Eukaryotic Microbes: Algae

Eukaryotic Microbes

• Algae are photosynthetic eukaryotes
• Algal cells may possess a pellicle (cell wall), a stigma (light-sensing), and flagella.
• Algae vary in size from tiny, unicellular, microscopic organisms to large, multicellular organisms like "lumot."
• Algae inhabit freshwater, saltwater, wet soil, or wet rocks.
• Most algae are photoautotrophs

Phylum Dinoflagellata

• Dinoflagellates are also known as fire algae, often red in color
• These are microscopic, unicellular, and flagellated organisms that are frequently photosynthetic
• Neurotoxins produced by dinoflagellates cause paralytic shellfish poisoning, also known as "red tide"

Phylum Chlorophyta

• The phylum consists of green algae
• They have cellulose cell walls and thrive in freshwater
• They can be unicellular or multicellular
• It is believed they gave rise to plants
• Examples include desmids, chlamydomonas, and volvox

Characteristics of Chlorophyta

• Spirogyra are filamentous algae
• Chlamydomonas are unicellular, biflagellated, possess one chlorophyll and a stigma
• Volvox are multicellular algae, with biflagellated cells arranged to form a sphere
• Desmids are unicellular and resemble a banana

Phylum Bacillariophyta

• Diatoms are used in abrasive procedures
• These are microscopic, unicellular organisms that inhabit both freshwater and saltwater

Phylum Phaeophyta

• Brown algae, containing alginin
• Their cell walls consist of cellulose and alginic acid
• They are multicellular
• Few species are microscopic
• They store carbohydrates
• They are harvested for alginin

Alginin

• An alginate absorbs water rapidly, making it valuable as an additive in dehydrated items such as slimming aids, and in the manufacturing of paper and textiles
• Also used for waterproofing and fireproofing textiles, as a gelling agent, to thicken drinks, ice cream, and cosmetics, and as a detoxifier that can absorb poisonous metals

Phylum Rhodophyta

• This phylum consists of red algae, including agar
• Their cell walls are made of cellulose
• Most are multicellular
• They store glucose polymer
• These are harvested for agar and carrageenan

Agar

• It serves to make jellies, puddings, and custards
• It provides a solid surface containing medium for the growth of bacteria and fungi

Carrageenan

• Used as a thickening and stabilizing agent in the food industry.
• Used in desserts, ice cream, milkshakes, sweetened condensed milk, and sauces
• Used as an inactive excipient in pills and tablets within the pharmaceutical industry

Phylum Euglenophyta

• Euglena belong in this phylum
• Possess both algal and protozoan characteristics.
• Contains stigma (light sensing organelle) and flagellum
• Algal feature: photosynthetic
• Protozoal feature: Cytostome (primitive mouth)
• Possesses pellicle (thickened cell membrane

Medical Significance of Prototheca

• Prototheca causes protothecosis and lives in the soil, entering through wounds on feet
• Small subcutaneous lesions to crusty, warty lesions and can be debilitating or fatal if it enters the lymphatic system

Medical Significance of Phycotoxins

• Phycotoxins are poisonous secretions to humans, fish, and other animals

Protozoa

• Protozoa are eukaryotic, unicellular, animal-like, and motile organisms
• A trophozoite is a motile, dividing, and feeding state
• Some produce cysts (dormant stage)
• Asexual reproduction occurs through fission, budding, or schizogony
• Sexual reproduction occurs through conjugation
• They don't have cell walls while a pellicle serves for protection
• Contractile vacuoles (in Amoeba and Paramecium) pump out water
• Some are parasites that break down and absorb host nutrients
• Pathogens includes malaria, giardiasis, African sleeping sickness and amebic dysentery
• Show Symbiotic relationship (in termites)

Ciliates

• Ciliates move by cilia
• They have complex cells
• Balantidium coli is the only human parasite
• Vorticella also belongs in this group

Amoebae

• Amoebae move through pseudopods
• They perform phagocytosis
• Entamoeba causes dysentery and extraintestinal abscesses
• Acabthamoeba can cause eye infection

Flagellates

• Flagellates have multiple flagella
• Giardia lamblia is a flagellate
• Trichomonas vaginalis (no cyst stage)

Sporozoa

• Sporozoa lack pseudopodia, flagella or cilia
• They are non-motile
• Plasmodium ssp. causes malaria
• Cryptosporidium parvum causes cryptosporidiosis

Fungi

• Diverse eukaryotic kingdom
• Most fungi are aerobic or facultatively anaerobic, found almost everywhere
• Some are saprophytic and others are Parasitic
• Decomposers of organic matter

