Microbes, or micro-organisms, are small living organisms, meaning they have to be seen using a microscope since they are too small to be observed by the naked eye. Microbes are extremely diverse and it has been estimated that on Earth, there could be as many as a billion different species.

Some of the most common microbes:

• Bacteria: Prokaryotes; single-celled organisms that can be found almost everywhere. Bacteria can be used for digestion, essential processes, and even make us ill. Bacteria come in many different shapes, such as rods (bacilli), spheres (cocci), and spirals (spirilla).
• Viruses: Viruses are another essential part of the microbial world, but are not always considered a living thing since they need a host cell in order to grow.
• Fungi: Eukaryotic; can be multicellular (like molds and mushrooms) or unicellular (like yeast). Can be useful in food production and can be vital in the decomposition process.
• Protists: Eukaryotic; can be unicellular or multicellular organisms that are usually found in moist environments. Some are plant-like (like algae), some animal-like (like amoebas), and some fungus-like. They can have the ability to photosynthesize, to move, or to feed on other organisms.

Useful Microbes

1. In Medicine

• A fungus, penicillium, produces penicillin, the first widely used antibiotic.
• Antibiotics streptomycin and tetracycline are produced from Streptomyces bacteria.
• Genetically modified bacteria like Escherichia coli, are used for producing insulin and other hormones.

2. In Agriculture

Microbes help in the fertilization of the soil and in plant growth. Examples include:

• Rhizobium bacteria, which live in the root nodules of leguminous plants and convert nitrogen from the atmosphere into a form that can be used by plants.
• Mycorrhizal fungi, which enhance nutrient and water uptake by plant roots.
• Biopesticides like Bacillus thuringiensis are used as organic pest control.

3. In Food Production

Microorganisms play a central role in the production of most food and beverages:

• Lactobacillus microbes are used in making yogurt, cheese, and pickles by fermenting milk or vegetables.
• Yeast (like Saccharomyces cerevisiae) is also used in bread production and brewing alcoholic drinks such as beer and wine.

4. Environmental Clean-Up

Some microbes are involved in breaking down poisonous substances:

• Oil-degrading bacteria like Pseudomonas are used in cleaning up oil spills (a process referred to as bioremediation).
• Bacteria are utilized by sewage treatment plants in decomposing organic matter and purifying wastewater.

Dangerous Microbes

1. Human Diseases

Various diseases are created by pathogenic microbes:

• Mycobacterium tuberculosis causes tuberculosis.
• Food poisoning results from Salmonella.
• Viruses such as the influenza virus, HIV, and the coronavirus (SARS-CoV-2) cause serious public health challenges worldwide.
• Plasmodium causes malaria due to protozoa such as Plasmodium through mosquito bites.

2. Plant Diseases

Microbial diseases can devastate crops:

• Wheat rust, a serious crop disease, is caused by the fungal pathogen Puccinia graminis.
• Xanthomonas bacteria lead to leaf spot and blights of crops in agriculture.
• Virus-induced plant diseases, like tobacco mosaic virus, reduce yields from crops.

3. Food Spoilage

Some microbes spoil food through the production of toxins or the breakdown of nutrients:

• Clostridium botulinum infects improperly canned food and causes botulism, a fatal food poisoning.
• Bread and fruit can be infected by molds like Aspergillus and rendered toxic.

4. Biological Weapons

Certain microbes have been used in terrorism or warfare. For example:

• Bacillus anthracis causes the disease anthrax and has also been used for bioterrorism.
• Smallpox virus, being eradicated now, was previously a major threat and is graded as a likely bioweapon.

Conclusion

Microbes are a vast but effective group of organisms. While some pose risks to health and agriculture, others are essential in medicine, farming, industry, and conservation. The key is to achieve the largest possible benefits and least harm from pathogens. Greater understanding of microbes can help people live healthier lives, eat safer food, and create a better world.

Written by Aisha Alduhoori