BACTERIA ENGINEERED TO TREAT DISEASES THAT BENEFIT FROM REDUCED GUT INFLAMMATION AND/OR TIGHTENED GUT MUCOSAL BARRIER

1 .- 44 . (canceled)

45 . A bacterium comprising at least one non-native gene or gene cassette for producing tryptophan and tryptamine,

wherein the at least one non-native gene or gene cassette is operably linked to a fumarate and nitrate reductase (FNR)-responsive promoter.

46 . The bacterium of claim 45 , wherein a first gene cassette comprises genes trpE fbr , trpD, trpC, trpB, and trpA, and a second gene cassette comprises genes aroG fbr and tdc, and

wherein the first gene cassette is operably linked to the FNR-responsive promoter, and wherein the second gene cassette is operably linked to the FNR-responsive promoter.

47 . The bacterium of claim 46 , wherein

1) the trpE fbr gene encodes a TrpE fbr polypeptide comprising a sequence that has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity to SEQ ID NO: 85;

2) the trpD gene encodes a TrpD polypeptide comprising a sequence that has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity to SEQ ID NO: 77;

3) the trpC gene encodes a TrpC polypeptide comprising a sequence that has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity to SEQ ID NO: 79;

4) the trpB gene encodes a TrpB polypeptide comprising a sequence that has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity to SEQ ID NO: 81;

5) the trpA gene encodes a TrpA polypeptide comprising a sequence that has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity to SEQ ID NO: 83;

6) the aroG fbr gene encodes a AroG fbr polypeptide comprising a sequence that has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity to SEQ ID NO: 84; and

7) the tdc gene encodes a Tdc polypeptide comprising a sequence that has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity to SEQ ID NO: 99.

48 . The bacterium of claim 45 , wherein the gene and/or gene cassette is located on a chromosome in the bacterium.

49 . The bacterium of claim 45 , wherein the at least one gene and/or gene cassette is located on a plasmid in the bacterium.

50 . The bacterium of claim 45 , wherein the bacterium is a probiotic bacterium.

51 . The bacterium of claim 50 , wherein the bacterium is selected from the group consisting of Bacteroides, Bifidobacterium, Clostridium, Escherichia, Lactobacillus , and Lactococcus.

52 . The bacterium of claim 51 , wherein the bacterium is Escherichia coli strain Nissle.

53 . The bacterium of claim 45 , wherein the bacterium is an auxotroph in a gene that is complemented when the bacterium is present in a mammalian gut.

54 . The bacterium of claim 53 , wherein the bacterium is an auxotroph in diaminopimelic acid or an enzyme in the thymine biosynthetic pathway.

55 . The bacterium of claim 45 , wherein the bacterium further comprises one or more native genes that have been mutated or deleted, wherein the native genes are trpR and/or tnaA.

56 . A pharmaceutically acceptable composition comprising the bacterium of claim 45 ; and a pharmaceutically acceptable carrier.

57 . A method of treating or preventing an autoimmune disorder, comprising the step of administering to a patient in need thereof, the composition of claim 56 .

58 . A method of treating a disease or condition associated with gut inflammation and/or compromised gut barrier function comprising the step of administering to a patient in need thereof, the composition of claim 56 .