Characteristics of Fungi

• No chlorophyll
• Cell walls contain chitin
• Many are unicellular (yeast)
• Others grow as filaments called hyphae, which intertwine to form a mass called mycelia(thallus)
• Some fungi have septate hyphae while others have aseptate hyphae, which contains multinucleated cytoplasm (coenocytic)

Reproduction of Fungi

• Reproduction occurs through budding, hyphal extension or formation of spores
• Fungal spores can be sexual and asexual spores
• Sexual spores result from the fusion of two gametes (ascospores, basidiospores, zygospores)
• Asexual spores are not formed by fusion (conidia)
• Some species produce both sexual and asexual spores
• Fungal spores are very resistant to heat, cold, acids, and bases

Classification of Fungi

• Divided into five phyla based on the mode of reproduction
• Lower fungi include Zygomycotina (e.g. bread molds, food spoilage) and Chytridiomycotina (e.g. water molds)
• Higher fungi include Ascomycotina (e.g. yeasts) and Basidiomycotina (e.g. fleshy fungi)
• Fungi Imperfecti (no sexual reproduction)- Deuteromycotina (e.g. penicillium)

Yeasts

• Unicellular fungi
• Blastoconidia are individual yeast cells
• Fission yeasts divide symmetrically
• Budding yeasts divide asymmetrically
• Pseudohypha form a string of elongated buds
• Chlamydosphores are thick-walled spore-like
• Used for wine, beer, and alcohol production, such as Saccharomyces cerevisiae (Baker's yeast)
• Produce many vitamins and proteins
• Some are human pathogens (e.g., Candida albicans)

Molds

• The fungi are seen in water & food

Fungal Thallus

• It is composed of hyphae while an amass of hyphae is a mycelium

The Great Potato Famine

• Phytophthora infestans, potato blight mold, was in Ireland
• It killed Ireland’s potato crops in 1845, 1846 and 1848
• More than 1 million people died of starvation
• Antoine de Bary proved that fungus caused the blight

Importance of Molds

• Antibiotics are acquired from Penicillium and Cephalosporium.
• Chemical alterations can increase activity within antibiotics, for example, synthetic penicillins like, ampicillin, amoxicillin, & carbenicillin
• Used for production of large quantities of enzymes (amylase, citric acid, organic acids)
• Molds provide flavor in diff. types of cheeses (camembert, limburger)

Fleshy Fungi

• Large Fungi includes Mushroom, toadstools, puffballs and bracket fungi
• Many mushrooms are edible, but some are extremely toxic and may cause permanent liver and brain damage or death if ingested

Fungal Infections (Mycoses)

• Superficial mycoses affect the outermost areas (skin)
• Cutaneous mycoses affect the living layer of the skin
• Opportunistic mycoses are caused by normal microbiota or fungi that are normally nonpathogenic
• Subcutaneous mycoses are beneath the skin

Dimorphic Fungi

• Pathogenic dimorphic fungi are yeast-like at 37°C and mold-like at 25°C
• Histoplasma capsulatum (histoplasmosis), Sporothrix schenckii (sporotrichosis), Coccidioides immitis (coccidiomycosis), and Blastomyces dermatitidis (blastomycosis)

Lichens

• A mix with Fungus + Alga, a mutualistic combination of an alga (or cyanobacterium) & fungus
• It is Symbiotic
• Alga produces and secretes carbohydrates while fungus provides holdfast
• Vary in colors, black, brown, orange, various shades of green, depending on combination of alga and fungus
• Classified as protists

Slime Molds

• These are found in soil and rotting logs
• Have both fungal and protozoal characteristics
• Start out in life as independent amoebae
• Slug is a motile, multicellular form
• Slug becomes a fruiting body (stalk and spore cap)
• From each spores emerges an amoeba

Cellular Slime Molds

• These Resemble amoebas, ingest bacteria by phagocytosis
• Cells aggregate into stalked fruiting body
• Some cells become spores

Plasmodial Slime Molds

• Plasmodial Slime Molds show multinucleated large cells
• Their Cytoplasm separates into stalked sporangia
• Nuclei undergo meiosis and form uninucleated haploid spores

Domain Bacteria

• Contains 23 phyla, 32 classes, 5 subclasses, 77 orders, 14 suborders, 182 families, 871 genera, and 5,007 species

Characteristics of Bacteria

• Cell morphology- study of sizex shape and arrangements
• Staining reactions
• Motility- movement

Simple Staining

• Determine the morphology(shapes)
• Dye is applied to the fixed smear, rinse, dried and examined using an oil immersion lens of microscope.

