Vloga mikroorganizmov pri redukciji šestvalentnega kroma

Plestenjak, Eva (author), Mandić Mulec, Ines (mentor), Ščančar, Janez (comentor)

V magistrskem delu smo preučevali sposobnost mikroorganizmov, da rastejo pri povišanih koncentracijah šestvalentnega kroma (Cr(VI)) ter možnosti redukcije le-tega v bistveno manj strupene zvrsti trivalentnega kroma (Cr(III)). Za preverjanje hipoteze o boljši učinkovitosti redukcije Cr(VI) z živimi mikroorganizmi v vzorcu v primerjavi z redukcijo z organsko snovjo v sterilnem vzorcu, smo iz vzorca odpadne vode, odvzete iz odlagališča usnjarskih odpadkov, izolirali in obogatili mikroorganizme, ki so bili sposobni rasti pri koncentraciji 600 mg/L Cr(VI). Preverili smo, katere koncentracije Cr(VI) zavirajo rast mikroorganizmov, ter preučili sposobnost bakterij za redukcijo različnih koncentracij Cr(VI) po 24, oziroma 48 urah. Cr(VI) v vzorcih smo določili s spektrofotometrijo in s tekočinsko kromatografijo v povezavi z masno spektrometrijo z induktivno sklopljeno plazmo (HPLC-ICP-MS). Rezultati raziskave potrjujejo hipotezo, da je redukcija Cr(VI) z mikroorganizmi bistveno bolj učinkovita kot z organsko snovjo. Po 48 urni inkubaciji organska snov reducira zanemarljiv delež Cr(VI), in to le pri nizkih koncentracijah Cr(VI) v gojišču (5 mg/L ). Obogatena mikrobna združba je v 48 urah skoraj v celoti reducirala večje množine Cr(VI) (5 in 25 mg/L) in več kot 50 % Cr(VI) s koncentracijo do 100 mg/L. Tako visoke koncentracije Cr(VI) se v okolju lahko pojavijo le ob ekoloških nesrečah ali izlitjih. Obogateno mikrobno združbo bi lahko uporabili za redukcijo Cr(VI) v močno onesnaženih vzorcih odpadnih vod.

• Language: Slovenian
• Keywords: mikrobne združbe, redukcija kroma, odpornost bakterij, šestvalentni krom, onesnaževanje voda s kromom, spektrofotometrične metode, FAAS, HPLC-ICP-MS
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [E. Plestenjak]
• Year: 2019
• PID: 20.500.12556/RUL-111516
• UDC: 579.26:546.776:543.42
• COBISS.SI-ID: 5105784
• Publication date in RUL: 02.10.2019

PLESTENJAK, Eva, 2019, Vloga mikroorganizmov pri redukciji šestvalentnega kroma [online]. Master’s thesis. E. Plestenjak. [Accessed 15 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=111516

Secondary language

• Language: English
• Title: The role of microorganisms in the reduction of hexavalent chromium

Abstract

In the Master Thesis, we studied the ability of microorganisms to grow at elevated concentrations of hexavalent chromium (Cr(VI)) and the possibility of its reduction to far less toxic forms of trivalent chromium (Cr(III)). In order to verify the hypothesis that the reduction of Cr(VI) with living microorganisms in the sample is more effective than those with the organic matter in the sterile sample, microorganisms in samples from the wastewater collected from the tanerry waste landfill, were isolated and enriched, to be capable of growth at a concentration of 600 mg/L Cr(VI). We tested which concentrations of Cr(VI) inhibited the growth of microorganisms and examined the ability of bacteria to reduce different amounts of Cr(VI) at 24 and 48 hours. Cr(VI) concentration in samples was determined by the spectrophotometry and liquid chromatography in hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The results of present investigation confirmed the hypothesis that the reduction of Cr(VI) with microorganisms is significantly more effective than with the organic matter. After 48 hours of incubation, the organic matter reduces negligible amounts of Cr(VI), only at low Cr(VI) concentrations in the medium (5 mg/L). The enriched microbial association almost completely reduced the large amounts of Cr(VI) (5 and 25 mg/L) and more than 50 % Cr(VI) at concentrations up to 100 mg/L in 48 hours. Such high Cr(VI) concentrations may occur in the environment only in the event of ecological disasters or spills. The enriched microbial associations could be applied for remediation of highly polluted wastewaters with Cr(VI).

• Keywords: microbial communities, chromium reduction, bacterial resistance, hexavalent chromium, water pollution by chromium, spectrophotometric methods, FAAS, HPLC-ICP-MS