Assist. Prof. Dr. Betül AKCESME 03 General Microbiology BIO306 Assist. Prof. Dr. Betül AKCESME

Microbial diversity Microbial diversity can be seen in many ways besides phylogeny, including cell size and morphology (shape), physiology, motility, mechanism of cell division, pathogenicity, developmental biology, adaptations to environmental extremes…

MICROBIAL DIVERSITY The tree domains of life Three phylogenetically distinct cellular lineages have been revealed. Eukaryotes cells Eukarya Prokaryotic cells Bacteria Archea All prokaryotes are not phylogenetically closly related Archaea are actually more closely related to eukarya than to bacteria

Metabolic Diversity All cell requires energy Organic Chemicals Inorganic Chemicals Light Microorganisms have exploited every conceivable means of obtaining energy from the environment

Waste Products inorganic compounds Chemotrophs are organisms that obtain energy from chemicals (by the oxidation of electron donors in their environments) Organisms that use organic chemicals are called Chemoorganotrophs. Aerobes use oxygen to obtain energy Anaerobes obtain energy in the absence of oxygen Organisms that use inorganic chemicals are called Chemolithotrophs. This form of metabolism is called Chemolithotrophy. Chemolithotrophy only occurs in prokaryotes. Inorganic compounds H2, H2S (hydrogen sulfide), NH3 (ammonia), and Fe21 (ferrous iron) can be oxidized Waste Products inorganic compounds İnorganic compounds H2, H2S (hydrogen sulfide), NH3 (ammonia), and Fe21 (ferrous iron).

Microorganisms that use light called phototrophs They have pigments that allows them to convert light energy into chemical energy. Phototrophs do not require chemicals as a source of energy. Oxygenic Phototrophs (produces oxygen) Anoxygenic Phototrophs (not produce oxygen)

•All cells require carbon as a major nutrient Heterotrophs Which require organic compounds as their carbon source Feed directly on autotrophs or live off products produced by autotrophs Auototrophs Which use carbon dioxide(CO2) as their carbon source. Sometimes referred to as primary producers Chemolithotrophs and phototrophs Chemoorganotrophs Auototrophs (Primary producers) heterotrophs

Microorganisms are present everywhere on Earth that will support life. Organisms that inhabit extreme environments are called extremophiles Habitats include boiling hot springs, glaciers, extremely salty bodies of water, and high-pH environments

Microbial Diversity Bacteria Archaea Eukaryo Prokaryote Eukaryote

Bacteria

1) Bacteria Proteobacteria Major group of bacteria All known disease-causing (pathogenic) prokaryotes are Bacteria. They include a wide variety of pathogens Escherichia Salmonella Vibrio Helicobacter Phototrophic and chemolithotrophic Proteobacteria. (a) The phototrophic purple sulfur bacterium Chromatium (the large, redorange, rod-shaped cells in this photomicrograph of a natural microbial community). A cell is about 10 m wide. (b) The large chemolithotrophic sulfur-oxidizing bacterium Achromatium. A cell is about 20 m wide. Globules of elemental sulfur can be seen in the cells (arrows). Both of these organisms oxidize hydrogen sulfide (H2S).

Bacteria Gram-Positive Gram-positive organisms are able to retain the crystal violet stain because of the high amount of peptidoglycan in the cell wall. cytoplasmic lipid membrane thick peptidoglycan layer capsule polysaccharides (only in some species) flagellum (only in some species) if present, it contains two rings for support as opposed to four in Gram-negative bacteria because Gram-positive bacteria have only one membrane layer.

Gram Staining It is based on the chemical and physical properties of their cell walls. Primarily, it detects peptidoglycan, which is present in a thick layer in Gram positive bacteria. A Gram positive results in a purple/blue color Gram negative results in a pink/red color.

Bacteria Cyanobacteria Phylogenetic relative of gram positive bacteria. They are oxygenic phototrophs. (obtain their energy through photosynthesis) First oxygenic phototrophs to evolve on Earth. Cyanobacteria can be found in almost every terrestrial and aquatic habitat: in oceans, fresh water - even bare rock and soil Cyanobacteria include unicellular and colonial species. Colonies may form filaments, sheets or even hollow balls.

Many Other Phyla of Bacteria – Green sulfur bacteria and green nonsulfur bacteria are photosynthetic – Deinococcus is extremely resistant to radioactivity – Chlamydia are obligate intracelluar parasites Deinococcus radiodurans Chloroflexus (green nonsulfur bacteria). Phototrophic green bacteria.

2) Archaea They have no cell nucleus or any other membrane-bound organelles within their cells. They are prokaryotic in general structure and they do share many bacterial characteristics. But evidence is accumulating that they are actually more closely related to Domain Eukarya than to bacteria. archaea and eukaryotes share a number of ribosomal RNA sequences that are not found in bacteria, protein synthesis and ribosomal subunit structures are similar.

