جداسازي و شناسايي Proteus sp.مقاوم به كادميوم و بررسي پتانسيل آن در حذف بيولوژيكي كادميوم

Isolation and Identification of Cadmium Resistant Proteus sp. and Its Potential in Cadmium Bio Removal

زﻣﯿﻨﻪ و ﻫﺪف: آﻟﻮدﮔﯽ اﮐﻮﺳﯿﺴﺘﻢﻫﺎ ﺑﺎ ﻓﻠﺰات ﺳﻨﮕﯿﻦ ﻣﺒﺤﺚ ﻣﻬﻤﯽ در دﻧﯿﺎي اﻣﺮوز اﺳﺖ. ﺣﺬف ﻓﻠﺰات ﺳﻨﮕﯿﻦ از ﻣﮑﺎنﻫﺎي آﻟﻮده ﺑﺎ اﺳﺘﻔﺎده از ﻣﯿﮑﺮوارﮔﺎﻧﯿﺴﻢﻫﺎ، در ﻣﻘﺎﯾﺴﻪ ﺑﺎ روشﻫﺎي ﺷﯿﻤﯿﺎﯾﯽ ﻣﻘﺮون ﺑﻪ ﺻﺮﻓﻪﺗﺮ اﺳﺖ. ﻫﺪف از اﯾﻦ ﻣﻄﺎﻟﻌﻪ ﺟﺪاﺳﺎزي و ﺷﻨﺎﺳﺎﯾﯽ ﺑﺎﮐﺘﺮيﻫﺎي ﻣﻘﺎوم ﺑﻪ ﮐﺎدﻣﯿﻮم، ﺗﻌﯿﯿﻦ ﮐﻢﺗﺮﯾﻦ ﻏﻠﻈﺖ ﻣﻬﺎري ﮐﺎدﻣﯿﻮم )MIC( و ﺑﺮرﺳﯽ ﺗﻮاﻧﺎﯾﯽ ﺣﺬف ﮐﺎدﻣﯿﻮم ﺗﻮﺳﻂ ﺳﻮﯾﻪﻫﺎ ﺑﻮد. روش ﺑﺮرﺳﯽ: ﺟﺪاﺳﺎزي ﺑﺎﮐﺘﺮيﻫﺎي ﻣﻘﺎوم ﺑﺎ روش ﻏﻨﯽﺳﺎزي در ﻣﺤﯿﻂ ﮐﺸﺖ ﺣﺎوي ﻓﻠﺰ ﮐﺎدﻣﯿﻮم ﺻﻮرت ﮔﺮﻓﺖ. MIC ﮐﺎدﻣﯿﻮم ﺑﺎ روش رﻗﯿﻖﺳﺎزي در آﮔﺎر و ﻣﯿﺰان ﺣﺬف ﮐﺎدﻣﯿﻮم ﺑﺎ اﺳﺘﻔﺎده از دﺳﺘﮕﺎه ﺟﺬب اﺗﻤﯽ ﺑﺮرﺳﯽ ﺷﺪ. ﺷﻨﺎﺳﺎﯾﯽ ﺑﺎ روش ﺑﺮﮔﯽ )Bergey( و ﻣﻄﺎﻟﻌﺎت ﻓﯿﻠﻮژﻧﺘﯿﮏ ﺑﺮ ﻣﺒﻨﺎي ﺗﻮاﻟﯽ ژن 16S rRNA اﻧﺠﺎم ﺷﺪ. ﯾﺎﻓﺘﻪﻫﺎ: در اﯾﻦ ﻣﻄﺎﻟﻌﻪ 40 ﺳﻮﯾﮥ ﻣﻘﺎوم ﺑﻪ ﮐﺎدﻣﯿﻮم از رودﺧﺎﻧﻪ ﺳﺎﻟﻮر در ﺷﻬﺮﺳﺘﺎن اﺳﻼﻣﺸﻬﺮ ﺟﺪا ﺷﺪﻧﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﺳﻮﯾﮥ ST1 ﮐﻪ از رﺳﻮﺑﺎت ﺟﺪا ﺷﺪه ﺑﻮد، ﻣﻘﺎوﻣﺖ ﺑﺎﻻﯾﯽ ﺑﻪ ﮐﺎدﻣﯿﻮم داﺷﺘﻪ و MIC ﮐﺎدﻣﯿﻮم ﺑﺮاي اﯾﻦ ﺳﻮﯾﻪ mM 6 ﺑﻮد. اﯾﻦ ﺳﻮﯾﻪ ﺗﻮاﻧﺎﯾﯽ ﺣﺬف 65/2 % ﮐﺎدﻣﯿﻮم را از ﻣﺤﻠﻮل mM 1 ﮐﺎدﻣﯿﻮم داﺷﺖ. ﻣﻄﺎﻟﻌﺎت ﻣﻮﻟﮑﻮﻟﯽ ﻧﺸﺎن داد ﮐﻪ ﺳﻮﯾﮥ ﺟﺪا ﺷﺪه ﺑﻪ ﺟﻨﺲ Proteus ﺗﻌﻠﻖ داﺷﺘﻪ و 99 % ﺑﺎ Proteus mirabilis ﻣﺸﺎﺑﻬﺖ دارد. ﺳﻮﯾﻪ ﺟﺪا ﺷﺪهProteus sp. HM_AF12 ﻧﺎﻣﯿﺪه ﺷﺪ و ﺗﻮاﻟﯽ ﻧﻮﮐﻠﺌﻮﺗﯿﺪي آن در GenBank ﺛﺒﺖ ﺷﺪ. اﯾﻦ ﺳﻮﯾﻪ ﺗﻮاﻧﺎﯾﯽ ﺗﺤﻤﻞ ﻣﺤﺪوده وﺳﯿﻌﯽ از pH )5/5-9( را داﺷﺘﻪ و در 7/5 % ﻧﻤﮏ ﻧﯿﺰ رﺷﺪ ﻣﯽﮐﺮد. ﻧﺘﯿﺠﻪﮔﯿﺮي: ﻧﺘﺎﯾﺞ ﻧﺸﺎن ﻣﯽدﻫﺪ ﮐﻪ Proteus sp. HM_AF12 ﻣﯽﺗﻮاﻧﺪ ﯾﮏ ﺟﺎذب زﯾﺴﺘﯽ ﮐﻢ ﻫﺰﯾﻨﻪ و دوﺳﺖدار ﻣﺤﯿﻂ زﯾﺴﺖ ﺑﺎﺷﺪ و كارﺑﺮدﻫﺎي ﻣﻬﻤﯽ در ﺣﺬف ﮐﺎدﻣﯿﻮم از ﻣﺤﯿﻂﻫﺎي آﻟﻮده داﺷﺘﻪ ﺑﺎﺷﺪ

