The homologous series of C-9-C-23 n-alkylbenzenes has been first identified in the products of thermal and thermocatalytic transformations of the insoluble part of the Arthrobacter sp. RV and Pseudomonas aeruginosa RM bacterial biomass, and their distribution has been revealed; a homologous series of n-alkyltoluenes has been discovered as well. It has been suggested that the n-alkylbenzenes are biomarkers.