@misc{RiedelBraunBoellmannetal., author = {Riedel, Ramona and Braun, Burga and B{\"o}llmann, J{\"o}rg and Martienssen, Marion}, title = {Neuer Standard-Abbautests f{\"u}r synthetische Phosphonate}, series = {BIOspektrum : Das Magazin f{\"u}r Biowissenschaften}, volume = {30}, journal = {BIOspektrum : Das Magazin f{\"u}r Biowissenschaften}, issn = {1868-6249}, doi = {10.1007/s12268-024-2194-x}, pages = {345 -- 347}, abstract = {The evaluation of the ready biodegradation of organic substances is usually carried out using the standardised OECD test methods 301 (A-F). However, this can become a great challenge for substances such as aminophosphonates which are chemically imbalanced and do not automatically promote microbial growth in standardized tests. Here, we report on the development of a standardized batch test that is suitable for phosphonates and overcomes important obstacles of the test methods above-mentioned.}, language = {de} } @misc{RiedelKrahlBuderetal., author = {Riedel, Ramona and Krahl, Kathrin and Buder, Kai and B{\"o}llmann, J{\"o}rg and Braun, Burga and Martienssen, Marion}, title = {Novel standard biodegradation test for synthetic phosphonates}, series = {Journal of Microbiological Methods}, volume = {Vol. 212}, journal = {Journal of Microbiological Methods}, issn = {1872-8359}, doi = {10.1016/j.mimet.2023.106793}, pages = {1 -- 13}, abstract = {Determination of biodegradation of synthetic phosphonates such as aminotris(methylenephosphonic acid) (ATMP), ethylenediamine tetra(methylenephosphonic acid) (EDTMP), or diethylenetriamine penta(methylenephosphonic acid) (DTPMP) is a great challenge. Commonly, ready biodegradability of organic substances is assessed by OECD 301 standard tests. However, due to the chemical imbalance of carbon to phosphorus synthetic phosphonates do not promote microbial growth and, thus, limiting its biodegradation. Therefore, standard OECD test methods are not always reliable to predict the real biodegradability of phosphonates. In the presented study, we report the development of a standardized batch system suitable to synthetic phosphonates such as ATMP, EDTMP, DTPMP and others. The novel standard batch test is applicable with pure strains, activated sludge from different wastewater treatment plants (i.e., municipal and industrial), and with tap water as inoculum. We optimized the required calcium and magnesium exposure levels as well as the amount of the start inoculum biomass. We demonstrated that our test also allows to determine several parameters including ortho-phosphate (o-PO43􀀀 ), total phosphorus (TP), ammonium (NH4+) and total organic carbon (TOC). In addition, also LC/MS analyses of cell-free medium is applicable for determining the mother compounds and metabolites. We applied our optimized standardized batch with selected phosphonates and evidenced that the chemical structure has a major influence of the microbial growth rates. Thus, our novel batch test overcomes drawbacks of the OECD 301 test series for determination of easy biodegradability for stoichiometric imbalanced organic compounds such as phosphonates.}, language = {en} } @misc{BoellmannRiedelMartienssen, author = {B{\"o}llmann, J{\"o}rg and Riedel, Ramona and Martienssen, Marion}, title = {Inhibition of Pseudomonas aeruginosa with silver in a new synthetic medium : investigation on the MIC, growth rate and lag-phase at the lower limit}, series = {Journal of microbiological methods}, volume = {230-231}, journal = {Journal of microbiological methods}, publisher = {Elsevier Bv}, address = {Amsterdam}, issn = {1872-8359}, doi = {https://doi.org/10.1016/j.mimet.2025.107095}, pages = {1 -- 9}, abstract = {The antimicrobial properties of silver are well-known and widely applied. Although it is known, that silver interacts and binds on complex organic substances like proteins, many experiments on the sterilisation efficiency and inhibiting properties are still carried out in complex culture media. Given, that silver is often applied in environments with no or few organic substrates, like cooling circuits or in the treatment of tap and process water, further insight on the minimum inhibition concentration and lethal concentration at those conditions is of interest. We have developed a defined medium for the standard bacterium Pseudomonas aeruginosa that is free of complex organic carbon with equal cultivation properties like commonly used nutrient solutions. With this medium we could narrow the range of the MIC between 2.5 μg to 10 μg∙L-1, which very much overlaps with the bactericidic concentration depending on the initial concentration of bacteria cells. These results might help to optimise the technical application of silver. We further observed a delayed growth of bacterial cultures of up to three days compared to silver free controls, which is caused either by a partial sterilisation down to theoretical one surviving cell or by a prolonged lag phase. Based on these observations we recommend a prolonged incubation for experiments on sterilisation with silver and the use of defined media, which do not interact with the disinfecting agent.}, language = {en} }