In our previous article we had explained the role of bacteria in maintaining the mountain ecology.
This article highlights the role of yet another important microorganism namely, FUNGI in shaping
the mountain ecology. Fungi are a group of diverse and widespread unicellular and multicellular
eukaryotic microorganisms.
Fungal species are commonly found in soil, in water, on plant debris, and as symbionts, parasites,
and pathogens of animals, plants, and other microorganisms. Saprophytic species are important in
the decomposition of plant litter and in the recycling of organic matter. Scientists have reported that
in nature fungal colonies have been known to continue growing for 400 years or more.
Many fungi are involved in symbiotic associations with various biotic partners within the mountain.
Classical examples are mycorrhizae, lichens, and mycetocytes.The systematic study of fungi dates
back to the early part of the 17th century. The ancient Greeks and Romans were experts in wine
fermentation but they had no modern tools to understand and imply that fungi were largely
responsible for these transformations. Fungus (pl.fungi) constitutes a group of living organisms
devoid of chlorophyll. Fungi resemble plants in structure and are capable of utilizing inorganic
nitrogen compounds but appear to be more related to animals in requiring oxygen in their
metabolism and eliminating carbon dioxide.
They have definite cell walls, usually non motile, (they may have motile reproductive cells) and
they reproduce by means of spores. Next to Bacteria, fungi are the most dominant group of
microorganisms in soil. The primary role of fungi on the mountain is to degrade the vast amounts of
complex organic molecules generated from time to time due to the addition of mature plant
residues, green manures, organic manures, leaf litter, and convert them into simpler compounds
necessary for plant growth and development. Farmers need to understand that most of the biomass
available on the farm is relatively free from toxic materials and can be used as stimulants for growth
and development of beneficial fungi.
Fungi are important agents in the bio degradation of cellulose, hemi cellulose, starch, pectin,
organic acids, disaccharides, fats and lignin which is particularly resistant to bacterial degradation.
Fungi are known to adapt themselves to even the most complex of food materials. Fungi are largely
responsible in the formation of ammonium and simple nitrogen compounds in soil. Many species of
fungi form symbiotic association with plant roots and help in plant growth. Fungi are capable of
utilizing simple substances and build them into compounds of higher molecular weight bearing
great complexity.
Secondly, We need to appreciate the role of fungi in improving soil texture and in soil aggregation.
Many fungi are known to produce substances similar to humic substances there by energizing the
humic content and organic matter content of the soil. The biomass and organic matter on the forest
floor is composed of polysaccharides of varying complexity. Fungi use starch as an excellent source
of carbon, chitin is used both as a carbon and nitrogen source by few species of streptomyces.
Lipids are attacked by molds. Complex proteins and polypeptides are further broken down with the
help of enzymes.
Fungi consist of filamentous mycelium
composed of individual hyphae. The hyphae
may be uni or multinucleate and with or without
cross walls. The length of fungal mycelium
ranges from 50 to 100 meters per gram of
surface soil and few microbiologists have
recorded values up to 500 meters. Based on
filament diameter, specific gravity and mycelial
length the weight of fungi ranges from
approximately 500 to 6000 kg per hectare of
surface soil. The fungal mycelium spreads like a
mat and is closely attached to soil particles.
These figures indicate the importance of fungi
in farm ecology.
The farm consists of well drained and well aerated soils for the simple reason that they cannot
tolerate water logged conditions. Luckily, for the farmer, these soil characteristics, together with a
thick cover of leaf biomass favors the growth and proliferation of beneficial fungi. Because of their
large diameter and underground net work of filaments they contribute significant amounts of total
microbial protoplasm, to the soil economy.
MYXOMYCOTA:
Myxomycetes are also known as SLIME MOLDS. The characteristic feature of these slime fungi
is that they colonize decaying wood, leaf litter, and other organic residues on the floor of the forest.
They profusely produce spores known as SPORANGIA. During favorable conditions the spores
germinate and the fungal mycelium spreads rapidly attacking the organic debri.
