1. Soil ORGANISMS

3. Global Soil Biodiversity Initiative
website

4. KINGDOMS OF LIFE

5. Eukaryotes have cell membranes and nuclei
All species of large complex organisms are eukaryotes, including animals, plants and fungi, although most species of eukaryotic protists are microorganisms.
Prokaryotes lack nucleus
bacteria
Protists: eukaryotic microorganisms that don’t form tissues

6. Organic portion composed of:5%
10%
85%
Humus & decomposing
organic litter

7. Living organisms <5% Fresh residue <10%
Photo credit: Collohmannia sp. Roy A. Norton, State University of New York at Syracuse
File name: M8 Mites and Leaf
Stabilized organic
matter
(humus)
33% - 50%
Decomposing organic matter
(active
fraction)
33% - 50%

8. The divisions of the 5%:
40% bacteria and actinomycetes

9. BACTERIA
Photo credit: Michael T. Holmes, Oregon State University, Corvallis
File name: PBUT

10. Bacterial biomass dominates :
grassland and agricultural landscapes
Fungal biomass dominates:
Forests

11. bacteria

12. Bacteria Abundant in rhizosphere Four FUNCTIONAL GROUPS:
Tiny (1 μm width), one-celled
Single cell division
In lab: 1 can produce 5 billion in 12 hours
(In real world limited by predators, water & food availability)
Abundant in rhizosphere
Four FUNCTIONAL GROUPS:
Decomposers
Mutualists : partner with plants
Pathogens
Chemoautotrophs

13. Some terms:
Autotrophs: can make organic compounds from inorganic compounds
Heterotrophs: feed on others to make organic compounds
Chemosynthetic: get energy from inorganic chemical reactions
Photosynthetic: get energy from sun
Aerobes: use aerobic respiration (need oxygen as electron acceptor)
Anaerobes: use inorganic or organic compounds for electron acceptor

14. Decomposers Organic chemicals in big complex chains and rings
Bacteria break bonds using enzymes they produce
Create simpler, smaller chains

15. Mutualists e.g., Nitrogen-fixing Bacteria
Nodules formed where Rhizobium bacteria infected soybean roots.
File name: Nods on Beans.jpg 277K (Also C-2 at 580K shows whole box.)
Photo credit: Stephen Temple, University of Minnesota, St. Paul. (NRCS may use this image for educational purposes.)
File name: Nods on beans

16. Root nodules

17. Chemoautotrophs Get energy from OTHER THAN CARBON compounds
From N, S, Fe, H

18. Actinomycetes Are bacteria but grow like fungi Filamentous but
morphology varies
Adaptable to drought
Important at high pH
Usually aerobic heterotrophs
Break down wide range of organic compounds
Produce geosmin (smell of “fresh soil”)

19. 40% other Microflora
Protozoa Algae Fungi

20. PROTOZOA Ciliates Amoeba Flagellates Largest of the three
Move by means of hair-like cilia
Eat other protozoa and bacteria
Amoeba
Also large
Move by means of a temporary foot (pseudopod)
Flagellates
Smallest of the three
Move by means of a few whip-like flagella.

21. Protozoa
Flagellates
Amoeba
Ciliates
Eat bacteria &
protozoa

22. protozoa Unicellular Heterotrophic Form symbiotic relationships
Eat bacteria, fungi
Form symbiotic relationships
e.g., flagellates in termite guts; digest fibers
Require water
Go dormant within cyst in dry conditions

23. Function of protozoa Make nutrients plant-available
Release excess N from the bacteria they eat
Regulate bacteria populations
Compete with pathogens

24. PROTOZOA bacteria Sand protozoa File name: Testate amoeba LR.jpg, 179K
Credit: Elaine R. Ingham, Oregon State University, Corvallis

25. Flagellate File name: vorticella prot LR.jpg, 278K
Credit: Elaine R. Ingham, Oregon State University, Corvallis.

26. Ciliate File name: ciliate2 LR.jpg 294K
Credit: Elaine R. Ingham, Oregon State University, Corvallis

27. Amoeba bacteria amoeba Photo credits:
(brown photo) No. 35 from Soil Microbiology and Biochemistry Slide Set J.P. Martin, et al., eds. SSSA, Madison, WI
(blue photo) Michael T. Holmes, Oregon State University, Corvallis. (We never used this in the Primer.)
File names:
(blue photo) AMOE
(brown photo) SSSA35
bacteria
amoeba

