UROP Project

Evaluation of bacterial community changes in soil by molecular analysis of nitrogen-fixing bacteria



Daniel Holder

Program Director UROP


+49 241 80-90695


Key Info

Basic Information

Project Offer-Number:
Biotechnology / Molecular Biotechnology
Organisation unit:
Biologie I, Ökologie des Bodens
Language Skills:
German and/or English
Computer Skills:
MS Office

A current research project in our group is dealing with alfalfa plants inoculated with different bacteria and the hereby caused effects on plants as well as on microbial communities in the soil. The applied bacteria are a nitrogen-fixing Rhizobium, S. meliloti, and a plant-growth-promoting bacterium, A. brasilense. Preliminary results showed no significant difference in soil communities of the differently inoculated plants. The conclusions were based on results of 16S-rDNA amplification which shows the whole bacterial community of the soil without previous cultivation. It could well be that the total bacterial community does not change by the inoculations; however, a more detailed analysis of specific bacterial groups might reveal differences. Such a group could be nitrogen-fixing bacteria. The additional analysis of this group can add valuable information to the whole output of the project.


The intern will perform analysis of nitrogen-fixing bacteria as part of the mentioned research project. The initial phase will involve testing and establishing of suitable primers for usage in PCR of soil DNA and cDNA, e.g. for the nif genes. Then, experiments will be performed with DNA extracted from soil of the ongoing inoculation experiments. The analysis of the obtained PCR products will be done by DGGE (denaturing gradient gel electrophoresis). The trainee will be involved in all the steps, starting with the first phase of planning the experiments, establishing the best method, coordinating the experiments with other project co-workers and finally evaluating the results. The principal methods (PCR, DGGE) are established at the institute, and intense support will be given to the intern to learn all the required experimental skills. However, previous experiences with working in a laboratory as well as a sound knowledge of the theoretical background of PCR are necessary.


Previous lab experience, interest in molecular biology, theoretical background in genetics, ability to work self-dependently and organized