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In situ microscopic observation of chitin and fungal cells with chitinous cell walls in hydrothermal conditions.

Deguchi S, Tsujii K, Horikoshi K - Sci Rep (2015)

Bottom Line: Recent findings of intact chitin in fossil records suggest surprisingly high recalcitrance of this biopolymer during hydrothermal treatments.We also know in the experience of everyday life that mushroom, cells of which have chitinous cell walls, do not fall apart however long they are simmered.The results show very hot and compressed water is needed to make mushrooms mushy.

View Article: PubMed Central - PubMed

Affiliation: Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 237-0061, Japan.

ABSTRACT
Recent findings of intact chitin in fossil records suggest surprisingly high recalcitrance of this biopolymer during hydrothermal treatments. We also know in the experience of everyday life that mushroom, cells of which have chitinous cell walls, do not fall apart however long they are simmered. We used in situ optical microscopy to examine chitin and fungal cells with chitinous cell walls during hydrothermal treatments, and obtained direct evidence that they remained undegraded at temperatures well over 200 °C. The results show very hot and compressed water is needed to make mushrooms mushy.

No MeSH data available.


In situ optical microscopic images showing dissolution of a flake of chitin in supercritical water.Images were taken under a constant pressure of 25 MPa. Each image is 170 μm × 170 μm. A video clip showing the dissolution process is available in Movie S1.
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f1: In situ optical microscopic images showing dissolution of a flake of chitin in supercritical water.Images were taken under a constant pressure of 25 MPa. Each image is 170 μm × 170 μm. A video clip showing the dissolution process is available in Movie S1.

Mentions: We first examined the behaviour of chitin in water up to the supercritical state of water (Fig. 1). Flakes of chitin from crab shell (Chionoecetes japonicus) were dispersed in water, and introduced to the sample chamber on the microscope. Specimen was then pressurized to 25 MPa and heated while maintaining the pressure. The observation was made while heating the specimen from room temperature up to 390 °C (Video showing entire process is available in Movie S1). We found that chitin was significantly more resistant to hydrothermal degradation than cellulose, and did not observe any noticeable change up to ~380 °C. Above ~380 °C, the flake of chitin gradually became thinner and disappeared completely at 390 °C. The thin flake rolled-up before complete dissolution (Movie S1), suggesting that chitin lost crystallinity and became plastic, just as crystalline cellulose did when it lost crystallinity20. Rolling of the chitin flake may also suggest structural heterogeneity inside the flake before dissolution24. Same result was obtained in observation of another chitin flake.


In situ microscopic observation of chitin and fungal cells with chitinous cell walls in hydrothermal conditions.

Deguchi S, Tsujii K, Horikoshi K - Sci Rep (2015)

In situ optical microscopic images showing dissolution of a flake of chitin in supercritical water.Images were taken under a constant pressure of 25 MPa. Each image is 170 μm × 170 μm. A video clip showing the dissolution process is available in Movie S1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493705&req=5

f1: In situ optical microscopic images showing dissolution of a flake of chitin in supercritical water.Images were taken under a constant pressure of 25 MPa. Each image is 170 μm × 170 μm. A video clip showing the dissolution process is available in Movie S1.
Mentions: We first examined the behaviour of chitin in water up to the supercritical state of water (Fig. 1). Flakes of chitin from crab shell (Chionoecetes japonicus) were dispersed in water, and introduced to the sample chamber on the microscope. Specimen was then pressurized to 25 MPa and heated while maintaining the pressure. The observation was made while heating the specimen from room temperature up to 390 °C (Video showing entire process is available in Movie S1). We found that chitin was significantly more resistant to hydrothermal degradation than cellulose, and did not observe any noticeable change up to ~380 °C. Above ~380 °C, the flake of chitin gradually became thinner and disappeared completely at 390 °C. The thin flake rolled-up before complete dissolution (Movie S1), suggesting that chitin lost crystallinity and became plastic, just as crystalline cellulose did when it lost crystallinity20. Rolling of the chitin flake may also suggest structural heterogeneity inside the flake before dissolution24. Same result was obtained in observation of another chitin flake.

Bottom Line: Recent findings of intact chitin in fossil records suggest surprisingly high recalcitrance of this biopolymer during hydrothermal treatments.We also know in the experience of everyday life that mushroom, cells of which have chitinous cell walls, do not fall apart however long they are simmered.The results show very hot and compressed water is needed to make mushrooms mushy.

View Article: PubMed Central - PubMed

Affiliation: Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 237-0061, Japan.

ABSTRACT
Recent findings of intact chitin in fossil records suggest surprisingly high recalcitrance of this biopolymer during hydrothermal treatments. We also know in the experience of everyday life that mushroom, cells of which have chitinous cell walls, do not fall apart however long they are simmered. We used in situ optical microscopy to examine chitin and fungal cells with chitinous cell walls during hydrothermal treatments, and obtained direct evidence that they remained undegraded at temperatures well over 200 °C. The results show very hot and compressed water is needed to make mushrooms mushy.

No MeSH data available.