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MICROBIOLOGY

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Bacteria. Bacteria ( Most bacteria have not been characterized, and only about half of the phyla of bacteria have species that can be grown in the laboratory.[9] The study of bacteria is known as bacteriology, a branch of microbiology.

Bacteria

Etymology Origin and early evolution Bacteria were also involved in the second great evolutionary divergence, that of the archaea and eukaryotes. Archaea. The Archaea ( Archaea were initially classified as bacteria, receiving the name archaebacteria (or Kingdom Monera), but this classification is outdated.[1] Archaeal cells have unique properties separating them from the other two domains of life: Bacteria and Eukaryota.

Archaea

The Archaea are further divided into four recognized phyla. Classification is difficult, because the majority have not been studied in the laboratory and have only been detected by analysis of their nucleic acids in samples from their environment. Classification[edit] New domain[edit] Current classification[edit] The classification of archaea, and of prokaryotes in general, is a rapidly moving and contentious field. A superphylum - TACK - has been proposed that includes the Aigarchaeota, Crenarchaeota, Korarchaeota and Thaumarchaeota.[18] This superphylum may be related to the origin of eukaryotes.

Species[edit] The classification of archaea into species is also controversial. Origin and evolution[edit] R.S. Prokaryote. Cell structure of a bacterium , one of the two domains of prokaryotic life. The division to prokaryotes and eukaryotes reflects two distinct levels of cellular organization rather than biological classification of species. Prokaryotes include two major classification domains: the bacteria and the archaea . Archaea were recognized as a domain of life in 1990. These organisms were originally thought to live only in inhospitable conditions such as extremes of temperature , pH , and radiation but have since been found in all types of habitats .

Eukaryote. Cell division in eukaryotes is different from that in organisms without a nucleus (Prokaryote).

Eukaryote

There are two types of division processes. In mitosis, one cell divides to produce two genetically identical cells. Biofilm. IUPAC definition Aggregate of microorganisms in which cells that are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS) adhere to each other and/or to a surface.

Biofilm

Note 1: A biofilm is a fixed system that can be adapted internally to environmental conditions by its inhabitants. Note 2: The self-produced matrix of extracellular polymeric substance, which is also referred to as slime, is a polymeric conglomeration generally composed of extracellularbiopolymers in various structural forms.[1] Microbes form a biofilm in response to many factors, which may include cellular recognition of specific or non-specific attachment sites on a surface, nutritional cues, or in some cases, by exposure of planktonic cells to sub-inhibitory concentrations of antibiotics.[4][5] When a cell switches to the biofilm mode of growth, it undergoes a phenotypic shift in behavior in which large suites of genes are differentially regulated.[6] L'étonnante stabilité de notre flore bactérienne. Colorations des structures cellulaires. About Microbiology - Microbes and climate change - Microbes and biofuels.

Biofuels are made from living things or the waste that they produce.

About Microbiology - Microbes and climate change - Microbes and biofuels

One of the most common biofuels, ethanol, is produced from plants. The plant material used is the edible part of the plant such as sugar cane (Brazil) and sugar beet (France) or corn kernels (USA) because it can easily be broken down to sugar (glucose). The sugar can then be fermented (broken down) to ethanol by microbes such as the yeast Saccharomyces cerevisiae. Not only is it expensive to convert edible plant material into ethanol; ethical issues are also involved. It has been argued that we shouldn’t grow food stuffs for fuel when people in some developing countries don’t have enough to eat. Scientists are investigating the use of cellulose to produce ethanol. Scientists have turned to their attention to microbes to see if they can find any that are capable of converting the cellulose and even hemicellulose in lignocellulose into ethanol.

Another common wood digester is the fungus Trichoderma reesei. Microbiology posters and booklets. SGM produces a wide range of microbiology teaching resources for all age groups from primary to post-16.

Microbiology posters and booklets

The material is carefully targeted to meet curriculum requirements and fit in with the specifications for science. Microbiologie alimentaire. Le rôle des microbes dans la fabrication des aliments De très nombreux produits alimentaires sont élaborés avec l'aide de microorganismes.

Microbiologie alimentaire

Citons les yaourts (Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium), les fromages (Lactococcus lactis, L. cremoris, Propionobacterium, Penicillium camemberti, P. roquerforti, etc.), les saucissons, les jambons, les viandes et les poissons fermentés (Bacillus halophiles), le vin, la bière et les autres diverses boissons fermentées alcoolisées (Saccharomyces, Botrytis cinerea), les vinaigres (Acetobacter, Gluconobacter), les pains (Saccharomyces, Lactobacillus), la choucroute (Leuconostoc mesenteroides, Leucobacillus plantarum), les produits d'ensilage pour les animaux (diverses espèces anaérobies), etc. Détérioration et décomposition des aliments Mais il arrive quelquefois que le développement de microorganismes sur des aliments ne se détectent ni visuellement, ni au goût.

La conservation des aliments Chlore, désinfection et eau : Introduction to geomicrobiology. Microbiologie (Prescott) Bioenergetic processes of Cyanobacteria. De la diversité au sein des bactéries. La diversité est une des clés de de la résistance bactérienne aux antibiotiques.

De la diversité au sein des bactéries

Une étude de l’université de Washington précise un mécanisme dans les cellules bactériennes qui est une clé de cette diversité. Un nouveau mode de diversification Lorsqu’elle se divise, une bactérie peut donner naissance à deux cellules qui possèdent le même génome mais pour lesquelles le partage des organites cellulaires n'a pas été équitable.

Ainsi une bactérie qui possède un flagelle va donner naissance à une cellule munie de cette structure et à une autre qui en est dénuée mais qui pourra en fabriquer un grâce à sa machinerie génétique. Les chercheurs ont constaté que ces deux cellules filles avaient des comportements radicalement différents. C'est un autre moyen pour les cellules de se diversifier. C-di-GMP.