Which of the following describes the definition of the Coliform group of bacteria as used in drinking water testing?

• Gram-positive bacteria that produce an acidic environment.
• Gram-negative, spore-forming bacteria that do not ferment lactose.
• Viruses capable of infecting and replicating within human host cells.
• Gram-negative, non-spore-forming bacteria that ferment lactose with gas within 48h at 35°C.