Use of one strain of Lactobacillus plantarum for the manufacture of a compositionfor increasing the diversity of the gastrointestinal tract by administrationof said strain to an individual with a view to producing an increased diversityindex compared to placebo is disclosed, as well as use of one strain of Lactobacillusplantarum for the manufacture of a composition for prophylactic treatment ofa healthy individual against developing a low bacterial diversity (LBD) ofan individual having LBD against developing one or more physiologically disturbedconditions, large intestine bacterial overgrowth (LIBO) or small intestinebacterial overgrowth (SIBO) and of an individual having LIBO or SIBO againstdeveloping one or more physiologically disturbed conditions, and a method forincreasing said diversity.