Soil microbiology and microbial growth

Bacteria[ edit ] Bacteria and Archaea are the smallest organisms in soil apart from viruses. Bacteria and Archaea are prokaryotic.

Soil microbiology and microbial growth

This increase is possible because the wavelengths of the electron beams are so much shorter than the wavelengths of light. Objects as small as 0. Specimens are observed by either transmission electron microscopy or scanning electron microscopy.

In TEM the electron beam passes through the specimen and registers on a screen forming the image; in SEM the electron beam moves back and forth over the surface of microorganisms coated with a thin film of metal and registers a three-dimensional picture on the screen.

Scanning electron micrograph of the spirochete Treponema pallidum attached to testicular cell membranes. Among these are confocal microscopy, the atomic force microscope, the scanning tunneling microscopeand immunoelectron microscopy.

These are particularly significant for studies of microorganisms at the molecular level. Nutritional and physiological characteristics Microorganisms as a group exhibit great diversity in their nutritional requirements and in the environmental conditions that will support their growth.

No other group of living organisms comes close to matching the versatility and diversity of microbes in this respect. Some species will grow in a solution composed only of inorganic Soil microbiology and microbial growth one of the salts must be a compound of nitrogen and a source of carbon dioxide CO2 ; these are called autotrophs.

Many, but not all, of these microbes are autotrophic via photosynthesis. Organisms requiring any other carbon source are called heterotrophs. These microbes commonly make use of carbohydrateslipidsand proteinsalthough many microbes can metabolize other organic compounds such as hydrocarbons.

Soil microbiology and microbial growth

Others, particularly the fungi, are decomposers. Many species of bacteria also require specific additional nutrients such as minerals, amino acidsand vitamins. Various protozoans, fungi, and bacteria are parasites, either exclusively obligate parasites or with the ability to live independently facultative parasites.

If the nutritional requirements of a microorganism are known, a chemically defined medium containing only those chemicals can be prepared. More complex media are also routinely used; these generally consist of peptone a partially digested proteinmeat extract, and sometimes yeast extract.

When a solid medium is desired, agar is added to the above ingredients. Agar is a complex polysaccharide extracted from marine algae. It has several properties that make it an ideal solidifying substance for microbiological media, particularly its resistance to microbial degradation.

Microorganisms vary widely in terms of the physical conditions required for growth. For example, some are aerobes require oxygensome are anaerobes grow only in the absence of oxygenand some are facultative they grow in either condition.

Eukaryotic microbes are generally aerobic. Those organisms which grow under optimally under one or more physical or chemical extremes, such as temperature, pressure, pH, or salinity, are referred to as extremophiles. Bacteria exhibit the widest range of temperature requirements.

Whereas bacterial and fungal growth is commonly observed in food that has been refrigerated for a long period, some isolated archaea e.

Other physical conditions that affect the growth of microorganisms are acidity or basicity pHosmotic pressure, and hydrostatic pressure. The optimal pH for most bacteria associated with the human environment is in the neutral range near pH 7, though other species grow under extremely basic or acidic conditions.

Most fungi are favoured by a slightly lower pH 5—6 ; protozoa require a range of pH 6. Reproduction and growth Bacteria reproduce primarily by binary fissionan asexual process whereby a single cell divides into two.

Historical background

Under ideal conditions some bacterial species may divide every 10—15 minutes—a doubling of the population at these time intervals. Eukaryotic microorganisms reproduce by a variety of processes, both asexual and sexual.

Some require multiple hosts or carriers vectors to complete their life cycles. Viruses, on the other hand, are produced by the host cell that they infect but are not capable of self-reproduction. The study of the growth and reproduction of microorganisms requires techniques for cultivating them in pure culture in the laboratory.

Data collected on the microbial population over a period of time, under controlled laboratory conditions, allow a characteristic growth curve to be constructed for a species. Metabolism Collectively, microorganisms show remarkable diversity in their ability to produce complex substances from simple chemicals and to decompose complex materials to simple chemicals.Without a doubt, the most important limiting factor for microbial growth in soil (assuming moisture is adequate) is the abundance of available organic carbon sources.

The vast majority of soil microbes require organic carbon compounds (these are called organotrophs) to oxidize for energy and to build the organic constituents of their cell .

Soil Science has traditionally been an umbrella for soil physics, soil chemistry, soil microbiology, soil fertility, soil morphology, and soil technology. in the short-term, include microbial allocation of C and N to growth, enzyme production, and microbial products that interact with the soil matrix.

AgriInfo: Current Category» Soil Microbiology Scope and Importance of Soil Microbiology. Living organisms both plant and animal types constitute an important component of soil. Microbiology, study of microorganisms, or microbes, a diverse group of generally minute, simple life-forms that include bacteria, archaea, algae, fungi, protozoa, and field is concerned with the structure, function, and classification of such organisms and with ways of both exploiting and controlling their activities..

The 17th-century discovery of living forms existing invisible. The clinical and epidemiological threat of the growing antimicrobial resistance in Gram-negative pathogens, particularly for β-lactams, the most frequently used and relevant antibiotics, urges research to find new therapeutic weapons to combat the infections caused by these microorganisms.

Soil Microbial Ecology. The study of biota that inhabit the soil, their functions, the processes that they mediate, and the effect of their activities on the character of the soil and the growth and health of plant life.

Soil microbiology - Wikipedia