Biodegradation of selected aminophosphonates by the bacterial isolate Ochrobactrum sp. BTU1.

Aminophosphonates, like glyphosate (GS) or metal chelators such as ethylenediaminetetra(methylenephosphonic acid) (EDTMP), are released on a large scale worldwide. Here, we have characterized a bacterial strain capable of degrading synthetic aminophosphonates. The strain was isolated from LC/MS standard solution. Genome sequencing indicated that the strain belongs to the genus Ochrobactrum. Whole-genome classification using pyANI software to compute a pairwise ANI and other metrics between Brucella assemblies and Ochrobactrum contigs revealed that the bacterial strain is designated as Ochrobactrum sp. BTU1. Degradation batch tests with Ochrobactrum sp. BTU1 and the selected aminophosphonates GS, EDTMP, aminomethylphosphonic acid (AMPA), iminodi(methylene-phosphonic) (IDMP) and ethylaminobis(methylenephosphonic) acid (EABMP) showed that the strain can use all phosphonates as sole phosphorus source during phosphorus starvation. The highest growth rate was achieved with AMPA, while EDTMP and GS were least supportive for growth. Proteome analysis revealed that GS degradation is promoted by C-P lyase via the sarcosine pathway, i.e., initial cleavage at the C-P bond. We also identified C-P lyase to be responsible for degradation of EDTMP, EABMP, IDMP and AMPA. However, the identification of the metabolite ethylenediaminetri(methylenephosphonic acid) via LC/MS analysis in the test medium during EDTMP degradation indicates a different initial cleavage step as compared to GS. For EDTMP, it is evident that the initial cleavage occurs at the C-N bond. The detection of different key enzymes at regulated levels, form the bacterial proteoms during EDTMP exposure, further supports this finding. This study illustrates that widely used and structurally more complex aminophosphonates can be degraded by Ochrobactrum sp. BTU1 via the well-known degradation pathways but with different initial cleavage strategy compared to GS.

Impact of preoperative Vitamin D3 administration on postoperative hypocalcaemia in patients undergoing total thyroidectomy (HypoCalViD): study protocol for a randomized controlled trial.

BACKGROUND: Total thyroidectomy is increasingly used as a surgical approach for many thyroid conditions. Subsequently, postoperative hypocalcaemia is observed with increasing frequency, often resulting in prolonged hospital stay, increased use of resources, reduced quality of life and delayed return to work. The administration of vitamin D is essential in the therapy of postoperative hypocalcaemia; calcitriol is most commonly used. What has not been examined so far is whether and how routine preoperative vitamin D prophylaxis using calcitriol can help to prevent postoperative hypocalcaemia. This study evaluates routine preoperative calcitriol prophylaxis for all patients who are to undergo a total thyroidectomy, compared with the current standard of post-treatment, i.e., selective vitamin D treatment for patients with postoperative hypocalcaemia. METHODS/DESIGN: This clinical observational (minimal interventional clinical trial) trial is a multicentre, prospective, randomized superiority trial with an adaptive design. Datasets will be pseudonymized for analysis. Patients will be randomly allocated (1:1) to the intervention and the control groups. The only intervention is 0.5 µg calcitriol orally twice a day for 3 days prior to surgery. For the primary endpoint measure (number of patients with hypocalcaemia), hypocalcaemia is defined as serum calcium of less than 2.1 mmol/l on any day during the postoperative course; this measure will be analyzed using a Chi-square test comparing the two groups. Secondary endpoint measures, such as number of days to discharge, quality of life, and economic parameters will also be analyzed. DISCUSSION: By virtue of the direct comparison of clinically and economically relevant endpoints, the efficacy as well as efficiency of preoperative calcitriol prophylaxis of hypocalcaemia will be clarified. These results should be available 24 months after the first patient has been enrolled. The results will be used to inform a revised practice parameter guideline of whether or not to recommend preoperative calcitriol for all patients in whom total thyroidectomy is planned. TRIAL REGISTRATION: Deutsches Register Klinischer Studien, DRKS00005615 (Feb.12.2016).