You will be shown a question, followed by excerpts from biomedical research papers. Please answer the question based on the provided context. Do not include any text in your response other than the answer.

Question: What is known about the gut bacteria and depression.

Context: Evidence indicates that major depression is accompanied by increased translocation of gut commensal Gram-negative bacteria (leaky gut) and consequent activation of oxidative and nitrosative (O&NS) pathways.
Comparative metaproteomics analysis shows altered fecal microbiota signatures in patients with major depressive disorder.
Major depressive disorder (MDD) is a highly prevalent and debilitating mental illness, which is associated with disorder of gut microbiota.
Evidence indicates that major depression is accompanied by increased translocation of gut commensal Gram-negative bacteria (leaky gut) and consequent activation of oxidative and nitrosative (O&NS) pathways.

Major depressive disorder (MDD) is a highly prevalent and debilitating mental illness, which is associated with disorder of gut microbiota.