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 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 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 (NH3 NO2)

and Nitrobacter (NO2 NO3) 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)

Figure 4.18

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), polysaccharide walls in other (as in Methanosarcinae) and glycoprotein walls in Halobacterium).

others (as in

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 ascospores

http://www.yeastgenome.org/images/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

sclerotia http://botit.botany.wisc.edu:16080/toms_fungi/oct2003.html slime molds

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.