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Fungi are prominent sources of pharmaceuticals and are used in many industrial fermentative processes, such as the production of enzymes, vitamins, pigments, lipids, glycolipids, polysaccharides and polyhydric alcohols.

During the past 50 years, several major advancements in medicine came from lower organisms such as molds, yeasts and the other diver’s fungi. Fungi are extremely useful in making high value products like mycoproteins and acts as plant growth promoters and disease suppressor. Fungal secondary metabolites are important to our health and nutrition and have tremendous economic impact. In addition to this, fungi are extremely useful in carrying out biotransformation processes. Recombinant DNA technology, which includes yeasts and other fungi as hosts, has markedly increased market for microbial enzymes.


Today, fungal biotechnology is a major participant in the global industry due to its mind blowing potential.

A) Designing of vectors

Yeast vectors are used in genetic engineering. E.g., shuttle vectors are used for expression
of desirable gene in both prokaryotic and eukaryotic systems.
YAC, YRP, YIP, YEP are some other yeast vectors.

B) Fungi as a food

Fungi are used as high cost food because of its high protein and low calorific value.
Europe, America, Australia and Japan are very playing industries in mushroom cultivation.

Some of the edible fungi (Mushrooms)are given as below.

1) Agaricus compestris

2) Volvariella (paddy straw mushroom)

3) Morchella (Temperate zone mushroom)

4) Pleurotus sp. (oyster mushroom)

5) Agaricus bisporus (white button mushroom)


C) Fungi as a rich source of SCP

Fungi are used as the rich sources of Single Cell Proteins. Some of the fungi for SCP are given as

1) Yeast (S. cerevisae)

2) Aspergillus niger

3) Penicillium chrysogenum

4) Fusarium avenacum

5) Neurospora sitoplila


D) Isolation of fungal metabolites of pharmaceutical importance

Aspergillus nidulans and other fungi are used for isolation of secondary metabolites. The secondary metabolites are used as drug. Ergot alkaloids (Ergometrin and Ergotoin) and Lovastatin, a popular cholesterol-lowering drug are the secondary metabolites.
Fungal metabolites have antitumour, antiviral, antibacterial and immunosuppressants activities.

E) Fungal pathogens as nibblers

Fungal pathogens are use as root nibblers to produce many root fibers that increase the maximum uptake of nutrients and water for more yield.Trichoderma viridae and fusarium has shown increased number of root fibres in Tomato & Maize plants.


F) Fungi in improving the quality of produce

It is evidence that some fungal diseases can enhance the nutritional quality of food & feed. E.g. smutted corn and rust infected wheat grains have more carbohydrate and phosphorus contents as compare to healthy plants.


G) Fungi as biofertilizes

Vesicular arbuscular mycorrhizae are the mutualistic symbiosis between the roots of higher plants and certain fungi. The mycorrhizae help in the phosphate nutrition of plants and protect the roots by forming the mantle.


H) Fungi as “Microbial weed killer “(Bioherbicides)

Fungi are known for its quite specific& effective action and have low residual effects in comparison with synthetic pesticides. Here are given some fungi as bioherbicides.

Fungi are used as bioherbicides,some examples with their targets are given in brackets.These are Septagloeum gillis (Mistletoes)

Wallrothiella arecuthobii (Mistletoes)

Colletotrichum gloeosporiordes(Mistletoes)

Phyllosticta (Glycosmis)

Leptosphaerulina trifolia(Passiflora)

Puccinia chondrillina(Rush weed)

Cercospora ageratinae(Pamakani weed)


I) Cellulose degradation by fungi


Heap of agricultural residues, forest residues deposited ample of celluloses in the soil. Only fungal cellulases are involved in degradation of deposited cellulose. Fusarium, Trichoderma, Penicillium derived cellulases are involved in degradation of celluloses.  Degradation of these leads maximum bioenergy production. Some of the other fungal enzymes are ? gluconase and ? glucosidase (cellobiase).


J) Bioconversion of lignin


White Rot fungi such as Coriolus versicolor, Polyporus ance and Brown Rot fungi like Poria monticola, Lenzitis trabea are used in depolymerization and degradation of lignin to low molecular weight Petroleum products. These fungi are also used in softening of wood in paper making industries.


K) Entamopathogenic fungi

This group of fungi secretes the toxin, which possesses the entemocidalproperties. The role of entamopathogenic fungi, its products and effects are given as below.


L) Industrial Applications of fungi

Fungi are widely used in fermentative industries for the production of ethanol, organic acids, antibiotics and enzymes like fungal cellulases, ? gluconase and ? glycosidase. Certain fungi like P.notatum, P.crysogenum and Cenococcum Sp.are used in antibiotics production where as S.cerevisae and Monilia Sp. are used in ethanol production. Fungi are also useful in ripening of cheese and processing of other products.


