Résumé
High cell density culture of Lactobacillus plantaru is a significant step of the preparation of lactic acid bacteria starter.Firstly,this experiment is designed to analyze the effects of different dissolved oxygen and pH on the batch fermentation of Lactobacillus plantarum.And then,on the base of the batch fermentation,fed-batch fermentation was studied,companied by chemic neutralization in the experiment to achieve the aim of high cell density cultivation.Finally,in the comparison of two kinds of feeding mode for fed-batch operation in 10L fermentor,it was demonstrated that two kinds of feeding mode made cell concentration increase differently,in which pH feedback feeding can control sucrose concentration within a certain lower range,therefore obtaining the maximum cell concentration.With the pH feedback feeding,the dry cell weight was up to 13.56g/L,which increased 90.05% over that of batch culture.
Résumé
The central corneal thickness (CCT) in age 48 years or less of Chinese was characterized and its relationship with gender, age, refraction and intraocular pressure (IOP) was investigated. Right eyes of 1669 participants were included in this study (880 men, 52.7% and 789 women, 47.3%). Mean age of the samples was 23.8 +/- 5.9 years. After the examination of corneal topography and refraction, Goldman applanation tonometry was carried out by one physician. Tonometric values were the mean of three consecutive readings. Subsequently, another physician carried out ultrasonic pachymetry with the DGH 2000 AP ultrasonic pachymeter. Six measurements were made at the center of the cornea of each eye. The mean value was used for analysis. The results showed that mean CCT of male participants was 551.33 +/- 34.62 microm, 5.79 microm more than that of female participants. Linear regression analyses revealed that CCT was negatively related with age only in female and no association was found between refractive status and CCT. IOP was positively related to CCT, and there was a difference in IOP of 1.5 mmHg (1 mmHg = 0.133 kPa) per 100 microm difference in CCT. Ocular hypertension group was prone to have thicker cornea than average. The results indicated that in adult Chinese CCT tended to decrease with aging in female only. IOP measured by Goldmann tonometry was positively related with CCT so that CCT should be measured along with IOP.