 Bacteria  Archaea  Fungi  Virus  Algae  Protozoa

 Maintain balance of environment (microbial ecology)  Basis of food chain  Nitrogen fixation  Photosynthesis  Digestion, synthesis of vitamins  Manufacture of food and drink

 Genetic modified organism (GMO)  genetic engineering  Synthesis of chemical products  Recycling sewage  Bioremediation: use microbes to remove toxins, oil spills  Use of microbes to control crop pests  Normal microbiota

 Cause disease (basis for bioterrorism)  Food spoilage

 the regulation of gene expression in response to fluctuations in cell- population density  QS enables microbes to co- ordinate their behaviour  Symbiosis, virulence, competence, conjugation, antibiotic production, motility, sporulation, and biofilm formation

Bacterial motility

Photo’s courtesy of : Sylvia T. Pratiwi

Differences between Bacteria and Fungi CharacteristicBacteriaFungi SizeSmallerLarger Cell WallPeptidoglycanChitin ClassificationProkaryotEukaryot Type of cellsUnicellular multicellular Cell membraneSterol absent, except in MycoplasmaSterol present SporesSurvivalreproduction ReproductionAsexualSexual (mitotic) Asexual (meiotic) MotilityVariableNon-motile MetabolismHeterotrophis, chemoautotrophic, photoautotrophic, aerobic, facultatively anaerobic Limited to Heterotrophs / chemoheterotrophs; aerobic/facultative anaerobic

 Fungi are eukaryotic protista; differ from bacteria and other prokaryotes. 1. Cell walls containing chitin (rigidity & support), mannan & other polysaccharides 2. Cytoplasmic membrane contains ergosterols 3. Possess true nuclei with nuclear membrane & paired chromosomes. 4. Divide asexually, sexually or by both 5. Unicellular or multicellular 6. heterotrophic organism devoid of chlorophyll that obtains its nutrients by absorption 7. reproduces by spores.

 On culture - produce smooth, creamy colonies e. g Cryptococcus neoformans (capsulated yeast) u Unicellular fungi, nonfilamentous, typically oval or spherical cells. Reproduce by mitosis:  Fission yeasts: Divide evenly to produce two new cells (Schizosaccharomyces).  Budding yeasts: Divide unevenly by budding (Saccharomyces). Budding yeasts can form pseudohypha, a short chain of undetached cells. Candida albicans invade tissues through pseudohyphae. u Yeasts are facultative anaerobes, which allows them to grow in a variety of environments.  When oxygen is available, they carry out aerobic respiration.  When oxygen is not available, they ferment carbohydrates to produce ethanol and carbon dioxide.

18  Form true mycelia & reproduce by formation of different types of spores.  Vegetative/ aerial hyphae e.g. Rhizopus, mucor

Molds u Multicellular, filamentous fungi. u Identified by physical appearance, colony characteristics, and reproductive spores.  Thallus : Body of a mold or fleshy fungus. Consists of many hyphae.  Hyphae (Sing : Hypha) : Long filaments of cells joined together. Hyphae grow by elongating at the tips. Each part of a hypha is capable of growth. u Vegetative Hypha : Portion that obtains nutrients. u Reproductive or Aerial Hypha : Portion connected with reproduction.  Mycelium : Large, visible, filamentous mass made up of many hyphae.

 Except for yeast, hyphae are organised around and within food source:  Composed of tubular walls containing chitin  Provide enormous surface area: 10cm 2 of soil may contain 1km of hyphae with 314cm 2 surface area  Hyphae of septate fungi are divided into cells by crosswalls called septa  Hyphae of aseptate fungi lack cross walls (coenocytic)  Parasitic fungi have modified hyphae called haustoria, which penetrate the host tissue but remain outside cell membrane

 Grow partly as yeasts and partly as elongated cells resembling hyphae which are called pseudohyphae. e.g. Candida albicans

24  Occur in 2 forms Molds (Filaments) – 25  C (soil) Yeasts – 37  C (in host tissue) Most fungi causing systemic infections are dimorphic:  Histoplasma capsulatum  Blastomyces dermatidis  Paracoccidioides brasiliensis  Coccidioides immitis  Penicillium marneffei  Sporothrix schenkii  Candida albicans

 The morphology of multicellular fungi enhances their ability to absorb nutrients  Fungi consist of mycelia, networks of branched hyphae adapted for absorption  Most fungi have cell walls made of chitin  Some fungi have hyphae divided into cells by septa, with pores allowing cell-to-cell movement  Coenocytic fungi lack septa  Some unique fungi have specialized hyphae that allow them to penetrate the tissues of their host

Hyphae adapted for trapping and killing prey Fungal hypha Haustorium Plant cell Haustoria Plant cell plasma membrane Plant cell wall Nematode Hyphae 25 µm

 Structural components:  chitin microfibrils [ß(1-4)-linked polymer of N- acetylglucosamine]  ß-linked glucans  Gel-like components:  Mannoproteins (form matrix throughout wall)  Antigenic glycoproteins, agglutinans, adhesions— on cell wall surface  Melanins—dark brown to black pigments (confer resistance to enzyme lysis, confer mechanical strength and protect cells from UV light, solar radiation and desiccation)  Plasma membrane—semi-permeable  Ergosterol is the major lipid component of the underlying plasma

DivisionFibrousGel-like Polymer BasidiomycotaChitin β -(1-3), β-(1-6) Glucan Xylomannoproteins α (1-3) Glucan Ascomycotachitin β -(1-3), β-(1-6) Glucan Galactomannoproteins α (1-3) Glucan ZygomycotaChitin Chitosan Polyglucuronic acid Glucuronomannoproteins Polyphosphate ChytridiomycotaChitin Glucan Glucan Taken from :