28. Soil-Dwelling “Vampires”
Vampyrellids
Vampyrellids are a group of amoebe that eat fungi by drilling round holes through the fungal cell wall and consumes the fluid inside.
In this picture, they attack Gaeumannomyces graminis, the fungus that causes “take-all disease” in wheat.
File name: vampraid.jpg, 451K (Also: E-4 at 1500KB, shows whole Bug Biography.)
Photo credit: Homma, Y. et al Phytopathology 69:
(Photo is in the public domain.)
Group of amoebe that drill holes in fungus and consume liquid

29. Archaea ( ar-KEY-ah) A recent discovery: 1970s Woese and Fox:
Divided bacteria into “normal” and “extremophiles” (archaeabacteria)
Changed classic “tree of life”
Bacteria
Archaea
Eukaryotes

30. Very similar to bacteria in shapes and size and reproduction
Differences:
Cell membranes contain lipids
Not chitin (like fungi)
Not cellulose (like plants)
Genes of archaea are more similar to eukaryotes than to bacteria
Can use a lot of various substances for energy

31. Importance Role in carbon cycle
Photoautotrophs, chemoautotrophs, photoheterotrophs, chemoheterotrophs
Many can survive in extreme environments (enzymes); heat, cold, salt, low pH
Many are methane-producers:
Swamp gas, cow farts
Sheer numbers:
Combined marine and soil archaea make them the most abundant organism on earth

32. Importance in Soil Role in N cycle Decomposition Ammonia oxidizers
Important anaerobic decomposers
Important in extreme environments where bacteria do not fluorish

33. algae Filamentous, colonial, unicellular Photosynthetic
Most in blue-green group, but also yellow-green, diatoms, green algae
Need diffuse light in surface horizons; important in early stages of succession
Form carbonic acid (weathering)
Add OM to soil; bind particles
Aeration
Some fix nitrogen

34. Fungi Break down OM, esp important where bacteria are less active
attack any organic residue
Most are aerobic heterotrophs
chemosynthetic: adsorb dissolved nutrients for energy

35. Grow from spores into branched hyphae
Hyphal strand divided into cells by septa that allow flow of liquids between cells
Masses of hyphae grow together in visible threads
called mycelia

36. Advantages over bacteria:
They can grow in length
Rate: 40 μm / min (bacterium travels 6 μm in its life)
Don’t need a film of water to move
Can find new food sources
Transport nutrients great distances
Produce enzymes that break down complex compounds
Can break down lignin (woody compound that binds cellulose), shells of insects, bones
Can break down hard surfaces

37. Clever, clever adaptations!
Infecting a nematode
Hypha twists back on itself and catches a nematode, hyphal cells swell and kill nematode then enter body and suck out nutrients
Oyster mushroom
Emits toxic drops from hyphal tips which touch nematode, immobilize it and hyphae enter body and remove nutrients
Trap arthropods or protozoa and digest them

40. Mycorrhizae: symbiotic absorbing organisms infecting plant roots, formed by some fungi
normal feature of root systems, esp. trees
increase nutrient availability in return for energy supply
plants native to an area have well-developed relationship with mycorrhizal fungi
Can extend the effective surface area of tree’s roots by x

42. Mycorrhizal structure
Mycorrhizae
Tree root
Photo credit: Randy Molina, Oregon State University, Corvallis.
File name: M4 Fungi LR.jpg, 328K
Fungal hyphae
Mycorrhizal structure

43. Ectomycorrhizal
Endomycorrhizal
Grow close to root surfaces
Hardwoods and conifers
Penetrate and grow inside roots
Vegetables, annuals, grasses, shrubs, perennials, softwoods

44. Ectomycorrhizae
Photo Credit: USDA, Forest Service, PNW Research Station, Corvallis, Oregon.
File name: Ectomy~1

45. Arbuscular Mycorrhizae (AM)
File name: VAM LR.jpg 205K
Photo Credit: Elaine R. Ingham, Oregon State University, Corvallis.

