Bacteria are single-celled, microscopic organisms that thrive in diverse environments. These species can live in the soil, in the ocean, and inside the human intestine.
They form a vast community of prokaryotic microorganisms. Bacteria typically have a few micrometers in length, and have a number of shapes , ranging from spheres to rods and spirals. Bacteria were among the first forms of life to emerge on Earth and are present in most of their habitats. Bacteria inhabit the soil , water, acidic hot springs, nuclear waste and the Earth's crust's deep biosphere. Bacteria also live with the plants and animals in symbiotic and parasitic relationships. Most of the bacteria have not been characterized and only about 27% of the bacterial phyla have species that can be grown in the lab. Bacterial study is called bacteriology, a branch of microbiology.
A gram of soil usually contains 40 million bacterial cells, and a million bacterial cells in a milliliter of fresh water. By extracting nutrients such as fixing nitrogen from the environment, bacteria are essential in several stages of the nutrient cycle, producing a biomass that exceeds that of both plants and animals. The nutrient cycle involves the decomposition of dead bodies; in this process, bacteria are responsible for the putrefaction stage.Extremophile bacteria provide the nutrients required to sustain life in the biological communities surrounding hydrothermal vents and cold seeps by converting dissolved compounds, such as hydrogen sulphide and methane, to energy.
They form a vast community of prokaryotic microorganisms. Bacteria typically have a few micrometers in length, and have a number of shapes , ranging from spheres to rods and spirals. Bacteria were among the first forms of life to emerge on Earth and are present in most of their habitats. Bacteria inhabit the soil , water, acidic hot springs, nuclear waste and the Earth's crust's deep biosphere. Bacteria also live with the plants and animals in symbiotic and parasitic relationships. Most of the bacteria have not been characterized and only about 27% of the bacterial phyla have species that can be grown in the lab. Bacterial study is called bacteriology, a branch of microbiology.
A gram of soil usually contains 40 million bacterial cells, and a million bacterial cells in a milliliter of fresh water. By extracting nutrients such as fixing nitrogen from the environment, bacteria are essential in several stages of the nutrient cycle, producing a biomass that exceeds that of both plants and animals. The nutrient cycle involves the decomposition of dead bodies; in this process, bacteria are responsible for the putrefaction stage.Extremophile bacteria provide the nutrients required to sustain life in the biological communities surrounding hydrothermal vents and cold seeps by converting dissolved compounds, such as hydrogen sulphide and methane, to energy.
Structure
Bacteria are classified as prokaryotes, which are single-celled organisms with a simple internal structure that lacks a nucleus, and contain DNA that floats either freely in a twisted, thread-like mass called the nucleoid, or in separate, circular pieces called plasmids. Ribosomes are the spherical units in the bacterial cell where the information encoded in ribosomal RNA is used to assemble proteins from individual amino acids.
Two protective coverings generally surround the bacterial cells: an outer cell wall and an inner cell membrane. Some bacteria, including the mycoplasmas, have almost no cell wall. Some bacteria may even have a third, protective outermost layer called the capsule. Whip-like extensions often cover long surfaces of bacteria called flagella or short ones called pili which help bacteria move around and attach themselves to a host.
Growth and reproduction
Bacteria grow to a fixed size and then replicate by binary fission, a form of asexual reproduction. Bacteria can grow and divide very rapidly under ideal conditions, and bacterial populations can double as fast as every 9.8 minutes. Two identical clone daughter cells are formed in cell division. While still reproducing asexually, some bacteria form more complex reproductive structures which help to disperse the newly formed daughter cells. Examples include Myxobacteria formation of the fruiting body and Streptomyces formation of aerial hyphae, or budding. Budding involves a protrusion forming a cell that breaks away and produces a daughter cell.
Discovery Of Bacteria
antonie van leeuwenhoek is considered to be the founder of microbiology. He is known for having bacteria discovered.
Van Leeuwenhoek discovered "protozoa"-the species with a single cell and he named them "animals." He also developed the microscope, and laid the microbiology base. He is commonly cited as the first microbiologist to study capillary muscle fibers, bacteria, spermatozoa and blood flow.