摘要：在菲的水溶液中筛选可将菲作为唯一碳源的降解菌，测定其对水溶液中菲的降解效果并对菌种进行初步鉴定。通过盆栽试验研究了降解菌在灭菌土壤与不灭菌土壤中的生长情况及其对多环芳烃(PAHs)的降解效果，同时还研究了在微生物降解PAHs情况下，菠菜中的PAHs含量和组成。本文筛选出两株菲降解菌，分别命名为F1和F2。经鉴定，F1、F2菌株分别为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)和嗜吡啶红球菌(Rhodococcus pyridinivorans)。在菲浓度为8 mg/L的水溶液中培养96 h后，F1菌株对菲的降解率达到80%，F2菌株则能达到100%。在35 d后，F1菌株对土壤中PAHs的降解率达到13%-14%，F2菌株对土壤中PAHs的降解率达到19%-21%。在土壤中，两菌株对4环PAHs的降解率最优，其中对荧蒽和芘的降解率最高。在灭菌土壤中，F2菌株对PAHs的降解效果与生长状况均优于不灭菌土壤条件，F1菌株则无明显差别。加菌处理土壤中种植的菠菜体内PAHs含量明显低于对照且生长情况优于对照，F2菌株处理效果优于F1菌株处理。
关键词：多环芳烃；菲降解菌；土壤；菠菜
Effects of two phenanthrene-degrading bacteria on degradation of PAHs and growth of spinach in soil
Student majoring in Environmental Science Liu Tiangang
Tutor Chai Chao
Abstract: Degrading bacteria that used phenanthrene as the sole carbon source were screened by the aqueous solution of phenanthrene. The strains were identified, and the degradation effect of the degrading bacteria on phenanthrene in the aqueous solution was determined. The growth situation of degrading bacteria and the effects of PAHs degradation in sterilized and non-sterilized soils were studied by pot experiment. The content and composition of PAHs in spinach in the case of microbial degradation were measured. Two phenanthrene-degrading bacteria were screened, and named F1 and F2, respectively. The F1 and F2 strains were identified as Bacillus amyloliquefaciens and Rhodococcus pyridinivorans, respectively. The degradation rate of F1 strain on phenanthrene was 80%, and the F2 strain reached 100% after 96 h in 8 mg/L phenanthrene in aqueous solution. The degradation rate of F1 strain on PAHs in the soil was 13% -14%, and the F2 strain reached 19%-21% after 35 days. In the soil, the degradation rate of 4 rings PAHs was optimal in both strain, and the degradation rate of fluoranthrene and pyrene was highest. The degradation effect and growth condition of F2 strain in the sterilized soil were better than those of the non - sterile soil condition, but there was no significant difference in F1 strain between the two soil treatments. The content of PAHs in spinach growing in the soil added the strains was significantly lower than that in the contrast and the growth condition was better than that in the contrast. The growth of spinach growning in the soil added F2 strain was better than that growing in the soil added F1 strain.
Key words: PAHs; phenanthrene-degrading bacteria; soil; spinach
引言
多环芳烃(PAHs)是具有代表性的土壤有机污染物，它是由两个及以上苯环以不同排列方式组合在一起的有机化合物[1-4]。PAHs能够在土壤中长期残留，并且其具有较强的吸附性，可以随尘土进入大气存在于大气颗粒物中，再经由呼吸进入人体与动物体内，或者进入水体、植物体随食物链进入人与动物体内[5-6]。
被PAHs污染的土壤的治理一直是受到广泛关注的热点之一[7]，使用微生物手段修复是一种操作简单，成本较低，无二次污染的修复方法[7-11]。研究表明，微生物可以利用PAHs作为唯一碳源或者用其他有机物质共代谢从而高效分解PAHs[12-13]。自从发现微生物能够降解PAHs开始，经过大量的研究目前从环境中分离出的PAHs降解菌已包括有假单胞菌属(Pseudomonas)、红球菌属(Rhodococcus)、气单胞菌属(Aeromonas)、芽孢杆菌(Bacillus)、伯克氏菌属(Burkholderia)、分支杆菌属(Mycobacterium)以及鞘氨醇单胞菌属(Sphingomonas)等[14-17]。
目前微生物修复PAHs污染土壤的主要局限是加入到土壤的降解菌可能因各种原因无法成为优势菌种最终导致结果与实验室内培养结果存在较大差异[7,18]。
为了探究多环芳烃降解菌在土壤中的实际降解效果。本研究使用菲含量较高的土壤从中筛选能降解菲的微生物，对其菌种进行鉴定并对其降解能力和生长状况进行测试，最终将菌株加入土壤之中测定其在土壤之中对PAHs的去除效果和对土壤中生长的菠菜的影响。为接近一步探究微生物和植物联合修复土壤奠定基础。
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