Enzyme preparation is a catalytic protein produced by biological body and an essential element in all metabolic processes. Using protoplast mutagenesis technology, many high-yield strains were obtained.
Hu Jie et al. [10] carried out UV-LiCl, N- methyl-N ′-nitro -N- nitrosoguanidine (N-method-N ′-nitro -N- nitroguanidine, Nt. Eight mutant strains with high neutral protease production were screened out, and the highest enzyme production was 1 162 times that of the original strain, which provided an excellent candidate library for cell fusion and genome recombination in the future.
3.2 Application of Antibiotic-producing Strain Breeding
Antibiotics are secondary metabolites of microbial cells. At present, microbial fermentation is mainly used for biosynthesis. Because the yield of producing strains is restricted by multi-step metabolic regulation, it is also difficult to select high-yield strains. Protoplast mutation, as a mutation technology, has been widely used in the breeding of high-yield strains of antibiotics.
Zhu et al. [1 1] mutagenized the protoplast of Streptomyces cerevisiae by ultraviolet, and obtained a high-yield mutant with a yield of 1 159g/L, which was10/65438 higher than the original strain.
3.3 Application in Breeding of Amino Acids, Production Solvents and Organic Acids
Amino acid is the basic unit of protein, and protein is a kind of biological functional polymer. Widely used in food, feed, medicine, chemical industry, agriculture and other industries, countries are vigorously developing amino acid production. Fermentation has become the main method of amino acid production. Therefore, breeding high-yield strains is an important direction for the development of amino acid industry.
Production solvents and organic acids are the primary metabolites of microorganisms, and protoplast mutagenesis technology has also achieved results in the breeding of production solvents and organic acid-producing bacteria.
3.4 Application of Biological Strain Breeding
Vitamins are a kind of organic substances that are necessary to maintain human and animal life activities, but cannot be synthesized by themselves, and play an important role in the process of growth, metabolism and development. Han et al. treated the protoplast of Penicillium PT95 with laser, and selected a mutant strain L05 with significantly increased sclerotium biomass and carotenoid content. The yield of mutant sclerotia increased by 98.6%, the carotenoid content in sclerotia increased by 28.3%, and the carotenoid yield increased by 154.0%.
3.5 Application of Insect Breeding
Bacillus thuringiensis is a bacterial microbial insecticide screened from nature, which is mainly used to control agricultural and forestry pests. Wang Leehom et al. [12] mutated the protoplast of Bacillus thuringiensis NU- 2 by UV-LiCl compound mutagenesis, and the fermentation period of the screened mutant was shortened from 44h to 40.3h, and the crystal protein content was increased by 10.03%.