BIOREMOVAL OF CHROMATES BY STRICT ANAEROBE CLOSTRIDIUM BUTYRICUM GMP1 DURING ANAEROBIC DESTRUCTION OF STARCH-CONTAINING SUBSTRATE
Bida I.1 Havryliuk O.2 Hovorukha V.2 Tashyrev O.2 Yastremska L.1
1National Aviation University,
Faculty of environmental safety, engineering and technology,
2D.K. Zabolotny Institute of Microbiology and Virology of the NAS of Ukraine,
Department of extremophilic microorganism’s biology
е-mail: irabida19@gmail.com
Chromium is one of the most hazardous contaminants. Chromium compounds (Cr2O72- and CrO42-) possess extremely toxic properties against living organisms. Physical-chemical methods of Cr(VI) compounds removal are economically costly. Biotechnological techniques based on application of chromium-resistant microorganisms (bacteria, fungi, and actinomycetes) are alternative methods to remove chromium ions from contaminated sites. Simultaneously, the accumulation of rotting household organic waste on landfills is a serious problem is that requires an immediate solution.
In this regard, the aim of the work was to investigate the patterns of microbial removal of toxic Cr(VI) compounds via anaerobic fermentation of starch-containing substrate.
Thermodynamic prediction was used to substantiate the optimal pathways of interaction of Clostridium butyricum GMP1 with Cr(VI) and its bioremoval. Cultivation of microorganisms was conducted in Nutrient Broth (Mumbai, India), 9 days at a temperature of 30°C. Ground sterile potatoes were used as model substrate of household organic waste. Solutions of Cr(VI) with a concentration of 50 and 100 ppm were added after 19 hours of cultivation. The effect of chromium compounds on the metabolic activity of microorganisms was determined after the addition of 50 and 100 ppm Cr(VI). The concentration of Cr(VI) was determined spectrophotometrically by the reaction with 1.5-Diphenylcarbazide.
According to thermodynamic prognosis, strict anaerobic microorganisms are able to remove toxic Cr(VI) by accumulation in biomass and reduction to insoluble and non-toxic Cr(OH)3. The high efficiency of Cr(VI) bioremoval from liquid nutrient medium was shown by Clostridium butyricum GMP1. The efficiency of removal of Cr(VI) was 99.6% during 4 hours at the 50 ppm Cr(VI). An increase in Cr(VI) concentration to 100 ppm inhibited the metabolic activity of microorganisms. Under such conditions, the duration of removal 2.5 times increased up to 10 hours, and the efficiency of removal was also high – 99.5%. The concentration of H2 decreased by 8% and 10% compared to the control at the presence of 50 ppm and 100 ppm Cr(VI), respectively.
Thus, the high efficiency of toxic chromium bioremoval by the strain of strict anaerobic microorganisms Clostridium butyricum GMP1 during the fermentation of potatoes was experimentally confirmed. The obtained results are promising for the development of environmental biotechnologies for chromate-containing wastewater purification and treatment of household organic waste.