Biosynthesis of CdS nanoparticles: A fluorescent sensor for sulfate-reducing bacteria detection

• CdS nanoparticles were microbially synthesized intracellularly and extracellularly.
• The microbial synthesized CdS nanoparticles were applied for SRB detection.
• The proposed SRB detection method could shorten detection time greatly.

CdS nanoparticles were synthesized with an environmentally friendly method by taking advantage of the characteristic metabolic process of sulfate-reducing bacteria (SRB), and used as fluorescence labels for SRB detection. The presence of CdS nanoparticles was observed within and immediately surrounded bacterial cells, indicating CdS nanoparticles were synthesized both intracellularly and extracellularly. Moreover, fluorescent properties of microbial synthesized CdS nanoparticles were evaluated for SRB detection, and a linear relationship between fluorescence intensity and the logarithm of bacterial concentration was obtained in the range of from 1.0×102 to 1.0×107 cfu mL−1. The proposed SRB detection method avoided the use of biological bio-recognition elements which are easy to lose their specific recognizing abilities, and the bacterial detection time was greatly shortened compared with the widely used MPN method which would take up to 15 days to accomplish the detection process.

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