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