Diversity.Pdf

Diversity The world of living things (Figure from Madigan et al. 2002) • Microbes in all three domains • Two of the domains are exclusively prokaryotic and microbial • The third contains both unicellular and multicellular organisms (including multicellular microbes) A word of caution about ‘a little knowing’ • Lab organisms limit the view of the world of microbiology A look at some of the bizarre, interesting, and maybe ‘no-way’ modes of microbial life BACTERIA Phototrophic and Lithotrophic metabolism • Phototrophs are those organisms that use light energy to establish a proton gradient to phosphorylate ADP o Cyanobacteria use oxygenic photosynthesis (H20 + CO2 Æ CH2O + O2) to fix carbon. These organisms are very common and exist in • all aquatic systems, • desert sands, and • soils. Many have the ability to fix elemental N2 into NH3 and this only enhances their ability to survive in diverse habitats Why is this important? (Table-Figures from Madigan et al. 2002) Figure 14.38 o Phototrophic bacteria Use anoxygenic photosynthesis (H2S + CO2 Æ CH2O + S2) to fix carbon into cell stuff Primarily found in restricted habitats • H2S must be available • Light must be available • Located in ‘bands in lakes and near the surface of muddy environments Some may grow chemoorganotrophically in the dark Some may grow photoheterotrophically (Figures from Madigan et al. 2002) • Chemolithotrophs o Organisms that obtain energy from oxidation of inorganic compounds o Most can fix CO2 into cell stuff using the Calvin Cycle (that is the one green plants use) o Many can obtain reduced coenzymes by operating electron transport chains in reverse. Nitrifying bacteria • Grow at the expense of reduced inorganic nitrogen and all oxidations are aerobic. • No single genus can oxidize NH3 all the ay to NO3 • Most common organisms are Nitrosomonas (NH3ÆNO2) and Nitrobacter (NO2ÆNO3) Sulfur oxidizing bacteria • Grow at the expense of reduced sulfur as an electron donor. • General metabolism takes H2S or some other reduced S- compound and produces SO4. • Net result of this metabolism is the production of H2SO4 • Since electrons are readily available from the reduced sulfur, these cells may use the electrons to drive electron transport system backwards and produce NADH+ without having to oxidize some organic compound • Example is Thiobacillus (Iron metabolism) Hydrogen bacteria • Almost all facultative Chemolithotrophs. • May grow chemolithotrophically using hydrogen as the sole electron donor and Calvin cycle to fix CO2 • May grow chemoorganotrophicly using organic sources of energy. ARCHAEA One of the three domains of life. Organisms with this domain are among the oldest organisms that have been identified Look at the location of the common ancestor on the tree of life. Cells in this group are not morphologically distinguishable from other prokaryotes and this feature retarded research into the group However, membranes are not composed of ester-linked phospholipids but are instead composed of ether linked phytanyls. (Madigan et al. 2002) Membranes in these cells may be bi-layer or monolayer Cells walls exist but are not of peptidoglycan. Instead, pseudo- peptidoglycan may be present (as in Methanobacteria), Figure 4.18 polysaccharide walls in other (as in Methanosarcinae) and glycoprotein walls in others (as in Halobacterium). Figure 4.19 Despite anatomical differences, metabolic physiology in just as diverse as that found in the Bacteria. o Extreme halophiles o Archae that require at 1.5 M NaCl and can grow at NaCl concentrations up to 5.5 M. They are easily isolated from the Great Salt Lake, the Dead Sea, and from Salt Pans. o Good example is Halobacterium (Figure 13.2 from Madigan et al. 2002) Methanogens (Figure 13.5 at right from Madigan et al 2002) o Cells producing methane (CH4) from CO2 and H2. o Many are autotrophs and all are anaerobes. o Good example is Methanobacteium Hyperthermophillic archae Organisms that have optimal temperatures for growth above 80C. Cells are obligatory anaerobic chemoorganotrophs or Chemolithotrophs. EUKARYA Members of the Eukarya are those cells have a true nucleus and are the ‘youngest’ of cells in the evolutionary map. Cells types include members of the o Algae o Fungi o Slime molds o Protozoa Algae (Table 14.3 and following figures from Madigan et al 2002) o Contain chlorophyll and conduct oxygenic photosynthesis. o Most are single cell or colonial o Algal cells contain one or more chloroplasts, however, some can grow chemoorganotrophically o Major groups separated by Morphology Type of chlorophyll and accessory pigments Nature of storage polymers Micrasteria Volvox Spirogyra Scenedesmus Euglena Polysiphonia Nitzchia Thalassiosira Asteriolampra Ornithocercus Fungi (Table 14.2, Fig. 14.1 and mold photo from Madigan et al. 2002) o Fungi are eukaryotes that lack chlorophyll and are all heterotrophs. o Extremely varied habitats (water, soil, people, plants, insects) o Cells walls are common and are often composed of cellulose or chitin. o Typically described by the terms molds (filamentous organisms) yeasts single cells, mushrooms (actually the fruiting structures or reproductive structures of some molds) o General growth form of the mold is the hyphae. A filament that grow at the tip and may be septate or non-septate (multi-nucleate) A collection of hyphae growing together to form a ‘colony’ is termed a mycelium o Yeast often resemble bacteria on agar surfaces Reproduce by budding and are quite large compared to bacteria o Reproduction of the fungi may be asexual or sexual. Asexual reproduction is by spores known as conidia. Sexual spores are formed in specialized structures As in the basiocarp or ascocarp http://www.plantpath.wisc.edu/soyhealth/biocont4.htm http://www.yeastgenome.org/images ascospores /ovals.jpg yeast http://turf.ufl.edu/residential/images/13bigweb.jpg fairy ring http://botit.botany.wisc.edu/images basidospores Slime molds o Organisms that are individual cells that can be drawn together by chemical signaling to form fruiting (reproductive) structures. o Non-cellular slime molds are multinucleate masses of protoplasm. o Movement occurs by cytoplasmic streaming. The plasmodium is diploid and may form a fruiting structure known as a sporangium. o Plasmodium my also dry out and form a resting structure known as http://botit.botany.wisc.edu:16080/toms_fungi/oct2003.html slime molds sclerotia Protozoa o The protozoa are phagotrophs (so no cell walls) with extremely cosmopolitan distribution. o Group is phylogenetically distinct and very poorly characterized. http://www.wolfbat359.com/funI105.jpg paramecium References: Madigan, M. T., J.M. Martinko, and J. Parker. 2002. Brock Biology of Microorganisms 10th ed. Prentice Hall. .

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