Question

40. Why have researchers turned to the techniques of metagenomics to get a grasp on the abundance and diversity of microbes in the marine environment? (2)

41. Prochlorococcus is a marine cyanobacteria. Since this organism is a prokaryote (no chloroplasts), how does it photosynthesize? (2)

Answer 1

40.

Ans: Traditional techniques such as cultivation of clonal cultures followed by genomic sequencing do not provide the complete picture of microbial diversity in the given area of sampling. However, the metagenomics leverage the advantage of lowering of price of genomic sequencing and provide the powerful tool to reveal previously unknown microbial life and microbial ecology at higher scale and in detail than any other traditional techniques.

Metagenomics offers wide applications in various fields such as given below.

# Agriculture: Inhabited microbial ecology of soil is very complex but plays important role in role in ecosystem servicing such as fixing the atmospheric nitrogen, sequestering of metal ions such Iron, suppression of diseases, recycling of nutrients and growth of plants. Metagenomics can contribute in indentifying the useful micro-flora which can provide enhanced disease protection of crops and livestock and also help the to improve health of the crops.

# Human health: Metagenomics of gut microflora can provide the status of human health and provide the cluster of organisms that are most important for the health of intestinal tract. Metagenomics approach also provide the promising and sensitive tool for rapid diagnosis of infection of patient by comparing with the databases of millions of microorganism.

41.

Though Prochlorococcus are prokaryotes and does not possess the chloroplasts,

They contain a remarkable pigment complement that consists of divinyl derivatives of chlorophyll a (Chl a ) and Chl b, which are also called as Chl a₂ and Chl b₂. Their photosynthetic apparatus also possess light-harvesting complexes which perform the similar function but are structurally different than algae and plants. Few strains also contain phycoerythrin.

Thus, the combination of Chl a, Chl b , and at least presence of one phycobiliprotein is a unique feature which allows these microorganism to do photosynthesise.