diffraction is a good method to measuring interparticle spacing by detecting the
interference of waves reflecting on different crystal planes. It is used in mineralogy
to determine the crystal structure of mineral particles. Several or some of these
techniques are extensively used to characterize many different metal NPs.
6.6 Specialized Metabolites in Actinobacteria
The use of antibiotics to human health care is rather new and emerged from the
discovery of penicillin in 1928. After the penicillin, mainly between the 1950s and
1970s, the search of new active molecules resulted in several classes of antibiotic,
antifungal, antihelminthic, and anticancer agents. In this period, actinobacteria
emerged as excellent bioactive metabolite producers, especially Streptomyces and
Micromonospora genera (Davies and Davies 2010). Discovery of antibiotics led to
the perception that these molecules were a kind of “wonder drugs” that killed bad
bugs and reduced human deaths by bacterial infections. However, almost immediately after the introduction of these wonder drugs to medicine, bacterial resistance
was observed. The apparition of bacterial resistance triggered a race towards the
discover of new antibiotics. However, the introduction of new drugs did not avoid
the appearance of short-term resistance in pathogens. This natural adaptation in
addition to the uncontrolled use of antibiotics in agriculture and medicine turned
resistance to antibiotic in a global concern. This problem encouraged researchers,
clinicians, industry, and politicians to work together in search of new bioactive
molecules using a biological platform actinobacteria.
As we previously mentioned, Actinobacteria is a diverse phylum in which the
metabolic versatility is a primordial feature (Dávila Costa and Amoroso 2014;
Alvarez et al. 2017). Primary metabolism is present in all living organisms and
encompasses all essential reactions. Secondary metabolism is more specific, distinctive, and often encompasses species-specific pathways (Hartmann 2008). Species
specificity is not an exception for the genera Bifidobacterium, Corynebacterium,
Mycobacterium, Nocardia, Amycolatopsis, Frankia, and Streptomyces, whereby
they have acquired medicinal, agriculture, and industrial importance. Probably, the
most specialized genera are Streptomyces and Amycolatopsis, which are sporulating
bacteria with filamentous growth, high G + C content, and linear genomes. Life cycle
of these bacteria begins with a unigenomic spore which germinates and grows to
form vegetative mycelia that, in response to nutrient limitation, produce aerial
hyphae, which subsequently form septa and eventually mature spores. Often, specialized metabolites are produced at the onset of the developmental process. Specialized metabolites synthesized by the genera Streptomyces and Amycolatopsis are
chemically diverse and include lactams, terpenes, nonribosomal peptides,
aminoglycosides, and polyketides.
6 Nanoparticles for New Pharmaceuticals: Metabolites from Actinobacteria
205
interference of waves reflecting on different crystal planes. It is used in mineralogy
to determine the crystal structure of mineral particles. Several or some of these
techniques are extensively used to characterize many different metal NPs.
6.6 Specialized Metabolites in Actinobacteria
The use of antibiotics to human health care is rather new and emerged from the
discovery of penicillin in 1928. After the penicillin, mainly between the 1950s and
1970s, the search of new active molecules resulted in several classes of antibiotic,
antifungal, antihelminthic, and anticancer agents. In this period, actinobacteria
emerged as excellent bioactive metabolite producers, especially Streptomyces and
Micromonospora genera (Davies and Davies 2010). Discovery of antibiotics led to
the perception that these molecules were a kind of “wonder drugs” that killed bad
bugs and reduced human deaths by bacterial infections. However, almost immediately after the introduction of these wonder drugs to medicine, bacterial resistance
was observed. The apparition of bacterial resistance triggered a race towards the
discover of new antibiotics. However, the introduction of new drugs did not avoid
the appearance of short-term resistance in pathogens. This natural adaptation in
addition to the uncontrolled use of antibiotics in agriculture and medicine turned
resistance to antibiotic in a global concern. This problem encouraged researchers,
clinicians, industry, and politicians to work together in search of new bioactive
molecules using a biological platform actinobacteria.
As we previously mentioned, Actinobacteria is a diverse phylum in which the
metabolic versatility is a primordial feature (Dávila Costa and Amoroso 2014;
Alvarez et al. 2017). Primary metabolism is present in all living organisms and
encompasses all essential reactions. Secondary metabolism is more specific, distinctive, and often encompasses species-specific pathways (Hartmann 2008). Species
specificity is not an exception for the genera Bifidobacterium, Corynebacterium,
Mycobacterium, Nocardia, Amycolatopsis, Frankia, and Streptomyces, whereby
they have acquired medicinal, agriculture, and industrial importance. Probably, the
most specialized genera are Streptomyces and Amycolatopsis, which are sporulating
bacteria with filamentous growth, high G + C content, and linear genomes. Life cycle
of these bacteria begins with a unigenomic spore which germinates and grows to
form vegetative mycelia that, in response to nutrient limitation, produce aerial
hyphae, which subsequently form septa and eventually mature spores. Often, specialized metabolites are produced at the onset of the developmental process. Specialized metabolites synthesized by the genera Streptomyces and Amycolatopsis are
chemically diverse and include lactams, terpenes, nonribosomal peptides,
aminoglycosides, and polyketides.
6 Nanoparticles for New Pharmaceuticals: Metabolites from Actinobacteria
205