L-methioninase has attracted a great deal of attention due to has potential use as an effective therapeutic agent for cardiovascular diseases, different types of human cancer, and other applications. Bacterial isolates were collected from marine samples obtained from the Jeddah coast In Saudi Arabia. Bacterial isolate's ability for L-methioninase productions was tested on a modified mineral salt M9 L-methionine agar medium using phenol red as the pH indicator. Colonies with pink-red and yellow zone around were selected as L-methionine degrading bacteria.Based on biochemical tests and 16S rDNA sequencing, the highest L-methioninase producing strain was identified as Serratia proteamaculans strain. The nutrition,fermentation period, temperature, and pH value affecting L-methioninase production by the strain were optimized.Maximum L-methioninase production by S. proteamaculans was (0.102U\min\ml) obtained after 24 and 48 h respectively at 35±2 °C of incubation in a constant incubator in a culture supplemented with fructose (0.7%) and free of L-methionine medium, at pH 7.5.