Advances on the production of organic acids by yeast / 生物工程学报

Organic acids are organic compounds that can be synthesized using biological systems. They often contain one or more low molecular weight acidic groups, such as carboxyl group and sulphonic group. Organic acids are widely used in food, agriculture, medicine, bio-based materials industry and other fields. Yeast has unique advantages of biosafety, strong stress resistance, wide substrate spectrum, convenient genetic transformation, and mature large-scale culture technology. Therefore, it is appealing to produce organic acids by yeast. However, challenges such as low concentration, many by-products and low fermentation efficiency still exist. With the development of yeast metabolic engineering and synthetic biology technology, rapid progress has been made in this field recently. Here we summarize the progress of biosynthesis of 11 organic acids by yeast. These organic acids include bulk carboxylic acids and high-value organic acids that can be produced naturally or heterologously. Finally, future prospects in this field were proposed.

Strain engineering and fermentation technology for production of long-chain dicarboxylic acid: a review / 生物工程学报

Long-chain dicarboxylic acid (DCA), a building block for synthesizing a variety of high value-added chemicals, has been widely used in agriculture, chemical, and pharmaceutical industries. The global demand for DCA is increasing in recent years. Compared with chemical synthesis which requires harsh conditions and complicated processes, fermentative production of DCA has many unparalleled advantages, such as low cost and mild reaction conditions. In this review, we summarized the chemical and microbial synthesis methods for DCA and the commercialization status of the fermentation process. Moreover, the advances of using molecular and metabolic engineering to create high-yielding strains for efficient production of DCA were highlighted. Furthermore, the challenges remaining in the microbial fermentation process were also discussed. Finally, the perspectives for developing high titer DCA producing strains by synthetic biology were proposed.

Risk factors and clinical features of mild cognitive impairment in patients with ischemic cerebral small vessel disease:a retrospective case series study / 国际脑血管病杂志

