Heterofermentative lactic acid bacteria: Which statement best describes their product profile and industrial use?

Introduction / Context:
Lactic acid bacteria (LAB) are categorized by fermentation end products: homofermentative strains mainly yield lactic acid, while heterofermentative strains yield mixed products. This classification affects flavor, gas production, and suitability for bulk lactic acid manufacture.

Given Data / Assumptions:

• We must characterize heterofermenters.
• Industrial lactic acid production favors yield and simplicity of downstream processing.

Concept / Approach:
Heterofermentative LAB metabolize sugars via the phosphoketolase pathway, producing lactic acid plus CO2 and either ethanol or acetic acid, with additional minor products. Homofermenters (Embden–Meyerhof pathway) produce lactic acid predominantly and are usually chosen for commercial lactic acid due to higher yields and fewer by-products.

Step-by-Step Solution:
Assess option a: describes homofermenters, not heterofermenters. Assess option b: matches heterofermentative profile (lactic acid + CO2 + ethanol/acetic acid). Assess option c: incorrect—industry prefers homofermenters for lactic acid mass production. Therefore choose option b.

Verification / Alternative check:
Fermentation textbooks show stoichiometries for both LAB groups; product distributions confirm gas and mixed acids for heterofermenters.

Why Other Options Are Wrong:
They either describe the wrong LAB group or make incorrect claims about industrial preference.

Common Pitfalls:
Assuming all LAB behave identically; end-product profiles determine both flavor in foods and process economics.

Final Answer:
They produce lactic acid along with carbon dioxide, ethanol or acetic acid, and traces of other products.