What name is given to the large family of bacteria that can both spoil food and aid in digestion?

The correct answer is Bacillus. This genus includes a wide range of bacterial species that play significant roles in both food spoilage and the digestive processes in organisms. Bacillus species are known for their ability to survive in harsh conditions, including heat and drought, which allows them to thrive in various environments, including on food. Some species within this genus can degrade food products when they spoil, while others contribute to fermentation processes in digestion, making them beneficial in certain contexts.

Lactobacillus, while it is also involved in digestive processes and is used in probiotics, is primarily known for fermentation and not as widely responsible for spoiling food as Bacillus can be. Escherichia includes strains that can be harmful or beneficial to digestion (like E. coli), but they are not generally noted for their role in food spoilage. Staphylococcus can also cause food spoilage and illness but does not have the same role in the digestive process as Bacillus. This is why Bacillus is the most accurate choice for the question asked.