 Sexual (by meiosis) - formation of zygospores, ascospores or basidiospores  Asexual reproduction (by mitosis) – budding or fission  Asexual spores are formed on or in specialized structures.  Vary in size, shape & color, but these characteristics are constant for a particular species.  Spores are the agent of dispersal responsible for geographic distribution of fungi:  Carried by wind or water  Germinate in moist places with appropriate substrata 10  m Parent cell Bud

Chytrids Zygote fungi Arbuscular mycorrhizal fungi Sac fun gi Club fungi Chytridiomycota Zygomycota Glomeromycota Ascomycota Basidiomycota

 The most primitive fungi  Fungi classified in the phylum Chytridiomycota, or chytrids  Are found in freshwater and terrestrial habitats, but mainly aquatic  Can be saprobic or parasitic  Chytrids are unique among fungi  In having flagellated spores, called zoospores 25  m 4  m Hyphae Flagellum

 Lower fungi;  Broad, nonseptate hyphae  Asexual spores - Sporangiospores: present within a swollen sac- like structure called Sporangium  They include fast-growing molds, parasites, and commensal symbionts  The zygomycetes are named for their sexually produced zygosporangia  Zygosporangia resistant to freezing and drying  Are capable of persisting through unfavorable conditions  Can undergo meiosis when conditions improve  The life cycle of black bread mold (Rhizopus stolonifer) is fairly typical of the phylum

Rhizoids = root-like hyphae The Rhizoids meet underground and mating occurs between hyphae of different molds (SEXUAL REPRODUCTION)

 Some zygomycetes, such as Pilobolus can actually “aim” their sporangia toward conditions associated with good food sources 0.5 mm This decomposer of animal dung bends toward bright light and shoots its sporangia up to 2 meters

 Fungi in the phylum Ascomycota  Include unicellular yeasts and complex multicellular (filamentous) cup fungi  Are found in a variety of marine, freshwater, and terrestrial habitats Morchella esculenta

 Sexual spores called ascospores are present within a sac like structure called Ascus.  Several asci may be seen within a fruiting body as seen in Penicillium, Aspergillus  Each ascus has 4 to 8 ascospores

In sexual reproduction, haploid mycelia of opposite mating strains fuse Asexual spores are called conidia borne on conidiophore Hyphae are septate

 It is characterized by basidia – club shaped hyphae that produce basidiospores during sexual reproduction.  Important decomposers of wood / plant material  Include:  Mycorrhiza-forming mutualists  Mushroom-forming fungi  Plant parasites e.g. rusts and smuts  Characterised by dikaryotic mycelium that reproduces sexually via basidiocarps

PHYLUM DEUTEROMYCOTA No Longer Exist!! 22,000 species. No known sexual stage. Saprophytic, parasitic and predatory. Many produce conidia. Most classified as Ascomycota. Fusarium wilt of tomato, potato and cotton. Athletes foot, ring worm

Penicillin Woops… now Ascomycota

Candida albicans “yeast infection”

Kingdom Fungi About 100,000 species Uses: medicine Food Ecological value: major decomposers symbiotic relationships (N 2 fixers) Problems: some strains are deadly athletes foot destroy library books destroy crops

 Fungi produce many products used in the medical field such as penicillin, cephalosporin antibotics, cortisone  Fungi are used in genetic engineering – vaccine for hepatitis B was developed using the yeast plasmid as the vector.  Yeast is used to make ethanol.  Yeast are known for making breads rise.  Mushrooms, morels and truffles are widely consumed by humans.

49 Source of food e.g. mushrooms Fermentation - Production of alcohol, bread, cheese e.g. Sacchromyces spps Antibiotic production e.g. Penicillin from Penicillium notatum

50 Ergot from Claviceps purpurea, used to induce uterine contractions Vaccines for Hepatitis B – Sacchromyces cerevisiae

 Fungi are heterotrophs that acquire nutrients by absorption  Secrete hydrolytic enzymes and acids to decompose complex molecules into simpler ones that can be absorbed  Specialised into three main types:  Saprobes - absorb nutrients from dead organic material  Parasitic fungi - absorb nutrients from cells of living hosts; some are pathogenic  Mutualistic fungi - absorb nutrients from a host, but reciprocate to benefit the host

 Called saprophytes, they act as recyclers of dead organic matter, obtaining food from this material.  Hyphal tips release enzymes that eventually decompose and release organic materials into the surrounding environment.  Saprophytic fungi appear on dead trees, logs, plant litter such as leaves, and even dead insects and animals. Examples: "Gem-studded Puffball" (Lycoperdon perlatum) and "Turkey Tail"(Trametes versicolor).

Lichen – symbiotic relationship between algae and fungi Endophyte

 Some fungi share their digestive services with animals  These fungi help break down plant material in the guts of cows and other grazing mammals  Many species of ants use the digestive power of fungi by raising them in “farms”

 About 30% of the 100,000 known species of fungi are parasites, mostly on or in plants.  Many people have allergies triggered by mold.  Fungal skin infections – skin, nails and hair  Ringworm, athlete’s foot  Internal organs – Histoplasmosis

56  Superficial mycoses :  2 types: surface and cutaneous mycoses  Skin, hair & nails.  Mild but chronic disease  Deep mycoses :  2 types: subcutaneous & systemic mycoses  Caused by soil saprophytes  Infection is accidental  Range from a symptomatic infection to fatal disease

57  Mainly caused by fungi which are common lab contaminant on culture media  Aspergillus  Penicillium  Mucor  Rhizopus  Candida  Produce serious & fatal infections