59 . The method of claim 57 , wherein the autoimmune disorder is selected from the group consisting of acute disseminated encephalomyelitis (ADEM), acute necrotizing hemorrhagic leukoencephalitis, Addison's disease, agammaglobulinemia, alopecia areata, amyloidosis, ankylosing spondylitis, anti-GBM/anti-TBM nephritis, antiphospholipid syndrome (APS), autoimmune angioedema, autoimmune aplastic anemia, autoimmune dysautonomia, autoimmune hemolytic anemia, autoimmune hepatitis, autoimmune hyperlipidemia, autoimmune immunodeficiency, autoimmune inner ear disease (AIED), autoimmune myocarditis, autoimmune oophoritis, autoimmune pancreatitis, autoimmune retinopathy, autoimmune thrombocytopenic purpura (ATP), autoimmune thyroid disease, autoimmune urticarial, Axonal & neuronal neuropathies, Balo disease, Behcet's disease, Bullous pemphigoid, Cardiomyopathy, Castleman disease, Celiac disease, Chagas disease, Chronic inflammatory demyelinating polyneuropathy (CIDP), Chronic recurrent multifocal ostomyelitis (CRMO), Churg-Strauss syndrome, Cicatricial pemphigoid/benign mucosal pemphigoid, Crohn's disease, Cogan syndrome, Cold agglutinin disease, Congenital heart block, Coxsackie myocarditis, CREST disease, Essential mixed cryoglobulinemia, Demyelinating neuropathies, Dermatitis herpetiformis, Dermatomyositis, Devic's disease (neuromyelitis optica), Discoid lupus, Dressler's syndrome, Endometriosis, Eosinophilic esophagitis, Eosinophilic fasciitis, Erythema nodo sum, Experimental allergic encephalomyelitis, Evans syndrome, Fibrosing alveolitis, Giant cell arteritis (temporal arteritis), Giant cell myocarditis, Glomerulonephritis, Goodpasture's syndrome, Granulomatosis with Polyangiitis (GPA), Graves' disease, Guillain-Barre syndrome, Hashimoto's encephalitis, Hashimoto's thyroiditis, Hemolytic anemia, Henoch-Schonlein purpura, Herpes gestationis, Hypogammaglobulinemia, Idiopathic thrombocytopenic purpura (ITP), IgA nephropathy, IgG4-related sclerosing disease, Immunoregulatory lipoproteins, Inclusion body myositis, Interstitial cystitis, Juvenile arthritis, Juvenile idiopathic arthritis, Juvenile myositis, Kawasaki syndrome, Lambert-Eaton syndrome, Leukocytoclastic vasculitis, Lichen planus, Lichen sclerosus, Ligneous conjunctivitis, Linear IgA disease (LAD), Lupus (Systemic Lupus Erythematosus), chronic Lyme disease, Meniere's disease, Microscopic polyangiitis, Mixed connective tissue disease (MCTD), Mooren's ulcer, Mucha-Habermann disease, Multiple sclerosis, Myasthenia gravis, Myositis, Narcolepsy, Neuromyelitis optica (Devic's), Neutropenia, Ocular cicatricial pemphigoid, Optic neuritis, Palindromic rheumatism, PANDAS (Pediatric autoimmune Neuropsychiatric Disorders Associated with Streptococcus), Paraneoplastic cerebellar degeneration, Paroxysmal nocturnal hemoglobinuria (PNH), Parry Romberg syndrome, Parsonnage-Turner syndrome, Pars planitis (peripheral uveitis), Pemphigus, Peripheral neuropathy, Perivenous encephalomyelitis, Pernicious anemia, POEMS syndrome, Polyarteritis nodosa, Type I, II, & III autoimmune polyglandular syndromes, Polymyalgia rheumatic, Polymyositis, Postmyocardial infarction syndrome, Postpericardiotomy syndrome, Progesterone dermatitis, Primary biliary cirrhosis, Primary sclerosing cholangitis, Psoriasis, Psoriatic arthritis, Idiopathic pulmonary fibrosis, Pyoderma gangrenosum, Pure red cell aplasia, Raynauds phenomenon, reactive arthritis, reflex sympathetic dystrophy, Reiter's syndrome, relapsing polychondritis, restless legs syndrome, retroperitoneal fibrosis, rheumatic fever, rheumatoid arthritis, sarcoidosis, Schmidt syndrome, scleritis, scleroderma, Sjogren's syndrome, sperm & testicular autoimmunity, stiff person syndrome, subacute bacterial endocarditis (SBE), Susac's syndrome, sympathetic ophthalmia, Takayasu's arteritis, temporal arteritis/giant cell arteritis, thrombocytopenic purpura (TTP), Tolosa-Hunt syndrome, transverse myelitis, type 1 diabetes, asthma, ulcerative colitis, undifferentiated connective tissue disease (UCTD), uveitis, vasculitis, vesiculobullous dermatosis, vitiligo, and Wegener's granulomatosis.

60 . The method of claim 59 , wherein the autoimmune disorder is selected from the group consisting of type 1 diabetes, lupus, rheumatoid arthritis, ulcerative colitis, juvenile arthritis, psoriasis, psoriatic arthritis, celiac disease, and ankylosing spondylitis.

61 . The method of claim 58 , wherein the disease or condition is selected from an inflammatory bowel disease, including Crohn's disease and ulcerative colitis, and a diarrheal disease.