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. 2019 Aug 5;7(8):239. doi: 10.3390/microorganisms7080239

Figure 2.

Figure 2

The detection of malodors. A GT-92L colorimetric tube was used for the detection of malodors produced by sodium l-lactate (SL) fermentation of S. epidermidis (B). (A) A device with a GT-92L tube (b) connected with a syringe (c) was inserted to a sample tube (a) containing 200 μL 97% diacetyl. Evaporated diacetyl was detected when chemical reagents in the GT-92L tube turned purple (arrow). (B) The devices were inserted into four samples tubes containing TSB media (M) only, media with bacteria (M+B), media with sodium l-lactate (M+SL) and media with bacteria and sodium l-lactate (M+B+SL). No phenol red was added into the media. The zoomed panels (B1–B4) from four tubes indicated that, 5 min after device insertion, evaporated malodors (purple) were abundantly detected in a sample tube containing media with bacteria and sodium l-lactate. The representative data was taken from three independent experiments. (C) The levels of malodors in each sample tube were quantified and expressed as the fold difference relative to the level of malodor in sample tube B1. Results were shown as mean ± SD of three independent experiments. * p < 0.05 (two-tailed t-test).