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Abstract：
A novel extracellular polymeric substance (EPS) with flocculating activity produced by Pseudomonas fluorescein isolated from soil was studied in this paper. Firstly, atmospheric and room temperature plasma (ARTP) was applied to get a mutant of P. fluorescein with higher EPS production. A mutant T4-2 exhibited a 106.48% increase in flocculating activity compared to the original strain. The maximum EPS yield from T4-2 was enhanced up to 6.42 g/L, nearly 10 times higher than the original strain on a 3.6-L bioreactor with optimized fermentation conditions. Moreover, the flocculating activity of the mutant reached 3023.4 U/mL, 10.96-fold higher than that of T4. Further identification showed that EPS from mutant T4-2 was mainly composed of polysaccharide (76.67%) and protein (15.8%) with a molecular weight of 1.17 × 105 Da. The EPS showed excellent adsorption capacities of 80.13 mg/g for chromium (VI), which was much higher than many reported adsorbents such as chitosan and cellulose. The adsorption results were described by Langmuir isotherm and pseudo-second-order kinetic model. The thermodynamic parameters (ΔG0, ΔH0 and ΔS0) revealed that the adsorption process was spontaneous and exothermic. Adsorption mechanisms were speculated to be electrostatic interaction, reduction, and chelation.
摘要：
本文研究了从土壤中分离的荧光假单胞菌产生的具有絮凝活性的新型胞外聚合物（EPS）。首先,应用大气和室温等离子体（ARTP）获得了具有较高EPS产量的P.荧光素突变体。与原始菌株相比，突变体T4-2的絮凝活性提高了106.48％。T4-2的最大EPS产量提高到6.42g/L，在优化发酵条件的3.6L生物反应器上，比原始菌株高出近10倍。此外，突变体的絮凝活性达到3023.4U/mL,比T4高10.96倍。进一步鉴定表明，突变体T4-2的EPS主要由多糖（76.67％）和蛋白质（15.8％）组成，分子量为1.17×105Da。EPS对铬（VI）的吸附能力为80.13mg/g，远高于许多报道的吸附剂，如壳聚糖和纤维素。吸附结果用Langmuir等温线和拟二级动力学模型描述。热力学参数（ΔG0，ΔH0和ΔS0）表明吸附过程是自发的和放热的。吸附机制推测为静电相互作用，reduction,和螯合。
