Bacteria are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats.
Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria play a vital role in many stages of the nutrient cycle by recycling nutrients and the fixation of nitrogen from the atmosphere.
The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy.
Bacteria also live in mutualistic, commensal and parasitic relationships with plants and animals. Most bacteria have not been characterized and there are many species that cannot be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology.
Like all animals, humans carry vast numbers (approximately 1013 to 1014) of bacteria.
Most are in the gut, though there are many on the skin. Most of the bacteria in and on the body are harmless or rendered so by the protective effects of the immune system, and many are beneficial, particularly the ones in the gut.
However, several species of bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy, tuberculosis, tetanus and bubonic plague.
The most common fatal bacterial diseases are respiratory infections. Antibiotics are used to treat bacterial infections and are also used in farming, making antibiotic resistance a growing problem. Bacteria are important in sewage treatment and the breakdown of oil spills, the production of cheese and yogurt through fermentation, the recovery of gold, palladium, copper and other metals in the mining sector, as well as in biotechnology, and the manufacture of antibiotics and other chemicals.
Once regarded as plants constituting the class Schizomycetes ("fission fungi"), bacteria are now classified as prokaryotes.
Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and rarely harbor membrane-bound organelles.
Although the term bacteria traditionally included all prokaryotes, the scientific classification changed after the discovery in the 1990s that prokaryotes consist of two very different groups of organisms that evolved from an ancient common ancestor. These evolutionary domains are called Bacteria and Archaea. Read more ...
Scientists Reveal How They Identified The Ancestor of All Life on Earth - LUCA Science Alert - August 16, 2024
The last universal common ancestor (LUCA) Wikipedia
Around 375 million years ago, our fish-like ancestors breathed through gills. Over 600 million years ago, the common ancestor of all animals emerged the microscopic urmetazoan. Billions of years before all of that happened, however, the common ancestor of all living organisms, the last universal common ancestor (Luca), must have existed. Scientists have worked on identifying Luca over the decades with different ideas about what Luca was like. Another point of contention is Luca's age. The earliest fossil evidence we have for life is around 3.4 billion years old.
Ancient Viruses May Have Given Our Ancestors The Edge to Evolve Live Science - July 28, 2024
Scientists have found the remnants of genomes left by ancient, giant viruses within the DNA of a single-celled organism with which complex organisms like ourselves share a common ancestor.
The fungal threat to human health is growing in a warmer, wetter, sicker world BBC - February 7, 2023
In the HBO show The Last of Us, characters identify zombies among them by the fungi that bursts from their bodies, and fungal parasites manipulate the humans to infect the communities around them. In real life, the fungal species that inspired the story, Ophiocordyceps, infects insects and does not cause problems for people.
New Vaccine Against Fatal Fungi Hopes To Be First Of Its Kind IFL Science - February 7, 2023
Scientists are developing a vaccine they hope could be the first immunization to fight against invasive fungal infections. While it has only been tested on animals so far, the research could eventually pave the way toward a broad-spectrum vaccine that could tackle the growing threat of drug-resistant fungi.
Scientists Revive 48,500-Year-Old Virus, Setting World Record. As temperatures rise because of climate change, melting permafrost could cause dormant diseases to re-emerge, researchers warn Smithsonian - December 2, 2022
Study Suggests Antibiotic-Resistant Bacteria Could Be More Devious Than We Thought Science Alert - November 29, 2022
Bacteria are known to travel around the human body using routes we know little about, yet it's rare to find a case study where an infection spreads in a clear-cut way. The case in Spain is an exception worth noting. The patient was admitted to an intensive care unit in the municipality of Badalona following a seizure. For 39 days, they were mechanically ventilated while doctors used antibiotics to fight off an infection in their lower airways. On day one, the patient's lungs had shown evidence of a bacteria called Pseudomonas aeruginosa - a common infection in the lungs, urinary tract, and gut - and it was suspected the patient had accidentally breathed in food, saliva, or vomit, possibly during their seizure or following ventilation.
Rapidly Melting Glaciers Are Releasing a Staggering Payload of Unknown Bacteria Science Alert - November 24, 2022
Fast-melting glaciers are releasing staggering amounts of bacteria into rivers and streams, which could transform icy ecosystems, scientists warn. In a study of glacial runoff from 10 sites across the Northern Hemisphere, researchers have estimated that continued global warming over the next 80 years could release hundreds of thousands of tonnes of bacteria into environments downstream of receding glaciers.
Scientists Revived Ancient 'Zombie Viruses' Frozen For Eons in Siberia Science Alert - November 25, 2022
300 Years of Research: Princeton Scientists Solve a Bacterial Mystery Scitech - November 18, 2022
Unexpectedly scientists discovered that the growth of the wild colonies consistently resembles other natural phenomena like the growth of crystals or the spread of frost on a windowpane.
Extinct Pathogens Along With Climate Change Ushered The Fall of Ancient Civilizations Science Alert - August 6, 2022
Research reveals that bacteria too have internal clocks that align with the 24-hour cycle of life on Earth PhysOrg - January 8, 2021
The research answers a long-standing biological question and could have implications for the timing of drug delivery, biotechnology, and how we develop timely solutions for crop protection. Biological clocks or circadian rhythms are exquisite internal timing mechanisms that are widespread across nature enabling living organisms to cope with the major changes that occur from day to night, even across seasons. Existing inside cells, these molecular rhythms use external cues such as daylight and temperature to synchronize biological clocks to their environment. It is why we experience the jarring effects of jet lag as our internal clocks are temporarily mismatched before aligning to the new cycle of light and dark at our travel destination.
Bacteria found in soil may harbor a potential game-changer for drug design PhysOrg - June 18, 2018
The new study by Scripps Research suggests scientists could build better drugs by learning from bacteria-derived molecules called thiocarboxylic acids. Taking a closer look ...