Biochemical oxygen demand sensor using Serratia marcescens LSY 4.

Area of Science:

• Environmental Science
• Biosensor Technology
• Microbiology

Background:

• Accurate estimation of biochemical oxygen demand (BOD) is crucial for water quality assessment.
• Existing BOD biosensors can be susceptible to interference from heavy metal ions.
• Serratia marcescens LSY 4 was identified as a suitable microorganism for BOD sensing.

Purpose of the Study:

• To develop and optimize a microbial biosensor for BOD estimation.
• To investigate and mitigate the interference of heavy metal ions on biosensor performance.
• To enhance the robustness and reliability of BOD biosensors in environmental monitoring.

Main Methods:

• Construction of a BOD biosensor using Serratia marcescens LSY 4 and an oxygen electrode.
• Investigation of sensor response across a pH range (6.0-8.0) in unbuffered solutions.
• Application of graft polymerization with sodium styrene sulfonate to modify the sensor membrane.
• Induction of Zn2+ tolerance in Serratia marcescens LSY 4 cells.

Main Results:

• The BOD sensor exhibited stable performance insensitive to pH variations (6.0-8.0) and minimal baseline drift.
• Heavy metal ions (Cu2+, Ag+, Cd2+, Zn2+) significantly decreased sensor response in unbuffered solutions.
• Membrane modification and Zn2+ tolerance induction reduced the inhibitory effects of Zn2+ and Cd2+.
• These modifications did not protect the sensor from interference by Cu2+ and Ag+.

Conclusions:

• The developed microbial BOD biosensor shows promise for water quality monitoring.
• Strategies for mitigating heavy metal interference, such as membrane modification and induced microbial tolerance, offer partial protection.
• Further research is needed to address interference from ions like copper and silver for broader applicability.