Use of mutant strains has been increased in industrial microbiology.

Explanation

(i) Use of microbes to obtain a product which is cheaper is now a trend is industrial Microbiology . Mutant strains are genetically improved strains which give higher yields and therefore decrease the cost of the products.
(ii) Mutant strains are formed by alterations of nucleotides is DNA of micro organisms to suit the needs of the industry.
(iii) Mutant strains are used for producing virus resistant bacterial strains are used in Dairy industry (milk products) so as to avoid the unwanted bacteria and virues attacking and out membering the original ones.
(iv) In alcohol industry mutant strains improve the flavour and quality of wine or beer.