Chitinases in the tree of life Ecological, kinetic and structural studies of archaeal and marine bacterial chitinases

Staufenberger, Tim (2012) Chitinases in the tree of life Ecological, kinetic and structural studies of archaeal and marine bacterial chitinases (Doctoral thesis/PhD), Christian-Albrechts-Universität, Kiel, Germany, 87 pp

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Abstract

Chitin is after cellulose the second most abundant biopolymer on earth. It’s production is enormous, with estimates of up to 1011 tons for both the annual production and the steady-state amount. Chitin consists of β-1,4 glycosidic bonded N-acetyl-glucosamine subunits. It’s degradation is especially in the oceans an important step to ensure the continuous availability of carbon and nitrogen. Chitin is very resilient to physicochemical degradation due to its structure. It is mainly biodegraded by microorganisms. Until now three degradation pathways are know, utilising different enzymes. One very important enzyme found in the biodegradation pathways of bacteria, fungi and archaea is the chitinase. Chitinases hydrolyse the β-1,4 glycosidic bond between the N-acetyl-glucosamine subunits. This enzyme is used not only for the recovery of nutrients in microorganisms, it plays also a major role in moulting of arthropods and is utilised in defence mechanisms of higher organisms. This important enzyme, as proxy for chitinolytic activity, is detected with molecular methods and cultivation based approaches. Most of the studies detecting chitinases do either test for the genetic capability or the growth capability of the respective microorganisms on chitin. Moreover, direct proof of the the chitinolytic enzyme itself is lacking in many studies. Until now a more comprehensive chitinase test panel, combining cultivation and molecular screening of the cultivated strains for their genetic capabilities has not been implemented yet. Furthermore, the search for chitinolytic organisms was mainly focused on bacteria and fungi, but almost no chitin degrading archaea were detected until now. Within this study a novel three step chitinase test panel was established and tested, consisting of isolation and cultivation of microorganisms on chitin as sole carbon and nitrogen source, the molecular screening of the cultivated strains and the evaluation of the respective chitinase activity. This approach was used to investigate bacteria isolated from different marine microbial communities (Mediterranean Deep Sea sediments and Baltic Sea shrimp carapaces). In addition, bacterial strains (bryozoan derived isolates and actinomycetes) of the KiWiZ strain collection were also investigated. In total, 145 bacterial strains were investigated in this study. Furthermore, the first crenarchaeal chitinase gene from Sulfolobus tokodaii was detected, expressed in E. coli and the resulting chitinase was described. In addition, the chitinase gene of the halophilic euryarchaeon Halobacterium salinarum was expressed for the first time in E. coli.

Document Type: Thesis (Doctoral thesis/PhD)
Thesis Advisors: Imhoff, Johannes F. and Schönheit, Peter
Additional Information: Print-Exemplar in der Bibliothek vorhanden - print edition available
Keywords: Microbiology; Chitinases, crenarchaeal citinases, GH18, GH19, Glycosyl hydrolases
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-MI Marine Microbiology
OceanRep > GEOMAR > Applied R&D > Centre for Marine Substances (KiWiZ)
Projects: KIWIZ
Date Deposited: 19 Jun 2012 13:40
Last Modified: 06 Dec 2012 13:38
URI: http://eprints.uni-kiel.de/id/eprint/14704

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