Recombinant DNA Technology

• Scope of Metagenomics:
• Over $99\%$ of environmental microorganisms cannot be cultured using standard microbiological media (the "great plate count anomaly").
• Metagenomics: Involves the direct extraction and shotgun high-throughput sequencing of total genomic DNA extracted directly from environmental samples (water, sediment, fish gut, biofilters).
• It comprehensively elucidates the taxonomic biodiversity, community structure, and metabolic/functional capabilities of entire uncultured microbial consortia.
• nalysis:
• (Biodiversity and functional aspect of microbial communities): Correct.

Correct option: (1) Biodiversity and functional aspect of microbial communities

• Generations of Sequencing Technologies:
• First-Generation Sequencing:
• Sanger Sequencing: Dideoxynucleotide chain termination using capillary electrophoresis. It is NOT a Next-Generation Sequencing (NGS) platform.
• Next-Generation Sequencing (NGS / 2nd Generation):
• Roche 454: Pyrosequencing on beads.
• Ion Torrent / Ion Proton: Semiconductor sequencing detecting released $H^+$ ions.
• Illumina: Reversible dye-terminator sequencing by synthesis.
• Third-Generation Sequencing (Long Reads):
• Oxford Nanopore Technologies (ONT): Direct electrical current disruption through protein nanopores.
• PacBio SMRT: Single-molecule real-time sequencing.
• nalysis:
• (Sanger sequencer): Correct (first-generation, not NGS).

Correct option: (1) Sanger sequencer

• Ribotyping and Microbial Identification:
• Ribotyping is a molecular fingerprinting method that identifies and classifies bacterial strains based on restriction fragment length variations in their ribosomal RNA genes.
• The 16S rRNA gene ($pprox 1500\text{ bp}$) is the universal molecular barcode for prokaryotes:
• Highly conserved regions provide universal primer binding sites across all bacteria.
• Interspersed hypervariable regions ($V_1 - V_9$) provide species- and genus-specific taxonomic signatures.
• nalysis:
• (16S rRNA): Correct (represented as 168 rRNA due to OCR scanning).

Correct option: (3) 168 rRNA