Metformin is the first-line treatment for type II diabetes patients and a pervasive pollutant with more than 180 million kg ingested globally and entering wastewater. The drug’s direct mode of action is currently unknown but is linked to effects on gut microbiomes and may involve specific gut microbial reactions to the drug. In wastewater treatment plants, metformin is known to be transformed by microbes to guanylurea, although genes encoding this metabolism had not been elucidated. In the present study, we revealed the function of two genes responsible for metformin decomposition (
Recently, we reported the discovery of a novel endoglucanase of the glycoside hydrolase family 12 (GH12), designated IfCelS12A, from the haloalkaliphilic anaerobic bacterium
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- NSF-PAR ID:
- 10484906
- Publisher / Repository:
- Springer Science + Business Media
- Date Published:
- Journal Name:
- Applied Microbiology and Biotechnology
- Volume:
- 108
- Issue:
- 1
- ISSN:
- 0175-7598
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Rosenzweig, Amy (Ed.)
mfmA andmfmB ) found in isolated bacteria from activated sludge. MfmA and MfmB form an active heterocomplex (MfmAB) and are members of the ureohydrolase protein superfamily with binuclear metal-dependent activity. MfmAB is nickel-dependent and catalyzes the hydrolysis of metformin to dimethylamine and guanylurea with a catalytic efficiency (kcat/KM) of 9.6 × 103M−1s−1and KMfor metformin of 0.82 mM. MfmAB shows preferential activity for metformin, being able to discriminate other close substrates by several orders of magnitude. Crystal structures of MfmAB show coordination of binuclear nickel bound in the active site of the MfmA subunit but not MfmB subunits, indicating that MfmA is the active site for the MfmAB complex. Mutagenesis of residues conserved in the MfmA active site revealed those critical to metformin hydrolase activity and its small substrate binding pocket allowed for modeling of bound metformin. This study characterizes the products of themfmAB genes identified in wastewater treatment plants on three continents, suggesting that metformin hydrolase is widespread globally in wastewater. -
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METHODS A total of 38 healthy adults (aged 36‐80 years) were studied using 7T dynamic contrast enhanced MRI. Blood volume fraction (
vb ) and capillary water efflux rate constant (k po) were determined by fitting changes in the1H2O longitudinal relaxation rate constant (R1) during contrast agent bolus passage to a two‐compartment exchange model. WM volume was determined by morphometric analysis of structural images.RESULTS R1values and WM volume showed similar trajectories of age‐related decline. Among all subjects,
vb andk poaveraged 1.7 (±0.5) mL/100 g of tissue and 2.1 (±1.1) s−1, respectively. Whilevb showed minimal changes over the 40‐year‐age span of participants,k podeclined 0.06 s−1(ca. 3%) per year (r = −.66;P < .0005), from near 4 s−1at age 30 to ca. 2 s−1at age 70. The association remained significant after controlling for WM volume.CONCLUSIONS Previous studies have shown that
k potracks Na+, K+‐ATPase activity‐dependent water exchange at the BBB and likely reflects neurogliovascular unit (NGVU) coupled metabolic activity. The age‐related decline ink poobserved here is consistent with compromised NGVU metabolism in older individuals and the dysregulated cellular bioenergetics that accompany normal brain aging. -
Characteristics of the life history of the coral reef‐dwelling cardinalfish
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