EUMYCOTA: MASTIGOMYCOTINA:
They are also referred to as algal fungi. This group comprises several molds, saprophytes, soil
forms, parasites and pathogens. Some are known to be parasitic on insects. The asexual spore
bearing structure is called SPORANGIUM. They may germinate directly giving rise to germ tubes
which form hyphae and mycelium. The fungus is also capable of sexual reproduction.
Some species of fungi are known to be plant pathogenic. E.g. Phytophthora infestans.
ZYGOMYCOTINA:
Mucor, Rhizopus and Pilobolus are the common genera under this group. They obtain their nutrients
from the substrate.
In the evolutionary ladder this group consists of advanced morphological characters and sexual forms
of reproduction. Zygomycetes and Trichomycetes are the two classes of fungi under this group.
ASCOMYCOTINA:
They are also referred to as sac
fungi because their spores are
formed in a sac called ascus.
Some fungi are unicellular like yeasts and some like Morchella are highly developed with large fleshy
structures. Ascomycetes are very important from the agricultural view point because they are adapted
to varied habitats. There are over 35,000 species under this sub division. They are more advanced than
the Phycomycetes.
YEASTS:
Yeasts are spherical, ovoid, or rod shaped unicellular fungi. They are widely distributed in mountain
soils and sometimes present even on plant parts.
They reproduce by the budding mechanism but under certain circumstances a few of them may
grow into filamentous forms.
BASIDIOMYCOTINA:
This group of fungi too is important from the farmer's perspective because some are saprophytes
and others are parasitic. There are more than 15,000 species under this sub division. Basidiomycetes
are highly developed fungi. They bear a reproductive structure known as BASIDIUM. The fungi
included in this group are mushrooms, toadstools, puffballs, rust, smut fungi, etc.
DEUTEROMYCOTINA:
Fungal species which produce only asexual spores and not sexual spores are considered to be
imperfectly understood, hence called Fungi Imperfecti (DEUTEROMYCETES). Some of the
fungal species under this subdivision are the Aspergillus, Trichoderma, Rhizoctonia, Penicillium,
and Gleosporium. The above mentioned fungi commonly inhabit berry soils and most of them are
of great commercial value in the preparation of microbial inoculants.
GROWTH AND REPRODUCTION:
There are two phases in the life cycle of fungi.
They may take place simultaneously or in succession. Way back in 1900 Klebs reported
that the reproduction in FUNGI is governed by 4 laws.
1. Growth and reproduction are life processes, which depend upon different sets of conditions;
in the lower organism's external conditions mainly, determine whether growth or
reproduction takes place.
2. Reproduction in the lower organisms does not occur as long as characteristic external conditions
which are favourable for reproduction are always more or less unfavourable for growth.
3. The process of growth and reproduction differ in that growth may take place under a wide range
of environmental; conditions than reproduction; growth may take place , therefore under conditions
which inhibit reproduction and
4. Vegetative growth appears to be mostly a preliminary step for reproduction in that it creates a
suitable internal environment for it. The pioneering work done by Klebs holds good even today.
EXTERNAL INFLUENCES ON FUNGAL GROWTH AND DEVELOPMENT
ORGANIC MATTER STATUS:
The quality and quantity of organic matter plays a major role in the abundance of fungi. The
number of filamentous fungi in soil varies depending on the amount of utilizable organic matter
present in soils. Addition of organic matter stimulates fungal activity and is maximum during the
initial period of decomposition.
HYDROGEN ION CONCENTRATION:
Fungi are dominant in acid soils because acidic environment is not favourable for the growth and
multiplication of either bacteria or actinomycetes. This special evolutionary mechanism to tolerate
highly acidic conditions results in the power of adaptation to hostile environments, including highly
acidic soils. However, fungi can also grow in neutral or alkaline soils and some species can tolerate
hydrogen ion concentrations beyond pH values of 8.0.
MOISTURE:
The moisture requirement varies from species to species. Soils which have relatively high moisture
regimes, suppress the growth and development of certain fungi. Fungi belonging to Basidiomycetes
multiply profusely in wood containing less than 20 % moisture. On the other hand the
Phycomycetous fungi require very high moisture content for its growth and multiplication. Various
moisture regimes determine the fate of spore germination. In general, a high level of moisture
facilitates the germination of spores and other reproductive structures of the fungus.
