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Capillary gas chromatography (GC) with flame ionization detection was used to determine the cellular fatty acid profiles of various food-borne microbial pathogens and to compare the fatty acid profiles of spores and vegetative cells of the same endospore-forming bacilli. Fifteen bacteria, representing eight genera (Staphylococcus, Listeria, Bacillus, Yersinia, Salmonella, Shigella, Escherichia, and Vibrio) and 11 species were used to compare the extracted fatty acid methyl esters (FAMEs). Endospore-forming bacilli were processed to obtain pure spores and whole cell FAMEs for GC analysis. A data set for each bacterial agent was prepared using fatty acid profiles from five replicates prepared on different days. The results showed that these fatty acid intensity profiles were unique for each of the 11 species and that they could be used as a fingerprint for the organisms. The cellular fatty acid profiles for Bacillus anthracis and Bacillus cereus show that there are two branched chain fatty acids, iso 17:1 omega10c and 17:1 anteiso, which are unique in these species. Iso 17:1 omega10c is present in B. cereus vegetative cells and spores but is not observed in B. anthracis. The 17:1 anteiso fatty acid is present in B. anthracis cells but not in B. cereus cells. Fatty acids 16:0 2OH and 17:0 iso 3OH are present in B. anthracis and B. cereus spores but not in the vegetative cells. In summary, analysis of FAMEs from bacteria and spores can provide a sensitive procedure for the identification of food-borne pathogens.

BackgroundIn May 2008, PulseNet detected a multistate outbreak of Salmonella enterica serotype Saintpaul infections. Initial investigations identified an epidemiologic association between illness and consumption of raw tomatoes, yet cases continued. In mid-June, we investigated two clusters of outbreak strain infections in Texas among patrons of Restaurant A and two establishments of Restaurant Chain B to determine the outbreak's source.Methodology/Principal FindingsWe conducted independent case-control studies of Restaurant A and B patrons. Patients were matched to well controls by meal date. We conducted restaurant environmental investigations and traced the origin of implicated products. Forty-seven case-patients and 40 controls were enrolled in the Restaurant A study. Thirty case-patients and 31 controls were enrolled in the Restaurant Chain B study. In both studies, illness was independently associated with only one menu item, fresh salsa (Restaurant A: matched odds ratio [mOR], 37; 95% confidence interval [CI], 7.2–386; Restaurant B: mOR, 13; 95% CI 1.3–infinity). The only ingredient in common between the two salsas was raw jalapeño peppers. Cultures of jalapeño peppers collected from an importer that supplied Restaurant Chain B and serrano peppers and irrigation water from a Mexican farm that supplied that importer with jalapeño and serrano peppers grew the outbreak strain.Conclusions/SignificanceJalapeño peppers, contaminated before arrival at the restaurants and served in uncooked fresh salsas, were the source of these infections. Our investigations, critical in understanding the broader multistate outbreak, exemplify an effective approach to investigating large foodborne outbreaks. Additional measures are needed to reduce produce contamination.

Photoactivation is the light-dependent ligation of Mn2+ into the H2O oxidation complex of photosystem II (PSII) and culminates in the formation of an enzymatically active complex containing Ca2+ and four Mn>/=3+. Previous kinetic analysis demonstrated that the genetic removal of the extrinsic manganese-stabilizing protein (MSP) increases the quantum yield of photoactivation 4-fold relative to that of the wild type, consistent with the hypothesis that MSP hinders access of Mn2+ to a site of photoligation [Burnap, R. L., et al. (1996) Biochemistry35, 874-882]. In this report, several Synechocystis sp. PCC6803 mutants with defined amino acid substitutions in the N-terminal region of MSP or the e-loop of intrinsic PSII protein CP47 [Putnam-Evans, C., et al. (1996) Biochemistry 35, 4046-4053] were characterized in terms of the binding of MSP to the intrinsic portion of the PSII complex and in terms of photoactivation kinetics. The charge-pair switch mutation, Arg384Arg385 --> Glu384Glu385 in the lumenal e-loop of CP47 (CP47 RR384385EE), exhibited the most severe impairment of MSP binding, whereas the Arg384Arg385 --> Gly384Gly385 (CP47 RR384385GG) mutation caused a more moderate impairment in binding. Single-substitution mutations at the highly conserved Asp9 or Asp10 positions in the amino-terminal region of MSP also resulted in a reduced binding affinity, but not as severe as that in CP47 RR384385EE. The relative quantum yield of photoactivation of hydroxylamine-extracted mutant PSII was generally found to correlate with the degree of MSP binding impairment, with the CP47 RR384385 mutants exhibiting the highest quantum yields. A two-locus, double-mutant construct involving deletion of MSP in the CP47 RR384385EE background was found to be only slightly more impaired in H2O oxidation activity than either of the corresponding single-locus mutant derivatives, indicating that mutations at these genetically separate loci encode physically interacting products affecting the same reaction parameter during H2O oxidation. Taken together, the results reinforce the concept that MSP interacts with the e-loop of CP47 at Arg384Arg385 and that disruption of this interaction causes significant alterations of the site of H2O oxidation in terms of assembly and enzymatic activity of the Mn cluster.