Kunz, Anna L. (2011) Nachweis der Phenazin-Produktion in marinen Bakterien. (Master thesis), Universität Bayreuth, Bayreuth, Germany, 113 pp.

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Abstract

Phenazines show antibacterial, antifungal, antiviral and cytotoxic activities [15, 33]. On the one hand, this class of metabolites presents a great potential for pharmaceutical applications. An example is clofazimine 9 which is already established as an antileprosy agent [47]. On the other hand, phenazines are very important in the biocontrol of phytopathogenic fungi. Pseudomonas chlororaphis M342 for example is used for seed treatment against fungal diseases [45]. Due to the biotechnological applications of the phenazines, the goal set within this Master’s Thesis was the detection of phenazines producing bacteria from marine habitats. Two approaches were performed. The genetic approach includes PCR amplification of two phz gene fragments as markers for the ability to produce phenazines. The amplification method of Mavrodi et al. (2010) was used to demonstrate phzF gene fragments [48], whereas the primer system of Schneemann et al. (2011) was applied for the detection of phzE gene fragments [55]. The cultivation-based approach comprises cultivation and extraction of bacterial strains and subsequent chemical analysis with HPLC-MS. In order to accomplish this method, the terrestrial P. chlororaphis strains and S. cinnamonensis DSM 1042T are used as controls, because these strains are known producers of phenazines. Following the establishment of the method, strains from environments were investigated. PCR amplification of both phz gene fragments was accomplished for 56 bacterial strains comprising four control strains and 52 marine strains. 17 strains showed positive results using phzE primers and only six strains exhibited phzF gene fragments. These results clearly demonstrated that the application of the phzE primer system of Schneemann et al. (2011) is a useful tool for the selection of phenazine producers from marine samples [55]. In addition 28 of the 56 bacterial strains were cultivated, extracted and analysed by HPLC-MS analyses. Nine of these strains were identified as phenazine producers which correlates a rate of 53% of the phzE positive strains. Compared to the cultivation-based approach, it is already well known that the genome of bacterial strains contains more gene clusters which are forecasted to execute the biosynthesis of secondary metabolites [80]. Thus, modification of the cultivation conditions might stimulate the production of phenazines in all phzE positive strains.

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