Question

The Orla-Jensen group of Limosilactobacillus fermentum is

• A. Betabacterium
• B. Thermobacterium
• C. Streptobacterium
• D. Alphabacterium

Hint:

Associate "Beta" in Betabacterium with heterofermentation (multi-product fermentation), whereas Thermobacterium and Streptobacterium are strictly homofermentative.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Sigurd Orla-Jensen proposed a seminal taxonomic system for lactic acid bacteria (LAB) based on their morphology, temperature relationships, and fermentation pathways.
He divided rod-shaped lactic acid bacteria (Lactobacilli) into three distinct genera: Thermobacterium, Streptobacterium, and Betabacterium.

Step 2: Detailed Explanation:
The group classifications proposed by Orla-Jensen are defined as follows:
Thermobacterium: Consists of homofermentative lactobacilli that grow well at high temperatures (typically up to 45$^{\circ}$C or higher) and do not produce carbon dioxide from glucose.
Streptobacterium: Consists of homofermentative lactobacilli that grow at lower temperatures (optimum around 30$^{\circ}$C) and form chains of cells.
Betabacterium: Consists of heterofermentative lactobacilli that ferment glucose to produce lactic acid, acetic acid/ethanol, and carbon dioxide.
Limosilactobacillus fermentum (formerly Lactobacillus fermentum) is an obligate heterofermentative species.
Consequently, it falls under the Betabacterium group of Orla-Jensen's classification.

Step 3: Final Answer
The correct option is (A).