The ability of the resting cells of Brevibacterium sp. B2D, a flocculent strain, to convert fumaric acid to L-malic acid was investigated under different fermentation conditions. The optimal temperature for the bioconversion is approx 36 degrees C, and the optimal pH is around 6.4. The bacteria do not require special cultural conditions for the development of fumarase. Ln the presence of relatively high concentrations of fumarate (60 g/L), the bacterial cells exhibited a high rate of L-malic acid production with high yield without the coproduction of unwanted byproducts like succinic acid. A yield of 89.8% of L-malic acid from fumaric acid and an average specific productivity of 0.41 g/g/h was obtained. The presence of surfactant, even at low concentrations like 0.02%, resulted in over a twofold increase in specific malic acid production rate.