- This protocol is optimized for measuring the levels of DSF
family signals in the cultures ofXccorXanthomonas oryzae
pv.oryzae(Xoo). It is also applicable for other bacterial species.
Please use the appropriate growth medium, antibiotics, and
growth conditions. - Acidification prior to the extraction is a critical step for DSF/
BDSF extraction in this protocol. Make sure that the culture
supernatant is acidified (pH lower than 4.0). - The methods described here are also applicable for detecting
DSF family signals in the reaction mixtures. The reaction mix-
ture should also be adjusted to a pH<4.0 by adding adequate
volume of 6 M hydrochloric acid. DSF family signals in the
reaction mixtures are then extracted and analyzed following the
protocol described in Subheadings3.3 and 3.4. - At this point, the samples can be frozen at 20 C or immedi-
ately analyzed, as described in the following steps.
Fig. 3Typical mass spectrum of CDSF. (a) Ion chromatograms of CDSF in the
culture supernatant ofΔrpfCstrain (20 times concentrated). (b) MS analysis
showing an exact molecular weight of 210.1547 Dalton for the detected CDSF
UPLC/MS Analysis for DSF-Family Signals 103