Biosensors — In bioelectronic sensor design, which biological recognition elements are commonly coupled to electronic circuits to detect analytes?

Introduction / Context:
Biosensors integrate a biological recognition element with a physicochemical transducer to generate measurable electronic signals. In industrial microbiology and environmental monitoring, both whole cells and purified enzymes are widely used as the biorecognition component.

Given Data / Assumptions:

• Whole-cell biosensors exploit cellular metabolism or regulatory circuits.
• Enzyme-based biosensors rely on specific catalytic reactions to detect substrates or products.
• Transducers (electrochemical, optical, piezoelectric) convert biological events into signals.

Concept / Approach:
Because both microorganisms and their enzymes can be immobilized on electrodes or membranes and interfaced with electronics, the best answer includes both. Examples range from glucose oxidase electrodes to microbial BOD sensors and bioluminescent reporter strains.

Step-by-Step Solution:

Verification / Alternative check:
Commercial and research biosensors use oxidoreductases, hydrolases, and living cells for diverse targets (glucose, lactate, pollutants).

Why Other Options Are Wrong:

• Microorganisms only or enzymes only: each is too restrictive.
• Neither: contradicts extensive biosensor literature and products.

Common Pitfalls:
Assuming only enzymes are used because they are simpler; whole-cell systems provide broader, pathway-level detection.

Final Answer:
Either microorganisms or microbially derived enzymes