{ "schema_version": "1.0", "level": "genus", "genus": "Azotobacter", "overview": { "short": "Azotobacter species are Gram-negative, obligately aerobic, free-living nitrogen-fixing rods commonly found in soil and water.", "clinical_context": "Rarely associated with human disease; most isolates are environmental or laboratory contaminants." }, "expected_fields": { "Gram Stain": "Negative", "Shape": "Rods", "Motility": "Variable", "Capsule": "Positive", "Spore Formation": "Negative", "Haemolysis": "Negative", "Haemolysis Type": "None", "Media Grown On": [ "Nutrient Agar" ], "Colony Morphology": [ "Large", "Mucoid", "Smooth" ], "Oxygen Requirement": "Aerobic", "Growth Temperature": "20//37", "Catalase": "Positive", "Oxidase": "Positive", "Indole": "Negative", "Urease": "Negative", "Citrate": "Positive", "Methyl Red": "Negative", "VP": "Negative", "H2S": "Negative", "DNase": "Negative", "ONPG": "Negative", "Coagulase": "Negative", "Gelatin Hydrolysis": "Variable", "Esculin Hydrolysis": "Negative", "Nitrate Reduction": "Variable", "NaCl Tolerant (>=6%)": "Negative", "Lipase Test": "Negative", "Lysine Decarboxylase": "Negative", "Ornithine Decarboxylase": "Negative", "Ornitihine Decarboxylase": "Negative", "Arginine dihydrolase": "Negative", "Glucose Fermentation": "Negative", "Lactose Fermentation": "Negative", "Sucrose Fermentation": "Negative", "Maltose Fermentation": "Negative", "Mannitol Fermentation": "Negative", "Sorbitol Fermentation": "Negative", "Xylose Fermentation": "Negative", "Rhamnose Fermentation": "Negative", "Arabinose Fermentation": "Negative", "Raffinose Fermentation": "Negative", "Trehalose Fermentation": "Negative", "Inositol Fermentation": "Negative", "Gas Production": "Negative", "TSI Pattern": "Unknown", "Colony Pattern": "Unknown", "Pigment": "Variable", "Motility Type": "Peritrichous" }, "field_notes": { "Oxygen Requirement": "Azotobacter species are strictly aerobic despite nitrogen fixation.", "Capsule": "Prominent polysaccharide capsule contributes to mucoid colonies.", "Glucose Fermentation": "Azotobacter are non-fermenters; energy is derived via oxidative metabolism." }, "key_differentiators": [ { "field": "Oxygen Requirement", "expected": "Aerobic", "distinguishes_from": ["Enterobacter", "Klebsiella"], "notes": "Strict aerobic growth helps exclude Enterobacterales." }, { "field": "Capsule", "expected": "Positive", "distinguishes_from": ["Pseudomonas"], "notes": "Heavy capsule and mucoid colonies are characteristic." }, { "field": "Glucose Fermentation", "expected": "Negative", "distinguishes_from": ["Enterobacterales"], "notes": "Non-fermentative metabolism separates Azotobacter from many Gram-negative rods." } ], "common_confusions": [ { "genus": "Pseudomonas", "reason": "Both are aerobic Gram-negative rods and oxidase positive." }, { "genus": "Burkholderia", "reason": "Environmental origin and non-fermentative metabolism may overlap." } ], "when_to_question_identification": [ "Growth under anaerobic conditions argues against Azotobacter.", "Strong glucose fermentation suggests Enterobacterales.", "Lack of capsule suggests another aerobic Gram-negative rod." ], "recommended_next_tests": [ { "test": "Oxidative/Fermentative glucose test", "reason": "Confirms oxidative (non-fermentative) metabolism." }, { "test": "Nitrogen fixation testing", "reason": "Demonstrates characteristic nitrogen-fixing capability." }, { "test": "MALDI-TOF MS", "reason": "Reliable for environmental species identification." } ], "supported_species": [ "chroococcum", "vinelandii" ] }