Q. How sex occurs in bacteria?

Occurrence of sex in bacteria was first described by Edward Tatum and Joshua Lederberg in 1946 (Nature, volume 158, page 558) who were studying mixed cultures of E. coli strains with various nutritional mutations. Mutant strains differed from wild type strains in lacking ability to synthesize growth factors like vitamins andamino acids, similar to strains in present problem. In one experiment, two triple mutants of E. coli, leucine, one requiring threonine and thiamine and the second requiring phenylalanine, biotin and cystine were grown in mixed cultures. At very low frequency, recombinant strains with no growth-factor requirement were obtained. They ruled out spontaneous mutations and transformation by culture medium as source of recombinant strains. In the words of Tatum andLederberg, 'These experiments suggest the occurrence of a sexual process in bacterium Escherichia coli.'