IMC captures heat flow in the microwatt (μW) range and enables detection of the metabolic heat evolved from ca. 10 000 mammalian cells or ca. 100 000 bacteria (Braissant et al., 2010). Thus, IMC has the potential to provide real-time quantitative data on metabolic activity, aggregation, and biomass formation in biofilms in situ. The sensitivity of IMC has been exploited in evaluating Small molecule library metabolism and growth of living cells in culture in medical and environmental microbiology (Howell et al., 2012). While IMC

has been applied to study the co-aggregation of different strains of biofilm-forming bacteria (Postollec et al., 2003), studies that focus on the use of this technique for investigating in vitro multispecies biofilms are scarce. The purpose of this study was to characterize a peri-implantitis-related biofilm by well-established commonly used microscopic methods and to complement this information using IMC to determine various measures ICG-001 in vitro of the metabolic activity. A three-species biofilm was allowed to form on surfaces of protein-coated titanium disks in a newly developed anaerobic flow chamber system. The selected bacterial species were an early colonizer, Streptococcus sanguinis; a pathogenic bridging organism, Fusobacterium nucleatum; and a common periodontal and peri-implant pathogen, Porphyromonas gingivalis (Quirynen et al.,

OSBPL9 2006; Fürst et al., 2007; Heuer et al., 2007). Streptococcus sanguinis (DSM 20068), F. nucleatum (ATCC 10953), and P. gingivalis (DSM 20709) were used for the biofilm formation. A 10 μL inoculum of S. sanguinis in skim milk solution (stored at −20 °C) was suspended in 5 mL Schaedler broth (BBL™; Becton Dickinson, Basel, Switzerland) and incubated aerobically at 37 °C for 8 h. The bacterial suspension was used

as an inoculum for a new subculture (1 : 50), which was incubated aerobically at 37 °C for 16 h. The culture was ultrasonicated for 30 s (22.5 W; Vibracell, Sonics & Materials, Newtown, CT), centrifuged at 5700 g for 5 min at room temperature, washed with physiological saline, and harvested by centrifugation. The S. sanguinis cells were resuspended in simulated body fluid (Cho et al., 1995) to a density of 1.1 × 108 ± 6.2 × 107 CFU mL−1. Fusobacterium nucleatum and P. gingivalis were maintained in Microbank® blue vials (Chemie Brunschwig AG, Basel, Switzerland) at −70 °C. One pearl of each frozen culture was inoculated into 10 mL thioglucolate aliquots (Biomerieux SA, Geneva, Switzerland), enriched with 5 μg mL−1 hemin (Fluka, Buchs, Switzerland) and 0.5 μg mL−1 menadione (VWR International, Dietikon, Switzerland), and incubated anaerobically at 37 °C for 96 h. The cultures were harvested; F. nucleatum and P. gingivalis were suspended to a density of 3.2 × 107 ± 1.9 × 106 CFU mL−1 and 2.1 × 109 ± 9.3 × 108 CFUmL−1, respectively.