Microbial ecology

Figure 21.3

DAPI fluorescent staining for DNA

Live dead stain

Fluorescent antibody

Arabidopsis root and shoot and DEC8D pgfp

FISH

Microbial mat and microelectrodes top cyanobacteria next anaerobic photosynthetics and heterotrophs

Figure 21.9

Figure 21.17

Figure 21.19A and B

Figure 21.22 Figure 21.23

Microbes Associated with Roots• The environment surrounding a plant root can be

further subdivided into two categories:

- Rhizoplane: The plant root surface

- Rhizosphere: The region of soil outside the rhizoplane that receives substances from the root

Particular microbial species are adapted to these environments.

Figure 21.27

Microbial Communities within Plants• Endophytes are bacteria or fungi that colonize the

transport vessels of plants.• - Produce alkaloids and enzymes that deter

plant pathogens and root-feeding nematodes

Endophytic pathogens pose a problem for the food industry because the bacteria cannot be “washed off” from raw produce.

Figure 21.31

Wetland Soils• A wetland is a region of land that undergoes seasonal

fluctuations in water level.• - Dry and oxygenated vs. water-saturated and anaerobic

Many kinds of anaerobic bacteria inhabit wetlands.

- Denitrifiers

- Fermenters

The anoxic conditions of wetlands also favor methanogenesis.

Figure 21.30

Figure 21.40 A and B

Figure 21.41

Vertebrate Gut Fermentation

Figure 21.42