RESUMO
To investigate the effects of temperature and stirring on antibiotic resistance genes (ARGs) and microbial communities during the anaerobic digestion of dairy manure, mesophilic and thermophilic anaerobic digestion experiments were performed with and without stirring. Two-way analysis of variance indicated that temperature affected biogas production more strongly than stirring (η2=0.934>0.911), and thermophilic and stirring increased the total biogas yield by 13.93% and 12.63%, respectively. The effect of temperature on the removal of ARGs was also stronger than that of stirring (η2=0.992>0.920), where thermophilic conditions enhanced the reduction of ARGs and MGEs to 0.09-1.53 (logarithm), while stirring had no significant effects. When temperature was altered from mesophilic to thermophilic, the microbial communities shifted, with Firmicutes becoming the dominant phylum after thermophilic anaerobic digestion, with a relative abundance of >86%. Network analysis demonstrated that eight genera including Sedimentibacter, Sphaerochaeta, and Pseudomonas were the hosts of ARGs and MGEs, and the redundancy analysis suggested that physicochemical parameters play important roles in shaping microbial communities, especially TAN and TVFAs, which indirectly affected the ARGs by altering their host bacteria.
Assuntos
Esterco , Microbiota , Anaerobiose , Antibacterianos/farmacologia , Resistência Microbiana a Medicamentos/genética , Genes Bacterianos/genética , Microbiota/genética , TemperaturaRESUMO
The buffering effect of acetate on hydrogen production during glucose fermentation by Ethanoligenens harbinense B49 was investigated compared to phosphate, a widely used fermentative hydrogen production buffer. Specific concentrations of sodium acetate or phosphate were added to batch cultures, and the effects on hydrogen production were comparatively analyzed using a modified Gompertz model. Adding 50 mM acetate or phosphate suppressed the hydrogen production peak and slightly extended the lag phase. However, the overall hydrogen yields were 113.5 and 108.5 mmol/L, respectively, and the final pH was effectively controlled. Acetate buffered against hydrogen production more effectively than did phosphate, promoting cell growth and preventing decreased pH. At buffer concentrations 100-250 mM, the maximum hydrogen production was barely suppressed, and the lag phase extended past 7 h. Therefore, although acetate inhibits hydrogen production, using acetate as a buffer (like phosphate) effectively prevented pH drops and increased substrate consumption, enhancing hydrogen production.
Assuntos
Bactérias Gram-Positivas/metabolismo , Hidrogênio/metabolismo , Acetatos/análise , Fosfatos/análise , Soluções Tampão , Biocombustíveis , Fermentação , Técnicas de Cultura Celular por Lotes , Glucose , Concentração de Íons de HidrogênioRESUMO
PURPOSE: To explore the value of diffusion-weighted imaging (DWI) and magnetic resonance imaging (MRI) on the follow-up of nasopharyngeal carcinoma (NPC) after radiotherapy. MATERIAL AND METHODS: Eighty-three NPC patients after radiotherapy were divided into two groups: 4 cases of residual tumor and 33 cases of non-residual within 6 months, the cases of recurrent and non-recurrent were 5 and 41 over 6 months, respectively. MRI and DWI imaging of these cases were closely analyzed, and the apparent diffusion coefficient (ADC) of the nasopharyngeal residual mass and nasopharyngeal wall thickening, skull base destruction and lateral pterygoid muscle were measured. RESULTS: The ADC of the lateral pterygoid muscle was (1.501 ± 0.069) × 10
Assuntos
Imagem de Difusão por Ressonância Magnética/métodos , Neoplasias Nasofaríngeas/patologia , Neoplasias Nasofaríngeas/radioterapia , Adolescente , Adulto , Idoso , Carcinoma , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Carcinoma Nasofaríngeo , Nasofaringe/patologia , Adulto JovemRESUMO
In order to increase the hydrogen yield from glucose, hydrogen production by immobilized Rhodopseudomonas faecalis RLD-53 using soluble metabolites from ethanol fermentation bacteria Ethanoligenens harbinense B49 was investigated. The soluble metabolites from dark-fermentation mainly were ethanol and acetate, which could be further utilized for photo-hydrogen production. Hydrogen production by B49 was noticeably affected by the glucose and phosphate buffer concentration. The maximum hydrogen yield (1.83 mol H(2)/mol glucose) was obtained at 9 g/l glucose. In addition, we found that the ratio of acetate/ethanol (A/E) increased with increasing phosphate buffer concentration, which is favorable to further photo-hydrogen production. The total hydrogen yield during dark- and photo-fermentation reached its maximum value (6.32 mol H(2)/mol glucose) using 9 g/l glucose, 30 mmol/l phosphate buffers and immobilized R. faecalis RLD-53. Results demonstrated that the combination of dark- and photo- fermentation was an effective and efficient process to improve hydrogen yield from a single substrate.