[Element composition of bacterial cells of various taxa]

The elemental compositions of cells of representatives of five bacterial genera (Hyphomonas vulgare NP-160, Caulobacter bacteroides NP-105, Flectobacillus major Mm, Escherichia coli, and Spirulina platensis) was studied by electron microscopic x-ray microanalysis. The contents of P, S, Cl, K, and Ca were determined. The bacterial species studied in this work substantially differ by the contents of these elements. A high content of K is typical of S. platensis, whereas F. major, an aquatic form, is rich in Cl. The other bacterial species were had the levels of K, Ca, and the K/Ca index, which correlated with the stability of their cell membranes and resistance to stress. In E. coli, the spectrum of the elemental composition and the values of P/S and K/Ca are indicative of high energy potential and low tolerance of membranes.