dissolved CO2. Particularly, the acidic BG11 medium effectively increased the biomass of extracellular polysaccharides during short-term outdoor cultivation. The BG11 liquid medium also led to extracellular polysaccharide production, independent of acidity and alkalinity, proportional to the increase in total sugars derived from cells supplied with high CO2 concentrations. These results suggest Parachlorella as a promising strain for indoor and outdoor cultivation to produce valuable materials.

本研究首次在拟小球藻属（Parachlorella sp.）中，针对可合成有用胞内脂质（intracellular lipids）与胞外多糖（extracellular polysaccharides）的绿色藻类BX1.5菌株，探究了其室内（50~450 mL规模）与室外（100~500 L规模）培养的适宜pH及溶解二氧化碳（dissolved CO2）条件。本研究对26种不同培养条件下收获的藻液开展了pH、溶解二氧化碳浓度及胞外多糖生物量的检测分析。BX1.5菌株可在初始培养基pH为3~11的宽泛范围内良好生长，且在通入2.0%溶解态二氧化碳的室内外培养条件下，可合成C16:0、C18:2及C18:3等高价值脂质。尤为值得关注的是，酸性BG11培养基可在短期室外培养过程中有效提升胞外多糖的生物量。BG11液体培养基同样可促进胞外多糖的合成，且该合成过程不受酸碱环境影响，与高浓度二氧化碳供给下细胞产生的总糖含量呈正相关。上述结果表明，拟小球藻属菌株是一种可用于室内外规模化培养以生产高价值产物的优质候选菌株。