8.5 The Impact of Microorganisms on Life

Types of MicroorganismsMicroorganism Characteristics

Bacteria -Unicellular organisms-Have cell walls made of a polymer called peptidoglycan.-Eg: Lactobacillus sp. and Staphylococcus sp.

Algae -Photosynthetic plant.-Have chloroplasts and chlorophyll.-Cell walls are made of cellulose.-Eg: Spirogyra sp.

Spirogyra sp.

Microorganism Characteristics

Fungi -Heterotrophic multicellular or unicellular eukaryotes.-Do not have chlorophyll.-Cell walls made of chitin.-Eg: Mucor sp. And yeast.

Protozoa -Unicellular organism.-Can carry out respiration, reproduction and excretion.-Use flagella, cilia or pseudopodia to move.-Eg: Euglena sp., Paramecium sp. and Amoeba sp.

Yeast Mucor sp.

Euglena sp.

Amoeba sp. Paramecium sp.

Microorganism Characteristics

Viruses -Smallest microorganisms.-Can only be seen under electron microscope.-Not a living cell because it cannot survive or reproduce on its own outside the host.-Must infect and use living cells to reproduce.-Composed of DNA and RNA surrounded by a protein coat.-Can be crystallized.-Eg: T4 bacteriophage and mosaic virus.

Tobacco mosaic virus

Human papilloma virus

T4 bacteriophage

Abiotic Components Affecting Microorganisms

• Activity of microorganisms is affected by abiotic components such as:– Concentration of nutrients– pH– Temperature– Light intensity

Abiotic component Effect to microorganism

Nutrients or water -All microorganisms need nutrients and water except virus for reproduction and growth.-Without it, microorganisms will die or form spores.

pH -Optimum pH for bacteria: slightly alkaline (pH around 7.4).-Optimum pH for mould, yeast and protozoa: acidic condition (pH between 4.5 and 5.0).

Temperature -Low temperature: microorganisms inactive.-Optimum temperature: 35°C to 40°C.-Beyond 60°C: growth of microorganisms inhibited.-Temperature up to 121°C: microorganisms and spores destroyed (sterilization).

Light intensity -Low light intensity (dark) : the prefer places for microorganisms.-High intensity of sunlight/ UV rays: can kill microorganism.-However, algae and photosynthetic bacteria need light to photosynthesis.

The Role of USEFUL Microorganisms in the Ecosystem

Useful microorganism Role

Decomposers -Decomposers (a group of saprophytic bacteria or fungi) carry out decomposition of dead organic remains.-Decomposers break down dead remains of plants, animals and waste products of animals.-Release nutrients into the soil.

Protozoa in alimentary canal of termites

-Protozoa such as Trichonympha sp. produce cellulase which digest cellulose (termites feed mainly on wood which contains cellulose).

Symbiotic bacteria found in human colon

- Synthesize vit B12, vit K

Denitrifying bacteria - Nitrogen fixing bacteria: convert atmospheric nitrogen to a form that can be used by plants.- Useful in Nitrogen cycle.

NITROGEN CYCLE

The Effect of Harmful Microorganisms

• Harmful microorganisms: can cause diseases and spoilage of food and substances.

• Pathogens: microorganisms that cause diseases.– Body have skin that is protected by a layer of cells.– Can only cause disease if it getting into body cells

(by cut or open wound).

Transmission of Diseases

1. Air 2. Water3. Food4. Vectors5. Direct contact6. Indirect contact

Controlling pathogens

The Uses of Microorganisms in Biotechnology

• Biotechnology – application of biologicalprocesses in the manufacturing andservicing industries

Appreciating Biodiversity

• Biodiversity can be appreciated through conservation and preservation.