Bacterial contamination is a major and constant threat to the establishment and subculture of in vitro plant culture. In this study, we used a slightly modified qualitative disk diffusion method to screen optimal antibiotics to control the growth of bacterial contaminants isolated from explants of cherry rootstock ‘Gisela 6’. Bacterial susceptibility to eight different antibiotics was tested. The results showed that tetracycline was the most effective antibiotic for controlling bacterial growth; cefotaxime, carbenicillin, kanamycin, and streptomycin were less effective, whereas ampicillin, penicillin, and cefazolin did not inhibit growth of the isolated bacteria. Using the quantitative E test, the minimal inhibitory concentration (MIC) of tetracycline was determined to be 1.0 µg mL−1. We also measured the Fv/Fm values, chlorophyll content, and enzymatic activity of superoxide dismutase and peroxidase to explore the effect of different tetracycline concentrations, 0, 0.064, 0.5, 1.0, 16, and 256 µg mL−1, on the growth of bacteria and explants over 30 days. Results indicated that 1.0 µg mL−1 tetracycline was effective in restricting bacterial growth, with non-significant negative effects on explants at low concentrations, but were enhanced negative effects at high concentrations. The application of the disk diffusion method and E test enabled the identification of an antibiotic and its MIC value effective for eliminating bacterial contaminants while causing minimal damage to explants, indicating a high potential of these methods to control bacterial contaminants in in vitro plant culture.
Porcine epidemic diarrhea virus (PEDV) is a porcine enteric coronavirus globally, causing serious economic losses to the global pig industry since 2010. Here, a PEDV CH/Yinchuan/2021 strain was isolated in a CV777-vaccinated sow farm which experienced a large-scale PEDV invasion in Yinchuan, China, in 2021. Our results demonstrated that the CH/Yinchuan/2021 isolate could efficiently propagate in Vero cells, and its proliferation ability was weaker than that of CV777 at 10 passages (P10). Phylogenetic analysis of the S gene revealed that CH/Yinchuan/2021 was clustered into subgroup GIIa, forming an independent branch with 2020-2021 isolates in China. Moreover, GII was obviously allocated into four clades, showing regional and temporal differences in PEDV global isolates. Notably, CH/Yinchuan/2021 was analyzed as a recombinant originated from an American isolate and a Chinese isolate, with a big recombinant region spanning ORF1a and S1. Importantly, we found that CH/Yinchuan/2021 harbored multiple mutations relative to CV777 in neutralizing epitopes (S10, S1A, COE, and SS6). Homology modelling showed that these amino acid differences in S protein occur on the surface of its structure, especially the insertion and deletion of multiple consecutive residues at the S10 epitope. In addition, cross-neutralization analysis confirmed that the differences in the S protein of CH/Yinchuan/2021 changed its antigenicity compared with the CV777 strain, resulting in a different neutralization profile. Animal pathogenicity test showed that CH/Yinchuan/2021 caused PEDV-typified symptoms and 100% mortality in 3-day-old piglets. These data will provide valuable information to understand the epidemiology, molecular characteristics, evolution, and antigenicity of PEDV circulating in China.
In this research, a regioregular poly (3-alkylthiophene) derivative had been synthesized via the post-polymerization functionalization, poly (3-hexylamine thiophene), which are soluble in water and water miscible solvents such as methanol, DMSO. The suitable energy level, good thermal stability and water/alcohol solubility of polymers which promising applied in polymer solar cells and processed by water or environmental-friendly solvents. In blend of functionalization polymers and fullerene derivative potassium [6,6]-phenyl-C61-butyrate shows significant UV absorption decay phenomenon and occur precipitates follow with time increase. To further investigate the mechanism of composite, FT-IR analysis and TEM investigate were used, the polymer would be bonded with carboxyl of fullerene derivative via hydrogen bonding in the carboxyl region and TEM images demonstration the mixture that be able to self-assembly a interpenetrating network composite.
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