Mehanizmi tolerancije slobodnoživećih bakterija i bakterija u biofilmovima na teške metale
Mechanisms of heavy metal tolerance in free living bacteria and bacterial biofilms
Author
Jeremić, Sanja R.Mentor
Nikodinović-Runić, Jasmina
Committee members
Jovčić, Branko
Vasiljević, Branka

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Show full item recordAbstract
Teški metali, čija se koncentracija u sredini sve više povećava kao rezultat povećane
industrijske aktivnosti i tehnološkog razvoja, ubrajaju se u najčešće zagađivače životne
sredine. Kada su prisutni u većim koncentracijama toksični su i predstavljaju ozbiljnu
pretnju kako za životnu sredinu tako i za zdravlje ljudi, jer se ne mogu razgraditi i jer se
nagomilavaju u lancima ishrane. Sa druge strane, ovakve sredine predstavljaju dobar izvor
mikroorganizama tolerantnih na teške metale, sa potencijalnom primenom u biološkom
uklanjanju (bioremedijaciji) i oslobađanju (bioluženju) teških metala. Cilj ovog rada je bila
izolacija, identifikacija, analiza diverziteta i aplikativnog potencijala novih bakterijskih
sojeva sa sposobnošću tolerancije visokih koncentracija teških metala iz površinskog i
podzemnog sedimenta iz rudnika bakra Bor. Metagenomskom analizom je detektovan veći
mikrobiološki diverzitet u uzorku površinskog sedimenta u poređenju sa podzemnim
sedimentom. Iz oba uzorka je izol...ovano 6 bakterija tolerantnih na visoke koncentracije
teških metala, primenom direktne kultivacije. Ovi izolati su taksonomski identifikovani
kao predstavnici rodova Arthrobacter i Staphylococcus. Pored ovih izolata, u ovu studiju je
bilo uključeno još 8 sojeva za koje je tolerancija na metale prethodno opisana u literaturi,
tako da je aplikativni potencijal slobodnoživećih bakterija i definisanih bakterijskih
zajednica, kao i njihovih biofilmova, ispitan kod ukupno 14 sojeva. Među 14 testiranih
sojeva, 6 sojeva je imalo sposobnost rasta u prisustvu nikla, 6 u prisustvu kadmijuma, 4 u
prisustvu bakra, 3 u prisustvu hroma i 1 je imao sposobnost rasta u prisustvu žive, dok
nijedan od sojeva nije imao sposobnost rasta u prisustvu gvožđa i cinka. Izdvojio se izolat
Staphylococcus sp. MSI08, koji je jedini imao sposobnost rasta u prisustvu tri teška metala
(nikl, kadmijum, hrom). Analizom genetičkih determinanti mehanizama tolerancije na
teške metale, kod 2 soja je detektovano prisustvo gena za determinantu tolerancije na
kadmijum, kod 2 soja prisustvo gena za determinantu tolerancije na hrom i kod 2 soja je
detektovano prisustvo gena za determinantu tolerancije na bakar. Svi testirani sojevi su
imali sposobnost formiranja biofilmova, s tim što su najveći potencijal za formiranje biofilmova pokazali Staphylococcus sp. MUI10, Arthrobacter sp. MSI31, Pseudomonas
aeruginosa PAO1 i Cupriavidus metallidurans CH34, dok su Staphylococcus sp. MSI08,
Rhodococcus sp. TN113, Pseudomonas putida KT2440 i Cupriavidus necator H16
pokazali nešto slabiji potencijal za formiranje biofilmova...
Heavy metals are one of the most common environmental pollutants due to increased
industrial activities and technological development. When present in excessive
concentrations, heavy metals are highly toxic and they pose a serious threat both to
environment and human health, due to their persistence in nature and accumulation in the
food chain. On the other hand, polluted sites have proven to be valuable sources of bacteria
capable to tolerate increased concentration of heavy metals that could be potentially applied
in biological removal (bioremediation) and release (bioleaching) of heavy metals. The aim
of this study was to obtain, identify, analyze diversity and application potential of novel
bacterial strains with the ability to tolerate high heavy metal concentrations from surface
and underground sediments from the copper mine Bor. Metagenomic analysis revealed a
higher microbial diversity in surface sediment compared to underground sediment. From
both sediments, 6 bacterial strain...s able to tolerate high heavy metal concentrations were
isolated using direct cultivation approach. These isolates were taxonomically identified as
members of Arthrobacter and Staphylococcus genus. In addition, this study involved 8
more strains with heavy metal tolerance previously described in the literature. Thus, 14
bacterial strains were included in analysis and evaluation of heavy metal tolerance and
application potential of free living bacteria and defined bacterial consortia, as well as their
biofilms. Among 14 tested strains, 6 strains had the ability to grow in the presence of
nickel, 6 in the presence of cadmium, 4 in the presence of copper, 3 in the presence of
chromium and 1 had the ability to grow in the presence of mercury, while none of the
strains had the ability to grow in the presence of iron and zinc. Staphylococcus sp. MSI08
singled out as the only strain with the ability to grow in the presence of three heavy metals
(nickel, cadmium, chromium). Analysis of genetic determinants conferring heavy metal
tolerance revealed presence of cadmium tolerance genes in 2 strains, chromium tolerance
genes in 2 strains, and copper tolerance genes were also detected in 2 strains. All strains
showed ability to form biofilms, but Staphylococcus sp. MUI10, Arthrobacter sp. MSI31,
Pseudomonas aeruginosa PAO1 and Cupriavidus metallidurans CH34 demonstrated the highest potential for the biofilm formation, while Staphylococcus sp. MSI08, Rhodococcus
sp. TN113, Pseudomonas putida KT2440 and Cupriavidus necator H16 were less
successful in biofilm formation...
Faculty:
Универзитет у Београду, Биолошки факултетDate:
27-09-2013Projects:
- Microbial diversity study and characterization of beneficial environmental microorganisms (RS-173048)