"Environment" research area

Identifying the Best Genetic Sequences for Removing Nitrate

Primary Investigator - Jeffrey GralnickPrimary InvestigatorJeffrey Gralnick
Industry Partners: MPCA (additionally Barr Engineering, Geosyntech Consultants)
Award Type: Research Scholar - Postdoctoral Research Scholar

Problem: Fertilizer use in Minnesota’s agricultural industry has led to environmental nitrate contamination. High levels of nitrate cause methemoglobinemia (“blue baby syndrome”) and increase the risk of non-Hodgkin’s lymphoma. Nitrates from Minnesota also contribute to the “dead zone” in the Gulf of Mexico. To combat this, certain bacteria are used to break down nitrates into nitrogen-containing gases; however, these bacteria prefer to breathe oxygen instead of nitrate when oxygen is present. If bacteria breathe oxygen, they won’t remove nitrates, restricting the practicality of using bacteria to solve the problem.

Solution: Researchers in the Gralnick Lab will test a new genomic technology that may allow them to deregulate nitrate respiration in bacteria. This would allow bacteria to break down nitrate even while oxygen is present. The lab will use a method called 2D-TnSeq to identify sets of genetic mutations that improve denitrification rates. They will test 2D-TnSeq on Escherichia coli first as a proof-of-concept before targeting Shewanella species, an efficient denitrifying group of bacteria.

Impact: Shewanella species can efficiently convert nitrate to innocuous nitrogen gas in anaerobic environments. Genetic modification using 2D-TnSeq could make the denitrification process viable in aerobic environments as well. This would provide more opportunities for nitrate bioremediation using Shewanella species in the environment.