Foodborne intoxications — Botulism is specifically caused by the preformed neurotoxin produced by which bacterium during growth in improperly processed foods?

Introduction / Context:
Botulism is a severe, potentially fatal foodborne intoxication. Unlike infections that require viable bacteria to colonize the host, botulism is usually caused by ingestion of preformed botulinum neurotoxin in food, most often linked to anaerobic conditions such as those in improperly canned or vacuum-packed products.

Given Data / Assumptions:

• The question asks for the bacterium whose toxin causes botulism.
• Focus is on toxin production under low-oxygen conditions and improper preservation.
• Only one option is the classical etiologic agent.

Concept / Approach:
Food microbiology distinguishes intoxication (toxins ingested) from infection (organisms ingested). Botulinum neurotoxin, among the most potent known, is produced by Clostridium botulinum under anaerobic, low-acid, low-salt, and temperature-abused conditions. Controlling pH, heat processing (thermal death of spores), salt, nitrite, and refrigeration are critical hurdles.

Step-by-Step Solution:

Verification / Alternative check:
Guidelines for low-acid canned foods emphasize control of C. botulinum spores (commercial sterility) to prevent toxin formation; this aligns with industry practice and public health records.

Why Other Options Are Wrong:

• C. tyrobutyricum: associated with late blowing in cheeses due to gas, not botulism.
• C. sporogenes: used as a surrogate in validation studies but not the primary agent in human botulism.
• None of these: incorrect because C. botulinum is well established.

Common Pitfalls:
Confusing spoilage clostridia with toxigenic species; assuming all Clostridium spp. pose identical risks.

Final Answer:
Clostridium botulinum