M) Biodegradation of pesticides/ Toxic chemicals and petroleum

White Rot fungi have the potential role in degradation of toxic pesticides like DDT, PCB and Lindane. In addition to this, it can degrade certain toxic chemicals like dioxin, benzopyrene, cyanides, azides, CCl4 and Pentachlorophenol (PCP). Aspergillus, Penicillium, Paecilomyces and Fusarium has found to be involved in petroleum degradation at 30 0C in contaminated soil.


N) Biodegradation of Azo dye and Hydrocarbons

Peroxidase enzyme of Penicillium crysosporium & Streptomyces sps. have potential biodegradable activities that degrade Amaranth dye, Orange G, heterocyclic dyes like, Azure B and Lip dye. The filamentous fungi are also having role in degradation of toxic hydrocarbons.


O) Fungi in Hazardous waste remediation

Fungi help in remediation of explosive contaminated soil by its lignin degrading Enzymes

TNT, RDX, HMX are some of the potential explosives that contaminates soil and water. Other degradable nitro explosives by Pleurotus ostreatus are as follows:

Nitrobenzene

4-Nitrophenol

4-Nitroaniline

1-Methoxy 4 nitrobenzene

2-Methoxy 4-nitro phenol

1, 2, di Methoxy 4 nitrobenzene


P) Biomineralization of Heavy Metals

The fungi have eminent role in the removal & recovery of heavy metals from wastewater and industrial effluents. Hg, Cu, Ni, Pb, Cd are extracted at pH 2-5 by myceliar beads of Penicillium.


Conclusion


Fungi are the organisms that have potential role in degradation of explosives. It is observed by repeated laboratory studies involving pure cultures of white rot fungi. It also helps in degradation of hydrocarbons in the environment. Fungi attract considerable attention due to their possible involvement in the diverse applications. So far, large numbers of enzymes have been purified from fungal cultures and characterized in terms of their biochemical and catalytic properties. It possesses antimicrobial activities and is used in biomineralization, as a food for its high protein contents and as a biofertilizers.


References

1) S.D. Aust, Degradation of environmental pollutants by phanerochaete-chrysosporium. Microbial Ecol 20:197-204. (1990)

2) J.A.Bumpus, S.D.Aust, Biodegradation of environmental pollutants by the white rot fungus phanerochaete chrysosporium: involvement of the lignin degrading system. BioEssays 6:166-170 (1987)

3) R.L. Crawford Lignin biodegradation and transformation. New York: John Wiley, (1981)

4) N.Capalash, and P. Sharma, Biodegradation of textile azo dyes by Phanerochaete chrysosporium. World J. Microbiol. Biotechnol.  8: 309-312. (1992)

5) M. Freitag, and J. J. Morell, Decolorization of the polymeric dye Poly R-478 by wood-inhabiting fungi.  Can. J. Microbiol.  38: 811-822. (1992)

6) E. Gogna, R. Vohra, and P. Sharma, Biodegradation of Rose Bengal by Phanerochaete chrysosporium.  Lett. Appl. Microbiol.  14: 58-60. (1992)

7) Paszczynski, V.B. Huynh, and R.L. Crawford, Comparison of ligninase-1 and peroxidase M-2 from the white-rot fungus Phanerochaete chrysosporium.  Arch. Biochem. Biophys. 244: 750-765. (1986)

8) T.L.Highley, Appl Environ Microbiol, 40:1145-1147. (1980)

9) W. Zhou and W. Zimmermann, Decolorization of industrial effluents containing reactive dyes by actinomycetes. FEMS Microbiol. Lett.  107: 157-162. (1993)

10) J.G.Leahy, R.R.Colwell, Microbiol Rev, 54:305-15. (1990)

by Ravi Dhande

Chloroplasts are one of the cellular organelles, and the site of photosynthesis, a basic metabolism in plants. the structure of chloroplasts is shown in image above. Chloroplasts posses an inner system of membranes, called thylakoids, which are surrounded by fluid compartments called stroma. Thylakoids contain chlorophyll where the light reaction occurs. In stroma, carbon reduction is carried out through the dark reaction. In the light reaction, ATP, chemical energy, and NADPH, reduction power, are synthesized using light energy. The ATP and NADPH generated by the light reaction system are transported to the dark reaction system, where carbon dioxide is fixed and carbohydrates are synthesized by the Calvin cycle. Some plants concentrate carbon dioxide into organic acids before the Calvin cycle.

