Bacterial pyrolysis mass spectrum

An ANN is an array of three or more interconnected layers of cells called nodes (much like columns of cells in a spreadsheet). Data are introduced to the ANN through the nodes of the input layer. For instance, each input layer node can contain the relative intensity of one of the m/z values from a bacterial pyrolysis mass spectrum. The output layer nodes can be assigned to iden-... 

Py-MS is used to decrease sample preparation time for bacterial profiling. One method hydrolyzes and methylates fatty acids from bacteria without using chromatographic separation [87]. Figure 20.11 shows a pyrolysis-mass spectrum of fatty add methyl esters (fames) from four pathogenic bacteria. 

Figure 16 Curie-point pyrolysis El mass spectrum of B. anthracis showing (A) fragment ions of a series [R-C=0 + 74], representing the contribution of particular types of fatty acid residues to the overall profile of bacterial fatty acids, and (B) molecular ions of dehydrated diacylgycerols (diacylpropenodiols) originating from cellular phospholipids.

Studies on the bulk pyrolysis of polyhydroxybutyric acid from Bacilli and of bacterial polyalkanoates have shown the formation of 2,3-butenoic acid and 2,3-pentenoic acid (18) The presence of 2,3-butenoic acids and pentenoic acid in the pyrolysate of the particulate matter from sample 20C is interpreted as an indication of polyhydroxy-alkanoates in the sample. These mixed polyesters of hydroxy acids with 4, 5 and sometimes 6 carbon atoms are especially abundant in activated sludges (19). The occurrence of m/z 86 and 100 as abundant mass peaks in the spectra of the fluvial material and as very characteristic peaks in the discriminant function spectrum indicates that a significant amount of the mud fraction may consist of sewage debris. This impression was confirmed by identification of a number of other pyrolysis products in the data file. 

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