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Genetic manipulation techniques have played an important role in enhancing the performance of microorganisms that are significant in the industrial, pharmaceutical and medical application areas. It is important to highlight the fact that they are generic, and also that they can be employed to improve the performance of any cell or microorganism for specific applications.
Mutagenesis:
Mutagenesis can be defined as the group of techniques or processes that produce changes in a DNA sequence which modifies either the expression of genes or the structure of the gene products.
Two subcategories of mutagenesis are usually applied in the genetic manipulation of microorganisms: classical mutagenesis and transposon- directed mutagenesis. Classical Mutagenesis involves the use of chemical mutagens to regulate a process of interest in the target microorganism.
The main purpose of this ‘classical’ approach is to find the mechanism of action of the targeted microorganism. Transposon-directed Mutagenesis consists in the genetic alteration of a few sites on the target chromosome in order to determine the function of this specific site of the chromosome.
By comparison with the previous category transposon-directed mutagenesis it is more specific, and is therefore preferred in specific applications that require higher selectivity.
Gene Transfer:
Electroporation involves the production of transient pores in a bacterial cell membrane following the application of high-voltage electric field (DC) pulses of short duration. Such pores allow the introduction of DNA into the cell under certain, favourable conditions. Such methods have been used with various microorganisms and even plasmids that are of significant use in the industry.
Another technique that is employed for the transference of genes involves Shuttle Vectors. Shuttle vectors are DNA constructs that are able to replicate and deliver DNA to widely divergent types of bacteria. DNA transference is obtained after the use of a microorganism whose mechanisms of action have been thoroughly studied, as for example, is the case of various E. coli strains.
Gene Cloning:
Gene cloning and genomic maps to clone the genes of industrially-significant microorganisms have also been reported to be subsequently introduced in native strains of the microorganism of interest.
DNA Analysis:
DNA analysis involves the study of a particular region of DNA by either physical or chemical techniques. It is usually carried out in order to obtain insights into the genetic organisation, the mechanisms of gene expression, or to obtain information that may be useful for the construction of shuttle vectors.
Applications to Food Industry:
Pioneering studies of genetic manipulation of microorganisms with significant applications to foods were initially based on Escherichia coli as a microbial model because of its ease of growing and manageability.
Subsequent studies were carried out in the production of dairy starters, as well as the amino acid and yeast production for brewing purposes, and more recently attempts are being made to produce butanol through fermentation.