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| Titel |
Microbial responses to chitin and chitosan in oxic and anoxic agricultural soil slurries |
| VerfasserIn |
A. S. Wieczorek, S. A. Hetz, S. Kolb |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 12 ; Nr. 11, no. 12 (2014-06-24), S.3339-3352 |
| Datensatznummer |
250117478
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| Publikation (Nr.) |
 copernicus.org/bg-11-3339-2014.pdf |
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| Zusammenfassung |
| Microbial degradation of chitin in soil substantially contributes to carbon
cycling in terrestrial ecosystems. Chitin is globally the second most
abundant biopolymer after cellulose and can be deacetylated to chitosan or
can be hydrolyzed to N,N′-diacetylchitobiose and oligomers of
N-acetylglucosamine by aerobic and anaerobic microorganisms. Which pathway of
chitin hydrolysis is preferred by soil microbial communities is unknown.
Supplementation of chitin stimulated microbial activity under oxic and
anoxic conditions in agricultural soil slurries, whereas chitosan had no
effect. Thus, the soil microbial community likely was more adapted to chitin
as a substrate. In addition, this finding suggested that direct hydrolysis
of chitin was preferred to the pathway that starts with deacetylation.
Chitin was apparently degraded by aerobic respiration, ammonification, and
nitrification to carbon dioxide and nitrate under oxic conditions. When
oxygen was absent, fermentation products (acetate, butyrate, propionate,
hydrogen, and carbon dioxide) and ammonia were detected, suggesting that butyric
and propionic acid fermentation, along with ammonification, were likely
responsible for anaerobic chitin degradation. In total, 42 different chiA
genotypes were detected of which twenty were novel at an amino acid sequence
dissimilarity of less than 50%. Various chiA genotypes responded to chitin
supplementation and affiliated with a novel deep-branching bacterial chiA
genotype (anoxic conditions), genotypes of Beta- and Gammaproteobacteria (oxic and anoxic
conditions), and Planctomycetes (oxic conditions). Thus, this study provides evidence that
detected chitinolytic bacteria were catabolically diverse and occupied
different ecological niches with regard to oxygen availability enabling
chitin degradation under various redox conditions on community level. |
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