Effects of Temperature and pH on Cell Growth of a Flocculating Microalga (Chlorella vulgaris) JSC-7

微藻是可广泛用于健康食品及水产养殖的饵料,同时,微藻细胞内积累的油脂可作为可再生生物燃料,因此微藻的生长和代谢受到广泛关注。温度和pH对微藻的生物量积累有很大影响,考察不同温度和pH条件下微藻细胞的生长有助于寻找最佳的条件进行微藻的培养。自絮凝小球藻JSC-7（Chlorella vulgaris JSC-7）可实现自沉降采收,有利于降低微藻生产成本,优化其生长条件对更好地利用该微藻具有重要意义。考察了温度（22∽40℃）及pH（6.0∽10.0）对其细胞生长、叶绿素含量和油脂产量的影响。在所选取的温度及pH范围内,JSC-7细胞均可生长,显示该藻种可以适应广泛的温度和pH条件。适合细胞生长的温度依次为31℃〉28℃〉35℃〉25℃,pH依次为7.0〉8.0〉6.0。pH 8.0时生物量和油脂的积累量最多,说明该藻株在弱碱条件下更适合生长和产油。当温度为31℃、pH为7.0时,可获得最高的生长量（OD690=0.941）、叶绿素含量（19 mg/L）及油脂产量（39.07%/克干重）。

Effects of Temperature and pH on Cell Growth of a Flocculating Microalga（ Chlorella vulgaris） JSC-7

Studies on the accumulation of microalgal biomass have attracted worldwide attention in recent years due to the widespread applications of microalgae as healthy foods and feed in aquaculture. In addition,considerable interest has been focused on lipid production of microalgae as renewable biofuels. Temperature and pH have profound effects on microalgal biomass accumulation,therefore,examination of biomass accumulation and lipid production under conditions of various temperatures and pH is conducive to seek optimal conditions for cultivation of the microalga. Cell flocculation enables simple and economic cell harvest,and is beneficial for large-scale biomass production. A selfflocculating microalga Chlorella vulgaris JSC-7 can flocculate spontaneously which is conducive to reduce the production cost,and optimization of its growth conditions is of important significance in preferable utilization of this microalga. In this study,the microalga was cultivated at temperature ranging from 22 ℃ to 40 ℃ and pH ranging from 6. 0 to10. 0,to investigate the differences in the cell growth and chlorophyll content,as well as lipid production. C. vulgaris JSC-7 was able to grow under all the examined conditions,with the suitable temperature for cell growth in the order 31℃ 28 ℃ 35 ℃ 25 ℃,and the favorable pH in the order 7. 0 8. 0 6. 0. Higher biomass and lipid content were obtained at pH 8. 0 than under pH 6. 0,indicating that weak alkaline conditions are more suitable than weak acid conditions for the growth and lipid production of this microalga. The highest biomass accumulation（ 0. 941 at OD690）,chlorophyll content（ 19 mg / L） and lipid content（ 39. 07% / g dry weight） were achieved at 31 ℃ and pH 7. 0.