Microbes in Human Welfare Test - 64

The order of bacteria active in the conversion of organic wastes into biogas is hydrolytic, acetogenic, methanogenic. 

Hydrolytic- Insoluble organic polymers, such as carbohydrates, are broken down to soluble derivatives which are used by bacteria.

Acetogenic- Acidogenic bacteria then convert the sugars and amino acids into carbon dioxide, hydrogen, ammonia, and organic acids. These bacteria convert these resulting organic acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide.

Methanogenic- The methanogens convert the product of acetogenic step to methane and carbon dioxide. The produced gas consisting of methane, carbon dioxide, and traces of other ‘contaminant’ gases is known as biogas.

So, the correct answer is 'Hydrolytic $$\rightarrow$$ Acetogenic $$\rightarrow$$ Methanogenic'.

Cytophaga is a genus of Gram-negative bacillus. Cellulomonas is a genus of Gram-positive bacillus. They have the ability to digest cellulose. They are called as cellulolytic bacteria. They are involved in biogas production. 

A.Correct option -B

• Potato wart disease is caused by the fungus Synchytrium endobioticum which is a fungal species causing disease in plants belonging to the genus Solanum.
• This fungus is a facultative parasite that infects the potato or any plant that is grown in the soil which already has the presence of the zoospore of the fungus. 
• Also, the condition required by the fungus to germinate is the moist atmosphere and warm temperature is provided by the potato stem along with nutrients required to grow.

So, the correct answer is 'Fungi'

Frankia is a genus of nitrogen-fixing bacteria. They live in symbiotic association with actinorhizal plants. Like Rhizobium, it usually infects host through root hair deformation and stimulates cell proliferation in host cortex. These are found in the root nodules of leguminous plants. It also induces root nodule formation in many plants. There are certain strains of Frankia that are free-living. They fix nitrogen in the free living state.

Bacillus denitrificans is a Gram-negative chemolithoautotroph. It is a denitrifying bacteria. It converts the nitrate present in the soil to atmospheric nitrogen. It reduces the amount of available nitrogen for plants in the soil. Hence, It reduces the fertility of soil and are harmful for crops.

The research for biodegradable plastics that are derived from renewable resources has been ongoing since the 1970s. Biodegradable plastics are polylactic acid and polyhydroxyalkanoates, These are obtained from Rhodococcus equi, a Gram-positive coccobacillus bacterium. Other bacteria from which biodegradable plastic can be obtained include Bacillus subtilis, Aspergillus species, Penicillium species, Pseudomonas species, Staphylococcus aureus, Streptococcus species, Proteus vulgaris, Ochrobacterum species. 

Activated sludge treatment is the step involved in the treatment of sewage water. The sewage is treated in a large aerated tank and bacteria. Once, the process of decomposition is over, the filtrate obtained is called the activated sludge because it contains a high number of bacteria. This is then recycled in the next slot of treatment when the polluted sewage is available for the treatment. The activated sludge speeds up the process of decomposition by acting as an inoculum in the aeration tank. Primary treatment is the removal of large solid particles from the sewage. Tertiary treatment involves chemical treatment of the sewage water.

Nitrogen-fixing microorganisms are recognized: free-living (non-symbiotic) bacteria, including the cyanobacteria. Anabaena and Nostoc and genera such as Azotobacter, Beijerinckia, and Clostridium and mutualistic bacteria such as Rhizobium, associated with leguminous plants.