Staufenberger, Tim (2006) Characterization of microbial communities associated with Laminaria saccharina. (Diploma thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 64 pp.

Text Dipl. 2006 Staufenberger, T.pdf - Reprinted Version Restricted to Registered users only Available under License German copyright act UrhG. Download (8MB) | Contact

Abstract

The bacterial communities associated with the brown algae Laminaria saccharina were investigated. For characterization in different geographical settings, seasons and also on the morphologically different parts of the alga, denaturing gradient gel electrophoresis (DGGE), cloning and phylogenetic analysis of l 6S rDNA sequences were used. Biologically active bacteria, isolated from L. saccharina in an earlier study, were sequenced and phylogenetically analyzed. In addition an infected laboratory culture of Laminaria digitata was studied by scanning electron microscopy and DGGE. Infected L. digitata samples yielded DGGE banding patters that indicated a stable bacterial community. Scanning electron microcopy revealed blister like structures on the infected phylloid, containing morphologically different microorganisms not occurring on healthy L. digitata phylloids. The 16S rDNA DGGE banding pattems of L. saccharina from natural habitats indicated a specific bacterial community associated with the young and healthy algal tissues. Seasonal, geographical and algal-part specific differences were observed. Cloning experiments identified 18 phylotypes ( 6 in the Alphaproteobacteria, 8 in the Gammaproteobacteria and 4 in the Bacteroidetes group) derived only from Baltic L. saccharina, not shared by water-derived samples. This indicated a specific association of bacteria to L. saccharina. Furthermore sequence analysis of the L. saccharina-derived antimicrobially active isolates identified strain LD8 l to be a novel member of the Alphaproteobacteria with less than 96% sequence similarity to its closest relatives, Koprimonas byunsanensis (DQ 167245) and Rhodospirillum rubrum (X87278). These findings lead to the assumption, that L. saccharina provides a abitat for specifically associated bacteria and a source for the detection of novel bacterial species with antimicrobial activities.

Actions (login required)

View Item