Knallgas-bacteria

Examples of Knallgas-bacteria in the following topics:

• Hydrogen Oxidation

  • Hydrogen oxidizing bacteria, or sometimes Knallgas-bacteria, are bacteria that oxidize hydrogen.
  • These bacteria include Hydrogenobacter thermophilus, Hydrogenovibrio marinus, and Helicobacter pylori.
  • There are both Gram positive and Gram negative knallgas bacteria.
  • While there are several mechanisms of anaerobic hydrogen oxidation (e.g. sulfate reducing- and acetogenic bacteria), hydrogen can also be used as an energy source aerobically.

• Signaling in Bacteria

  • Signaling in bacteria, known as quorum sensing, enables bacteria to monitor extracellular conditions, ensure sufficient amounts of nutrients are present, and avoid hazardous situations.
  • There are circumstances, however, when bacteria communicate with each other.
  • When the population density of the bacteria reached a certain level, specific gene expression was initiated: the bacteria produced bioluminescent proteins that emitted light.
  • Autoinducers are signaling molecules secreted by bacteria to communicate with other bacteria of the same kind.
  • In return for camouflage, the squid provides food for the bacteria.

• 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.

• Bacterial Flora

  • The large intestine absorbs some of the products formed by the bacteria inhabiting this region.
  • An individual that depends on absorption of vitamins formed by bacteria in the large intestine may become vitamin-deficient if treated with antibiotics that inhibit other species of bacteria as well as the disease-causing bacteria.
  • Bifidobacteria are also abundant, and are often described as 'friendly bacteria'.
  • A mucus layer protects the large intestine from attacks from colonic commensal bacteria.
  • Escherichia coli is one of the many species of bacteria present in the human gut.

• 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.