ABSTRACT. Extended-spectrum β-lactamases (ESBLs) and AmpC β-lactamases produced by a clinical isolate of Klebsiella pneumoniae from chickens were detected with confirmatory phenotypic tests of the Clinical and Laboratory Standards Institute. The minimum inhibitory concentrations of 18 antibacterial drugs against K. pneumoniae were determined by the 2-fold microdilution method. The genotype and subtype of the ESBL-producing and AmpC β-lactamase-producing K. pneumoniae isolate were identified by PCR amplification of the enzymeencoding genes followed by DNA sequencing analysis. K. pneumoniae K 1 isolate was an ESBL-producing and AmpC β-lactamase-producing bacteria with high resistance to β-lactam antibiotics, such as penicillins, third-generation cephalosporins, fluoroquinolones, and aminoglycosides. The sequence analysis showed that K. pneumoniae K 1 harbored TEM-type, SHV-type, CTX-M-type, and ACT-type AmpC β-lactamase nucleotide

AbstractAnaerobic ammonium-oxidizing (anammox) bacteria play a key role in the global nitrogen cycle and the treatment of nitrogenous wastewater. These functions are closely related to the unique biophysical structure of anammox bacteria. However, the research on the biophysical ultrastructure of intact anammox bacteria is lacking. In this study, in-situ three-dimensional nondestructive ultrastructure imaging of whole anammox cell was performed using synchrotron soft X-ray nano-computed tomography and the total variation-based simultaneous algebraic reconstruction technique (TV-SART). Statistical and quantitative analyses of the ultrastructures of intact anammox bacteria were performed. The linear absorption coefficient values of the ultrastructures of anammox bacteria were calculated and the asymmetric structure of the anammox bacteria was quantified. On this basis, the shape adaptation of the anammox bacteria responses to Fe2+ were explored, and the underlying regulation mechanism of Fe2+ on anammox bacteria was explored. Furthermore, a promising method to study the biophysical properties of cells in different environments and engineering processes was proposed.Graphical AbstractStatement of SignificanceAnaerobic ammonium-oxidizing (anammox) bacteria play key role in global nitrogen cycle, and this physiological function depends on the unique morphology of anammox bacteria. In this study, synchrotron soft-X ray imaging technique coupled with simultaneous algebraic reconstruction technique with total variation (SART-TV) algorithm were performed to quantify the three-dimensional ultrastructure of the whole anammox bacteria for the first time. On this basis, the shape adaptation and mechanism of the anammox bacteria responses to Fe2+ were explored and a promising method for detecting the physiological properties of anammox bacteria was proposed.