The present invention provides an isolated lactic acid bacterium, Lactobacillus plantarum subsp. plantarum PS128 deposited under DSMZ Accession No. DSM 28632, for prophylaxis or treatment of a stress-induced disorder. The present invention further provides a composition for prophylaxis or treatment of a stress-induced disorder that comprises Lactobacillus plantarum subsp. plantarum PS128. Moreover, the present invention provides a method for prophylaxis or treatment of a stress-induced disorder in a subject that comprises a step of administering an effective amount of Lactobacillus plantarum subsp. plantarum PS128 to the subject.