Bactericidal and antibiofilm properties of Rumex japonicus Houtt. on multidrug-resistant Staphylococcus aureus isolated from milk.

Multidrug-resistant (MDR) Staphylococcus aureus and its biofilm formation have been challenging to control in milk and dairy industries. Biofilms formed by Staph. aureus may result in the failure of antibacterial agents and disinfectants to penetrate the biofilm in an attempt to control contamination. Novel natural antibacterial agents are required to combat MDR bacteria and biofilms. In this study, we evaluated the bactericidal, antibiofilm, and antimotility effects of Rumex japonicus Houtt. (RJH) extract on MDR Staph. aureus isolated from milk. The RJH extract exhibited good antibacterial activity against MDR strains with minimum inhibitory concentrations (MIC) ranging from 0.78 to 6.25 mg/mL and minimum bactericidal concentrations ranging from 3.125 to 12.5 mg/mL. The extract showed strong inhibition of biofilm formation (81.9%) at sub-MIC value and eradication of biofilm at higher concentrations. The motility of Staph. aureus was effectively blocked by the extract. Major compounds emodin, chrysophanol, and physcion were identified in RJH extract using HPLC-linear trap quadrupole (LTQ)/Orbitrap-mass spectrometry. The extract was nontoxic to human epithelial cell lines such as Caco-2 and HT-29 cell lines at concentrations ranging from 0.1 to 0.5 mg/mL, and from 0.1 to 0.75 mg/mL, respectively. These findings suggest that RJH extract could be an alternative to synthetic preservatives in milk and dairy products.

Infrared radiation properties of Ho³âº in multicomponent germanium tellurite glasses.

Ho(3+)-doped and Ho(3+)/Yb(3+)-codoped multicomponent germanium tellurite (MGT) glasses with multifarious emission channels in the near-infrared wavelength region have been fabricated and characterized. Judd-Ofelt intensity parameters of Ho(3+)-doped MGT glasses are solved to be Ω2=5.32×10(-20) cm(2), Ω(4)=2.73×10(-20) cm(2), and Ω(6)=1.12×10(-20) cm(2), indicating a higher asymmetric and stronger covalent environment around Ho(3+) ions in MGT glasses. Efficient infrared fluorescences have been observed in MGT glasses, and spontaneous emission probabilities are derived to be 230.4, 79.9, and 138.3 s(-1) for the (5)I(6)→(5)I(8), ((5)F(4),(5)S(2))→(5)I(5), and (5)I(7)→(5)I(8) radiative transitions, respectively. In Ho(3+)/Yb(3+)-codoped MGT glasses, the maximum stimulated emission cross-section of 2.0 µm emission is calculated to be 4.93×10(-21) cm(2), and the corresponding gain cross-section is derived to be 3.62×10(-21) cm(2) when the excited state population fraction P reaches 0.8. Multifarious infrared emissions show that Ho(3+) in MGT glasses is a good candidate for optical amplifiers and optoelectronic devices.