Twenty-three of the most prominent spots which are visible on two-dimensional (2-D) protein gels of Bacillus subtilis crude extracts were selected as marker spots for the construction of a 2-D protein index. N-terminal sequencing of the corresponding proteins resulted in the identification of enzymes involved in glycolysis, TCA cycle, pentose phosphate cycle, amino acid metabolism, nucleotide biosynthesis and translation. Using computer analysis of the 2-D protein gels, most of these metabolic enzymes were found to be synthesized at a reduced rate after different stresses and glucose starvation. Such an approach permits a rapid and global evaluation of the regulation of different branches of metabolism in response to various physiological conditions.