AERATION:
Mountain soils which are well aerated contain abundant fungi because most of the fungal species
are aerobic.
TEMPERATURE
Most fungal species are mesophilic (25 to 35 degree centigrade). However in compost pits, the
presence of thermophilic fungi is commonly observed. Thermophilic fungi multiply at 50 to 60
degree centigrade but not at 65 degree centigrade.
SEASON:
Since the mountains are exposed to different seasons, it has a very deleterious effect on the fungal
population. The rainy season provides ideal conditions for the proliferation of fungi but in heavy
rainfall regions receiving in excess of 200 inches per annum [includes snow] the growth of fungi are
restricted. December and January are winter months in the mountain area and fungi are at low ebb
during these months.
TYPE OF VEGETATION:
Incorporation of crop residues, green manures and carbonaceous materials improves the microbial
load, particularly the fungal growth. Certain species dominate initially, but subsequently their
numbers decline. Some species maintain high population levels for relatively long periods after the
incorporation of plant residues.
DEPTH:
Different species of Fungi are known to occupy different ecological niches. They exhibit selective
preferences for various depths of soil. At different soil horizons different species of fungi reside. In
berry soils, fungi are most numerous in the surface layers. A great number of species occur on the
surface, and sub surface of soils than in deeper layers of soil. The influence of depth on the distribution
and abundance of fungal species may be due to the availability of organic matter and the composition
of soil atmosphere.
FARM PRACTICES:
Fertilizers, chemicals, weedicides, nematicides, algaecides, pesticides and insecticides influence the type
of fungal flora. Ammonium fertilizers are commonly applied in commercial farms. The addition of
ammonium fertilizers increases the fungal population and diminishes the bacterial and actinomycete
population.
NUTRITION:
Most fungi are heterotrophs and to date there are no reports of fungi having the pigment chlorophyll
to manufacture their own food. The nutrients enter the fungal cell / hypha in solution. Some fungi
can use any of the wide range of compounds as sources of carbon and energy while others have
highly specific nutritional requirements. A number of fungi require specific growth factors.
Inside the mountain fungi obtain their food either as PARASITES (infecting living organisms) or by
attacking dead organic matter as SAPROBES. Fungi that live on dead matter and are incapable of
infecting living organisms are called OBLIGATE SAPROBES ; those capable of causing disease or of
living on dead organic matter, according to circumstances are referred to as FACULTATIVE
SAPROBES, and those that cannot live except on living protoplasm are called OBLIGATE PARASITES.
WESTERN MOUNTAIN & CHAIN REACTIONS:
The eco system increasingly relies on natural processes for decomposition of organic matter, recycling
of nutrients, maintenance of humus, regulation of pest population, and the control of disease causing
microorganisms. It in this context that the farmer can appreciate the role of FUNGI in maintaining
equilibrium within the habitat. The fungal interactions with the inhabitants of the mountain are
essential for the effective transformations of various elements, especially insoluble rock phosphate
ultimately leading to release of nutrients for most of the biotic partners. Fungi are also important in
the mobilization of nitrogen and phosphorus. Some species of fungi are known to impart drought
tolerance to plants.
MOST COMMONLY ENCOUNTERED SOIL FUNGI:
Fusarium, Aspergillus, Pencillium, Acrostalagmus, Trichothecium, Alternaria, Pythium, Rhizopus,
Botrytis, Verticillium, Pullularia, Trichoderma, Cephalosporium, Gliocladium,Scopulariopsis,
Cladosporium, Spicaria, Absidia, Monilia, Cunninghamella, Mortierella, Rhiozoctonia,
Chaetomium, Mucor, Dematium, Helminthosporium, Humicola, Metarrhizium
CHEMICAL COMPOSITION OF THE FUNGAL CELL ON DRY WEIGHT BASIS
The major constituent is water to the extent of 90 %. The ash content varies.
CARBON 45-55%
NITROGEN 5-8%
An assay of fungal cells may yield carbohydrates ranging from 5-60%, 2-10% chitin, 15-40%
protein, 5-20% lipids.
