Simple and Sensitive Detection of Bacterial Hydrogen Sulfide Production Using a Paper-Based Colorimetric Assay

Hydrogen sulfide (H(2)S) is known to participate in bacteria-induced inflammatory response in periodontal diseases. Therefore, it is necessary to quantify H(2)S produced by oral bacteria for diagnosis and treatment of oral diseases including halitosis and periodontal disease. In this study, we introduce a paper-based colorimetric assay for detecting bacterial H(2)S utilizing silver/Nafion/polyvinylpyrrolidone membrane and a 96-well microplate. This H(2)S-sensing paper showed a good sensitivity (8.27 blue channel intensity/μM H(2)S, R(2) = 0.9996), which was higher than that of lead acetate paper (6.05 blue channel intensity/μM H(2)S, R(2) = 0.9959). We analyzed the difference in H(2)S concentration released from four kinds of oral bacteria (Eikenella corrodens, Streptococcus sobrinus, Streptococcus mutans, and Lactobacillus casei). Finally, the H(2)S level in Eikenella corrodens while varying the concentration of cysteine and treatment time was quantified. This paper-based colorimetric assay can be utilized as a simple and effective tool for in vitro screening of H(2)S-producing ability of many bacteria as well as salivary H(2)S analysis.