SEM Mucins (IMAGE) American Society for Microbiology Caption The viscoelastic properties of mucus and saliva are attributed to mucins, large glycoproteins that play a key role in host defense and maintaining a healthy microbiome. Human salivary mucins protect teeth from dental cavities, which are primarily caused by Streptococcus mutans colonization. Credit Photo by Nicole Kavanaugh. Usage Restrictions attribution License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.