Q.80 Which of the following is/are example(s) of animal–microbe mutualism?
(A) Human – Mycobacterium tuberculosis
(B) Dog – Rabies lyssavirus
(C) Human – Lactobacillus plantarum
(D) Cow – Ruminococcus albus

Correct Answer: (C) and (D)

Animal-microbe mutualism involves symbiotic relationships where both the animal host and microbe benefit, such as through nutrient provision or protection.​

Option Analysis

Option (A) Human – Mycobacterium tuberculosis
This represents parasitism, not mutualism. Mycobacterium tuberculosis causes tuberculosis, harming the human host by damaging lung tissue while benefiting from the host environment for replication and transmission.​

Option (B) Dog – Rabies lyssavirus
This is a pathogenic interaction. Rabies lyssavirus (RABV) infects dogs, leading to fatal encephalitis; the virus benefits by using the host for replication and spread, but the dog suffers neurological damage and death.​

Option (C) Human – Lactobacillus plantarum
This exemplifies mutualism. Lactobacillus plantarum colonizes the human gut microbiome, aiding digestion, producing vitamins, modulating immunity, and inhibiting pathogens, while gaining nutrients and shelter from the host.​

Option (D) Cow – Ruminococcus albus
Classic rumen mutualism. Ruminococcus albus ferments cellulose in the cow’s rumen into volatile fatty acids for host energy, while the cow provides a anaerobic habitat and substrate; both thrive interdependently.​

Animal-microbe mutualism examples highlight beneficial symbioses essential for digestion and health, as seen in CSIR NET life sciences questions like Q.80. These interactions power nutrient cycling in herbivores and human gut microbiomes.​

Key Mutualism Mechanisms

Mutualism thrives via resource exchange: microbes provide nutrients or antimicrobials, hosts offer habitat.​

• Gut colonization by probiotics like Lactobacillus plantarum boosts human immunity and pathogen resistance.​

• Rumen bacteria like Ruminococcus albus degrade plant fibers, enabling cows to extract energy from grass.​

CSIR NET Q.80 Breakdown

This exam question tests symbiosis classification.​
Correct choices (C) and (D) show true mutualism; (A) and (B) are pathogenic.​

Broader Applications

Rumen mutualisms inspire biofuels; gut probiotics advance therapies. For CSIR NET aspirants, mastering these distinguishes mutualism from parasitism.​