Abstract: A nano-sized Lactobacillus plantarum (L. plantarum) nF1 strain isolated from kimchi and which has a particle size distribution of 0.5 to 1.0 ?m. Pharmaceutical compositions and functional food compositions comprising the nano-sized L. plantarum nF1 strain may be used to prevent and treat colorectal diseases including colitis and colorectal cancer.

Abstract: A method of producing a large volume of Lactobacillus bacteria and increasing the activity of the obtained Lactobacillus is provided. The Lactobacillus is prepared by culturing in a culture medium and adding an alkaline chemical while controlling the pH, and sterilizing the Lactobacillus by applying stress in the later stage of the cultivation so as to produce Lactobacillus having the ability to induce IL-12 production. Applying stress is selected from the group consisting of: (a) cultivating without adding an alkaline chemical; (b) cultivating at a temperature range in which propagation is suppressed; (c) cultivating by adding 1% by weight or more of salt; and/or (d) cultivating at pH of 5 or below.