Chitin Diagenesis in Deep-Water Sediments

Poulicek, Mathieu; Machiroux, R.; Toussaint, Caroline

doi:10.1007/978-1-4613-2167-5_62

Cited by 11 publications

(6 citation statements)

References 11 publications

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“…Thus if there is an adequate supply of both organic matter and iron(III) hydroxide, not only is chitin partially protected by adsorbed Fe 2ϩ ions, but also an iron(II)-rich clay mineral such as berthierine or ferroan saponite may nucleate on the arrays of Fe 2ϩ ions adsorbed on the chitin. A similar process, nucleation of heavy-metal oxyhydroxides, has been observed to occur on mollusk-shell detritus in some deep-sea settings (Poulicek, Machiroux, and Toussaint, 1986). Berthierine, a clay mineral of composition such as (Fe II , Mg) 3Ϫx (Fe III ,Al) y Si 2Ϫz Al z O 5 (OH) 4 , with y ϭ x ϩ z Ͻ 1 and with more iron(II) than magnesium, is suggested here as one possible early diagenetic iron(II)-rich silicate, because it is a common diagenetic silicate in iron(II)-rich sediments (Taylor and Curtis, 1995).…”

Section: Nucleation and Growth Of Iron(ii)-rich Layer Silicates On Prmentioning

confidence: 86%

Mechanisms of fossilization of the soft-bodied and lightly armored faunas of the Burgess Shale and of some other classical localities

Petrovich¹

2001

American Journal of Science

126

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The splendid preservation of the Middle Cambrian Burgess Shale fauna, a fauna of exceptional importance for our understanding of the evolution of life, has not been adequately explained. Preservation of diagenetically altered remnants of the original organic tissues and formation of chlorite/illite coatings and cuticle replacements, both documented in the Burgess Shale fossils though not necessarily occurring together, can be understood as products of the same mechanism of fossilization of soft tissues. It is argued here that this mechanism consists of the following steps: (1) adsorption on structural biopolymers such as chitin, cellulose, and collagens of Fe 2؉ ions released during the oxidation of organic matter by iron(III)-reducing bacteria, (2) inhibition by the adsorbed Fe 2؉ ions of further bacterial decomposition of these biopolymers, which enables them to persist and later become kerogens; (3) in some microenvironments, nucleation of crystals of an iron(II)-rich clay mineral, a berthierine or a ferroan saponite, on the Fe 2؉ ions adsorbed on the preserved biopolymers and growth of such clay-mineral crystals to form a coating on the organic remains and/or to replace parts of the organism. The critical factors in the Burgess Shale-type preservation of Early and Middle Cambrian soft-bodied and lightly armored animals were probably: (1) rapid transport of live or freshly killed organisms into suboxic water, (2) extensive suboxic diagenesis in a sediment of high iron(III)/ (organic carbon) ratio, and (3) curtailment of the supply of sulfate ions shortly after the onset of pyritization. The proposed model of early diagenesis that results in Burgess Shale-type fossil preservation critically depends on the availability of steady suboxic depositional environments in open oceanic settings at depths of the order of 100 m in which iron(III)-rich fine-grained sediments, rapidly deposited with the entrained animals by turbidity currents, could accumulate without being disturbed by storm waves and deep currents. Evidence discussed in the present paper suggests that such conditions were common in the Early and Middle Cambrian.Adsorption of Fe 2؉ ions on structural biopolymers as a means of protecting organic fossil remains from decomposition by bacterial enzymes is a novel suggestion and needs to be demonstrated by direct experimentation. It is based on the following considerations. First, Fe 2؉ ions are strongly adsorbed on chitin under experimental conditions comparable to those in pore waters of suboxic iron-rich sediments, and while data on Fe 2؉ ion adsorption on collagen and cellulose seem to be lacking, other heavy-metal ions are strongly adsorbed on these biopolymers under appropriate conditions. Second, Fe 2؉ ions bonded with functional groups of chitin, collagen, or cellulose would prevent the very specific configuration and bonding which a biopolymer strand has to achieve within the active-site cleft of the appropriate bacterial enzyme to make enzymatic hydrolysis possible.Close examination of two other mecha...

