Antibiotics and Immunity

Colistin is the antibiotic produced by Paenibacillus polymyxa var. colistinus. Its target area is the cell membrane. It has both hydrophilic and lipophilic moieties. These regions interact with the cell membrane. They solubilise the membrane in an aqueous environment that exerts a bactericidal effect.

Lactone synthase plays a crucial role in the biosynthesis of erythromycin. It catalyses polyketide synthesis, which is a major step in erythromycin synthesis.

A-factor induces streptomycin production by Streptomyces griseus. It triggers cellular differentiation in Actinomyces. A-factor exerts its regulatory role by binding to a specific receptor protein which, in the absence of A-factor, acts as a repressor-type regulator for morphological and physiological differentiation.

Cephalosporin is produced by the fungus Acremonium chreysogenum. The other organisms employed for cephalosporin production are Emericeliopsis sp, Paecilomyces sp and Streptomyces sp.

Streptococcus and Streptomyces produce lantibiotics. They are effective against other Gram-positive bacteria.

Medarrhodine A is produced by hybrids that are obtained by genetic manipulations between Streptomyces coelicolor and S. violaceoruber genes.

Undeylprodigiosin is produced through the cloning of antibiotic biosynthesis genes of Streptomyces.

The serendipitous discovery of penicillin can be attributed to Staphylococcus aureus. In 1928, Fleming noticed a petri dish containing Staphylococcus that had been mistakenly left open. It was contaminated by blue-green mould from an open window, which formed a visible growth and formed zones of inhibition. He isolated the mould and coined the term penicillin.

Neplamosin A is produced by Ampullariella regularis. It possesses anti-viral activity.

Teixobactin was discovered in 2015 using a new method of culturing bacteria, Eleftheria terrae, in the soil. It is effective against Mycobacterium and Staphylococcus aureus.

Penicillin is produced by using Wis. Q176 strain. It is the most preferred strain of penicillin manufacturers.

Trimethylamine is an flammable tertiary amine. It is a product of decomposition of plants and animals. It is the substance mainly responsible for the odour often associated with fouling fish, infection and bad breath. It is also associated with taking large doses of choline and carnitine.

This is the correct answer as both statements b and c are incorrect. Members of a group of microbes have some traits, i.e. many biochemical processes inside their cells are similar. As a result, drugs that block one of these biochemical mechanisms in one member of the group will be effective against many other members of the group. The same drug will not be effective against a microbe belonging to a different group. Antibiotic penicillin acts against bacteria by blocking the biochemical pathways important for bacteria.

This option is correct as 0.2% solution of phenol acts as anticeptic whereas 1% solution acts as disinfectant.