bacteria

(noun)

A type, species, or strain of bacterium.

Related Terms

  • DNA hybridization
  • microorganism
  • bacteriostatic
  • replication
  • archaea
  • prokaryotes
  • microorganisms
  • eukaryote
  • species
  • chromosome
  • food spoilage
  • antimicrobial
  • taxonomy
  • Gram stain

(proper noun)

Bacteria constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, and are present in most habitats on the planet.

Related Terms

  • DNA hybridization
  • microorganism
  • bacteriostatic
  • replication
  • archaea
  • prokaryotes
  • microorganisms
  • eukaryote
  • species
  • chromosome
  • food spoilage
  • antimicrobial
  • taxonomy
  • Gram stain

Examples of bacteria in the following topics:

  • Syntrophy and Methanogenesis

    • Bacteria that perform anaerobic fermentation often partner with methanogenic archea bacteria to provide necessary products such as hydrogen.
    • A frequently cited example of syntrophy are methanogenic archaea bacteria and their partner bacteria that perform anaerobic fermentation.
    • Partner bacteria of the methanogenic archea therefore process these products.
    • Methanogenic bacteria are important in the decomposition of biomass in most ecosystems.
    • Methanogenic archea bacteria can also form associations with other organisms.
  • Bacteroidetes and Chlorobi

    • Bacteria categorized under the Phylum Bacteroidetes and Phlyum Chlorobi are closely related base on comparative genomic analysis.
    • The Phylum Chlorobi are characterized by bacteria that are obligately anaerobic photoautotrophic which includes green sulfur bacteria.
    • The green sulfur bacteria are photolithotropic oxidizers of sulfur and utilize a noncyclic electron transport chain.
    • Chlorobium species typically exist in symbiotic relationships with a colorless, nonphotosynthetic bacteria .
    • An image of a green sulfur bacteria which is categorized under the Phlyum Chlorobi and shares a close relationship with bacteria in the Phlyum Bacteroidetes.
  • Agrobacterium and Crown Gall Disease

    • Crown Gall Disease is caused by a bacteria called Agrobacterium tumefaciens.
    • Bacteria normally use plasmids for horizontal gene transfer, so they can share genes with related bacteria to help them cope with stressful environments.
    • Typically bacteria transfer plasmids through conjugation: a donor bacteria creates a tube called a pilus that penetrates the cell wall of the recipient bacteria and the plasmid DNA passes through the tube.
    • In either case, the recipient bacteria receives new genetic material.
    • These opines can be used by very few other bacteria and give A. tumefaciens a competitive advantage .
  • Shared Features of Bacteria and Archaea

    • Most of the metabolic pathways, which comprise the majority of an organism's genes, are common between Archaea and Bacteria.
    • Archaea and Gram-positive bacteria also share conserved indels in a number of important proteins, such as Hsp70 and glutamine synthetase I.
    • Gupta has proposed that the Archaea evolved from Gram-positive bacteria in response to antibiotic selection pressure.
    • This is suggested by the observation that archaea are resistant to a wide variety of antibiotics that are primarily produced by Gram-positive bacteria, and that these antibiotics primarily act on the genes that distinguish Archaea from Bacteria.
    • Describe the evidence for the evolution of the Archaea from Bacteria
  • The Sulfur Cycle

    • Many bacteria can reduce sulfur in small amounts, but some bacteria can reduce sulfur in large amounts, in essence, breathing sulfur.
    • These bacteria get their energy by reducing elemental sulfur to hydrogen sulfide.
    • The most well known sulfur reducing bacteria are those in the domain Archea, which are some of the oldest forms of life on Earth.
    • Sulfur metabolic pathways for bacteria have important medical implications.
    • For example, Mycobacterium tuberculosis (the bacteria causing tuberculosis) and Mycobacterium leprae (which causes leoprosy) both utilize sulfur, so the sulfur pathway is a target of drug development to control these bacteria.
  • Squid-Aliivibrio Symbiosis

    • The bacteria are fed a sugar and amino acid solution by the squid.
    • The mucus collects near the opening of the light organ which traps passing bacteria.
    • The squid weeds out unwanted bacteria in several ways.
    • It may also provide a supply of bacteria for squid hatchlings.
    • Bobtail squid rely on their mutualist bacteria Allivibrio fischerii to generate light.
  • Common Bacterial Traits

    • Bacteria are a subset of prokaryotes and while very different, they still have some common features.
    • Bacteria constitute a large domain of prokaryotic microorganisms.
    • But what defines a bacteria?
    • Bacteria as prokaryotes share many common features, such as:
    • Eukaryotes are colored red, archaea green and bacteria blue.
  • Bacterial Genomes

    • Recent advances in sequencing technology led to the discovery of a high correlation between the number of genes and the genome size of bacteria, suggesting that bacteria have relatively small amounts of junk DNA.
    • Evolutionary paths led some bacteria to become pathogens and symbionts.
    • The lifestyles of bacteria play an integral role in their respective genome sizes.
    • Free-living bacteria have the largest genomes out of the three types of bacteria; however, they have fewer pseudogenes than bacteria that have recently acquired pathogenicity.
    • Facultative and recently evolved pathogenic bacteria exhibit a smaller genome size than free-living bacteria, yet they have more pseudogenes than any other form of bacteria.
  • Kirby-Bauer Disk Susceptibility Test

    • Kirby-Bauer testing measures sensitivity of bacteria to antibiotics by culturing bacteria on solid growth media surrounding sources of drug.
    • First, a pure culture of bacteria is isolated from the patient.
    • If the bacteria are susceptible to the particular antibiotic from a wafer, an area of clear media where bacteria are not able to grow surrounds the wafer, which is known as the zone of inhibition.
    • Administering antibiotics that specifically target the particular bacteria that are causing the infection can avoid using broad-spectrum antibiotics, which target many types of bacteria.
    • If an antibiotic stops the bacteria from growing, one can see circular areas around the wafers where bacteria have not grown.
  • Anoxygenic Photosynthetic Bacteria

    • There are several groups of bacteria that undergo anoxygenic photosynthesis: green sulfur bacteria, green and red filamentous anoxygenic phototrophs (FAPs), phototrophic purple bacteria, phototrophic acidobacteria, and phototrophic heliobacteria.
    • The green sulfur bacteria are a family of obligately anaerobic photoautotrophic bacteria most closely related to the distant Bacteroidetes.
    • The purple sulfur bacteria are a group of Proteobacteria capable of photosynthesis.
    • Bacteriochlorophylls are photosynthetic pigments that occur in various phototrophic bacteria.
    • Describe the mechanisms that specific bacteria use to undergo anoxygenic photosynthetic bacteria, including: green sulfur and purple sulfur bacteria
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