In this study, the influence of ciprofloxacin, chlorotetracycline, lincomycin, and sulfamethoxazole on the composition of the bacterial community structure was studied during aerobic composting with swine manure. Firmicutes (26.67%) and Chloroflexi (23.33%) were the most widely distributed phyla. Under all antibiotic treatments, the relative abundances of Bacillaceae, Streptosporangiaceae, Limnochordaceae, and Peptostreptococcaceae increased during the composting process. Moreover, norank_SBR1031, Planococcaceae, Thermomonosporaceae, Peptostreptococcaceae, Erysipelotrichaceae, Limnochordaceae, and Clostridiaceae_1 were the families showing the most significant differences across all treatments (p < 0.05). Principal co-ordinates analysis indicated that the family composition in the ciprofloxacin treatment significantly differed from the other treatments. The presence of ciprofloxacin increased both the abundance and diversity of the bacterial community (the Chao index changed from 588.44 to 680.17, and the Shannon index changed from 3.41 to 4.06) in the end of composting. Crocinitomicaceae dominated (relative abundance of 79.10%) among the unique families in the ciprofloxacin treatment. Network analysis indicated that ciprofloxacin altered the synergistic or competitive relationships between different families (norank_SBR1031 and Microscillaceae), leading to different bacterial community composition compared with other treatments. Further, a structural equation model showed that the C:N ratio was significantly negatively correlated with the bacterial community (λ = −0.869, p < 0.01), whereas pH showed a direct, significant positive relationship with the bacterial community (λ = 0.701, p < 0.01), especially in ciprofloxacin treatment. Overall, ciprofloxacin significantly influenced the physical and chemical properties of composting, altered the bacterial community structure. These findings have important implications for a better understanding of the effects of antibiotic types on bacterial community structure and the involved mechanisms during swine manure composting.
Electrochemical disinfection (ED) is effective in removal of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) during wastewater treatment. However, the inner relationship of antibiotic-resistant phenotypes with their genotypes of ARB is still unclear in the ED process. This study explored the disinfection mechanism at the microcosmic level using four Escherichia coli (E. coli) strains with different antibioticresistant phenotypes. Results showed that bacteria with multiple antibiotic resistance tended to have stronger viability in disinfection compared with those resistant to fewer antibiotics. Interestingly, antibiotic-resistant phenotypes changed little in the disinfection process, while genotypes closely responded to bacterial resistance of different E. coli. In detail, beta-lactamase resistance genes played a leading role in the cross-resistance between antibiotics and electrochemical oxidation. They were proved to reduce oxidative destruction by increasing the strength of the cell wall and membrane. In addition, diaminopyrimidine and macrolide-lincosamide-streptogramin B resistance genes are also closely related to the bacterial resistance to ED. Combined with the quantitative determination of ARGs, the abundance of IntI1 and aminoglycoside resistance genes can be regarded as indicators for the risk of cross-resistance to antibiotics and electrochemical oxidation. This study provided important references for in depth understanding and accurate control of antibiotic resistance with advanced oxidation processes.
A method of efficient directional optical manipulation of nanoparticles based on a laser photothermal trap is proposed, and the influence mechanism of external conditions on the photothermal trap is clarified. Through optical manipulation experiments and finite-element simulations, it is determined that the main cause of gold nanoparticle directional motion depends on the drag force. The laser power, boundary temperature, and thermal conductivity of the substrate at the bottom of the solution and liquid level essentially affect the intensity of the laser photothermal trap in the solution and then affect the directional movement and deposition speed of gold particles. The result shows the origin of the laser photothermal trap and the three-dimensional spatial velocity distribution of gold particles. It also clarifies the height boundary of photothermal effect onset, which clarifies the boundary between light force and photothermal effect. In addition, nanoplastics are manipulated successfully based on this theoretical study. In this study, the movement law of gold nanoparticles based on the photothermal effect is deeply analyzed through experiments and simulations, which is of significance to the theoretical study of the optical manipulation of nanoparticles using the photothermal effect.
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