The Isolation and
Identification of Rhizopus from a
Decaying Bread were conducted. The black
mould used in the practical was collected from bread. It is allowed to stay in moist environment or
at room temperature for 2 to 3 days. The
mould is then inoculated in the nutrient egar (N.A.) incubated and was isolated
and view under the microscope for cultural characteristics.
In the experiment a mass of soft, closely woven white, silky
threads was observed. In the microscope
examination, non-deptate masses of round black spores, rhizoid. This characterized by Rhizopus SP.
In conclusion, since
foodstuff from which the mould is isolated is bread, Rhizopus SP which is more
prominent in bread than in any other foodstuff.
1.1 Aim and Objectives
1.3 Statement of Problem
1.4 Significance of Study
1.5 Limitation of the Study
2.1 Composition of Bread and It’s Requirement
2.2 Source of Contamination
2.3 Rhizopus as a spoilage Organism
2.4 Physiological Characteristic of Rhizopus
3.1 Sample Collection
3.2 Direction for Method of preparation of the
3.3 Isolation Method
3.4 Method of Identification
4.1 general Morphology of Rhizopus
4.2 Mode of Life
4.3 Reproduction of Rhizopus
5.1 Table I
Rhizopus nigricans belongs to a group of fungi
known as the “black moulds”. It is also
known commonly as the “read mould” because if grows freely on moist, state
bread. It appears as a delicate black
mass. It is a common mould, which is
widespread in occurrence. Rhizopus forms
a mass of soft, closely woven white silky threads. This mass, which is known as a mycelium is
the vegetative part of the Fungs. Each
silky thread like structure is a hypha.
The ‘mycelium grows not only on the surface of the bread but into it as well. The bread is known as the substrate.
The mycelium consists
of three sorts of hyphae. These three
sorts of hyphae as stolons which grow horizontally on the substrate (bread),
rhizoid or root like hyphae which arise at points where the stolons come into
contact with the substrate and sport-angiophores. The rhizoids are much branched hyphae which
penetrate into the substrate. They are
able to digest and absorb organic food.
The sporangiophores are erect unbranched hyphae arising from the stolons
at the same points where rhizoids are formal.
They grow vertically
upwards and give rise to the reproductive structures called sporangia. (Sargini et al, 1979).
The common bread mould (Rhizopus) finds new bakery items by
means of air-born spores. Once the baked
good is invaded, it won’t be long before black sporangia full of spores are
formed. Rhizopus stolonifera
(black mould) causes the black bread mould that forms cottony masses on the
surface of moist bread exposed to the air.
Rhizopus is aerobic and grow easily on bread since the slight acidity of
bread is conductive to their development it can also grow on solid substance
such as cloth, vegetables, leather, paper, food, and many other materials when
they are neglected in cupboard, boxes or other damp places, especially during
the wet seasons.
Effect of contaminated
bread in the society can lead to an epidemic of gastro-intestine disorder,
where by that particular environment that consumed the contaminated bread
becomes affected. As a result of this, a
lot of consideration should be given to breads that are served into the
community to be sold, and this is done by the standardized system called
“Hazard Analysis Critical Control Point” (HCCP).
This method is now
generally considered as a choice for ensuring safety of foods. (Jay, 1996, De Beer and Beunier 1999). Hazard analysis critical control point
involves in identifying places in the production process where hazards could
occur i.e. the ccp “Critical Control Point)” and put monitoring procedures in
place to prevent these hazard occurring.
Even with this system in place.
A sample still needs to be tested for the presence of microorganisms.
1.1 AIM AND OBJECTIVES OF THE STUDY
This project work is
based on the Isolation and Identification of the fungal organism responsible
for the spoilage of Bread. It is also to
determine the rate of growth of the Organisms and to know its ability to grow
on inhibitory media. To examine the
species of fungi that infests breads at room temperature.
Ho - Fungi
(filamentous) and yeast has no affect on bread.
Hi - Filamentous fungi
and Rhizopus are responsible for spoilage of bread when
1.3 STATEMENT OF PROBLEM
Problem encountered by
the society as a result of the consumption of contaminated bread ingested with
fungal organisms at circulation in the market places are related health
wise. Health wise in the sense that when
contaminated breads are eaten, it leads to gastrointestinal disorder which is
as a result of ingestion of toxins deposited by some fungal organism on the
bread. This can lead to an epidemic,
when a batch of contaminated bread is in circulation and is being purchased and
consumed by various individual.
1.4 SIGNIFICANCE OF STUDY
The justification of
this research study is to ensure that well prepared baked bread devoid of
fungal growth is being circulated or sold.
It is also carried out on the basis of selling well-baked breads,
uncontaminated so as to avoid any sort of food poising associated with the
ingestion of bread.
1.5 LIMITATION OF THE STUDY
This research work will be limited to the isolation and
identification of fungal organism present i.e. (Rhizopus nigrican),
incubated under room temperature. This
is also limited or restricted on the examination of the end product, which is
the baked bread and not its raw material which is the flours. Practical works won’t be carried out on the
pathogenicity of species identified, on.
This could be another area of study for interested microbiologists.
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