146
2015). Although antibiotics belong to the most important veterinary drugs, information about their biotransformation in plants is only limited. Migliore and his group
(2003) studied phytotoxicity, uptake, and biotransformation of enrofloxacin in crop
plants such as Cucumis sativus, Lactuca sativa, Phaseolus vulgaris and Raphanus
sativus. Their results showed that plants were able to metabolize enrofloxacin into
ciprofloxacin via deethylation reaction. The other example includes the biotransformation of the NSAID diclofenac. NSAID diclofenac is found in the environment
worldwide due to its intensive use and poor elimination during wastewater treatment processes. In order to test phytoremediation as a tool for the removal of this
drug from wastewater, the uptake of the compound into plant tissues and its metabolic pathway was addressed using barley (Hordeum vulgare) and a hairy root cell
culture of horseradish (Armoracia rusticana) as model species. Diclofenac was
taken up by plants and underwent rapid biotransformation. A phase I reaction
resulted in the hydroxylated metabolite 40OH-diclofenac, which was conjugated
subsequently in phase II to a glucopyranoside, a typical plant-specific metabolite
(Huber et al. 2012).
5.4
Biotransforming Enzymes in Microbes
The recognition of microbial biotransformation has created a boom in the chemical
and pharmaceutical industries. In recent years, microbial biotransformation has
become an inevitable process in green chemistry. The wide variety of microbial
strains and enzymes with their selective biotransformation potential has resulted in
the bioconversion of a myriad of different substances into desired products.
It is only after the nineteenth century, targeted application of microbial transformations came into emergence. The fusion of two sciences, namely, organic chemistry and microbiology, has resulted in the tremendous growth of this field. The
technology of microbial transformation deals with the isolation of microbial
enzymes to catalyse bioconversions of organic compounds.
Microbial transformation offers the advantages of operating at non-extreme pH,
near room temperature and reduced levels of toxic waste products with high selectivity. This metabolic flexibility of the microorganisms is exploited in the production of different enzymes for different reactions. However, the syntheses of these
enzymes are regulated according to the physiological needs of the cells. The practice of biotransformation with recombinant microbial enzymes is gaining importance; the applications may include the production of hormones, antibiotics and
special chemicals. Microbial transformation might be useful in cases where there is
no chemical solution for chemical transformations.
Microbial transformations make use of enzyme-catalysed reactions within living
cells, typically exploiting single chemical reactions like oxidation, reduction,
hydrolysis and degradation, formation of C-C or C-hetero atom bonds (Gopishetty
et al. 2007) (Table 5.4).
Economically, microbial biotransformations can be used in the manufacture of
alkaloids, antibiotics, vitamins, amino acids, fermented beverages and fermented
foods. Another feature of microbial transformation is its ability to imitate
S. Sudhakaran et al.
2015). Although antibiotics belong to the most important veterinary drugs, information about their biotransformation in plants is only limited. Migliore and his group
(2003) studied phytotoxicity, uptake, and biotransformation of enrofloxacin in crop
plants such as Cucumis sativus, Lactuca sativa, Phaseolus vulgaris and Raphanus
sativus. Their results showed that plants were able to metabolize enrofloxacin into
ciprofloxacin via deethylation reaction. The other example includes the biotransformation of the NSAID diclofenac. NSAID diclofenac is found in the environment
worldwide due to its intensive use and poor elimination during wastewater treatment processes. In order to test phytoremediation as a tool for the removal of this
drug from wastewater, the uptake of the compound into plant tissues and its metabolic pathway was addressed using barley (Hordeum vulgare) and a hairy root cell
culture of horseradish (Armoracia rusticana) as model species. Diclofenac was
taken up by plants and underwent rapid biotransformation. A phase I reaction
resulted in the hydroxylated metabolite 40OH-diclofenac, which was conjugated
subsequently in phase II to a glucopyranoside, a typical plant-specific metabolite
(Huber et al. 2012).
5.4
Biotransforming Enzymes in Microbes
The recognition of microbial biotransformation has created a boom in the chemical
and pharmaceutical industries. In recent years, microbial biotransformation has
become an inevitable process in green chemistry. The wide variety of microbial
strains and enzymes with their selective biotransformation potential has resulted in
the bioconversion of a myriad of different substances into desired products.
It is only after the nineteenth century, targeted application of microbial transformations came into emergence. The fusion of two sciences, namely, organic chemistry and microbiology, has resulted in the tremendous growth of this field. The
technology of microbial transformation deals with the isolation of microbial
enzymes to catalyse bioconversions of organic compounds.
Microbial transformation offers the advantages of operating at non-extreme pH,
near room temperature and reduced levels of toxic waste products with high selectivity. This metabolic flexibility of the microorganisms is exploited in the production of different enzymes for different reactions. However, the syntheses of these
enzymes are regulated according to the physiological needs of the cells. The practice of biotransformation with recombinant microbial enzymes is gaining importance; the applications may include the production of hormones, antibiotics and
special chemicals. Microbial transformation might be useful in cases where there is
no chemical solution for chemical transformations.
Microbial transformations make use of enzyme-catalysed reactions within living
cells, typically exploiting single chemical reactions like oxidation, reduction,
hydrolysis and degradation, formation of C-C or C-hetero atom bonds (Gopishetty
et al. 2007) (Table 5.4).
Economically, microbial biotransformations can be used in the manufacture of
alkaloids, antibiotics, vitamins, amino acids, fermented beverages and fermented
foods. Another feature of microbial transformation is its ability to imitate
S. Sudhakaran et al.