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Osmophilic organisms are microorganisms adapted to environments with high osmotic pressures, such as high sugar concentrations. Osmophiles are similar to halophillic
Halophiles are extremophile organisms that thrive in environments with very high concentrations of salt. The name comes from the Greek for "salt-loving". While the term is perhaps most often applied to some halophiles classified into the Archaea domain, there are also bacterial halophiles and some...

 (salt-loving) organisms because a critical aspect of both types of environment is their low water activity
Water activity
Water activity or aw was developed to account for the intensity with which water associates with various non-aqueous constituents and solids. Simply stated, it is a measure of the energy status of the water in a system...

, aW. High sugar concentrations represent a growth-limiting factor for many microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...

s, yet osmophiles protect themselves against this high osmotic pressure by the synthesis of osmoprotectant
Osmoprotectants or compatible solutes are small molecules that act as osmolytes and help organisms survive extreme osmotic stress. Examples include betaines, amino acids, and the sugar trehalose. These molecules accumulate in cells and balance the osmotic difference between the cell's surroundings...

s such as alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

s and amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

s. Nearly all osmophilic microorganisms are from the yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...


Osmophile yeasts are important because they cause spoilage in the sugar and sweet goods industry, with products such as fruit juices, fruit juice concentrates, liquid sugars (such as golden syrup), honey and in some cases marzipan.

Among the most osmophillic are:
OrganismMinimum aW
Saccharomyces rouxii 0.62
Saccharomyces bailii 0.80
Debaryomyces is a genus of yeasts in the family Saccharomycetaceae....

Saccharomyces cerevisiae
Saccharomyces cerevisiae
Saccharomyces cerevisiae is a species of yeast. It is perhaps the most useful yeast, having been instrumental to baking and brewing since ancient times. It is believed that it was originally isolated from the skin of grapes...



Osmophiles with possible pathogenesis
The pathogenesis of a disease is the mechanism by which the disease is caused. The term can also be used to describe the origin and development of the disease and whether it is acute, chronic or recurrent...

 are Aspergillus
Aspergillus is a genus consisting of several hundred mold species found in various climates worldwide. Aspergillus was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli...

, Saccharomyces
Saccharomyces is a genus in the kingdom of fungi that includes many species of yeast. Saccharomyces is from Greek σάκχαρ and μύκης and means sugar fungus. Many members of this genus are considered very important in food production. One example is Saccharomyces cerevisiae, which is used in making...

, Enterobacter aerogenes
Enterobacter aerogenes
Enterobacter aerogenes is a Gram-negative, oxidase negative, catalase positive, citrate positive, indole negative, rod-shaped bacterium....

and Micrococcus
Micrococcus is a genus of bacteria in the Micrococcaceae family. Micrococcus occurs in a wide range of environments, including water, dust, and soil. Micrococci have Gram-positive spherical cells ranging from about 0.5 to 3 micrometers in diameter and are typically appear in tetrads...

. However, none of them are highly pathogenic, and only cause opportunistic infections, i.e. infections in people with weakened immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...

. They are rather a cause of general food spoiling than causing any food poisoning in humans.