The Heterogeneity Research Of Meacurement Condition For Fatty Acid Biomarker Of Bacillus

39of Bacillus type strains, which were bought from GSMZ of Germany, were activated to enlargecultures by the method of vacuum freeze-drying preservation after propagated. The preservation of thestrains were done with activity detection at the regular intervals. The result proved that activity of thestrains could calculate up to109orders of magnitude without bacterial contamination by the colonialmorphology identification. The method of vacuum freeze-drying preservation was a good way forpreservation of the strains.MIDI system of PLFAs were verified to confirm repeatability and accuracy by detection of Bacillussphaericus and Bacillus thuringiensis. Eight replicates of each strains for all the tested species wereconducted to identify species accurately and the difference of similarity coefficient was less than0.1. Atthe same time the factors which affecting extraction of fatty acid from the strains were studied. Theresult showed that there have little influence in the result of MIDI identification system when the eligibleamount of bacteria was at the range of20mg～50mg, the time of saponification water bath was at therange of20-30min and the dosage of methylating agent was at the range of1.5～2.5mL; the effect ofidentification was better when the dosage of saponification reagent was at the range of0.5～2.0mL.33of Bacillus strains were identified by MIDI microbe identification system. The result showed that12strains of Bacillus were not existed in the database of MIDI identification system. There were15strains to be identified to species accurately in the rest of21strains of Bacillus, e.g. Brevibacillus brevisFJAT-8753, Bacillus amyloliquefaciens FJAT-8754, Bacillus atrophaeus FJAT-8755, Bacillus badiusFJAT-8757, Bacillus cereus FJAT-8760, Bacillus sphaericus FJAT-8783, Bacillus licheniformisFJAT-8771, Bacillus pumilus FJAT-8779, Bacillus thiaminolyticus FJAT-8786,4Bacillus alcalophilusFJAT-1001, Bacillus subtilis FJAT8784, Bacillus coagulans FJAT-8763, Bacillus cohnii FJAT-10017.The6rest strains could be identified to Genus. The effect of different conditions on the accuracy of theMIDI identification system was analyzed to found that the effect of eligible amount of bacteria, culturetime and culture temperature on the accuracy of the MIDI identification system were assumed in theorders that culture temperature>culture time>eligible amount of bacteria.C₁4:0iso, C₁6:00, C₁6:0iso, C₁6:1ω11c, C₁7:0ante iso, C₁4:00, C₁5:0iso and C₁5:0ANTE ISO weremainly fatty acid of33strains of Bacillus. The effect of eligible amount of bacteria, culture time andculture temperature on the content of fatty acid for the species of Bacillus was tested to found that theeffect on the species of fatty acid assumed in the orders that culture time>eligible amount ofbacteria>culture temperature; the effect on the content of fatty acid assumed in the orders that culturetemperature>culture time>eligible amount of bacteria..Finally, optimal identification conditions of33strains of Bacillus were summed up by this research,33strains of Bacillus could be identified to25species.