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Section: Nucleation and Growth Of Iron(ii)-rich Layer Silicates On Prmentioning

confidence: 86%

Mechanisms of fossilization of the soft-bodied and lightly armored faunas of the Burgess Shale and of some other classical localities

Petrovich¹

2001

American Journal of Science

126

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“…It has been estimated that more than 10 11 metric tons of this polysaccharide are produced annually and the oceans represent a huge resource of chitin that should be transformed in other biological materials to avoid carbon and nitrogen depletion in these environments. Actually, marine sediments contain only trace of chitin, the degradation of which is a main step in the cycling of nutrients in the oceans that is traditionally attributed mainly to bacteria [10,11,12]. In addition, fungi can contribute substantially to chitin degradation and recycle, particularly in some marine environments such as sediments and estuaries [10,13].…”

Section: Introductionmentioning

confidence: 99%

High Production of Chitinolytic Activity in Halophilic Conditions by a New Marine Strain of Clonostachys rosea

et al. 2019

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Twenty-eight fungal strains have been isolated from different natural marine substrates and plate screened for their production of chitinolytic activity. The two apparent best producers, Trichoderma lixii IG127 and Clonostachys rosea IG119, were screened in shaken cultures in media containing 1% colloidal chitin, 1% yeast nitrogen base and 38‰ NaCl, for their ability to produce chitinolytic enzymes under halophilic conditions. In addition, they were tested for optimal growth conditions with respect to pH, salinity and temperature. The Trichoderma strain appeared to be a slight halotolerant fungus, while C. rosea IG119 clearly showed to be a halophilic marine fungus, its optimal growth conditions being very coherent for life in the marine environment (i.e., pH 8.0, salinity 38‰). Due to its high and relatively fast activity (258 U/L after 192 h of growth) accompanied by its halophilic behaviour (growth from 0 to 160‰ of salinity), C. rosea was selected for further studies. In view of possible industrial applications, its medium for chitinolytic enzyme production was optimized by Response Surface Methodology using 1% colloidal chitin and different concentrations of corn step liquor and yeast nitrogen base (0–0.5%). Time course of growth under optimized condition showed that maximum activity (394 U/L) was recorded after 120 h on medium containing Corn Steep Liquor 0.47% and Yeast Nitrogen Base 0.37%. Maximum of productivity (3.3 U/Lh) was recorded at the same incubation time. This was the first study that demonstrated high chitinolytic activity in a marine strain of C. rosea.

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“…The parts of the cuticle most likely to be preserved are the exocuticle, a composite of chitin fi bers embedded in a protein matrix, and the outer epicuticle, a waxy layer that protects terrestrial arthropods from water uptake and desiccation (Hadley, 1986). The current annual production of chitin is enormous, but is balanced by the degradation of chitin by chitinolytic microorganisms (e.g., Poulicek et al, 1985;Poulicek and Jeuniaux, 1991;Gooday, 1990).…”

Section: Introductionmentioning

confidence: 99%

Molecular signature of chitin-protein complex in Paleozoic arthropods

Cody

Gupta

Briggs

et al. 2011

Geology

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The conventional geochemical view holds that the chitin and structural protein are not preserved in ancient fossils because they are readily degradable through microbial chitinolysis and proteolysis. Here we show a molecular signature of a relict chitin-protein complex preserved in a Pennsylvanian (310 Ma) scorpion cuticle and a Silurian (417 Ma) eurypterid cuticle via analysis with carbon, nitrogen, and oxygen X-ray absorption near edge structure (XANES) spectromicroscopy. High-resolution X-ray microscopy reveals the complex laminar variation in major biomolecule concentration across modern cuticle; XANES spectra highlight the presence of the characteristic functional groups of the chitin-protein complex. Modifi cation of this complex is evident via changes in organic functional groups. Both fossil cuticles contain considerable aliphatic carbon relative to modern cuticle. However, the concentration of vestigial chitin-protein complex is high, 59% and 53% in the fossil scorpion and eurypterid, respectively. Preservation of a high-nitrogen-content chitin-protein residue in organic arthropod cuticle likely depends on condensation of cuticle-derived fatty acids onto a structurally modifi ed chitin-protein molecular scaffold, thus preserving the remnant chitin-protein complex and cuticle from degradation by microorganisms.

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Chitin Diagenesis in Deep-Water Sediments

Cited by 11 publications

References 11 publications

Mechanisms of fossilization of the soft-bodied and lightly armored faunas of the Burgess Shale and of some other classical localities

Mechanisms of fossilization of the soft-bodied and lightly armored faunas of the Burgess Shale and of some other classical localities

High Production of Chitinolytic Activity in Halophilic Conditions by a New Marine Strain of Clonostachys rosea

Molecular signature of chitin-protein complex in Paleozoic arthropods

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