Process Biotechnology

Methane-oxidising bacteria (methanotrophs) consume methane that reaches the soil surface. In areas without petroleum deposits, methane from deep geological sources reaches the surface and is consumed by methanotrophs, creating detectable methane anomalies. Where petroleum deposits exist, they act as barriers, reducing surface methane flux and methanotroph activity. This inverse relationship helps identify petroleum prospecting targets.

During Penicillin G fermentation, Penicillium chrysogenum incorporates phenylacetic acid (or its precursor phenylacetamide) into the penicillin nucleus, forming the characteristic benzyl side chain of Penicillin G. This precursor addition is essential for biosynthesis. Phenoxyacetic acid is used for Penicillin V, and acetic acid is not a penicillin precursor.

In situ bioremediation method, oxygen is diffused only a few centimetres to 30 cm into the soil to achieve desirable rate of bioremediation.

Saccharomyces cerevisiae (baker's yeast) is a eukaryotic microorganism with immense industrial importance in baking (bread leavening), brewing (beer and wine production), and bioethanol production. Penicillium chrysogenum (option A) is also eukaryotic and industrially important but the question specifically notes Saccharomyces. Bacillus subtilis (option B) and Streptomyces griseus (option D, misspelled) are prokaryotic bacteria, not eukaryotes.

Rifamycin is primarily an antibacterial antibiotic effective against mycobacteria (tuberculosis, leprosy), not an antiviral agent. Actinomycin D is correctly matched as anti-tumor, Daunorubicin as anti-tumor/anti-cancer (not anti-protozoal), and Griseofulvin as anti-fungal. Therefore, only pair 3 (Rifamycin - Anti viral) is incorrectly matched.

In a chemostat under steady-state, if the dilution rate exceeds the maximum specific growth rate, cells wash out. Partial cell recycling returns biomass to the reactor, increasing the effective cell concentration and allowing steady-state operation at dilution rates higher than μmax. This decouples the dilution rate from the growth rate by maintaining biomass independently of growth rate.

In high viscosity fermentation, the stagnant liquid film surrounding gas bubbles becomes the rate-limiting resistance to oxygen transfer. High viscosity reduces turbulent mixing, creating a thicker boundary layer where molecular diffusion (much slower than convection) becomes the dominant transport mechanism. Bulk liquid transport and cell interface transfer are less affected by viscosity.

Dunaliella salina (a halophilic green alga) produces glycerol as an osmoprotectant in response to salt stress. Corynebacterium glutamicum is the industrial workhorse for glutamic acid (MSG) production. Alcaligenes faecalis (now reclassified as Achromobacter faecalis) produces curdlan, a bacterial polysaccharide. Streptomyces nodosus produces amphotericin B (likely what 'Amphoterin' refers to, possibly a variant name or typo).

Alcohol disrupts the cytoplasmic membrane integrity (2), iodine oxidizes sulfhydryl groups in enzymes (1), acridine dyes intercalate into nucleic acids (4), and quaternary ammonium compounds denature proteins (3). The matching A-3, B-1, C-4, D-2 correctly pairs each agent with its primary site of action.

In paper chromatography, compounds with identical Rf values in a given solvent system cannot be separated. Aspartic acid and glycine both have Rf=23 in the N-butanol-acetic acid-water (4:1:5) system, meaning they will migrate the same distance and remain unresolved.

Yoghurt is fermented by L. delbrueckii and S. thermophillus (3), cheese involves L. casei and S. thermophillus (4), sauerkraut uses L. mesenteroides and L. plantarum (2), while kefir traditionally contains L. acidophilus and L. delbrueckii (1).

Since some amino acids (like aspartic acid and glycine) co-migrate in one solvent but separate in another, two-dimensional chromatography is required. This technique uses two different solvent systems sequentially to achieve complete separation of all components.

Ethanol is produced by Zymomonas mobilis (b), streptomycin is an antibiotic from Streptomyces griseus (c), citric acid is fermented by Aspergillus niger (a), and cellulase is produced by Trichoderma reesei (d).