Microbes In Human Welfare

Aspergillus niger is a fungus widely used in the industrial production of citric acid.
Citric acid is used in food preservation, pharmaceuticals, and beverages.
Other acids:
- Lactic acid – produced by Lactobacillus}.
- Acetic acid – by Acetobacter}.
- Butyric acid – by anaerobic bacteria like Clostridium}.

Lady birds (ladybugs) are beneficial insects that prey on aphids, which are crop-damaging pests.
They are widely used in biological control programs in agriculture.
Other options:
- Baculovirus: used to control insect pests, especially caterpillars, not aphids.
- Dragonfly: predates mosquitoes and small insects, but not specialized for aphids.
- Trichoderma: a fungal biocontrol agent, useful against plant pathogens but not aphids.

Lactobacillus} is a genus of bacteria that plays a major role in the curdling of milk by converting lactose (milk sugar) into lactic acid.
These bacteria are dependent on external organic substances for nutrition, making them heterotrophic.
Let’s eliminate other options:
- Cyanobacteria are autotrophic and photosynthetic, not involved in curd formation.
- Archaebacteria are ancient extremophiles found in harsh conditions like hot springs, not in curd.
- Chemosynthetic bacteria obtain energy from inorganic chemical reactions, not involved in dairy fermentation.
Hence, Lactobacillus} is correctly classified as heterotrophic bacteria.

Step 1: Glomus} is a genus of arbuscular mycorrhizal (AM) fungi.
Step 2: These fungi form symbiotic associations with the roots of higher plants.
Step 3: They help in the absorption of **phosphorus** and other minerals from the soil.
Step 4: Rhizobium}, Frankia}, and Anabaena} are nitrogen-fixing organisms.