Hop 22 29 ene

Extracellular metabolite concentrations were analyzed by high-performance liquid chromatography (86 (link)). Extraction and quantification of fatty acids, sterols, and tetrahymanol by GC-FID was performed as previously described (20 (link), 36 (link)). A 6-point calibration of the GC-FID system with hop-22(29)-ene (Sigma-Aldrich, 0.1 mg ⋅ mL⁻¹ in isooctane) was used for quantification of hop-22(29)-ene and other detected hopanoid compounds. Detailed methods for detection and identification of hopanoid compounds by GC-MS are described in SI Appendix. Optical density was measured at 600 nm for anaerobic cultures with an Ultrospec 10 cell density meter (Biochrom, Harvard Biosience) placed in the anaerobic chamber. For aerobic cultures, optical density at 660 nm was measured on a Jenway 7200 spectrophotometer (Bibby Scientific).