FIRST LIVING ORGANISMS
3 Billion years ago, bacteria and archaea were the dominant life forms on earth. At the beginning, only anaerobic heterotrophic bacteria existed in ocean water.
The first fossils of bacteria discovered in rocks which considered to be from the Devonian period. It is estimated that five million trillion or you can say 5×1030 bacteria are present on earth. Most of which are still to be discovered.
Millions of tiny living organisms inhabit the human body which is collectively called the human microbiota. Bacteria inhabit the skin, ear, mouth, nose and especially stomach in which bacteria help to digest food.
The breakdown of sugar and starch through bacteria is termed as fermentation. Fermented products are commonly used in our daily life e.g; cheese, yogurt, pickles, etc. Most of the fermented foods composed of 105-107 lactic-acid bacteria per gram/ml. The bacteria, basically, use to preserve fermented foods. Fermented foods widely contain the species of Enterococcus, Pediococcus, Lactococcus, Weisella, Lactobacillus, Leuconostoc, etc.
EARTHY SMELL (GEOSMIN)
When conditions are damp and warm, the type of filamentous bacteria called actinomycetes grow in the soil. These bacteria produce spores in the dried soil. The moist air after rainfall, causes the spores to move up in the air, we breathe. These spores have an earthy smell which is commonly associated with rain.
In this process, microbes, i.e; bacteria, archaea, and fungi, are used to degrade contaminants which cause a high risk to humans and the environment as well. Mostly used for cleaning pollutants such as pesticides, crude oil, sewage, gasoline, etc. The bacterial species which participate in bioremediation include Dechloromonas aromatica, Methylibium petroleiphilum, Pseudomonas putida etc.
Methanogens or anaerobic bacteria digest the organic matter, such as food waste, agricultural waste, sewage, etc, in the anaerobic digester, bioreactor or biodigester. This produces methane and CO2 with traces of H2S, moisture, and siloxanes. In the presence of oxygen, methane, CO, and H2 can be combusted to produce energy. This is used as fuel for different purposes.
Basically, antibiotics are chemicals used to kill or inhibit the growth of bacteria but there are some antibiotics that are naturally produced by bacteria. For example, streptomycin and tetracycline are produced by Streptomycin griseus and Streptomycin aureofaciens respectively.
Bioterrorism is a type of terrorism in which biological agents like bacteria, fungi, viruses or toxins are used to kill or sicken humans, animals or crops. The most commonly used agent is Bacillus anthracis. That is why the CDC banned the transport of these fetal biological agents from one country to the other.