Multivariate tests and multiple test-procedures for abundance data of microorganisms in consideration of information from phylogenetic sequences

• Applicant: Professor Dr. Siegfried Kropf
• Subject Area: Epidemiology and Medical Biometry/Statistics
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 253253386

Analysis of the composition of microbial communities is an important component of agricultural, medical and ecological research. Nowadays the preferred methods are based directly on DNA samples and therefore are independent of the reproduction of microbial organisms under laboratory conditions. The developmental progress from electrophoretic methods of analysis to specialized microarrays and furthermore to modern next generation sequencing techniques as pyrosequencing or sequencing by Illumina MiSeq increased the number of detected OTUs (operational taxonomic units) and the ability to directly interpret and compare them within and between samples. The result of pyrosequencing is a quantification of the occurrences of OTUs which is independent in scale for species and as a byproduct provides information of the corresponding sequences which can be used to quantify the phylogenetic similarity of OTUs, too.Currently, international groups of researchers focus on incorporating this supplementary information in statistical analysis. Computationally expensive methods for ecological distances were established that combine information from abundance and phylogenetic distances. A common theoretical basis for the two most popular variants, the weighted Unifrac distance and the DPCoA (double principal coordinate analysis), has been published last year.The first target of this application is to adjust multivariate methods that were developed in our institute to the use of additional phylogenetic information and to compare the results against published methods. The methods from our institute are permutation or rotation tests based on distance measures.The main target is to use these methods afterwards together with univariate tests as building blocks in procedures for multiple testing which partition high dimensional data as far as possible into smaller sets of variables (e.g. on a higher taxonomical level) or even into single variables (OTUs) while still controlling the familywise error rate in the strong sense. To achieve this, several multiple test procedures that were developed in (or together with) our institute will be adjusted to the use of phylogenetic distances. We will work closely together with our partners from the Julius Kühn-Institut, a Federal Research Centre for cultivated plants in Quedlinburg/Braunschweig.

• DFG Programme: Research Grants
• International Connection: Denmark, Sweden, Switzerland
• Participating Persons: Dr. Rauf Ahmad; Dr. Ekkehard Glimm; Dr. Holger Heuer; Professorin Dr. Kornelia Smalla; Professor Dr. Søren Sørenson