重金屬污染環境中抗高濃度類金屬碲微生物之分離與探討

Isolation and identification of microorganisms that resist to tellurite from heavy metal contaminated soil

韓竹婷(Chu-Ting Han)

指導教授 ： 簡志青

元智大學/工程學院/生物科技暨生物資訊研究所/碩士(2007年)

摘要

本研究主要是從重金屬污染的土壤環境中，分離且探討，能抵抗高濃度類金屬碲的微生物。首先利用LB medium 添加1000 μM tellurium以優化培養的方式篩選出台南二仁溪的泥土中能抗類金屬碲(tellurium)的微生物，分別將其命名為Te B、Te C 與TeW。菌株經由16S rDNA定序分析結果顯示Te B、Te C為Shewanella sp. 而TeW為 Paenibacillus sp.。
本研究探討這些菌株對於類金屬碲的耐受性，經實驗結果証實: Te B、Te C各為6000 μM與 7000 μM，而TeW為3000 μM，據文獻指出大於2000 μM即為對類金屬碲具有高抗性的菌株，有鑑於此，本研究分離出之三株菌株對於tellurite之耐受性皆為高抗性的菌株。 本實驗進一步利用試劑Sodium diethyl dithiocarbamate (DDTC)偵測tellurium的濃度，探討菌株能抵抗高濃度tellurite的同時，是否也可吸收(移除) tellurite。經實驗結果顯示，三株菌株不論培養在含有100 μM或是1000 μM tellurite的LB medium中，皆可降低60%以上培養基中tellurite的濃度。
本研究也利用穿透式電顯(TEM)來觀察菌株是否可將tellurite 吸收至菌體內。經實驗結果証實: 三株菌株體內皆有tellurium沉澱在菌體內。使用掃描式電子顯微鏡(SEM)觀察則在探討高濃度下的培養環境下，菌體的外觀形態是否會改變，結果發現TeB 培養於1000 μM 的環境下，菌體會積聚堆疊，而TeC則是會從長桿狀轉變成球狀， TeW則皆無改變皆呈長桿狀。

關鍵字

重金屬污染 ； 碲 ； 穿透式電子顯微鏡 ； 掃描式電子顯微鏡

並列摘要

Microorganisms reside in heavy metal contaminated area may evolve mechanisms for resistance to these toxic ions. In this study, I isolated three strains of microorganisms that are able to resist tellurite ion (TeO32-) from sediments from Er-Ren River, Tainan by enrichment culture techniques. The three bacteria were designed as strain TeB, TeC and TeW. Strain TeB and TeC were identified as Shewanella sp. and strain TeW was identified as a Paenibacillus sp. by 16S rDNA sequence analysis. Black precipitates (presumably the product of reduction of tellurite such as tellurium) occurred in cultures of all three strains after growth in medium containing tellurite. Quantitative determination of tellurite concentration in the liquid culture was carried out by using diethyldithiocarbamate (DDTC). The results showed that the concentration of tellurite was reduced from 100 μM to 50 μM in 20 hours in these cultures. Observation of cells of TeB, TeC and TeW grown in medium with and without tellurite by transmission electron microscopy and scanning electron microscopy were also performed in this study.

並列關鍵字

Heavy metal contamination ； Tellurite resistance ； Shewanella ； Paenibacillus ； Transmission electron microscopy ； Scanning electron microscope

參考文獻

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