Content:
“Red heat” is an industry term that describes the appearance of mostly red-pink coloured macroscopic microbial colonies on salt-cured hides and skins. Red heat-affected stock is undesirable as the resultant leather often shows obvious defects; but why this contamination is only superficial in other instances remains unclear. Previous work has focused on pigmented halophiles (‘salt-loving’ microbes) isolated from curing salts as the primary culprit. However, the identity of causative agents remains unspecified. Also, the involvement of non-pigmented microbes, and of microbes native to hides and skins, could be better understood. Thus, an investigation of the microbial communities that inhabit untreated bovine hide, curing salt, unaffected salt-cured bovine hide, and red heat-affected cured hide is proposed to uncover the microbial agents responsible for this contamination. This project aims to define these microbial communities using both a culture-dependent and –independent approach. Methods of microbe identification focus on marker gene amplification and sequencing. This is in contrast to earlier work which was restricted solely to phenotypic analyses. The 16S ribosomal RNA gene marker is used to identify members of Bacteria and Archaea, while the 18S and ITS2 regions of the fungal ribosomal RNA operon are targeted to detect fungi. Metagenomic amplicon sequencing using the Illumina MiSeq platform employs these same markers to determine taxonomic composition and relative abundance. Preliminary results from culturing identified different dominant species in curing salts screened for microbial growth. In agreement with earlier culture-based studies, these isolates were mostly pigmented, highly salt-tolerant members of the halophilic archaea of family Halobacteriaceae, as determined by marker gene sequencing. However, in agreement with more recent work within food preservation technology, nonpigmented isolates of halophilic archaea of genus Natrinema and bacterial genus Chromohalobacter were also found. It was also revealed that non-pigmented, quick-growing, salt-tolerant, proteolytic microbes were easily cultured from red heat-affected hide, most of the isolates were identified by marker gene sequencing as bacterial Pseudomonas halophila or Salicola. To determine red heat-causing microbes, future work involves the screening of isolates for extracellular enzyme activity; the most likely cause of red heat-associated damage. Sterile-salted hide samples will be inoculated with selected individual and combinations of isolates, and then further examined using confocal microscopy to check for reproducibility of red heat-associated damage.
Take-Away:
Different microbial species are found in different curing salts.
Not all microbes involved in 'red heat' contamination are pigmented.
The purpose is the possibility to overcome all the restrictions connected with the pin-wheel machine, the improvement of actual EN ISO methods of leather measurement and a better instrument to define
tolerances considering the couple leather-machine.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:34368 |
| Date | 28 June 2019 |
| Creators | Grace, Shelley M., Patchett, M. L., Norris, G. E. |
| Contributors | International Union of Leather Technologists and Chemists Societies |
| Publisher | Verein für Gerberei-Chemie und -Technik e. V., Forschungsinstitut für Leder und Kunststoffbahnen (FILK) gGmbH |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:conferenceObject, info:eu-repo/semantics/conferenceObject, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | urn:nbn:de:bsz:14-qucosa2-340872, qucosa:34087 |
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