Thiomargarita
Thiomargarita magnifica is a titan of bacterial life.
Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Caulobacter crescentus, the primary models for bacterial cell biology, are more or less typical in size, with individual cell volumes between ∼0.4–3 µm3 (or 0.4–3.0 femtoliters; femtoliter or fL is equal to 10−15 L).
Smallest size of bacteria is 0.15 μμm while largest size of bacteria is 500 μμm.
So, the largest bacterium species is Thiomargarita namibiensis.
Everyone likes a world record, right? Meet the newly described myxobacterium Myxococcus llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogochensis. That's right: 73 letters (68 if you count by Welsh orthography, treating 'ch' and 'll' as digraphs).
The E. coli break down molecules of food that the human body can't disassemble on its own, and they crowd out other bacteria less suited to cooperation with a human host (and more likely to go rogue and send us back to the toilets, or worse).
The most deadly bacterial disease contracted by human beings is mycobacterium tuberculosis, the world's leading infectious disease with more than 1,700,000 deaths per year. As much as 13% of cases are resistant to most antibiotics, and about 6% are resistant or unresponsive to essentially all treatment.
Bacteria are bigger and more complex than viruses, though they can still spread through the air. A bacterium is a single cell, and it can live and reproduce almost anywhere on its own: in soil, in water and in our bodies.
Disinfectants kill only select strains of germs. No disinfectant is capable of killing all germs found on a hard surface. The absence of all germs is referred to as sterilization and is a process that surpasses the efficacy level achieved with any disinfectant solution.
The reason many products say 'kills 99.9 percent' of bacteria on the label is because that is the performance threshold for the sanitizer test EPA requires (ASTM E1153) if people want to market products as sanitizers. In other words, a 99.9 percent reduction is EPA's arbitrary cutoff for sanitizer performance.
You can squish bacteria, but it's not easy. Bacteria are tiny (about 2 micrometers long, or 2×10−6 meters), which means if you stepped on one even on a smooth floor, the microgrooves in the floor would be plenty big to protect them.
Mimivirus is the largest and most complex virus known.
Viruses are tiny compared to all other living things, but they're giants compared to atoms and molecules.
Deinococcus radiodurans, a poly-extremophilic bacterium, isn't only radiation-resistant. These immortal animals can also die and come back to life thanks to their incredible DNA repair response.
Staphylococcus aureus (MRSA)
Probably the most famous hospital-acquired infection or 'superbug', MRSA is so-called because of its resistance to the antibiotic methicillin (hence Methicillin Resistant Staphylococcus Aureas).
Bacteria and some yeast
Many unicellular organisms age: as time passes, they divide more slowly and ultimately die. Asymmetrically dividing bacteria and yeast also age. However, symmetrically dividing bacteria and yeast can be biologically immortal under ideal growing conditions.
When cyanobacteria evolved at least 2.4 billion years ago, they set the stage for a remarkable transformation. They became Earth's first photo-synthesizers, making food using water and the Sun's energy, and releasing oxygen as a result.
The first ever living organism on Earth was a bacteria known as cyanobacteria.
The archaeal lineage may be the most ancient that exists on earth. Within prokaryotes, archaeal cell structure is most similar to that of gram-positive bacteria, largely because both have a single lipid bilayer and usually contain a thick sacculus of varying chemical composition.
It is commonly believed that bacteria are microscopic – stealthy and hidden from the naked eye. But the bacterium, Epulopiscium fishelsoni, is a microbial behemoth you can see with the human eye alone.
Pelagibacter ubique is one of the smallest known free-living bacteria, with a length of 370 to 890 nm (0.00037 to 0.00089 mm) and an average cell diameter of 120 to 200 nm (0.00012 to 0.00020 mm). They also have the smallest free-living bacterium genome: 1.3 Mbp, 1354 protein genes, 35 RNA genes.