黄孢原毛平革菌BKMF-1767产絮凝剂PCF-1767的絮凝特性及其机理解析

Flocculation characteristics and mechanism of flocculant PCF-1767 produced by Phanerochaete chrysosporium BKMF-1767

【背景】传统絮凝剂的使用会带来安全和环境污染方面的问题,而微生物絮凝剂具有无毒、无二次污染、易生物降解的优点,因此寻找高效廉价的微生物絮凝剂具有重要意义。【目的】研究黄孢原毛平革菌BKMF-1767产生的胞外多糖絮凝剂的絮凝特性及机理。【方法】使用高岭土进行PCF-1767的絮凝活性测定,分析絮凝剂获取时间、Ca2+浓度、投加量、pH、温度对絮凝效率的影响,并测定PCF-1767的热稳定性。测定絮凝剂的单糖组成、糖苷键连接类型、多糖分子量、Zeta电位变化、对絮体形态观察,探讨了PCF-1767的絮凝机理。【结果】培养6–12 d获得的PCF-1767的絮凝活性良好;7 d絮凝剂要获得较好的絮凝效率至少需加入2 mmol/L Ca2+作为助凝剂,最佳投加浓度为0.75–1.35 mg/L,最适pH为3.0-9.0,对温度高于50°C的废水絮凝活性逐渐降低,经过沸水浴处理3 h后的絮凝活性几乎不变。PCF-1767中多糖的一级结构主要由葡萄糖以→4)Glup(1→的方式连接,多糖分子量随培养时间的延长而增大,变化范围为9.897×105–2.126×106 Da。结合Zeta电位变化与絮体显微图像分析表明其絮凝机理主要为吸附架桥和卷扫作用,而非电荷中和作用。【结论】PCF-1767具有很高絮凝活性,其用量低、适用条件广、热稳定性高,是一种非常具有应用前景的絮凝剂。

[Background]The use of traditional flocculants poses security and environmental problem,while microbial flocculants have the advantages of non-toxic,no secondary pollution and easy biodegradation.Therefore,it is of great significance to find efficient and economical microbial flocculants.[Objective]To study the flocculation characteristics and mechanism of PCF-1767,an extracellular polysaccharide flocculant produced by Phanerochaete chrysosporium BKMF-1767.[Methods]The flocculating activity of the PCF-1767 was determined using a Kaolin suspension.The effects of flocculant acquisition time,flocculant dosage,pH,Ca2+concentration and temperature on the flocculation efficiency were studied,as well as the thermal stability of PCF-1767.Flocculation mechanism of PCF-1767 was discussed from the monosaccharide composition and glycoside bond connection type,the molecular weight of polysaccharides,Zeta potential determination,and flocs morphology observation.[Results]The PCF-1767 obtained at 6–12 d displayed high flocculating activity.For higher flocculation activity of the PCF-1767 obtained at 7 d,at least 2 mmol/L Ca2+should be added as coagulant.The optimal flocculant dosage was 0.75–1.35 mg/L,with an optimum pH range of 3.0–9.0.The flocculating activity decreased when the water temperature was higher than 50°C.The flocculation activity of PCF-1767 was almost unchanged after 3 h water bath treatment.The primary structure of the polysaccharide in PCF-1767 obtained in different periods was similar,mainly connected by glucose in the manner of→4)Glup(1→.The molecular weight of PCF-1767 increased with the culture time,at the range of 9.897×105–2.126×106 Da.Zeta potential determination and flocs image analysis showed that the main flocculation mechanism was adsorption bridging flocculation and sweeping,instead of charge neutralization.[Conclusion]The flocculant PCF-1767 produced by P.chrysosporium BKMF-1767 has high flocculation efficiency with low dosage,wide application range and good thermal stability.In brief,PCF-1767 has good application prospects.