What do coliforms refer to in the context of Enterobacteriaceae?

• A. They are bacteria that can produce hydrogen sulfide
• B. They are a subset of Enterobacteriaceae that can ferment lactose within 48 hours at 35°C
• C. They are pathogenic bacteria associated with foodborne illnesses
• D. They are non-fermenters within Enterobacteriaceae

Answer: (B)

Coliforms are a specific group of bacteria within the Enterobacteriaceae family that are characterized by their ability to ferment lactose in a relatively short time frame, specifically within 48 hours at a temperature of 35°C. This property is essential for their identification and is commonly used as an indicator of microbial contamination in water and food safety testing.

The ability to ferment lactose is important because it distinguishes coliforms from non-coliform members of Enterobacteriaceae, which may not have this capability. Since coliforms include various species such as Escherichia coli, their presence in a sample can indicate fecal contamination and potential presence of other harmful pathogens. This characteristic makes coliform testing particularly valuable in environmental monitoring and public health.