【分　 类】 化工与理学
【关 键 词】 苯酚；生物降解；固定化细胞
【来 　源】 互联网
【收　 录】 中文学术期刊网

正文：
Agrobacterium, Burkholderia, Acinetobacter, Ralstonia, Klebsiella, Bacillus, Rhodococcus,  Rhizobium（土壤杆菌属、布克氏菌属、不动杆菌属、青枯菌属、克雷白氏杆菌、牙孢杆菌属、红球菌属、根瘤菌属）^[14]。还有实验研究发现Sphingomonas（鞘氨醇单胞菌属）也具有降解苯酚的能力^[23]。我们的研究表明，在苯酚初始浓度为800mg/l的情况下，Acinetobncter sp. XA05 和 Sphingomonas sp. FG03（不动杆菌XA05和鞘氨醇单胞菌FG03）生长良好，且在45h内，能分别降解99.5% 和97.6%的苯酚。这证明了XA05 和FG03菌株在降解苯酚方面出色的能力。
    值得一提的是，当XA05 和FG03菌种以1:1比例混合时，30h内可以降解99.8% 初浓度为800mg/l的苯酚样本。较之于纯种培养，混合培养的细胞对苯酚的去除效率更高，对芳香族的利用效率也更高。其原因可能是来自不同环境的XA05 和FG03菌株具有不同的酶系统，并且会以不同的方式降解苯酚和其它芳香族化合物。当两菌种混合培养时，可能是因为菌种间的相互协作从而缓解了抑制作用，这些问题都有待进一步的研究。
将XA05 和FG03菌种以1:1的比例混合，通过自由悬浮和固定化细胞对苯酚的降解研究表明二种方式都有很高的苯酚生物降解效率，对于初浓度为800mg/l的苯酚样本，35h内两种细胞的去除率均超过95%。较之自由悬浮细胞，固定化细胞的表现更好，且稳定性更强。原因是在相同条件下，固定化细胞的载体物质可以有效的隔绝苯酚的毒性。也有其他的研究者指出固定化可以使细胞的活力增强，并且证明了固定化可以改变细胞的生理特性，如增强酶的诱导力^[24]。另外，我们还发现温度对固定化细胞的影响要小于对自由悬浮细胞的影响，因为PVA载体的固定作用可以增强细胞的热力学稳定性。在我们的研究中，PVA载体在重复使用二十次之后仍然具有很好的韧性并且不会发生膨胀现象，培养基也能保持清亮，这说明了PVA载体具有很高的机械强度。此结果明显优于先前报道的使用藻酸钠的细菌固定化方法^[19]。
 
4、结论
（1）分别从活性污泥和酚污染土壤中分离出的XA05 和FG03菌株是新发现在两种具有降解苯酚能力的微生物，这两种微生物具有很高的苯酚生物降解能力以及很强的耐受力。根据16s RNA基因序列分析，可以确定XA05 和FG03菌种分别与Acinetobacter sp. 和 Sphingomonas sp. 相关，因此分别将其命名为Acinetobacter sp. XA05 和 Sphingomonas sp. FG03。
（2）将XA05 和FG03菌株按1:1比例混合，以聚乙烯醇（PVA）作为凝胶基质用来细胞固定化。研究表明自由悬浮和固定化细胞都有很高的苯酚降解效率，当苯酚初浓度为800mg/l时，35h内两种方法的苯酚去除率均超过95%。较之与自由悬浮细胞，固定化细胞具有更高的降解效率以及更广的pH适应范围，而且受温度的影响也更小。
（3）固定化细胞与自由悬浮细胞相比，具有更好的贮存稳定性且能够重复使用二十次以上。
 
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