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Microbiology for Leather TechnologyB Sc (Chemical Engineering)Leather technology specialization
ByCentral Leather Research Institute, IndiaLeather Industry Development Institute, Ethiopia
Microbiology for Leather TechnologyB Sc (Chemical Engineering)Leather technology specialization
ByCentral Leather Research Institute, IndiaLeather Industry Development Institute, Ethiopia
Introduction to Microbiology
What is Microbiology?
• Microbiology is the study of
microorganisms.
• What are microorganisms then?
Mikrós (Greek) : Small;
Organismós (Greek) : Organisms
They are simple life forms
They are not visible to naked eyes
History
• The hypothesis of existence of microorganisms was put
forth much before the actual discovery
• The existence of microorganisms was postulated by
Jainism based on Mahavir’s preaching in 6 BC
History
• Girolamo Fracastoro an Italian physician
in 1546 proposed that the epidemic
diseases were caused by transferable
seed like entities
• Robert Hook (Netherland, 1632 - 1723)
in 1665, recorded first microscopic
observation of fruiting bodies of molds
History
• Anthony Van Leeuwenhoek (Netherland,
1632 - 1723) in 1676, invented single lens
microscope and observed microorganisms
in water, vinegar and wine; called them
animalcules
• Edward Jenner (English, 1749 - 1823) in
1796 developed small pox vaccine
History
• Luis Pasteur (French, 1822 - 1895)
disproved spontaneous generation theory,
discovered pasteurization, invented
vaccines for anthrax and rabies
• Robert Koch (German, 1843 - 1910)
invented methods to purify Bacillus from
blood samples and developed pure
cultures
Naming Microorganisms
• Hierarchy of microbial
taxonomy
Kingdom
Phylum
Class
Order
Family
Genus
Species
Subspecies
Organism used in yogurt
production
Kingdom : Bacteria
Phylum : Firmicutes
Class : Bacilli
Order : Lactobacillales
Family : Lactobacillaceae
Genus : Lactobacillus
Species : L. delbrueckii
Subspecies : L. d. bulgaricus
Kingdom of Microorganisms
Bacteria
Bacterial cell and organelles
Five structural components of bacterial cell are• Nucleoid (DNA)
• Ribosomes
• Cell membrane
• Cell wall
• Surface layer
Three architectural regions• Appendages (pili or flagella)
• Cell envelope (contains capsule, cell wall and plasma membrane)
• Cytoplasmic region (chromosomes and ribosomes)
Characteristics of Bacteria• Bacteria ranges from 0.2 to 2 μm diameter and
2 to 8 μm length
• There are three basic shapes
Spherical (cocci)
Rod (bacili)
Spiral
• Bacteria divide by binary fission (splitting into
two); single DNA molecules replicates and both
copies attach to cell membrane; cell membrane
begins to grow between two DNA molecules;
cell membrane then begins to pinch inward
Growth of Bacteria
Growth Factors of Bacteria• Growth factors
• Carbon and energy source
• Temperature
• pH
• Moisture
• Inhibitors and retarders
• Salt
• Biocides
Fungi - Basic facts
• Eukaryotic and non-photosynthetic
• Aerobic or facultative anaerobic
• Chemoheterotrophic (use chemicals for carbon and energy)
• Unicellular or multi-cellular
Fungi - Morphology• Most fungi grow as hyphae -
cylindrical; 2 to 10 μm diameter and
several cm long
• New hyphae is emerged fro the tips
of existing hyphae by branching
• Hyphae can be septate or
coenocytic
• Mycelium is the interlocked network
of hyphae
Penicillin
1. Hypha; 2. Conidiophore; 3. Phialide; 4. Conidia; 5. Septa
Fungi - Morphology• Septate hyphae are
compartmentalized and each
comportment is a cell
• Coenocytic are not
compartmentalized
• Septa have spores that allow
cytoplasm, organelles and
sometimes nuclei to pass through
Fungi - Reproduction
Yeasts - Basic Facts • Eukaryotic microorganism of the kingdom
of Fungi
• Unicellular with few exceptions
• Typically 3 to 4 μm in diameter may be 40
μm in some cases
• Most reproduce asexually by mitosis
Our Life with Microorganisms• What happens when milk curdles?
• Why wine is sour but grape juice is not?
• Why the body temperature goes up when we are infected?
• Do you know peptic ulcer is caused by a bacteria?
• Why in cold weather curdling is not favored?
• Do you know synthetic human insulin is produced by engineered bacteria?
• What is happening in a septic tank?
• Do you know penicillin is produced by a fungi?
• Do you know there are carcinogenic fungi?
Leather Microbiology
Putrefaction
Lysozyme initiates the denaturation of animal skin or hide after removal
This process of autolysis is followed by microbial growth
Microorganisms, particularly bacteria beaks down the skin components
mainly the proteins into simpler compounds
Bacteria derive energy and obtain carbon from the proteins
This process is putrefaction
Effect of Bacterial Growth on Skin
Red heat
Grain disturbance (snuffed effect)
Loss of substance (over batted effect)
Hair slip
Control of Putrefaction
Putrefaction can be controlled either by
controlling the growth factors or by
administering retarders
Growth factors such as moisture,
temperature and pH can be controlled to
control bacterial growth (Eg.: drying,
salting, chilling, freezing, pickling)
Growth retarders (salt or bactericides) can
also be used for preventing putrefaction
FellmongeringAs soon as the skin or hide is removed from the
animal the autolytic process sets on (lysozyme
acts)
Following autolysis, the bacteria grows on skin
or hide
Bacteria secure carbon and energy from skin
components particularly proteins
Disadvantage is that the process can seldom be
controlled; and leather making material is also
denatured
Fungal Growth on Tanned Leather
Tanned leathers are not easily susceptible
to bacterial growth; but they are much
susceptible to fungal growth
Fungus such as A. niger, A. flavus, T. viride
grow on tanned leather
Fungal growth can be controlled by
administering appropriate fungicide
Effect of Fungal Growth on Leather
Fungus
may leave permanent stain on leather
may disturb the grain
Fungus
at the outset breaks the tannin-collagen link through
polyphenol oxidase and laccase
then protease and lipase are secreted and the leather
making substance also disintegrated
EnzymesEnzymes are proteins and act as (bio)catalysts; accelerating biochemical reactions
They can be sourced from animals, plants and microorganisms
Enzymes such as protease, lipase, amylase and xylanase are used in leather manufacturing and they are produced using microorganisms
Wastewater Treatment
Bacteria (both aerobic and anaerobic) are
used for the treatment of wastewater
In Activated Sludge Process (ASP) aerobic
bacteria are used for breaking down the
organic pollutants
In anaerobic lagoon and UASB anaerobic
organisms are used
Thank you