(a) Mention the common bacterium found in the anaerobic sludge during sewage treatment and also in the rumen of cattle. How is this bacterium commercially useful?

OR

b) Name the effective biocontrol agents of several plant pathogens belonging to the group of viruses. Also, write about the ways they support the environment.

(a) Methanogen bacteria are common in the anaerobic sludge during sewage treatment and the rumen of cattle.
Methanogen bacteria help in biological methanation and use methane to produce energy.

OR

(b) Biocontrol agents prevent the host plants from pathogens that cause infection.
Biocontrol agents are antagonist in nature.
Examples of biocontrol agents are
i Pseudomonas spp.
ii. Bacillus spp.
iii. Burkholderia spp., and
iv. Trichoderma sp.
Features of BCAs are
i. Used in disease management of plant pathogens,
ii. Shows different mechanisms to control plant pathogens that facilitate the optimization of control.
iii. Effective strains is beneficial to environment.
iv. Used against pathogens that cause foliar and soil-borne diseases.
Examples
a. Agrobacterium radiobacter var radiobacter,
b. Erwinia spp.,
c. Fusarium spp.,
d. Rhizoctonia solani,
e. Phytophthora spp., and
f. Pythium spp.