假單胞菌屬菌株EJ01胞外多醣體形成與移除重金屬能力之探討

Extracellular polysaccharide (EPS) production and heavy metal removal by Pseudomonas sp. strain EJ01

吳俊賢(Chun-Hsien Wu)

指導教授 ： 簡志青

元智大學/工程學院/生物科技與工程研究所/碩士(2012年)

https://doi.org/10.6838/YZU.2012.00365

摘要

本研究主要針對從台南縣二仁溪地區長期受汙染的土讓樣本，分離篩選出能抵抗重金屬的為生物並研究其機制。本實驗室在先前的研究中，針對重金屬鎘耐受性高的為生物進行篩選與純化培養，其中一株為Pseudomonas sp. strain EJ01。先前隻研究亦藉由轉位子突變法的方式針對EJ01形成生物膜之相關基因進行突變，篩選出突變菌株m-3055。本研究即是針對原生菌株EJ01與突變菌株m-3055進一步的探討與比較，研究內容主要為其對於重金屬耐受性，生物膜生產能力、胞外多醣體extracellular polysaccharide (EPS)產生能力、重金屬吸附能力等分析探討。
在重金屬耐受性試驗中，我們評估菌株Strain EJ01在培養基(LB broth)中添加各種不同種類與濃度重金屬離子環境下的生長情形，並檢視其產生EPS與吸附溶液中的重金屬離子的特性。結果顯示在含有3 mM的鎘、鎳離子環境下，Strain EJ01的EPS的生產量在不含重金屬環境下的3倍，可以推論菌株在逆境下生存可生產較多之EPS。同時透過生長曲線及電漿原子發射光譜儀(ICP) 對EJ01吸附/移除重金屬離子的情形做探討，菌株在生長飽和後培養基內的重金屬離子降低約50%。
突變株在生物膜形成的能力也明顯的較菌株EJ01下降，而其對重金屬離子的耐受性相對於菌株EJ01也較差，但在合成EPS能力卻無顯著差異。然而ICP的檢測結果卻發現到突變株產生的EPS無法有效的
吸附重金屬離子。此結果建議Pseudomonas sp. strain EJ01抗重金屬離子能力與生物膜的形成有其相關性。突變株m-3055被轉位子所影響之基因為與鞭毛合成相關之基因，也指出除了EPS吸附重金屬外，其他影響生物膜形成的因素也可能與此菌株對重金屬離子耐受能力有關。

關鍵字

重金屬 ； 假單胞菌屬 ； 胞外多醣體 ； 生物膜

並列摘要

The aim of this research was isolation and characterization of heavy metal resistance microorganisms from Er-Jen River, a heavily contaminated river, and to study the possible mechanisms of heavy metal resistance. We have isolated a heavy metal resistance Pseudomonas sp. (designated as strain EJ01) and demonstrated that this bacterium was able to tolerate high concentrations of cadmium ion (Cd2+). Transposon mutagenesis was employed for generate mutants to study the relationship between biofilm formation and the bacterium’s resistant to heavy metals. Mutant stain m-3055 was obtained as a biofilm mutant and was used to study its traits of heavy metal resistance, EPS production as well as biofilm formation.
The production of EPS by Pseudomonas sp. EJ01 grown in the medium containing different concentrations of heavy metal was examined. The results showed that there was more EPS produced when the cells grown in the medium containing 3 mM Cd2+ or Ni2+, when compared to those grown on the medium without heavy metals. Cadmium ion in the medium was reduced about 50% of the initial concentration after the growth of strain EJ01 as measured by Plasma atomic emission spectrometer (ICP).
The ability of biofilm formation and heavy metal resistance was significantly reduced in mutant strain m-3055 compared to strain EJ01. However, there was no significantly difference of the amount of EPS production between strains m-3055 and EJ01. The results suggested that heavy metal resistance in EJ01 may not only associated with its EPS production, but also related to biofilm formation and other physiological traits and remained to be studied.

並列關鍵字

Heavy metal ； Pseudomonas ； Extracellular polysaccharide

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