In chloroplast there are independent genes. These are some of the extranuclear genes. Some chloroplasts proteins are synthesized in chloroplasts. The complete chloroplast genomes of several plants have been sequenced. Chloroplasts reproduce by division rather than synthesis and are divided between the two daughter-cells during cell division. However, at the time of sexual reproduction, chloroplast genes are transferred only through the maternal gamete in most cases. For this reason characters based on differences in chloroplast genes do not follow the Mendelian pattern of inheritance. Chloroplast DNA also contains introns, i. e. base sequences that do not code for protein. When proteins are synthesized, the mRNA is processed to remove the introns at first, and then the base sequences that code for protein are connected. This process is called splicing.

It is said that plants appeared on the earth during the time between the Ordovician period and the Silurian period of the Paleozoic era, some four hundred million years ago. The first plants that appeared on land may have been Pteridopytes or Bryophytes, and it is Pteridopytes that had become large-sized on land and markedly expanded their habitat by Carboniferous period of the Paleozoic era. Although unlike plants living in water, Pteridopytes cannot absorb water and nutrients from the whole plant body, they developed the tube system called vascular bundles, which enabled the plants to absorb water and nutrients at one part of the plant body and transport them to the other parts. In addition, after developing stomata on the surface of leaves, they are able to prevent water loss and lower the leaf temperature by opening and closing stomata. Thanks to these changes Pteridopytes adapted themselves to dry land conditions to some extent. Pteridopytes, however, need external water at the time of reproduction and their habitats were limited to areas not too dry, such as river coasts.

It is Spermatophytes that have evolved from Pteridopytes. Spermatophytes can tolerate dry conditions more pronouncedly. Because Spermatophytes do not need external water at the time of reproduction, they were suitable to life under dry inland conditions. Spermatophytes developed cuticle layers on the surface of the whole plant body, which effectively prevent water loss from the surface of the plant body, Spermatophytes include Gymnosperms and Angiosperms, and in the flower former ovules are exposed, whereas in the flower of the latter ovules are covered by ovaries. Gymnosperms appeared in the late Devonian period of the Paleozoic era and prospered during the time from the Carboniferous period to the Permian period. Angiosperms appeared during the time from the Jurassic period to the Cretaceous period of the Mesozoic era, and diversified during the period from then to the Cenozoic era. Angiosperms further differentiated into Monocotyledons and Dicotyledons.

At end of the process of plant evolution, crops appeared after the appearance of human beings, very recently in the history of the earth. Crops may have evolved from ancestral wild plant species by artificial selection. They can be distinguished from wild plants by many characteristics. One of them is the non-dormant characteristics of the seeds, by which crops germinate uniformly when planted. Crops do not contain toxic substances n store organs like fruits. The seeds or fruits of wild plants generally are detached from the plant body when mature, whereas the seed or fruits of crops are not and efficient harvest is possible. In crops, harvested organs, such as the grains of cereal crops, the fruits or fruit vegetables and the corms or tuberous roots in root crops, are enlarged abnormally.

Plants show characteristic responses to submergence. When plants and soil are submerged by water, the air in the gaseous space in the soil is quickly replaced with water. Plant roots generally obtain oxygen from the gaseous space in the soil. Thus, when this space is filled with water, plant roots rapidly fall into oxygen deficiency, leading to the retardation of the absorption of water and nutrients, which then adversely affects the growth and development of the aboveground parts. Characteristic responses of plants when submerged are leaf epinasty (increased growth on the upper surface of a leaf, causing it to bend downward), thickening of the stem base and the development of adventitious roots. Although the ecological significance of leaf epinasty is not well known, thickening of the stem base and the development roots are considered to be adaptive responses of plants to water submergence. The thickening of the stem base is caused by the development of aerenchyma (air spaces in plants) in the stem, which helps the transport of oxygen from aboveground to underground parts. Adventitious roots play the role of dead or lowfunctioning roots damaged by water submergence. Hygrophytes are plants adapted to marshland, which is generally submerged in water. Most of them develop aerenchyma in the stem, which enables the efficient transport of air from aboveground to underground parts, in order to adapt their roots to anaerobic conditions.

Salt accumulation in the soil (soil salinity) adversely affects plants. Various salts accumulate in the soil and the most problematic ones are chlorine and sodium ions. For animals, both chlorine and sodium are indispensable for their lives, but for plants they are not prerequisite and over-absorption often induce toxic effects of these ions are one of the causes of plant damage by soil salinity. Halophytes, which are adapted to saline soils in the coast or dry area, can protect themselves from the toxic effects of chlorine and sodium ions absorbed in their bodies. The other cause of plant damage by soil salinity is the blockage of water absorption. When salts are accumulated in the soil, the water absorption of roots is retarded, even though sufficient water is in the soil.