Background: The contamination of ecosystems with heavy metals is an important issue in current world. Removal of heavy metals from contaminated sites using microorganisms is a cheaper alternative to chemical technologies. The aim of present study was isolation and characterization of Cadmium resistant bacteria, determination of Minimum Inhibitory Concentration (MIC) and bio removal potential of the isolates. Materials and Methods: Isolation of Cadmium resistant bacteria was carried out by enrichment method by medium supplemented with Cadmium chloride. The minimum inhibitory concentration of Cd2+ was determined by the agar plate dilution method and the Cadmium removal evaluated by atomic absorption spectroscopy. Identification was carried out in accordance with Bergey's Manual of Systematic Bacteriology and phylogenetic analysis was performed based on 16S rRNA gene sequences. Results: A total of 40 Cadmium resistant strains were isolated from Salour River in Islamshahr. The results showed that bacterial strain ST1 isolated from sediments was highly resistant to Cadmium. The MIC of Cd2+ for selected isolate was 6 mM. The isolate was able to remove 65.2% of Cadmium at Cadmium concentration of 1 mM. Phylogenetic analysis showed that ST1 belongs to the genus Proteus with 99% similarity to Proteus mirabilis then designated as Proteus sp. HM_AF12. The strain had a wide pH tolerance of 5.5–9.0, and salt tolerance was up to 7.5% NaCl. Conclusion: The results implied that Proteus sp. HM_AF12 can be a low cost and environmental friendly bio sorbent that may have important application in Cd2+removal from polluted environment.