蛋白核小球藻高效同化硝态氮联产微藻蛋白

High efficient assimilation of NO3–-N with coproduction of microalgal proteins by Chlorella pyrenoidosa

摘要:

本研究旨在建立利用微藻去除高浓度废水中硝酸根并转化为藻蛋白的创新技术。先在摇瓶中研究了培养模式和光照模式对于混养蛋白核小球藻的生物量产量、硝酸根同化速率和藻蛋白产量的影响，随后在5 L光发酵罐中成功进行了放大验证。结果表明，在摇瓶培养中，不回流培养基的补料分批培养是最佳培养模式，可获得最高生物量产量为35.95 g/L，硝酸根平均同化速率为2.06 g/(L·d)，藻蛋白含量可高达42.44%干重；采用阶梯式增加光强的光照模式，能显著提高细胞比生长速率，最高达到0.65 d–1。在5 L光发酵罐中连续培养128 h，最高生物量产量和硝酸根平均同化速率分别达到66.22 g/L和4.38 g/(L·d)，最高藻蛋白含量可达干重的47.13%。本研究能为高效处理工业废硝酸或高浓度硝酸盐废水提供微藻光发酵技术，基于微藻的生物转化过程可联产高蛋白微藻生物质，有利于实现这类废水资源化利用、变废为宝。

Abstract:

The aim of this study was to establish a novel technology using microalgae for NO3– removal from high concentration wastewater and conversion to algal proteins. The effects of cultivation modes and illumination modes on the biomass yield, NO3– assimilation rate and algal protein yield were first investigated in shaking flasks for mixotrophic cultivation of Chlorella pyrenoidosa, and subsequently the scale-up verification in 5-L photo fermenter was successfully conducted. Fed-batch cultivation without medium recycling was the best cultivation mode in shaking flask system, in which the highest biomass yield (35.95 g/L), the average NO3– assimilation rate (2.06 g/(L·d)) and algal protein content (up to 42.44% of dry weight) were achieved. By using a staged increase of light intensity as illumination modes, the specific growth rate of cells could be significantly promoted to the highest (0.65 d–1). After a 128-hour continuous cultivation in a 5-L photo fermenter, the highest biomass yield and the average NO3– assimilation rate were reached to 66.22 g/L and 4.38 g/(L·d) respectively, with the highest algal protein content at 47.13% of dry weight. Our study could provide a photo fermentation technology of microalgae for highly efficient treatment of waste industrial nitric acid and/or high concentration nitrate wastewater. This microalgae-based bioconversion process could coproduce protein-rich microalgal biomass, which facilitates the resource utilization of these type wastewater by trash-to-treasure conversion.