6890 series gc system

Floral volatiles were collected in the field at 14:00 using dynamic headspace adsorption methods in the SL population in 2011. Volatiles of the aphids were collected from aphids found on the inflorescences. We placed 20 wingless aphids (1–2 mm in length but representing mixed-growth instars) in a clean glass vial containing 1 ml of pentane for 120 seconds. The volatiles were analyzed on a Hewlett-Packard 6890 Series GC System coupled to a Hewlett-Packard 5973 Mass Selective Detector using an Agilent 7683 Series Automatic Liquid Sampler [32 (link)]. (See Supporting Information for details of collection and analyses)

The respiratory quinone and polar lipids were extracted and analyzed from freeze-dried cells following the method as presented previously^{44 (link),45 (link)}. The TLC chromatograms of polar lipids were sprayed with appropriate detection reagents for visualization of various spots as described previously^{9 (link),45 (link),46 (link)}. The cellular fatty acids of strains Kopri-42^T, Kopri-43, and reference strains were extracted after late log phase grown at 10 °C on R2A using the standard MIDI protocol (Sherlock Microbial Identification System, version 6.0B) and analyzed with a gas chromatograph (6890 Series GC System; Hewlett Packard) using the TSBA6 database of the Microbial Identification System⁴⁷ .

During the last week of each phase (18 wk for phase 1 and 32 wk for phase 2), odor emission was measured using the modified flux chamber method (Eklund, 1992 ). In brief, freshly voided excreta samples weighing approximately 150 g were placed in a 6 L plastic box. To make a concentration equilibrium of odor substances, 1 L/min of N gas (99.99%) was injected into the plastic box for 10 min. The emitted odor was measured using a Gastec detector (GV-100S, Gastec Co., Kanagawa, Japan) equipped with gas detector tubes for carbon dioxide, ammonia, hydrogen sulfide, and trimethylamine.
The concentrations of volatile fatty acids (VFA) were measured with freshly voided fecal droppings. At the end of the experiment, 1 g of fresh excreta samples was added to 9 mL of distilled water and mixed using a vortex mixer. The mixture was added with 0.05 mL of saturated HgCl₂, 1 mL of 25% H₃PO₄, and 0.2 mL of 2% pivalic acid, and centrifuged (20 min, 1,000 × g, and 4°C). Then, the 1 mL of supernatant was used to measure the concentrations of VFA in excreta samples by the gas chromatography (6890 Series GC System, Hewlett Packard, Palo Alto, CA) as described by Lee et al. (2022) (link).