Question

A. Porins allow bacteria to move nutrients and waste across the cell membrane
B. Type III Secretion System (TTSS) allows bacteria to move nucleoprotein complex across the cell membrane
C. EPS is a virulence factor in wilt-causing bacteria
D. LPS allows bacteria to bind to host lectins
E. Hydrolytic enzymes are not virulence factors for bacteria
Choose the correct answer from the options given below:

• A. B and E only
• B. B only
• C. A, C and D only
• D. D only

Hint:

Remember that the Type III Secretion System (T3SS) is for effector proteins, whereas the Type IV Secretion System (T4SS) is for nucleoproteins (like Agrobacterium T-DNA). This distinction is a common topic in microbial pathogenesis questions.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Bacterial pathogens possess various structures and secretions that enable them to survive, colonize host tissues, and cause disease.
These include membrane channels, secretion systems, extracellular polysaccharides (EPS), lipopolysaccharides (LPS), and cell-wall degrading enzymes.

Step 2: Detailed Explanation:
Let us evaluate each statement to determine its accuracy:
Statement A: Porins are beta-barrel proteins located in the outer membrane of Gram-negative bacteria.
They form channels that allow the passive diffusion of low-molecular-weight nutrients into the cell and metabolic waste out of the cell. This is correct.
Statement B: The Type III Secretion System (TTSS or T3SS) acts as a molecular syringe to inject bacterial effector proteins directly into the host plant cell cytoplasm.
It does not transport nucleoprotein complexes. That is the function of the Type IV Secretion System (T4SS), which Agrobacterium tumefaciens uses to transfer T-DNA. Thus, Statement B is incorrect.
Statement C: Extracellular Polysaccharides (EPS) are high-molecular-weight polymers secreted by bacteria.
In vascular wilt-causing bacteria (such as Ralstonia solanacearum), EPS accumulates in the water-transporting xylem vessels, clogging them and preventing water movement. This causes the characteristic wilting symptoms, making EPS a major virulence factor. Thus, Statement C is correct.
Statement D: Lipopolysaccharides (LPS) are outer membrane components of Gram-negative bacteria.
The O-antigen of the LPS molecule interacts with host plant cell-wall proteins, specifically plant lectins. This interaction plays an important role in host recognition and attachment. Thus, Statement D is correct.
Statement E: Hydrolytic enzymes (such as pectinases, cellulases, and proteases) break down host cell-wall components and are essential virulence factors, especially for soft-rot bacteria like Pectobacterium. Thus, stating they are not virulence factors is incorrect.

Step 3: Final Answer:
Since statements A, C, and D are correct, while B and E are incorrect, the correct option is (C) A, C and D only.