Introduction to Microorganisms Lecture Notes PDF

an introduction to the world of… Microscopic Organisms  What are microorganisms?  Are known to be in every possible ecological niche (ubiquitous)  Are usually too small to be seen with the naked eye.  A microscope or a magnifying glass would be needed to view the tiny...

an introduction to the world of… Microscopic Organisms  What are microorganisms?  Are known to be in every possible ecological niche (ubiquitous)  Are usually too small to be seen with the naked eye.  A microscope or a magnifying glass would be needed to view the tiny ones clearly.  Because of their size and in terms  of population size, they outnumber all other groups of bigger animals or plants. Comprise 3 of 5 Kingdoms  Taxonomic Classification of microorganism follows the Linnaean System of Classification of living things.  Species is the fundamental rank.  Does not apply to viruses, viroids and prions.  Microorganism - Cell types  Of the 5 taxonomic Kingdoms, Fungi and Protists all have cells that are of the eukaryotic type (living)  Only the Bacteria have cells that are of the prokaryotic type (living)  The viruses, viroids and prions are acellular, also known as non-living entities Prokaryote vs Eukaryote Cell types Eukaryote Microorganisms Prokaryote Microorganisms  THE FUNGI : MOULDS & YEASTS  The Fungi Kingdom  Fungi can be found to live in:  soil  on & inside plants and animals  water and  on non-living things or items  Studies have identified 80, 000 species, but it is thought that there must be at least 1.5 million species  Evolutionary history of the fungi is not very clear, however, it is theorized that the hypothetical common ancestor is an aquatic, unicellular, flagellated protist (similar to chytrids)  …..What do Fungi look like? Here are some representatives….  Fungi: friend or foe?  Fungi may not have a good reputation with humans. Why?  Known to spoil food or are pests/nuisance  Cause disease in plants and animals  Contribute to bio-deterioration  Few are carnivorous  Fungi can benefit humans directly. How?  Some are edible  Some aid in food & beverage production  Some useful in biological research  Some produce antibacterial substances  Few aid in decomposition processes - biodegradation  Few form mutual relationships with other living things that have a indirect benefit to humans  Fungi Characteristics  Moulds are aerobic, spore bearing, eukaryotic cells  Yeasts are anaerobic, elliptical, eukaryotic cells  Most moulds form macroscopic structure, while yeasts are unicellular(single celled)  Heterotrophs – secrete enzymes that digest the substrate (food) they live on  Have cell walls that is largely made of chitin (tough, flexible carbohydrate)  Storage carbohydrate is glycogen  Have unique reproductive cycles – both asexual and sexual modes of reproduction Fungi grow on their food substrate  Hyphae absorbing nutrients (vegetative hyphae) remain hidden in their food, while the reproductive structures (aerial hyphae) emerge at the surface and are visible  Yeast Structure  Yeast are oval or elliptical in shape  They do not have any external appendages  Cell wall is made of chitin  Being a eukaryotic organism, it has a number of different types of membrane bound organelles and a nucleus all wrapped in a cell membrane  Mold Structure  Moulds have numerous threadlike filaments called ‘hyphae’.  Mass of aggregated hyphae is referred to as ‘mycelia’.  Spores are found at the ends of the hyphae in specialized structures.  Some moulds are large in size and can be seen without microscopes - mushrooms  Reproductive structure produces ‘spores’ which can be formed through asexual or sexual reproduction THE PROTISTA  The Protista Kingdom  Are the simplest of the eukaryotic organisms  Place in this Kingdom by the virtue of being a eukaryotic organism that did not fit the description of a plant, animal or fungus.  Scientists have described just over 100, 000 species of protists  All of them are metabolically diverse displaying great variety in: size, structures, modes of nutrition, locomotion, reproduction and cell surface  Classification/grouping is often done in order of being: - animal-like protista - plant-like protista - fungus-like protista  Importance of Protists  Metabolic diversity implies wide variety of role/function in human life or other living things – not well studied  Autotrophic algae carry out photosynthesis producing some of the oxygen in earth’s atmosphere which supports food webs globally  Algae living in association with fungi in rocks and tree bark form lichen  Some members contribute to the first step in producing soil from bare rock(rock erosion) – big role in SOIL PRODUCTION  BIOLOGICAL INDICATORS of ATMOSPHERIC POLLUTION Protista: friend or foe….  