46. Higher fungi have basidium : club-shaped structure , bearing fruiting body
toadstools, mushrooms, puffballs, bracket fungi

47. Fungi and Soil Quality Decompose carbon compounds
Improve OM accumulation
Retain nutrients in the soil
Bind soil particles
Food for the rest of the food web
Mycorrhizal fungi
Compete with plant pathogens
Photo credit: No. 48 from Soil Microbiology and Biochemistry Slide Set J.P. Martin, et al., eds. SSSA, Madison WI.
File name: SSSA48

48. 12% Earthworms
(Macrofauna: > 1 cm long) ANNELIDS

49. earthworms Some 7000 species 3 categories:
Epigeic (leaf litter/compost dwelling )
Endogeic (topsoil or subsoil dwelling )
Anecic (deep burrow drillers)

50. Giant Benefits to soil Move air in and out of soil
Castings are rich in available nutrients
Produce 10 lbs / yr

51. 1 acre good garden soil: 2-3 million
1 acre forest soil: 50,000

52. Other Macrofauna (5%) and Mesofauna(3%)
CHORDATES (vertebrates) mammals, amphibians, reptiles PLATYHELMINTHES (flatworms) ASCHELMINTHES (roundworms, nematodes) MOLLUSKS (snails, slugs) ARTHROPODS : (insects, crustaceans, arachnids, myriapoda)

53. vertebrates
Squirrels, mice, groundhogs, rabbits, chipmunks, voles, moles, prairie dogs, gophers, snakes, lizards, etc.
Contribute dung and carcasses
Taxicabs for microbes

54. nematodes

55. NEMATODES File name: large todes LR.jpg, 262K
Credit: Elaine R. Ingham, Oregon State University, Corvallis.

56. NEMATODES Bacteria feeder Fungal feeder
Top left is the bacterial-feeding nematode, Elaphonema.
Bottom right is a fungal-feeding nematode.
Photo credits: (for both) Elaine R. Ingham, Oregon State University, Corvallis
File names:
BFTODE
FFTODE
Fungal feeder

57. Predatory Nematode File name: predatory tode LR.jpg 254K
Credit: Kathy Merrifield, Oregon State University, Corvallis.

58. Root-feeding nematodes
Upper left is the lesion nematode, Pratylenchus.
Lower right is the root-feeding nematode, Trichodorus.
File names:
Upper Left: rootfeedingtode prat LR.jpg, 233K
Lower right: rootfeedingtode trich LR.jpg, 184K
Credits:
Upper Left: Kathy Merrifield, Oregon State University, Corvallis.
Lower right: Elaine R. Ingham, Oregon State University, Corvallis.

59. Fungal hyphal rings constrict when a nematode swims through.
Nematode Trappers
Fungal hyphal rings constrict when a nematode swims through.
Some fungi make circular rings of hyphae.
The rings constrict when a nematode swims through.
Genus of this fungi is Arthobotrys.
File name: Arthrobotrys.jpg at 265K. (Also: F-4 at 1600KB shows whole Bug Biography)
Photo credit: George L. Barron, University of Guelph, Ontario.

60. Nonsegmented, blind roundworms > 20,000 species
Eat bacteria or fungi or plants (stylet)
And protozoa, other nematodes, algae
Specialized mouthparts
Can sense temperature and chemical changes

61. nematode

62. arthropods ¾ of all living organisms
Exoskeleton, jointed legs, segmented body
Insects
Crustaceans
Arachnids
Myriapoda

63. Shredders
Microbial taxis

64. Mites
arachnids

65. Extracted from one ft2 of top two inches
of forest litter and soil

67. Springtails Arthropods Spring or hop Detrivores 100,000 / m3 topsoil
Invertebrates with external skeleton
Spring or hop
Detrivores
100,000 / m3 topsoil

68. Beetles Arthropods; order Coleoptera 400,000 species (40% of all
known insect species)
Some omnivores, some
eat plants, fungi, some
are carnivores
Larvae (grubs)

69. pseudoscorpons Arachnid Carnivorous: eat larvae, ants, mites, flies
Joint-legged invertebrate
Carnivorous: eat larvae, ants, mites, flies

71. Feeding Habits Carnivores : parasites and predators Phytophages: eat above ground green plant parts, roots, woody parts Saprophages: eat dead and decaying OM Microphytic feeders: eat spores, hyphae, lichens, algae, bacteria

72. Movement existing pore spaces, excavate cavities, transfer material to surface improve drainage, aeration, structure, fertility, granulation

75. Rove beetles