How was insulin obtained before the advent of $rDNA$ technology? What were the problems encountered?

Which of the following is produced using $E. coli$?

Human insulin is being commercially produced from a transgenic species of

Some of the steps involved in the production of humulin are given below. Choose the correct sequence.
$(i)$ Synthesis of gene $(DNA)$ for human insulin artificially.
(ii) Culturing recombinant $E. coli$ in bioreactors.
(iii) Purification of humulin.
(iv) Insertion of human insulin gene into plasmid.
$(v)$ Introduction of recombinant plasmid into $E. coli$.
(vi) Extraction of recombinant gene product from $E. coli$.

Which genetically modified organism is used for the commercial production of human insulin?

Which company first produced human insulin?