The feasibility of mass lproduction of polylysine, an antibacterial substance, employing the two step fermentation of Streptomyces albulus has been investigated. Since the maximum accumulation of pplylysine had appeared between 4.0 to 4.5 of pH during fermentor cultivation of which the pH of the broth has declined to 3.2 from 6.8, the strain growing in the broth on late log phase had been washed with sterilized water, then the sole mycelium had been transferred to another medium containing 2% citric acid having pH adjusted with NaOH to optimum of 4.2 to improve the production of the amino acid. The total accumulation of polylysine by washed myceliunl of Streptomyces albulus from this two step procedure has exhibited 6 times more than the normal production of the simple one step fermentation