Soil and Microbes
Due care should be taken while handling the soil samples collected from different locations. Preliminary examination of the soil samples can be carried out by wetting the soil sample with water and squeezing them between the fingers to ascertain the type of soil, if the soil is sandy it falls apart, silty soil gives a flour type feeling and if the soil has clay then it holds together.
Soil samples may contain microorganisms such as Bacteria, Fungi, Algae, Actinomycetes and Viruses. All the microorganisms may either exist singly or in colonies. There are various techniques to detect form, pattern and arrangement of microorganisms in soil such as Microscopic methods and Microscopic methods plus culturing.
Microscopic methods involve examination of soil samples under a light microscope by using simple stains such as phenol aniline blue and fluorescent stains such as fluorescein isothiocyanate (FITC), acridine orange, rhodamine (fluoresces red), europium chelate (europium (iii) thenoyltrifluoroacetonate), DAPI (4'-6'-diamidino-2-phenyl-indole), ethidium bromide and Hoechst 33258 (bisbenzimide). While the first method can be adopted with any bright field white light microscope assuming that light can be transmitted through the object under examination but in the second method, the stain emits light at a visible wavelength on illumination with ultraviolet light.
In microscopic methods plus culturing the soil samples are impregnated with agar or polyacrylate resins and sectioned into thin plates and examined by direct microscopy. ...