Question

43. How does the antibiotic Optochin kill bacteria? Explain.

44. Explain one culturable method to examine a water body for contamination

45. Explain one non-culturable method to examine a water body for contamination.

Answer 1

Ans .(43) Optochin ( or ethylhydrocupreine hydrochloride) is a derivative of hydroquine introduced in 1911 by Morgenroth and Levy with the intention to treat pneumococci infection.

In very high dilution inhibits the growth of reprsentatives of all four groups of pneumococci in invitro.

Ans .(44) Cell culture :- The sample is inoculated into susceptible host cell cultures, and the cultures are incubated to allow the viruses or parasites to infect the cells and proliferate . After an incubation period sufficient to produce enough nucleic acid for direct detection or further amplification, the nucleic acid is denatured and fixed either insitu or after extraction. Then the target nucleic acid is detected by hybridisation with a gene probe either directly or after further amplification by PCR.

Ans .(45) Non-culturable method :- This method include the use of non-selective media( yeast extract, nonselective broth, or agar media), less selective media( containing fewer or reduced concentrations of inhibitory agents). These methods are rarely used to detect pathogens in water bodies.

Filtration ( non-culturable method ) :- microbes can be recovered and concentrated from water by a variety of filtration methods.The most widely used filtration method for recovering bacteria is membrane filtration using microporous membranes typically composed of cellulose esters.