2 domain: Euryarchaeota Crenarchaeota

Archaea 1. Euryarchaeota Euryarchaeota can be organized into four types Methanogens procaryotes that produce methane, strict anearobic, can not tolerate very low oxygen. Extreme halophiles prokaryotes that live at very high concentrations of salt (NaCl) for metabolism and reproduction. Require oxygen Extreme (hyper) thermophiles prokaryotes that live at very high temperatures. Carbon source CO2 Thermoacidophiles grow in moderately high temperatures and low-pH environments

Halophiles around the world Halophiles around the world. (a) An aerial view of a salt pond at San Francisco Bay, California. The archaea that thrive in this warm, highly saline habitat produce brilliant red, pink, and orange pigments.

Figure 2. 31 Extremely acidophilic Archaea Figure 2.31 Extremely acidophilic Archaea. The organism Thermoplasma lacks a cell wall. The cell measures 1 m wide. Figure 2.30 Extremely halophilic Archaea. A vial of brine with precipitated salt crystals contains cells of the extreme halophile, Halobacterium. The organism contains red and purple pigments that absorb light and lead to ATP production. Cells of Halobacterium can also live within salt crystals themselves

Archaea 2. Crenarchaeota Most abundant archaea in the marine environment. All cultured Crenarchaea had been thermophilic or hyperthermophilic organisms, some of which have the ability to grow at up to 113 °C These organisms are either chemolithotrophs or chemoorganotrophs and grow in hot environments such as hot springs and hydrothermal vents

Not all archaea are adapted to extremes, and many are widely distributed in more moderate environments such as soils, oceans, and even animal intestines.

For rRNA analysis no necessarily need for culture Microbiologists believe that we have cultured only a small fraction of the Archaea and Bacteria For rRNA analysis no necessarily need for culture Isolate rRNA from natural sample (soil or water) Bypass the culturing steps (bottleneck in microbial diversity studies)

Microbial Eukaryo Eukaryotic microorganism are related by cell structure and phylogenetic history Plant-Animal “most derived” Structurally simple eukaryotes lacking mitochondiral and some other organalles.

3) Eukaryo Protist Algae Protozoa Fungi Slime modes

Eukaryo 1) Protist Diverse group of eukaryotic microorganism. Mostly unicellular organism. Simple cellular organisation distungiused the protists from other eukaryotes, such as fungi, animals and plants.

1) Protist Algae Most are photosynthetic like plants "simple" because their tissues are not organized into the many distinct organs found in land plants. They contain chloroplast Environment containing few minerals Primary Producers! All true algae therefore have a nucleus enclosed within a membrane and plastids bound in one or more membranes. Can live in environment containing only a few minerals, water, CO2, light.

1) Protist Protozoa Protozoa are a diverse group of unicellular eukaryotic organisms Many of them are motile. Protozoa commonly range from 10 to 52 micrometers, but can grow as large as 1 mm, and are seen easily by microscope Has no cell wall like algea and fungi. Example of protozoa Flagella Paramecium

2) Fungi large group of eukaryotic organisms Cell wall One major difference is that fungal cells have cell walls that contain chitin, unlike the cell walls of plants, which contain cellulose Fungi perform an essential role in the decomposition of organic matter and have fundamental roles in nutrient cycling and exchange.

They are motile and lack cell walls. (similar to protazoa) 3) Slime molds They are motile and lack cell walls. (similar to protazoa) Differ from protozoa Their phylogeny Complex life cycle Motile cells aggragate to form a multicellular structure called fruiting body.

As a summary Protists include algae and protozoa Fungi are decomposers The algae are phototrophic Protozoa NOT phototrophic Fungi are decomposers Algae and fungi have cell walls, whereas protozoa and slime molds do not are organisms that break down dead or decaying organisms, and in doing so, carry out the natural process ofdecomposition.[1] Like herbivores and predators, decomposers are heterotrophic, meaning that they use organic substratesto get their energy, carbon and nutrients for growth and development.

Microbial Eukarya. (a) Algae; dark-field photomicrograph of the colonial green alga Volvox. Each spherical cell contains several chloroplasts, the photosynthetic organelle of phototrophic eukaryotes. (b) Fungi; interference-contrast photomicrograph of spores of a typical mold. Each spore can give rise to a new filamentous fungus. (c) Protozoa; phase-contrast photomicrograph of the ciliated protozoan Paramecium. Cilia function like oars in a boat, conferring motility on the cell. Microbial Eukarya. (a) Algae; dark-field photomicrograph of the colonial green alga Volvox. Each spherical cell contains several chloroplasts, the photosynthetic organelle of phototrophic eukaryotes. (b) Fungi; interference-contrast photomicrograph of spores of a typical mold. Each spore can give rise to a new filamentous fungus. (c) Protozoa; phase-contrast photomicrograph of the ciliated protozoan Paramecium. Cilia function like oars in a boat, conferring motility on the cell.

END of Second Chapter!