319
12.4.6 Filamentous Fungi
Fungi have been historically recognized as the food of gods. Many fungi are considered as sources of highly nutritious and palatable sources of food materials since
ancient times. Many cultures, particularly the Asian culture, had an understanding
of the curative properties of fungi and were sometimes referred to as an elixir of life.
Today, fungi are being explored as potential sources of pharmaceutically important
molecules. The macroscopic fungi represented by edible morels, mushrooms, puffballs and cultivated agarics sold as food form only a tiny fraction of the fungal
kingdom. The microscopic fungi represented by molds and yeasts form the majority
of economically important plant parasites, allergenic species and opportunistic
pathogens of humans and animals. The microscopic fungi are characterized by filamentous vegetative outgrowths called as the hyphae. A mass of such hyphae forms
the vegetative body of the fungus called the thallus composed of mycelium. The
hyphae of fungi can be aseptate as seen in phylogenetically primitive molds like
water molds, bread molds and other sporangial forms. They produce coenocytic
filaments composed of multinucleate cells without cross walls. Septated hyphae are
produced by advanced fungi in which the filaments are separated into uninucleate
or multinucleate compartments by the formation of the septum. The septa help in
intercytoplasmic communication. Certain fungi like the yeast do not form filamentous hyphae. They exist as unicellular organisms that reproduce by vegetative budding. Some fungi, especially opportunistic pathogens like Candida albicans, are
dimorphic in nature with the ability to grow as hyphal forms outside the host and as
vegetative reproducing yeast inside the host system. Fungi are heterotrophic in
nature and can either be saprophytic or parasitic. Saprophytic fungi rely on nonliving organic matter as the source of carbon, while parasitic fungi utilize living
organic matter for carbon source. Micromolecules like simple sugars and amino
acids enter the fungal cell by simple diffusion after accumulating around the hyphae.
Macromolecules are digested in the extracellular atmosphere before being taken up
into the cell by secreted proteolytic, glycolytic and lipolytic enzymes.
12.4.6.1 Antimicrobials from Fungi
The fungi belonging to basidiomycota and ascomycota are valuable reservoirs of
biologically active molecules. Several biomedically significant secondary metabolites have been isolated from the fungal fruiting bodies, mycelia and culture broth
of submerged cultivations. Basidiomycota and ascomycota represent the most
diverse groups in the fungal kingdom. They produce secondary metabolites with
wide range of biological activity including antibacterial, antiviral, antifungal, antitumor, anti-inflammatory and immunomodulatory effects along with an impact on
cardiovascular disorders, hypercholesterolemia and diabetes. Some of the recently
identified antimicrobial lead compounds from fungi are enlisted in Table 12.2.
12.4.6.2 Antibacterial Antibiotics
The first antibiotic ever isolated from a natural source came from a fungus belonging to the phylum ascomycota. Penicillin was discovered in 1928 by the Scottish
12 Antimicrobials from Microbes
12.4.6 Filamentous Fungi
Fungi have been historically recognized as the food of gods. Many fungi are considered as sources of highly nutritious and palatable sources of food materials since
ancient times. Many cultures, particularly the Asian culture, had an understanding
of the curative properties of fungi and were sometimes referred to as an elixir of life.
Today, fungi are being explored as potential sources of pharmaceutically important
molecules. The macroscopic fungi represented by edible morels, mushrooms, puffballs and cultivated agarics sold as food form only a tiny fraction of the fungal
kingdom. The microscopic fungi represented by molds and yeasts form the majority
of economically important plant parasites, allergenic species and opportunistic
pathogens of humans and animals. The microscopic fungi are characterized by filamentous vegetative outgrowths called as the hyphae. A mass of such hyphae forms
the vegetative body of the fungus called the thallus composed of mycelium. The
hyphae of fungi can be aseptate as seen in phylogenetically primitive molds like
water molds, bread molds and other sporangial forms. They produce coenocytic
filaments composed of multinucleate cells without cross walls. Septated hyphae are
produced by advanced fungi in which the filaments are separated into uninucleate
or multinucleate compartments by the formation of the septum. The septa help in
intercytoplasmic communication. Certain fungi like the yeast do not form filamentous hyphae. They exist as unicellular organisms that reproduce by vegetative budding. Some fungi, especially opportunistic pathogens like Candida albicans, are
dimorphic in nature with the ability to grow as hyphal forms outside the host and as
vegetative reproducing yeast inside the host system. Fungi are heterotrophic in
nature and can either be saprophytic or parasitic. Saprophytic fungi rely on nonliving organic matter as the source of carbon, while parasitic fungi utilize living
organic matter for carbon source. Micromolecules like simple sugars and amino
acids enter the fungal cell by simple diffusion after accumulating around the hyphae.
Macromolecules are digested in the extracellular atmosphere before being taken up
into the cell by secreted proteolytic, glycolytic and lipolytic enzymes.
12.4.6.1 Antimicrobials from Fungi
The fungi belonging to basidiomycota and ascomycota are valuable reservoirs of
biologically active molecules. Several biomedically significant secondary metabolites have been isolated from the fungal fruiting bodies, mycelia and culture broth
of submerged cultivations. Basidiomycota and ascomycota represent the most
diverse groups in the fungal kingdom. They produce secondary metabolites with
wide range of biological activity including antibacterial, antiviral, antifungal, antitumor, anti-inflammatory and immunomodulatory effects along with an impact on
cardiovascular disorders, hypercholesterolemia and diabetes. Some of the recently
identified antimicrobial lead compounds from fungi are enlisted in Table 12.2.
12.4.6.2 Antibacterial Antibiotics
The first antibiotic ever isolated from a natural source came from a fungus belonging to the phylum ascomycota. Penicillin was discovered in 1928 by the Scottish
12 Antimicrobials from Microbes