Vitamin B₁₂ is commercially produced only by fermentation, i.e. microbiological method, due to its very complex structure.

Blakeslea trispora is the most preferred strain for production of beta-carotene due to its high yield. It produces 3 g/l beta-carotene.

Rhodopseudomonas protamicus is a hybrid strain of Rhodopseudomonas spheroides and Protaminobacter rubber and can produce as high as 135 mg/l of vitamin B₁₂ utilising carbon source. Thus, it is the strain that yields the greatest amount of vitamin B₁₂.

Ashbya gossypii is the most preferred organism for the industrial production of riboflavin as it is more stable with a high producing capacity of riboflavin.

Dodecane, i.e. kerosene increases the solubility of hydrophobic substrates and doubles the production of beta carotene in fermentation by + and - mix strains of trispora.

Phosphoenol pyruvate carboxylase regulates the production of L-glutamate by converting phosphoenol pyruvate to oxaloacetate, which is required for glutamic acid synthesis.

Hydrocarbonoclastic microorganisms like methanogenic archaea benefit humans in the petroleum industry. They can metabolise or alter crude or refined petroleum products.

L-glutamic acid was the first amino acid to be produced by microorganisms.

Pseudomonas aeruginosa is used for producing alginate.

C. glutanicum, i.e. glutamic acid-producing bacteria have a high activity of glutamate dehydrogenase and a low activity of α-ketoglutarate dehydrogenase, which favours high amount of glutamic acid synthesis by Corynebacterium glutanicum.

The soil fungus Mortierella alpina is used for the production of oils rich in arachidonic acid.

The organisms which lack the formation of regulatory end product are called auxotrophic mutants. The intermediates of the metabolic pathways accumulate and get excreted.

Yoghurt is obtained by the action of Streptococcus thermophilus, using milk as raw material.

Xanthan gum is a bacterially-produced polymer used in EOR (Enhanced Oil Recovery) to assist the water thickening process. Its properties of viscosity, shear resistance, and temperature and salt tolerance make it almost an ideal polymer for use in EOR.

This is the correct match. Pollulan is produced by using the fungus Aureobasidium pollulans. Gellan is produced by Pseudomonas elodea. The exopolysaccharide curdlan is commercially produced by employing Alcaligenes faecalis. Scleroglucan is a fungal heoxpolysaccharide. It is commercially produced by Sclerotium glucanicum.