Adipocere formation in biofilms as a first step in soft tissue preservation

Abstract

The preservation of soft tissue in the fossil record is mostly due to the replacement of organic structures by minerals (e.g. calcite, aragonite or apatite) called pseudomorphs. In rare cases soft tissues were preserved by pyrite. We assume that adipocere, as the shaping component, might be a preliminary stage in the pyritisation of soft tissues under anaerobic conditions. Using high-performance liquid chromatography coupled to ultraviolet and mass spectrometric detection (HPLC–UV/MS) and confocal Raman spectroscopy (CRS) we were able to demonstrate the transformation of the hepatopancreas (digestive gland) of the crayfish Cambarellus diminutus [Hobbs 1945] into adipocere within only 9 days, just inside a biofilm. Microorganisms (bacteria and fungi) which were responsible for the biofilm (Sphaerotilus [Kutzig 1833] and Pluteus [Fries 1857]) and maybe the adipocere formation (Clostridium [Prazmowski 1880]) were detected by 16S rRNA gene amplicon sequencing. Furthermore, micro-computed tomography (µ-CT) analyses revealed a precipitation of calcite and further showed that in animals with biofilm formation calcite precipitates in finer grained crystals than in individuals without biofilm formation, and that the precipitates were denser and replicated the structures of the cuticles better than the coarse precipitates.

Chimera of fossil biomolecules found in Pleistocene fossil in tropical cave: Fossil biofilm characterization by micro Raman spectroscopy

“…7B). In this stage the interaction of the microorganism and fossil surface become almost irreversibly via stronger hydrophilic/hydrophobic interactions by agella, pili, lipopolysaccharides, exopolysaccharides, collagenbinding adhesive proteins 44,45 . As nutrient consumption increases the auto-induced production as well the bio lm passes to a development of multilayers (Fig.…”

Oxygen-dependent biofilm dynamics in leaf decay: an in vitro analysis

“…Sarkar et al (2022) emphasize that clostridia are effective H 2 and acid producers using carbohydrates such as cellulose and sucrose as substrates 34 . Numerous studies showed that saprophytic clostridia are associated with the decay of plants, phytoplankton, animal and human tissues 14 , 35 .…”

Enzymatic phosphatization of fish scales—a pathway for fish fossilization

“…Apatite permineralization is not a process that commonly occurs post-mortem in subaquatic environments. Instead, vertebrate bodies decay relatively quickly after death or are consumed by scavengers unless the decay is slowed down due to increased salinity or alkaline pH 11 – 14 . However, they are generally returned to the biological cycle, through decomposition, and no physiological information is retained.…”

“…The chemical pathway for these mineralization processes is still poorly understood. In hard tissues such as bones, teeth, or shells, the potential for preservation is great, but the exact conditions for soft tissue preservation are still a matter of ongoing research and intensively debated, although significant progress has been made on certain mechanisms 10 , 11 , 15 – 18 . Here, we assessed a potential mechanism for the preservation of fish scales via apatite formation, which does not necessarily follow the same preservation processes of soft tissues.…”