ABSTRACT
This project was designed for the
isolation and identification of some fungi found in the soil. These
microorganisms may be either pathogenic or non-pathogenic to the plants and
humans. Two soil samples one from garden soil and the other one from compost
soil were put into serial bags and taken to the laboratory for analysis. One
gram of each sample was put into 9ml of serial water. Using pipette one in ten
folds dilutions was done on each sample. Exactly 0.1 ml of each dilution was
poured into Sabroaud dextrose agar plates and was spread using spreader on each Sabroaud dextrose agar
plates and left on the table for 24 to 48hrs. The representative growth on each
plate was sub-cultured on Sabroaud dextrose agar slant to obtain pure culture
for identification and left for at least 72hrs for spores to be formed. Slide
culture technique was used for proper identification of the filamentous fungi.
Lacto phenol blue was used to stain the growth on the slide and cover slip and
viewed under the microscopy. A total of
three fungal isolates were obtained from the soil samples on the Sabroaud
dextrose agar plates. Three fungi species,were identified and from the fungal
isolates species belonging to the genera Aspergillus
spp and Mucor sp.The identified
soil fungi from the two soil sample were Aspergillusniger,
Aspergillus fumigatus and Mucor sp.
and the three were isolated from two soil samples. In this result fungi growth
occur more in compost soil than in garden soil and the most common organism wasAspergillus spp. The two soil fungi
obtained in this work were known to be pathogenic to human beings. Some Aspergillus spp are known to produce mycotoxic which can
cause disease in man e.g. Aflatoxins. It is a cumulative toxins. Also Mucor sp are known to cause disease in
man through inhalation of the spores in the air e.g. systematic mucormycosis in
diabetic patients.
CHAPTER
1
INTRODUCTION
A fungus is a eukaryote that digests food externally
and absorbs nutrients directly through its cell walls. Most fungi reproduce by
spores and have a body (thallus) composed of microscopic tubular cells called
hyphae. Fungi are heterotrophs and, like animals, obtain their carbon and
energy from other organisms. Some fungi obtain their nutrients from a living
host (plant or animal) and are called biotrophs; others obtain their nutrients
from dead plants or animals and are called saprotrophs. Some fungi infect a
living host, but kill host cells in order to obtain their nutrients; these are
called necrotrophs. Fungi were once considered to be primitive members of the
plant kingdom, just slightly more advanced than bacteria. Fungi are an ancient
group not as old as bacteria, which fossil evidence suggests may be 3. 5
billion years old but the earliest fungal fossils are from the Ordovician, 460
to 455 million years old (Redeckeret al.
2000). Based on fossil evidence, the earliest vascular land plants didn't
appear until approximately 425 million years ago, and some scientists believe
that fungi may have played an essential role in the colonization of land by
these early plants (Redekeret al.
2000). Mushrooms exquisitely preserved in amber from the Late Cretaceous (94
million years ago) tell us that there were mushroom forming fungi remarkably
similar to those that exist today when dinosaurs were roaming the planet
(Hibbettet al. 2003). Fungi are an
important group of plant pathogens most plant diseases are caused by fungi but
fewer than 10% of all known fungi can colonize living plants (Knogge, 1996).
Plant pathogenic fungi represent a relatively small subset of those fungi that
are associated with plants. Most fungi are decomposers, utilizing the remains
of plants and other organisms as their food source. Other types of associations
include the role of fungi as decomposers, as beneficial symbionts, and as
cryptic plant colonizers called endophytes.Most fungi are associated with
plants as saprotrophs and decomposers.
Soil is normally considered as the fine earth which
covers land surfaces as a result of the in situ weathering of rock materials or
the accumulation of mineral matter transported by water, wind, or ice. The
distinctive feature of soil is that to this weathered mineral material is added
organic material. This organic material may be both living and dead. The dead
organic matter will include little altered and freshly added dead plant roots
and leaf and other plant litter, dead fauna, and organic material in various
stages of decomposition from little modified relatively fresh materials to the
complex decomposed material called humus. It is this mixture of mineral and
organic material which gives the soils their distinctive characteristics.
The soil is a highly complex system with many
components playing diverse functions and could be due mainly to the activity of
soil organisms (Chiang andSoudi, 1994). Soil microflora plays a pivotal role in
evaluation of soil conditions and in stimulating plant growth (Nagamaniet al., 2006). Microorganisms are
beneficial in increasing the soil fertility and plant growth as they are
involved in several biochemical transformation and mineralization activities in
soils. Type of cultivation and crop management practices are found to have
greater influence on the activity of soil microflora (Mc. Gillet al., 1980). Continuous use of
chemical fertilizers over a long period may cause imbalance in soil microflora,
as result affecting indirectly biological properties of soil leading to soil
degradation (Manickam andVenkataraman, 1972). Fungi are fundamental for soil
ecosystem functioning (Warcup, 1951).
Soil is the upper layer of most of the earth’s
surface and varies in depth from inches to over twenty feet. It is a product of
weathered rock, but quite distinct in its characteristic. Soils are excellent
cultural media for the growth of many types of organisms (Angelov, (2008).
This includes bacteria, fungi, algae, protozoa and viruses. A spoonful of soil
contains billions of microorganisms. In general the majority of microbial
population is found in the upper six to twelve inches of soil and the number
decreases with depth (Cattle, et al.,
2002). The number andkinds of organisms found in soil depend upon the nature of
soil, depth, season of the year, state of the cultivation, reaction, organic
matter, temperature, moisture, aeration, etc.
AIM
This research is aimed at isolation and
identification of fungi in compost and garden soils.
OBJECTIVES
·
To isolate fungi from the soil using
routine culture media.
·
To identify the fungi community from the
soil sample collected from Godfrey Okoye University farms and wastes surrounding.
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