Some are medically important parasites of humans (e.g. malaria parasite) and plants  Some species of algae make chocolate smooth and creamy or used in food processes (e.g. jelly)  Other species make paint reflective or other industrial purposes  Some play a major role in biological research  Distinctive protist fossils are often good indicators of petroleum reserves  Maybe one day mankind can fully harness the energy from multitudes of photosynthetic protists in bioreactors that use sunlight and CO2 to produce oils and other biofuels What do they look like? Here are some representatives….  Algae Characteristics  Some protists (algae) are photosynthetic  Cells of algae contain chloroplasts that store a rainbow of yellow, gold, brown, red & green photosynthetic pigments.  These organelles use light energy and CO2 to produce carbohydrates and other organic molecules that support freshwater and marine food webs.  O2 is released as a metabolic waste product.  Algae - typical structure  Algae may take the form of being:  single-celled  Colonial  Filamentous or  Multi-cellular  Algae body shape resemble plants, but lack the distinctive reproductive structures that define plants.  Algal Groups 1) Euglenoids e.g. euglena – can be autotrophs or heterotrophs 2) Dinoflagellates – characterised by flagella; are major component of plankton; 50% are photosynthetic; some mutually live in tissues of marine animals; some are predators or parasites (harmful algal blooms or toxic to humans from fish); others are bioluminescent 3) Diatoms (unicellular; good indicators of environmental quality because sensitive to pH, salinity & other factors), golden and brown algae (some are photosynthetic and contribute to food web; others can cause fish kills) 4) Red algae – some secrete CaCO3 and help build reefs; used in culture medium for microbes; gel in canned meats, thickener in ice cream & yoghurt; emulsifier in chocolate bars, stabilizes paint, cosmetics and creamy food, one type(nori) used for wrapping sushi 5) Green algae – very plant-like; possess chlorophyll a & b and photosynthesize; some live in symbiosis with fungi(lichen).  Slime and Water mold traits  Slime molds resemble fungi in some ways:  Are heterotrophic  Some are single-celled, others multi-cellular  Some produce filaments  Found alongside fungi in nature  Water molds (Oomycetes) are largely decomposers or parasites in nature  Produce swimming spores that aids in dispersal  Contain cellulose instead of chitin in cell wall  Cause of major plant disease – downy mildew of grapes and potato blight disease  Protozoa characteristics  Largely unicellular, aerobes and anaerobes  Vast majority heterotrophs, few autotrophs  Move by flagella, cilia or pseudopodia  Some free-living; others obligate parasites  Protozoa categorized as:  Ameboid protozoa move by pseudophodia (amoeba)  Flagellated protozoa move by flagella (trypanasoma, giardia, leishmania, sporozoa)  Ciliated protozoa move by cilia (paramecium)  Apicomplexa – non-motile, spore-forming, internal parasites of man (cryptosporidium, toxoplasma & plasmodium (malaria parasite) THE BACTERIA  The Monera Kingdom  Species types could be anywhere between 100,000 – 10,000,000  Said to have a huge influence on the earth’s history and impact on life on earth today  Bacteria are ubiquitous – virtually no place on & in earth and the atmosphere is free of bacteria  Most of what we know about bacteria comes from the handful that have been able to grow in artificial (lab) conditions  Bacteria Features  Bacteria (archae and eu bacteria)  Single-celled & reproduces asexually by binary fission  Is the only group of organisms with a prokaryotic cell structure:  Lacks a nucleus (no nuclear membrane)  Its DNA does not contain histone proteins  Has a circular DNA molecule  Has very limited internal membrane-bound organelles (only ribosomes & mesosomes)  Has extra chromosomal material (plasmid)  Cell wall chief component is peptidoglycan General Bacteria Structure Bacteria under the microscope  Bacteria – typical features  Typically 10-100 times smaller than eukaryotic cells  Bacteria are classified at the species level as having 70% similarities in biochemical characteristics  Metabolically very diverse by growing in:  Light or darkness  Use of organic & inorganic compounds  Can be aerobic, anaerobic or facultative anaerobes  extreme temperatures  extreme pH’s  extreme barometric pressure  extreme osmotic conditions Bacteria shapes  What do they look like? Here are some representatives….  Bacteria & their importance  Some are parasitic/pathogenic to animals & plants  Some enjoy a mutualistic relationship with other organisms (ruminant bacteria, endophytes, nitrogen fixing bacteria)  Others have a commensalistic relations with plant & animals (body micro flora)  Some are used in medical research  Some contribute to the biogeochemical cycle  Some are used in the food and industry  Some produce antibiotics and other useful substance used in the food and drug industry