Soil Microbiology

1. SOIL MICROBIOLOGY POOJA S NATHAN S3 BT 44

2. SOIL MICROBIOLOGY Soil microbiology  is the study of organisms in soil, their functions, and how they affect soil properties. Microorganisms in soil are important because they affect soil structure and fertility. Soil microorganisms can be classified as bacteria, actinomycetes,fungi, algae and protozoa

3. SOIL SAMPLE UNDER MICROSCOPE

4. MICROBIAL DISTRIBUTION IN SOIL

5. 1.BACTERIA

6. Bacteria and Archaea are the smallest organisms in soil apart from viruses. Bacteria and Archaea are prokaryotic. All of the other microorganisms are eukaryotic. Most soil bacteria live close to plant roots and are often referred to as rhizobacteria(lives on rhizosphere)

7. RHIZOSPHERE 1/10 inch. Exudates: carbohydrates and proteins secreted by roots. Attracts bacteria, fungi, nematodes, protozoa.

8. Rhizosphere

9. EXAMPLES: : Some genera like Pseudomonas, Arthrobacter, Clostridium, Achromobacter, Sarcina, Enterobacter  etc.

10. PICS:

11. 2.ACTINOMYCETES

12. Actinomycetes are a fungi-like bacteria forming long filaments that stretch through the soil. Actinomycetes live predominantly aerobically and are heterotrophs. They have sometimes been classed as fungi because they both look like, and decompose similar material as fungi.

13. Antibacterial agents work against them but antifungal agents do not.  Make “earthy” smell by producing geosmin Adaptable to drought Can act in high pH Break down “recalcitrant” compounds

14. One of the most notable characteristics of the Actinomycetes is their ability to produce antibiotics ,like Streptomycin

15. EXAMPLES: Nocardia asteroides Dermatophilus congolensis Streptomyces etc.

16. PICS:

17. 3.FUNGI

18. Fungi are important in the soil as food sources for other, larger organisms, pathogens, beneficial symbiotic relationships with plants or other organisms and soil health. Most of the environmental factors that influence the growth and distribution of bacteria and Actinomycetes also influence fungi.

19. The quality as well as quantity of organic matter in the soil has a direct correlation to the growth of fungi, because most fungi consume organic matter for nutrition. Fungi thrive in acidic environments, while bacteria and Actinomycetes cannot survive in acid.

20. EXAMPLES: 1.Saprophytic fungi (decomposers)  Pleurotus ostreatus (oyster mushroom) Lentinula edodes (shiitake) Stropharia rugosoannulata (king Stropharia). 2. Mutualists Fungi Zygomycota Basidiomycota

21. 3.Pathogenic fungi Pythium, Rhizoctonia, Phytophthora Verticillium.

22. PICS:

23. 4.ALGAE

24. Filamentous, colonial, unicellular Photosynthetic Algae can be split up into three main groups: Cyanophyceae Chlorophyceae Bacillariaceae Blue-green algae(Cyanophyceae) are responsible for nitrogen fixation.

25. EXAMPLES: Cyanophyta (Blue-green algae)   Chlorophyta (Grass-green algae)  Xanthophyta (Yellow-green algae)  Bacillariophyta (diatoms or golden- brown algae)

26. PICS:

27. 5.PROTOZOA

28. Protozoa are eukaryotic organisms The first microorganisms to reproduce sexually, a significant evolutionary step from duplication of spores, like those that many other soil microorganisms depend on.

29. Protozoa can be split up into three categories Flagellates Amoebae Ciliates.

30. EXAMPLES: Flagellates (e.g.,  Giardia lamblia ) Amoeboids (e.g.,  Entamoeba histolytica ) Sporozoans (e.g.,  Plasmodium knowlesi )

31. PICS:

32. IMPORTANCE OF SOIL MICROBES Organic matter decomposition and soil aggregation; Breakdown of toxic compounds Inorganic transformations that make available nitrates, sulphates and phosphates as well as essential elements such as Fe and Mn;

33. N fixation into forms usable by higher plants. Mycorrhizae or root fungi form a dense network of thin filaments that reach far into the soil, acting as extensions of the plant roots they live on or in . Pathogenic microbes are also there but beneficial is out numbered

34. DESTRUCTION OF SOIL MICROBES Natural disturbances Wind and water erosion Flood Fire Seasonal changes Disturbances due to land management Chemical fertilizers and pesticides used for cultivation. Vehicles used for cultivation

35. Disturbances associated with dispersal of waste and industrial activities. Sewage sludge and manure Elevated levels of atmospheric carbon dioxide. Plastic wastes

36. Any Questions ?