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 ƒ use oxygenic photosynthesis (H20 + CO2 Æ CH2O + O2) to fix carbon. ƒ These organisms are very common and exist in • all aquatic systems, • desert sands, and • soils. ƒ Many have the ability to fix elemental N2 into NH3 and this only enhances their ability to survive in diverse habitats ƒ Why is this important? (Table-Figures from Madigan et al. 2002)

Figure 14.38 o Phototrophic bacteria ƒ Use anoxygenic photosynthesis (H2S + CO2 Æ CH2O + S2) to fix carbon into cell stuff ƒ 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 ƒ Some may grow chemoorganotrophically in the dark ƒ 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. ƒ 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) ƒ 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) ƒ 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 ƒ One of the three domains of life. ƒ Organisms with this domain are among the oldest organisms that have been identified ƒ Look at the location of the common ancestor on the tree of life. ƒ Cells in this group are not morphologically distinguishable from other prokaryotes and this feature retarded research into the group ƒ However, membranes are not composed of ester-linked phospholipids but are instead composed of ether linked phytanyls. (Madigan et al. 2002) ƒ Membranes in these cells may be bi-layer or monolayer ƒ 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

ƒ 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)

ƒ 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 ƒ Hyperthermophillic archae ƒ Organisms that have optimal temperatures for growth above 80C. ƒ Cells are obligatory anaerobic chemoorganotrophs or Chemolithotrophs.

EUKARYA ƒ Members of the Eukarya are those cells have a true nucleus and are the ‘youngest’ of cells in the evolutionary map. ƒ Cells types include members of the o Algae o Fungi o Slime molds o Protozoa

ƒ 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 ƒ Morphology ƒ Type of chlorophyll and accessory pigments ƒ Nature of storage polymers

Micrasteria Volvox Spirogyra Scenedesmus

Euglena Polysiphonia

Nitzchia Thalassiosira

Asteriolampra Ornithocercus

ƒ 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 ƒ molds (filamentous organisms) ƒ yeasts single cells, ƒ mushrooms (actually the fruiting structures or reproductive structures of some molds) o General growth form of the mold is the hyphae. ƒ A filament that grow at the tip and may be septate or non-septate (multi-nucleate) ƒ A collection of hyphae growing together to form a ‘colony’ is termed a mycelium o Yeast often resemble bacteria on agar surfaces ƒ Reproduce by budding and are quite large compared to bacteria o Reproduction of the fungi may be asexual or sexual. ƒ Asexual reproduction is by spores known as conidia. ƒ Sexual spores are formed in specialized structures ƒ 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

ƒ 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

ƒ 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.