@article{TillichLehmannSchulzeetal.2012, author = {Tillich, Ulrich M. and Lehmann, Sandra and Schulze, Katja and D{\"u}hring, Ulf and Frohme, Marcus}, title = {The Optimal Mutagen Dosage to Induce Point-Mutations in Synechocystis sp. PCC6803 and Its Application to Promote Temperature Tolerance}, series = {PLoS ONE}, volume = {7}, journal = {PLoS ONE}, number = {11}, issn = {1932-6203}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-6186}, pages = {8}, year = {2012}, abstract = {Random mutagenesis is a useful tool to genetically modify organisms for various purposes, such as adaptation to cultivation conditions, the induction of tolerances, or increased yield of valuable substances. This is especially attractive for systems where it is not obvious which genes require modifications. Random mutagenesis has been extensively used to modify crop plants, but even with the renewed interest in microalgae and cyanobacteria for biofuel applications, there is relatively limited current research available on the application of random mutagenesis for these organisms, especially for cyanobacteria. In the presented work we characterized the lethality and rate of non-lethal point mutations for ultraviolet radiation and methyl methanesulphonate on the model cyanobacteria Synechocystis sp. PCC6803. Based on these results an optimal dosage of 10-50 J/m2 for UV and either 0.1 or 1 v\% for MMS was determined. A Synechocystis wildtype culture was then mutagenized and selected for increased temperature tolerance in vivo. During the second round of mutagenesis the viability of the culture was monitored on a cell by cell level from the treatment of the cells up to the growth at an increased temperature. After four distinct rounds of treatment (two with each mutagen) the temperature tolerance of the strain was effectively raised by about 2°C. Coupled with an appropriate in vivo screening, the described methods should be applicable to induce a variety of desirable characteristics in various strains. Coupling random mutagenesis with high-throughput screening methods would additionally allow to select for important characteristics for biofuel production, which do not yield a higher fitness and can not be selected for in vivo, such as fatty acid concentration. In a combined approach with full genome sequencing random mutagenesis could be used to determine suitable target-genes for more focused methods.}, language = {en} } @article{SchulzeLopezTillichetal.2011, author = {Schulze, Katja and L{\´o}pez, Diana A. and Tillich, Ulrich M. and Frohme, Marcus}, title = {A simple viability analysis for unicellular cyanobacteria using a new autofluorescence assay, automated microscopy, and ImageJ}, series = {BMC Biotechnology}, volume = {11}, journal = {BMC Biotechnology}, number = {118}, issn = {1472-6750}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-6192}, pages = {8}, year = {2011}, abstract = {Currently established methods to identify viable and non-viable cells of cyanobacteria are either time-consuming (eg. plating) or preparation-intensive (eg. fluorescent staining). In this paper we present a new and fast viability assay for unicellular cyanobacteria, which uses red chlorophyll fluorescence and an unspecific green autofluorescence for the differentiation of viable and non-viable cells without the need of sample preparation.}, language = {en} } @article{SchulzeTillichDandekaretal.2013, author = {Schulze, Katja and Tillich, Ulrich M. and Dandekar, Thomas and Frohme, Marcus}, title = {PlanktoVision - an automated analysis system for the identification of phytoplankton}, series = {BMC Bioinformatics}, volume = {14}, journal = {BMC Bioinformatics}, number = {115}, issn = {1471-2105}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-6364}, pages = {10}, year = {2013}, abstract = {Phytoplankton communities are often used as a marker for the determination of fresh water quality. The routine analysis, however, is very time consuming and expensive as it is carried out manually by trained personnel. The goal of this work is to develop a system for an automated analysis.}, language = {en} } @article{TillichWolterSchulzeetal.2014, author = {Tillich, Ulrich M. and Wolter, Nick and Schulze, Katja and Kramer, Dan and Br{\"o}del, Oliver and Frohme, Marcus}, title = {High-throughput cultivation and screening platform for unicellular phototrophs}, series = {BMC Microbiology}, volume = {14}, journal = {BMC Microbiology}, number = {239}, issn = {1471-2180}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-6007}, pages = {13}, year = {2014}, abstract = {In this work we describe and test high-throughput methods with the model organism Synechocystis sp. PCC6803. The required technical automation for these processes was achieved with a Tecan Freedom Evo 200 pipetting robot. The cultivation was performed in 2.2 ml deepwell microtiter plates within a cultivation chamber outfitted with programmable shaking conditions, variable illumination, variable temperature, and an adjustable CO2 atmosphere. Each microtiter-well within the chamber functions as a separate cultivation vessel with reproducible conditions. The automated measurement of various parameters such as growth, full absorption spectrum, chlorophyll concentration, MALDI-TOF-MS, as well as a novel vitality measurement protocol, have already been established and can be monitored during cultivation. Measurement of growth parameters can be used as inputs for the system to allow for periodic automatic dilutions and therefore a semi-continuous cultivation of hundreds of cultures in parallel. The system also allows the automatic generation of mid and long term backups of cultures to repeat experiments or to retrieve strains of interest.}, language = {en} }