IDENTIFICATION OF VOLATILES DERIVED FROM CITROBACTER-FREUNDII FERMENTATION OF A TRYPTICASE SOY BROTH

Twenty-two compounds emanated as volatiles from an 8-day fermentation of trypticase soy broth by Citrobacter freundii, American Type Culture Collection (ATCC 8090), were identified by dynamic headspace analysis techniques. Compound identifications were made on the basis of a comp arison of Kovats indices and GC/MS spectra for unknowns and authentic samples. Of the compounds identified, nine were pyrazines, four were a lcohols, two were aldehydes, two were ketones, two were esters, two we re sulfides, and one was phenol. In decreasing order, the five most ab undant compounds in the volatiles were 3-methyl-1-butanol (91.1%), phe nol (5.00%), 2,5-dimethylpyrazine and phenethyl alcohol (each 1.18%), and 2-methyl-1-propanol (0.38%). Low molecular weight amines (ammonia, methyl- and ethylamine) were not detected in the volatiles. Pyrazines identified in the bacteria-produced supernatant (BPS) were generated almost exclusively by heating (autoclaving) the broth; their formation did not seem to be influenced by bacterial action. Laboratory bioassa y of 4- and 8-day BPS derived from C. freundii against mixed sexes of adult Mexican fruit flies, Anastrepha ludens, showed the supernatants were comparable in attractancy to a 30% NuLure solution.