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This study aims at investigating the abiotic degradation pathway of
ethylenediaminetetra(methylenephosphonic acid) (EDTMP) simulated applying UV
irradiation. The degradation of EDTMP and formation of degradation products was
determined using LC-MS and ³¹P-NMR. In the laboratory scale experiments, EDTMP was
degraded within 30 min and the degradation products, iminodi(methylenephosphonic
acid) (IDMP), ethylaminobis(methylenephosphonic acid) (EABMP), and amino-
(methylenephosphonic acid) (AMPA), were simultaneously released. IDMP was the
main degradation product of EDTMP. Therefore, we conclude that the initial cleavage of
EDTMP is a heterolytically driven process, which starts the degradation process at the
intramolecular C-N bond. In contrast, the main product of a possible homolytic C-C
cleavage of methylaminobis(methylenephosphonic acid) could not be confirmed with
either LC-MS or ³¹P-NMR. Additionally, there was no evidence for a primary attack on
the C-P bond. All identified degradation products of EDTMP have been mineralized to
carbon dioxide (CO₂). Three additional degradation products (M1, M2, and M3) have
been found using the ³¹P-NMR analysis but have not yet been quantified using LC-MS.
We assume that the unidentified degradation product M1 is related to m/z 312, M2
to m/z 341, and M3 to m/z 409. Thus we concluded that EDTMP undergoes photochemical
conversion to IDMP, the main degradation product. EABMP and AMPA also accumulate,
but in smaller amounts. All intermediates are further mineralized to CO₂.
DNA extraction for molecular biological applications usually requires target optimized extraction procedures depending on the origin of the samples. For environmental samples, a range of different procedures has been developed. We compared the applicability and efficiency of ten selected DNA extraction methods published in recent literature using four different environmental samples namely: activated sludge from a domestic wastewater treatment plant, river sediment, anaerobic digestion sludge and nitrifying enrichment culture. We assessed the suitability of the extraction procedures based on both DNA yield and quality. DNA quantification was performed by both ultra violet (UV) spectrophotometry and fluorescence spectrophotometry after staining with PicoGreen. In our study, DNA yields based on UV measurement were overestimated in most cases while DNA yields from fluorescence measurements correlated well with the sample load on agarose gels of crude DNA. The quality of the DNA extracts was determined by gel electrophoresis of crude DNA and PCR products from 16S rDNA with the universal primer set 27f/1525r. It was observed that gel electrophoresis of crude DNA was not always suitable to evaluate DNA integrity and purity since interfering background substances (e.g. humic substances) were not visible. Therefore, we strongly recommend examining the DNA quality of both crude DNA and 16S rDNA PCR products by gel electrophoresis when a new extraction method is established.
Summarizing, we found four out of ten extraction procedures being applicable to all tested samples without noticeable restrictions. The procedure G (according to the standard method 432_10401 of the Lower Saxony State Office for Consumer Protection and Food Safety) had the broadest application range over procedure J
(published by Wilson, 2001). These were followed by procedures F (Singka et al., 2012) and A (Bourrain et al., 1999). All four extraction procedures delivered reliable and reproducible crude DNA and PCR products. From an economical point of view, all procedures tested during this study were cheaper compared to commercial DNA extraction kits.
The data presented in this article provide supporting information to the related research article “Comparison of ten different DNA extraction procedures with respect to their suitability for environmental samples” (revised manuscript submitted to J. Microbiol. Methods). In that article, we compared the suitability of ten selected DNA extraction methods based on DNA quality, purity, quantity and applicability to universal PCR. Here we provide the data on the specific DNA gel sample load, all unreported gel images of crude DNA and PCR results, and the complete cost analysis for all tested extraction procedures and in addition two commercial DNA extraction kits for soil and water.
The FISH (fluorescence in situ hybridization) method is widely used to identify various types of cells. In comparison to cultivation-dependent methods, identification of microbes by FISH is easier
and generally takes several hours. This paper presents a review of improvements to the FISH method, its advantages and disadvantages, as well as examples of applications. Particular consideration was
given to the efficiency of microbes identification in samples taken from sewerage. The effectiveness of the method was confirmed by the results obtained in samples from the membrane bioreactor (MBR).
DTPMP is predominantly utilized as scale inhibitor. We investigated the reaction rates and degradation mechanism of DTPMP with and without addition of Fe²⁺, Mg²⁺ and Ca²⁺ by performing LC/MS and ³¹P-NMR analyses. DTPMP undergoes conversion with and without addition of bivalent metal ions. The initial cleavage of DTPMP is initiated at the C-N bond leading to release of IDMP as its major breakdown product. The release of smaller quantities of EABMP and AMPA confirmed the nucleophilic attack on the DTPMP amines. Oxidation of Fe²⁺ to Fe³⁺ during the initial 30 min indicated an intramolecular electron transfer changing the electron density distribution at the nitrogen centre, which increased the radical attack during UV irradiation. Independent of the fact that Fe acted as catalyst and Mg²⁺ and Ca²⁺ acted as reactants, we found no significant differences in their degradation mechanisms. However, the reaction rates were strongly affected by the addition of the bivalent metal ions as Fe²⁺ accelerated most DTPMP degradation followed by Mg²⁺ and Ca²⁺. The UV treatment without metal ion addition was four times slower compared with Fe²⁺ addition. We conclude that in environments rich in ferrous iron and/or at reduced redox potential, photolysis of DTPMP will be catalysed by iron and will lead to accumulation of IDMP, EABMP and AMPA and several other none-quantifiable breakdown products.
Phosphonates comprise a very large group of organophosphonates including aminophosphonates. Their main chemical feature leads to complexation of earth alkaline metals and transition metals (under stoichiometric). Therefore they are very often applied as complexing agents of detergents, as compounds of industrial cleaning products, or as antiscalants in cooling water systems and desalination processes. The high consumption of phosphonates within the past two decades leads to an increased discharge into the aquatic environment, of which the environmental risk is still uncertain. To date, there are several analytical methods published to determine phosphonates from environmental samples. However, no standard method has been defined until now. Different treatment technologies to break down phosphonates have been studied extensively such as photochemical degradation, chemical degradation and other advanced oxidation processes. The results obtained from those studies gained our chemical understanding with respect to possible implementation of such pre-treatment approaches in wastewater treatment, cooling water treatment and desalination process. The biological degradation of phosphonates has been studied for more than forty years. It was demonstrated that microorganisms are capable to breakdown the C-P bond with at least three different degradation pathways.