乌勇布拉克盐湖嗜盐古菌絮凝效果筛选及活性检测

Flocculation effect and activity of halophilic archaea isolated from Uyong Brac salt lake

摘要:

【目的】从嗜盐古菌中筛选可产生生物絮凝剂的菌株，对发酵液、上清液、菌悬液、胞外聚合物的絮凝作用进行检测，筛选能够适应高盐废水处理，且具有广谱盐度及pH作用范围的微生物絮凝剂。【方法】以新疆乌勇布拉克干盐湖沉积物为研究对象，利用纯培养方法对嗜盐古菌进行分离，对絮凝菌株进行初筛及16S rRNA基因测序，构建系统进化树，初步判断菌株分类地位；复筛检测不同生物材料的絮凝效果；选择絮凝效果较好的生物材料，检测其盐度、pH的絮凝效果稳定性。【结果】采用纯培养方法共分离到28株嗜盐古菌，絮凝初筛共筛选出16株嗜盐古菌，分布于碱线菌属(Natrinema)、盐缓长菌属(Halopiger)和盐土生菌属(Haloterrigena)。菌株发酵液、上清液、菌悬液、胞外聚合物具有不同程度的絮凝效果。菌株A279-1、A133、RP33、NGA0064、RM-152、A389的发酵液、上清液的絮凝效果较好，其中菌株A389的发酵液絮凝率为61.06%，上清液为67.92%。所有菌株菌悬液的絮凝率达到80%以上。菌株所产胞外聚合物表现出较好的絮凝效果，菌株RM-152所产胞外聚合物的絮凝率最高，达89.86%，其次是A389 (81.53%)。菌株A389所产胞外聚合物的产量最大，达12.53 g/L，具有广泛的盐度和pH适应性。【结论】乌勇布拉克干盐湖沉积物中蕴含丰富的可产生微生物絮凝剂的嗜盐古菌资源。嗜盐古菌菌株发酵液、上清液、菌悬液及胞外聚合物均具有良好的絮凝作用，尤其是胞外聚合物表现出较好的絮凝效果，具有广谱的盐度和pH耐受性。嗜盐古菌所产生物絮凝剂的发现对于后续高盐废水功能材料开发具有重要应用价值。

Abstract:

[Objective] The present study screened the halophilic archaeal strains with flocculation effect and evaluated the flocculation effect of the fermentation liquid, fermentation supernatant, cell suspension, and extracellular polymeric substances of the strains, aiming to develop the microbial flocculants that can adapt to a wide range of salinity and pH for high-salt wastewater treatment. [Methods] The pure culture method was designed to isolate halophilic archaea from the sediment samples of Uyong Brac salt lake in Xinjiang. The 16S rRNA gene sequencing and phylogenetic analysis were performed to evaluate the taxonomic positions of the isolated strains. Furthermore, the flocculation effects of the fermentation liquid, fermentation supernatant, cell suspension, and extracellular polymeric substances of the strains were evaluated. The flocculation stability was evaluated under a wide range of salinity and pH conditions. [Results] A total of 28 strains of halophilic archaea were isolated by pure culture method, among which 16 strains were selected based on the primary screening results. The 16S rRNA sequences and phylogenetic tree suggested that these strains mainly belonged to Natrinema, Halopiger, and Haloterrigena. The fermentation liquid, fermentation supernatant, cell suspension, and extracellular polymeric substances of strains A279-1, A133, RP33, NGA0064, RM-152, and A389 had better flocculation effects than those of other strains. The fermentation liquid and supernatant of strain A389 showcased the flocculation rates reaching 61.06% and 67.92%, respectively. The cell suspensions of all the strains had the flocculation rates over 80%. The extracellular polymeric substances produced by strain RM-152 had the highest flocculation rate of 89.86%, followed by those of strain A389 (81.53%). Strain A389 had the yield of 12.53 g/L of extracellular polymeric substances and it adapted to a wide range of salinity and pH. [Conclusion] There were abundant halophilic archaea in the sediment of Uyong Brac salt lake. The fermentation liquid, fermentation supernatant, cell suspension, and extracellular polymeric substances of halophilic archaea had good flocculation effect. In particular, the extracellular polymeric substances demonstrated good flocculation effect and could withstand a wide range of salinity and pH, being suitable for further industrial recycling and utilization. The isolated strains may serve the subsequent development of functional materials for industrial high-salt wastewater treatment.