Update(MM/DD/YYYY):12/04/2019
Diverse Types of Microorganisms Work Together to Stably Degrade 1,4-dioxane, a Recalcitrant Pollutant in Industrial Wastewater
– The roles of unknown microorganisms in the natural environment identified by using a new high-sensitivity stable isotope tracing technique –
Researchers: HORI Tomoyuki, Senior Researcher, and AOYAGI Tomo, Researcher, Environmental Microbiology Research Group, Environmental Management Research Institute, KIKUCHI Yoshitomo, Senior Researcher, Environmental Biofunction Research Group, Bioproduction Research Institute, and MATUMI Daisuke, Senior Researcher, Geomicrobiology Research Group, Research Institute for Geo-Resources and Environment
Summary
Using an AIST-developed, high-sensitivity stable isotope tracing technique with a detection sensitivity 500-fold higher than that of the conventional method, the researchers discovered many microorganisms that degrade 1,4-dioxane, a persistent artificial pollutant, in petrochemical industrial wastewater, and showed that these bacteria work together to maintain the stable degradation of 1,4-dioxane.
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Application of the high-sensitivity stable isotope tracing technique to the biological treatment of petrochemical industrial wastewater |
Background
1,4-dioxane is generated as a byproduct during the manufacture of petrochemical products and has been commonly used as a stabilizer for chlorinated solvents. It is a persistent artificial pollutant that is globally regulated because it is a potential human carcinogen. There is growing interest in low-cost, low-environmental-load biological treatments for 1,4-dioxane. So far, 1,4-dioxane degrading bacteria have been studied only using the culture-dependent method, which is time-consuming and laborious. Consequently, only several 1,4-dioxane-degrading bacteria have been identified.
New findings
Using the AIST-developed, culture-independent method, high-sensitivity stable isotope tracing technique with a detection sensitivity 500-fold higher than that of the conventional method, the researchers added 13C-labelled 1,4-dioxane, which was synthesized with a stable natural isotope of carbon, 13C, to activated sludge and incubated the sample for 8 hours. The concentration of 13C-labelled 1,4-dioxane decreased and 13CO2 was produced. After extracting the RNA of the microorganisms in the incubated sludge, the researchers performed high-speed ultracentrifugation of the tube containing the RNA sample and discovered different types of 1,4-dioxane-degrading bacteria from a biological treatment tank for petrochemical industrial wastewater. They found that these bacteria work together to stably remove 1,4-dioxane.
Future plans
The researchers will determine the characteristics of the discovered 1,4-dioxane-degrading bacteria from information on the relatives of the bacteria and optimize the einvironmental conditions needed to promote the growth of the bacteria in biological treatment tanks containing petrochemical industrial wastewater, with the aim of developing a control method for maintaining and maximizing their degradation activity.