Rational design of a 500 m3 fermenter for erythromycin production by Saccharopolyspora erythraea / 生物工程学报

Erythromycin is a macrolide antibiotic produced by Saccharopolyspora erythraea. Its yield is greatly affected by the fermentation conditions and the bioreactor configurations. In this study, a novel scale-up method for erythromycin fermentation was developed based on computational fluid dynamics (CFD) and time constant analysis. Firstly, the dissolved oxygen (DO) was determined as a key parameter according to the physiological properties of S. erythraea cultivated in a 50 L bioreactor. It was found that the time constant of oxygen supply (tmt) in a 500 m3 bioreactor should be less than 6.25 s in order to satisfy the organism's oxygen uptake rate (OUR). Subsequently, a 500 m3 bioreactor was designed using the time constant method combined with empirical correlations. The impeller combination with one BDT8 impeller at bottom and two MSX4 impellers at upper part was determined, and then validated by numerical simulation. The results indicated that the tmt of the bioreactor (< 6.25 s) and the fluid properties, including gas hold-up, shear stress and fluid vector, met the requirements of erythromycin fermentation. Finally, the industrial production of erythromycin in the 500 m3 showed the design method was applicable in large scale fermentation.

Effect of early monitoring of oxygen uptake rate in patients resuscitated from cardiogenic cardiac arrest / 中华急诊医学杂志

Objective To investigate the correlation of oxygen extraction rate (ERO2) with blood lactate clearance rate and cardiac output (CO) in the early stage of post-restoration of spontaneous circulation (ROSC) in patients resuscitated from cardiogenic cardiac arrest,and to analyze the relationship between the ERO2 and prognosis.Methods Fourteen patients successfully resuscitated from in-hospital cardiogenic cardiac arrest in the emergency ICU from October 2012 to January 2014 were retrospectively analyzed.These patients were assigned to survival group (n =5) or death group (n =9) as per the outcome at 72 h after ROSC.At admission (0 h),3,6 and 12 h after ROSC,arterial blood and venous blood were drawn to detect ERO2 and lactate clearance rate.Cardiac output (CO) was measured by thoracic impedance method,APACHE Ⅱ scores were assessed,and survival time was recorded.Results The patients in the death group died during the period of 12-72 hours after ROSC.The significantly decreased ERO2 at 6 h and 12 h after ROSC,and decreased blood lactate clearance rate and decreased CO at 3 h,6 h and 12 h after ROSC were found in the death group compared with the survival group (all P ＜ 0.05).The ERO2 at 6 h and 12 h after ROSC was significantly positively related to blood lactate clearance rate (r =0.857,r =0.947,both P ＜ 0.05) and CO (r =0.968,r =0.936,both P ＜ 0.05) at 3 h,6 h and 12 h after ROSC.The ERO2 at 6 h and 12 h after ROSC was significantly negatively related to APPACHE Ⅱ score (r =-0.970,r =-0.973,both P ＜ 0.05);APPACHE Ⅱ scores were significantly negatively correlated with blood lactate clearancerates (r=-0.880,r=-0.899,r=-0.850,all P＜0.05) and CO (r=-0.876,r=-0.922,r=-0.916,all P＜0.05) at 3 h,6 h and 12 h after ROSC.Conclusions The ERO2 at 6h after ROSC may be used to assess the severity and prognosis of patients resuscitated from cardiogenic cardiac arrest.