user: Question: What are the results for testing the species with voges-proskauer when citrate yields a Positive result?
Columns: ['Species', 'Indole', 'Methyl Red', 'Voges-Proskauer', 'Citrate']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Escherichia coli', 'Positive', 'Positive', 'Negative', 'Negative']
SQL:

assistant: SELECT "Voges-Proskauer" FROM "Table" WHERE "Citrate" = 'Positive';