共存碳源对克雷伯氏菌NIII2发酵蔗糖产絮凝剂的影响

研究了共存碳源对克雷伯氏菌NIII2以蔗糖为主要碳源发酵产絮凝剂的影响.实验结果表明:柠檬酸为共存碳源时,克雷伯氏菌NIII2分泌絮凝剂过程中容易产酸,使得絮凝剂的产量和碳源转化率都较低.当丁二酸、乙酸、乳酸为共存碳源时,发酵液pH均高于7.5,絮凝剂产量有所提高,最高可达10.87g/L,碳源转化率也较高,为43.48%.与柠檬酸为共存碳源相比,当投加丁二酸时,克雷伯氏菌NIII2所产微生物絮凝剂中蛋白质与糖含量比值提高了33%,絮凝剂的Zeta电位值由-60.00 mV升高至-28.07 mV,絮凝剂分子粒径广泛分布在0~300μm之间且大粒径分子所占比例增加,聚合度加大,絮凝剂表面形貌呈现结块团状无定型结构,从而提高絮凝剂的活性和性能.该微生物絮凝剂投加量为4.0 mg/L,对2 g/L高岭土的SS去除率可达97.3%.

Effects of co-carbon source compounds on production of bioflocculant by Klebsiella sp. NIII2 with sucrose

Effects of co-carbon source compounds on the production of bioflocculant by Klebsiella sp. NIII2 with sucrose were investigated. The results showed that with citrate as co-carbon source compounds in fermentation medium, NIII2 was easy to produce acid, which often resulted in decrease of the bioflocculant yield and carbon conversion rate. With succinic acid, acetate or lactate as co-carbon source, the values of pH were higher than 7. 5, the yield could reach the highest of 10. 87 g/L and the carbon conversion rate was as high as 43. 48%. Compared with citrate as co-carbon source, succinate as co-carbon source could make the ratio of protein and saccharide increase by 33%; Zeta potential flocculation activity was improved from-60 . 00 mV to -28 . 07 mV;the particle size of bioflocculant widely distributed in the range of 0~300μm and the proportion of large particle size was augmented. With the increasing high degree polymerization of the bioflocculant and with flocculation surface rendering agglomerate amorphous structure, it improved the flocculation activity and performance. With a 4. 0 mg/L dose of such bioflocculant, the removal rate of the suspended solid in kaolin solution (2 g/L) was up to 97. 3%.