Creating a halotolerant degrader for efficient mineralization of
p-nitrophenol substituted organophosphorus pesticides in high saline
wastewater
Abstract
The bioaugmentation performance is severely reduced in the treatment of
high saline pesticide wastewater because the growth and degradation
activity of pesticide degraders are significantly inhibited by high salt
concentrations. In this study, an artificial halotolerant degrader
J9U-MP capable of mineralizing p-nitrophenol (PNP) substituted
organophosphorus pesticides (OPs) [e.g., methyl parathion (MP)] was
created by integrating a MP-mineralizing pathway into the genome of a
salt-tolerant chassis Halomonas cupida J9. MP degradation coupled
with stable isotope analysis indicated that J9U-MP was able to
metabolize MP as a sole carbon source to finally produce CO
2 and H 2O in high-salt media (up to 120
g/L NaCl). J9U-MP was genetically stable during passage culture and
exogenous gene integration did not negatively influence growth and
metabolism of J9U-MP. A real-time monitoring system was established with
enhanced green fluorescent protein (EGFP) to track the movement and
activity of J9U-MP in environmental remediation. A low-oxygen tolerant
system was developed by enhancing oxygen utilization, which makes J9U-MP
maintain the MP-mineralizing activity under oxygen-limited conditions.
More importantly, efficient mineralization of MP by J9U-MP in high
saline wastewater was demonstrated. This study highlights that synthetic
biology has opened up new avenues for creating stress-resistant
pollutants-mineralizing microbes. Competitive advantages of J9U-MP in
high-salinity and low-oxygen environments make this degrader suitable
for bioaugmentation of pesticide wastewater.