Structural Staining

• Use to observe bacterial capsules, spores, and flagella/ identify specific structure

Differential Staining

• classification (para macategorize)
• Gram staining
• Acid-fast staining

ACID-FAST STAINING

• Use to identify Mycobacteria spp
• Carbol fuschin (bright red) is driven into the bacterial cell using heat and softens the waxes of the cell walls of Mycobacteria, enabling the stain to penetrate
• A decolorizing agent (acid-alcohol) is then used in an attempt to remove the red color from the cells.
• Because Mycobacteria are not decolorizedby the acid-alcohol, they are said to be acid-fast
• Most bacteria are non-acid-fast
• Acid-fast stain is especially used in TB labs.

Atmospheric Requirements

• Obligate Aerobes require O2 comparable to too air (20 to 21%)
• Microaerophiles require O2 for multiplication lower than the room air (5%)
• Anaerobes do not require O2 for life & reproduction
• Obligate anaerobes can only grow in an anaerobic environment
• Aerotolerant anaerobes do not require O2 but grows better in the absence of O2
• Facultative Anaerobes capable of surviving in either the presence or absence of O2
• CAPNOPHILES grow better in the presence of increased CO2

NUTRITIONAL REQUIREMENTS of Bacteria

• Nitrogen in amino acids, proteins
• Most bacteria decompose proteins. Some bacteria use NH4 + or NO3
• A few bacteria use N2 in nitrogen fixationSulfur
• In amino acids, thiamine, biotin
• Most bacteria decompose proteins, some use S04 2 or H2S
• Phosphorus in DNA, RNA, ATP, and membranes PO4 3 - is a source of phosphorus

Organic Growth Factors

• Organic compounds obtained from the environment
• Vitamins, amino acids, purines, pyrimidines
• Carbon, structural organic molecules, energy source

Pathogenicity of Bacteria

• Capsules
• Pili - may fimbrae (for conjugation)
• Endotoxins (-) naglalabas ng toxins
• Exotoxins(+) nag-aalis ng toxins
• Exoenzyme

Unique Bacteria - Viruses

• Obligate intracellular parasites, Ehrlichia and Anaplasma spp. Tick-borne, ehrlichiosis
• Rickettsia, Arthropod-borne, spotted fevers such as R. prowazekii Epidemic typhus, R. typhi Endemic murine typhus, and R. rickettsia Rocky Mountain Spotted Fever

Chlamydia

• Are Energy parasites
• Mode of transmission is -inhalation of aerosols or direct contact between hosts
• C. trachomatis causes Trachoma while it is a STD causes urethritis
• C. pneumoniae is a pathogen
• C. psittaci causes psittacosis

Mycoplasma

• Wall-less, pleomorphic
• 0.1 - 0.24 μm
• M. pneumoniae

Photosynthetic Bacteria

• Includes purple bacteria, green bacteria and cyanobacteria
• Photosynthesis in thylakoids
• Oxygenic photosynthesis
• Anoxygenic photosynthesis

Domain ARCHEA

• Discovered in 1977
• Contains 2 phyla, 8 classes, 12 orders, 21 families, 69 genera, and 217 species
• Genetically, archaeans are closely related to eukaryotes than bacteria

Thermophiles

• Heat-loving archaebacteria found near hydrothermal vents and hot springs
• Many thermophiles are chemosynthetic using dissolved sulfur or other elements as their energy source and iron as a means of respiration

Halophiles

• Thrive in unusually salty habitats while some can thrive in water that’s 9% salt; seawater contains only 0.9% salt
• Have light-sensitive pigment bacteriorhopsodin which absorbs energy from sunlight

In Vitro

• Desiccation, the drying all bacteria undergo
• Psychrophiles likes extremely cold temperatures (even down to -10degrees Celsius)
• They live in arctic and antartic oceans

Factors that Affect Bacterial Growth

• Availability of nutrients
• Moisture, Temperature and PH
• Osmotic pressure and salinity B- arometric pressure, and a Gaseous atmosphere

Power of Hydrogen

• The Acidity or alkalinity
• Most microorganism prefer a neutral or slightly alkaline medium
• Most bacteria grow between pH 6.5 and 7.5
• Molds and yeasts grow between pH 5 and 6
• Acidophiles can live in stomach, pickled food

Osmotic Pressure and Salinity

• Osmotic pressure is pressure that is exerted on a cell membrane by solutions both inside and outside the cell
• Osmosis-movement of a solvent thru a permeable membrane from a solution having a lower concentration of solute to a solution of a higher concentration

Bacterial Growth in the Laboratory

• This involves Petri dishes, test tubes, bunsen burners/alcohol lamps and wire inoculating loops

Bacterial population

• If determined by growing a pure culture .The organism will use a liquid medium at a constant temperature.