Research on the suitable sample processing conditions for establishing marine pathogenic vibrio database based on MALDI-TOF MS

Abstract

Objective To explore the suitable sample processing conditions of establishing marine pathogenic vibrio database based on matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Methods Thirty-two strains of marine pathogenic vibrio were cultured for 24 h, 48 h, 72 h, and then identified respectively by direct transfer method, extensional direct transfer method and formic acid extraction method. The results were statistically analyzed with SPSS20.0 statistical analysis software to find the suitable conditions for establishing MALDI-TOF MS marine pathogenic vibrio database. Results The average value of 24 h culture identification score was 2.321 with the accuracy rate of genus identification was 96.88% and species identification was 90.63%. The average value of 48 h identification score was 2.315 with the accuracy rate of genus identification was 93.75% and the species identification was 90.63%. The average value of 72 h culture identification score was 2.316 with the accuracy rate of genus identification was 93.75% and the species identification was 87.50%. There was no statistical difference among these three pretreatment methods (P=0.129、P=0.078). In contrast, the average value of identification score by direct transfer method was 1.986, with the accuracy rate of genus identification was 78.13%, and the species identification was 59.38%; the average value of the extended direct transfer method was 2.135 with the accuracy rate of genus identification was 90.63% and the species identification was 78.13%; the average value of formic acid extraction was 2.306 with the accuracy rate of genus identification was 96.88% and species identification was 90.63%. There were significant differences among the three kinds of pretreatment methods on genus level (P=0.006) and species level(χ2=8.691, P=0.013). Conclusions In the establishment of MALDI-TOF MS marine pathogenic vibrio database, the culture time should be set at 24h and the pretreatment method should be formic acid extraction method, which can get high quality protein fingerprints. Key words: Marine, Vibrio; Matrix-assisted laser desorption/ionization time of flight mass spectrometry; Bacteria database