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Bakterijska rezistenca na povečane vsebnosti potencialno toksičnih kovin v tleh
Matijašić, Kristina (Author), Suhadolc, Marjetka (Mentor) More about this mentor... This link opens in a new window

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Abstract
Potencialno toksične kovine (PTK), ki se kopičijo v tleh, predstavljajo grožnjo organizmom, vključno s človekom. Problem povečanih vsebnosti PTK je, da se za razliko od nekaterih ostalih onesnažil ne razgradijo in zato v okolju ostajajo. Pri presojanju njihove škodljivosti za organizme je bolj kot skupna vsebnost pomembna njihova biodostopnost. Biodostopnost v tleh je odvisna od razporejanja kovin med trdno in tekočo fazo, kar pa določajo interakcije med kovinami in trdnim delom talnega matriksa. Na omenjene interakcije vplivajo fizikalno-kemijske lastnosti tal in biološki procesi, preko katerih onesnaževalec vstopi v celico. Nekatere bakterije so se na onesnaženo okolje prilagodile tako, da lahko s pomočjo specifičnih encimov PTK pretvorijo v manj toksične ali neškodljive oblike, ali zmanjšajo njihovo (bio)dostopnost. To storijo s pomočjo različnih mehanizmov rezistence, ki so zapisani na rezistenčnih genih na kromosomu, plazmidih ali transpozonih. Med najbolj raziskanimi mehanizmi so: zmanjšan privzem iz okolja, povečano izločanje z izlivnimi črpalkami, zunajcelična zaplemba, znotrajcelična zaplemba ter kemijska modifikacija PTK. Znano je, da onesnaženje s PTK lahko izzove ko-selekcijski proces, tako da pride do selekcije bakterij, ki izkazujejo tako rezistenco na PTK kot tudi na antibiotike. Lastnost bakterij, da so zmožne rasti v okolju s povečanimi vsebnostmi PTK, omogoča njihovo uporabo v okoljski biotehnologiji, za bioremediacijo tal. Zaenkrat so ta potencial pokazali le v laboratorijskih razmerah. Za spodbujanje fitoremediacije so uporabne predvsem na PTK rezistentne PGPB (angl. Plant growth promoting bacteria), med katerimi najdemo endofitske bakterije in rizobakterije. Delo vsebuje pregled literature na temo bakterijske rezistence na povečane vsebnosti PTK v tleh in njihovo potencialno uporabo v biotehnologiji.

Language:Slovenian
Keywords:potencialno toksične kovine, rezistenca, biodostopnost, bakterije, tla, bioremediacija
Work type:Bachelor thesis/paper (mb11)
Tipology:2.11 - Undergraduate Thesis
Organization:BF - Biotechnical Faculty
Year:2019
Publisher:[K. Matijašić]
UDC:631.453:546.48/.49:546.19:546.815:631.461(043.2)
COBISS.SI-ID:9370745 Link is opened in a new window
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Downloads:21
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Secondary language

Language:English
Title:Bacterial resistance to higher contents of potentially toxic metals in soil
Abstract:
Potentially toxic metals (PTM) that are accumulating in soil represent a threat to organisms, including human. The problem of increased contents of PTM in soil is that they do not degrade, hence they resist in the environment in contrast to some other contaminants. When estimating their harmfulness toward organisms, their bioavailability is more important than their total content. Bioavailability is dependent on the arrangement of metals between solid and liquid soil fraction, that is defined by the interactions between metals and the solid part of a soil matrix. These interactions depend on the physico-chemical characteristics of the soil and biological processes included in transport of PTM into the cell. Some bacteria have adapted to the contaminated environment, so that they can convert PTM to less toxic forms or change their bioavailability. They do that using different mechanisms of resistance that are encoded on resistance genes on chromosome, plasmids or transposons. Among most studied mechanism are: reduced uptake from the environment, increased secretion by the efflux pumps, extracellular sequestration, intracellular sequestration and chemical modification of PTM. It is well known that contamination with PTM can provoke so called co-selection process, leading to the selection of bacteria that exhibit resistance to PTM as well as to antibiotics. The trait of bacteria to be able to live in the environment with increased PTM contents could be used in environmental biotechnology, for bioremediation. For now researchers have only shown this potential under laboratory conditions. For the promotion of phytoremediation are especially useful PTM resistant plant growth promoting bacteria (PGPB), among which are found endophytic bacteria and rhyzobacteria. This work includes an literature overview of bacterial resistance to increased PTM contents in soil and their potential use in biotechnology.

Keywords:potentially toxic metals, resistance, bioavailability, bacteria, soil, bioremedation

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