FUNGAL SPORES:
Two types of spores are produced by fungi. namely SEXUAL and ASEXUAL. Asexual
reproduction does not involve the union of sex cells or sex organs. Sexual reproduction is
characterized by the union of two nuclei. Asexual reproduction is considered to be more important
for the propagation of the species because it occurs several times during a season, where as sexual
multiplication generally occurs only once a year.
Most of the fungal species are capable of producing spores in great masses. Because of their light
weight, spores are easily dispersed to great distances by wind and air currents. These spores are
highly resistant to unfavourable environmental conditions such as high temperatures, heat, extreme
cold, desiccation, ultra violet light, extremes of hydrogen ion concentration, and low nutrient
supply. The spores are more resistant to heat than the fungal mycelium. The specialized structures
that permit survival of the population are conidia, sclerotia, oospores, chlamydospores,
sporangiospores, ascospores, sporangia, and rhizomorphs.
FUNGI AS BIOCONTROL AGENTS:
The mountain soils are known to contain different species of nematodes. The root lesion nematode,
Pratylenchus coffeae is known to cause great economic damage in most farms including cherry,
berry and tobacco are tolerant. Some species of fungi have developed a mechanism to entrap
nematodes and devour them. It has taken millions of years for fungi to develop tentacles helpful in
fooling predators. It appears that a normal micro flora has an important protective function against
pathogenic and opportunistic microorganisms. Other species of fungi are known to predate over
protozoas.
A PEEP INTO THE FUTURE:
A number of fungi present within the mountain farms have medicinal, therapeutic and high protein
value. Farmers can easily exploit their usefulness by simply learning the behaviour of such fungi. An
interesting fact about fungi is that they can be easily mass cultured inside the farm itself without any
sophisticated laboratory equipment. The raw material or the substrates on which the fungus grows is
abundantly available on the farm itself. Farmers have to take extreme care only in the isolation and
identification of pure cultures. Once the pure culture is isolated, the farmer should inoculate a sample
flask or a glass container having the requisite medium with the fungal culture and store it in a
refrigerator for further mass multiplication. This saves precious time and energy in subsequent field
isolations.
Microbial inhabitants find comfort in the forest sanctuary. Nature employs microbes on a higher
scale to establish and maintain a balance among the diverse forms of life inside the NW mountain.
The presence of different species of microorganisms inside thee mountain is a symbol of co
existence. Fungi play a pivotal role in the slow but constant changes taking place inside the
mountain. Fungi are key drivers in the recycling of important chemical elements that, without their
activity, would remain forever locked up in dead plant and animal bodies. They transform
abundantly available leaf litter and wood wastes to worthwhile end products containing high
nutrient value.
Fungi are more beneficial to the mountain ecology compared to many other microorganisms. Every
day new techniques are being discovered which are relatively easy to perform at the farm level
itself. There is little doubt that basic and applied research with microorganisms within the mountain
will continue to provide valuable information and technology of economic value to the farmers.
This knowledge can be used for improvements of commercial cultures for improving the
productivity of the farm. The presence of fungi inside the mountain signals a technique that can
distinguish between healthy and diseased or abnormal plant tissues. These techniques are of
immense value in reducing the time required to identify genetic defects and mutations. Farmers
world wide should be convinced that the beneficial activities of fungi can be exploited in increasing
the over all productivity of the eco-friendly farm.
German scientist Albrecht Kaupp , has this to say. The human being is, after all, one of the most
poorly optimized combustion engines of this planet. For thousands of years the design has remained
unchanged. We continue to burn the most expensive energy, in a completely inefficient body. There
are too many of us and our numbers are growing fast. On the other hand just look at Fungi; They
form an invisible net work of mycelial mats that are so small and highly efficient in converting non
edible crop residues into energy rich nutrients, there by supplying the needs of the entire biotic
community. Of great significance are certain fungi that form mycorrhizal associations with both
forest trees and farms, providing valuable phosphorus and other essential nutrients for growth and
development. Certain species of fungi impart drought tolerance to various plant species. In addition
several fungal species act as natural bio-control agents against a diverse array of disease causing
organisms within the farm.
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