Investigating the Impact of Serum on the Growth of TM7x and Host XH001

Abstract

Nanosynbacter lyticus strain TM7x is an ultra-small, parasitic bacterium that lives on the surface of host, Actinomyces odontolyticus strain XH001. Studies have reported a considerable increase in TM7x abundance in patients with periodontal disease, and this association warrants further investigation. Interestingly, gingival crevicular fluid (GCF) flow also increases during periodontitis. The prevalence of TM7x during periodontal disease may thus result from attraction to GCF. However, GCF is not commercially available for testing. Since its composition is similar to that of fetal bovine serum (FBS), FBS was tested instead. The objectives of this project are to determine whether FBS promotes the growth of TM7x and XH001 and to develop the optimal culture medium for analysis of these microbes. TM7x/XH001 co-culture and XH001 monoculture were separately cultivated in media (RPMI and FMC) supplemented with FBS. Cultures grown in the same, non-supplemented media served as control samples. Serial dilutions were performed and spotted onto plates at several time points, and samples were quantified in colony-forming units (CFU)/mL. 2% FBS FMC induced a significant increase in the growth of culture samples, as compared to control FMC (p = 0.0140 and p = 0.0424 for the co-culture and monoculture, respectively). Furthermore, microscopy revealed a heightened presence of TM7x in FBS-supplemented media in comparison to control media. These findings signify that FBS is an effective supplement to RPMI and FMC, both of which support TM7x/XH001 growth. Overall, the utilization of these media with FBS can ensure optimal cultivation of TM7x for investigation of its potential pathogenicity.