Pyridine degradation characteristics of Rhodococcus sp. LV4 under high salinity conditions / 生物工程学报

Biodegradation of pyridine pollutant by microorganisms is one of the economical and effective methods to solve the environmental pollution of pyridine under high salinity conditions. To this end, screening of microorganisms with pyridine degradation capability and high salinity tolerance is an important prerequisite. In this paper, a salt-resistant pyridine degradation bacterium was isolated from the activated sludge of Shanxi coking wastewater treatment plant, and identified as a bacterium belonging to Rhodococcus on the basis of colony morphology and 16S rDNA gene phylogenetic analysis. Salt tolerance experiment showed that strain LV4 could grow and degrade pyridine with the initial concentration of 500 mg/L completely in 0%-6% saline environment. However, when the salinity was higher than 4%, strain LV4 grew slowly and the degradation time of pyridine by strain LV4 was significantly prolonged. Scanning electron microscopy showed that the cell division of strain LV4 became slower, and more granular extracellular polymeric substance (EPS) was induced to secrete in high salinity environment. When the salinity was not higher than 4%, strain LV4 responded to the high salinity environment mainly through increasing the protein content in EPS. The optimum conditions for pyridine degradation by strain LV4 at 4% salinity were 30 ℃, pH 7.0 and 120 r/min (DO 10.30 mg/L). Under these optimal conditions, strain LV4 could completely degrade pyridine with an initial concentration of 500 mg/L at a maximum rate of (29.10±0.18) mg/(L·h) after 12 h adaptation period, and the total organic carbon (TOC) removal efficiency reached 88.36%, indicating that stain LV4 has a good mineralization effect on pyridine. By analyzing the intermediate products in pyridine degradation process, it was speculated that strain LV4 achieved pyridine ring opening and degradation mainly through two metabolic pathways: pyridine-ring hydroxylation and pyridine-ring hydrogenation. The rapid degradation of pyridine by strain LV4 in high salinity environment indicates its application potential in the pollution control of high salinity pyridine environment.

Efficacy of microbubble-enhanced sonothrombolysis on platelet-rich thrombi and erythrocyte-rich thrombi of different ages / 中国医学影像技术

Objective To investigate the efficacy of microbubble-enhanced sonothrombolysis on platelet-rich thrombi (PRT) and erythrocyte-rich thrombi (ERT) in different ages.Methods PRT and ERT in different ages were prepared both in vitro and in vivo of common carotid artery in rats.All the participants were divided into 8 groups with 4 in vitro and another 4 in vivo experiment,including PRT 3 h,PRT 24 h,ERT 3 h,ERT 24h in vitro groups and PRT 3 h,PRT 24 h,ERT 3 h,ERT 24 h in vivo groups.Microbubble-enhanced sonothrombolysis was carried out in both in vitro and in vivo experiments,and the ultrasonic images were collected.The components of PRT and ERT were identified by histopathological examination.The percentage increase of luminal cross sectional area and lytic ratio in vitro,and the recanalization rate and mean blood flow velocity of common carotid artery in vivo were mainly analyzed.Results After sonothrombolysis,both in vitro and in vivo experiment showed there was no statistically significant difference of the percentage increase of luminal cross sectional area ([121.12 ± 13.21]％ vs [130.09 ± 15.34]％),lytic ratio ([39.83± 7.09]％ vs [42.14±5.17]％),recanalization rate (83.33％ vs 91.67％) and blood flow velocity of common carotid artery ([0.21±0.02]m/s vs [0.22±0.01]m/s) between PRT 3 h group and ERT 3 h group (both P＞0.05).PRT 24 h group compared with EPR 24 h group,PRT 24 h group compared with PRT 3 h group,as well as ERT 24 h group compared with ERT 3 h group,the percent increase of luminal cross sectional area,lytic ratio,recanalization rate and blood flow velocity of common carotid artery reduced (all P＜0.05).Conclusion The efficacy of microbubble-enhanced sonothrombolysis on PRT and ERT in vitro and in vivo of of rat common carotid artery model decrease with the increase of thrombus age,especially for the PRT.