Objective To investigate the risk factors and clinical features of mild cognitive impairment (MCI) in patients with ischemic cerebral small vessel disease (SVD) for early diagnosis and prevention.Methods Montreal Cognitive Assessment Scale (MoCA) was used to screen MCI.The related risk factors and other clinical data were collected,and other neuropsychological tests were conducted.SVD was divided into leukoaraiosis (LA),lacunar infarction (LI),and LA + LI.Results A total of 143 patients with SVD were enrolled (68 in an MCI group,75 in a non-MCI group).Univariate analysis showed that there was no significant difference in the constituent ratio of age and gender between the MCI group and the non-MCI group,but the years of education in the MCI group was shorter than that in the non-MCI group,while the composition ratios of hypertension (69.11％ vs.45.33 ％;x2 =8.215,P =0.004),diabetes (57.35％ vs.40.00％;x2 =4.301,P =0.038),hyperlipidemia (48.53％ vs.24.00％ ; x2 =9.352,P =0.002),carotid atherosclerosis (41.18％ vs.21.33％ ;x2 =6.592,P =0.010),and smoking (32.35％ vs.14.67％ ;x2 =6.285,P =0.012),as well as the levels of uric acid (351.81 ± 83.21 mmol/L vs.323.03 ± 80.43 mmol/L; t =2.102,P =0.037) and total cholesterol (5.26 ± 1.26 mmol/L vs.4.56 ± 1.23 mmol/L; t =3.326,P =0.001) were significantly higher than those in the non-MCI group.Multivariate logistic regression analysis showed that hypertension (odds ratio OR]2.227,95％ confidence interval [CI],1.001-4.954; P =0.026),diabetes (OR 2.056,95％ CI 1.862-4.937; P =0.046),hyperlipidemia (OR 2.528,95％ CI 1.361-5.770; P =0.028),carotid atherosclerosis (OR 2.658,95％ CI 1.110-6.367; P =0.029),smoking (OR 2.566,95％ CI 1.017-6.474; P =0.046),and years of education (OR 0.825,95％ CI 0.745-0.914; P =0.000) were the independent risk factors for the occurrence of MCI in patients with SVD.The subscores in the MCI group,including MoCA total score (18.44 ± 5.60 vs.27.09 ± 1.37; t =-12.422; P =0.000),as well as visuoconstructional skills (2.65 ± 1.39 vs.4.49 ± 0.74; t =-9.762; P =0.000),attention (4.48 ± 1.70vs.5.89 ± 0.31; t =6.706,P=0.000),language (1.69 ± 0.80vs.2.41 ± 0.95 ; t =4.893,P=0.018),abstraction (0.85 ± 0.69 vs.1.71 ± 0.53; t=-7.081,P=0.000),delayed recall (1.29 ±1.01 vs.4.04 ± 0.99; t =13.824,P =0.000) were significantly lower than those in the non-MCI group,and there were no significant differences in naming and orientation scores.In the MCI group,the subscores such as theMoCA total score in the LA+LI group (17.04 ± 6.15 vs.21.04 ± 3.98; P＜0.05),as well as visuoconstructional skills (1.68 ± 1.16 vs.3.24 ± 1.13; P ＜ 0.05),attention (3.92 ± 2.03 vs.5.19 ±0.87; P ＜0.05),delayed recall (1.35 ± 1.01 vs.1.86 ± 1.58; P ＜0.05) were significantly lower than those in the LI group; the subscores such as the MoCA total score in the LA group (18.18 ± 5.31 vs.21.04 ± 3.98; ＜ =0.05),as well as visuoconstructional skills (2.56 ± 1.78 vs.3.24 ± 1.13; P＜0.05),language (0.64 ± 0.23 vs.1.24 ± 0.83; P ＜0.05),delayed recall (0.69 ± 0.58vs.1.86 ± 1.58;P＜0.01)were significantly lower than those in the LI group; the visuoconstructional skills in the LA + LI group was significantly lower than that in the LA group (1.68 ± 1.16 vs.2.56 ± 1.78; P＜0.05) and the LI group (1.68 ± 1.16 vs.3.24 ± 1.13; P＜ 0.05).Conclusions Hypertension,diabetes,hyperlipidemia,carotid atherosclerosis,smoking,and the low level of education were the independent risk factors for MCI in patients with SVD.After SVD,the cognitive impairment in MCI presented as multiple cognitive domains impairments,including visuoconstructional skills and delayed recall.Cognitive impairment differed among the different types of SVD.

Association of risk factors with subtypes of mild cognitive impairment / 中华老年医学杂志

Objective To explore the association of risk factors with amnestic versus nonamnestic of mild cognitive impairment.Methods All the subjects with mild cognitive impairment (MCI) aged 65-75 years were recruited from Neurology Department of 3 third-class hospitals of Qingdao,admitted from January 2011 to September 2011.They were systematically evaluated with mini-mental state examination( MMSE )and Montreal cognitive assessment (MoCA),then health conditions were collected.According to Petersen's standards,patients were divided into 89 cases with amnestic mild cognitive impairment(aMCI) and 51 cases with non-amnestic mild cognitive impairment (non-aMCI)groups to compare different risk factors between them.Results There were statistical differences in high total cholesterol (P=0.011),diabetes mellitus (P=0.009),MoCA score (P=0.040) between aMCI and non-aMCIgroups.MoCAscore (OR=1.081,95％CI:1.001-1.204,P=0.040) in the aMCI group was lower than that in non aMCI group.Diabetes mellitus ratio (OR=0.258,95％CI:0.096-0.695,P=0.009) was higher in non-aMCI group than in aMCI group.The level of total-cholesterol(OR=13.345,95％CI:1.127-158.085,P=0.011) in aMCI group was higher than that in non-aMCI group.The high total cholesterol was a independent risk factor for aMCI.Conclusions Different risk factors appear to exert different effects for aMCI and nonaMCI.