利用酵母菌生产有机酸的研究进展

有机酸是含有一种或多种低分子量酸性基团(如羧基、磺酸基)的可生物合成的有机化合物,广泛应用于食品、农业、医药、生物基材料工业等领域。酵母菌具有生物安全、抗逆性强、底物谱广泛、方便遗传改造,以及大规模培养技术成熟等独特优点,因此利用酵母菌生产有机酸的研究日益受到国内外学者的关注。目前利用酵母生产有机酸还存在浓度低、副产物多,以及发酵效率低等缺陷。随着酵母菌代谢工程和合成生物学技术的发展,利用酵母菌生产有机酸取得了快速进展。本文总结了利用酵母合成11种有机酸的研究,包括内源和异源合成的大宗羧酸和高价值有机酸,并对该领域的未来研究方向进行了展望。     

An in-depth analysis reveals two new genetic variants on 22q11.2 associated with vitiligo in the Chinese Han population

Molecular Biology Reports - Vitiligo is a complex disease in which patchy depigmentation is the result of an autoimmune-induced loss of melanocytes in affected regions. On the basis of a...     

Enhanced production of (+)-terrein by Aspergillus terreus strain PF26 with epigenetic modifier suberoylanilide hydroxamic acid

New strategies for improving the fermentation yield of (+)-terrein which is a fungal metabolite with multiple bioactivities are very urgent. In this study, the effect of suberoylanilide hydroxamic acid, one kind of epigenetic modifier, on the biosynthesis of (+)-terrein by Aspergillus terreus strain PF26 isolated from the marine sponge Phakellia fusca was investigated. It was found that suberoylanilide hydroxamic acid exhibited a positive impact on (+)-terrein production, resulting from promoting the biosynthesis of 6-hydroxymellein, the precursor of (+)-terrein. Through optimization of feeding concentration and time of suberoylanilide hydroxamic acid, 5.58 g/L (+)-terrein could be obtained in shake flask cultivation, 29.5% higher than the control. Correspondingly, the fermentation of A. terreus strain PF26 in 7.5-L stirred bioreactor with feeding suberoylanilide hydroxamic acid (900 μM, day 4) yielded 9.07 g/L (+)-terrein, 77.1% higher than the control. These results showed that the epigenetic modifier-suberoylanilide hydroxamic acid could be utilized to enhance the production of (+)-terrein, which laid the foundation of massive production of (+)-terrein by fermentation.     

Phylogenetically Diverse Denitrifying and Ammonia-Oxidizing Bacteria in Corals Alcyonium gracillimum and Tubastraea coccinea

To date, the association of coral–bacteria and the ecological roles of bacterial symbionts in corals remain largely unknown. In particular, little is known about the community components of bacterial symbionts of corals involved in the process of denitrification and ammonia oxidation. In this study, the nitrite reductase (nirS and nirK) and ammonia monooxygenase subunit A (amoA) genes were used as functional markers. Diverse bacteria with the potential to be active as denitrifiers and ammonia-oxidizing bacteria (AOB) were found in two East China Sea corals: stony coral Alcyonium gracillimum and soft coral Tubastraea coccinea. The 16S rRNA gene library analysis demonstrated different communities of bacterial symbionts in these two corals of the same location. Nitrite reductase nirK gene was found only in T. coccinea, while both nirK and nirS genes were detected in A. gracillimum, which might be the result of the presence of different bacterial symbionts in these two corals. AOB rather than ammonia-oxidizing archaea were detected in both corals, suggesting that AOB might play an important role in the ammonia oxidation process of the corals. This study indicates that the coral bacterial symbionts with the potential for nitrite reduction and ammonia oxidation might have multiple ecological roles in the coral holobiont, which promotes our understanding of bacteria-mediated nitrogen cycling in corals. To our knowledge, this study is the first assessment of the community structure and phylogenetic diversity of denitrifying bacteria and AOB in corals based on nirK, nirS, and amoA gene library analysis.     

The RNA Pol II Elongation Factor Ell3 Marks Enhancers in ES Cells and Primes Future Gene Activation

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Highlights? Ell3 is preferentially found at active, poised, and inactive enhancers in ES cells ? Promoter-proximal Pol II occupancy at key developmental genes requires Ell3 ? Cohesin functions in Ell3-associated enhancer-promoter communication ? Recruitment of P-TEFb within SEC during differentiation is Ell3 dependent     

Proteomic analysis of the similarities and differences of soil drought and polyethylene glycol stress responses in wheat (Triticum aestivum L.)

Plant Molecular Biology - Our results reveal both soil drought and PEG can enhance malate, glutathione and ascorbate metabolism, and proline biosynthesis, whereas soil drought induced these...     

Huntingtin forms toxic NH2-terminal fragment complexes that are promoted by the age-dependent decrease in proteasome activity

Although NH2-terminal mutant huntingtin (htt) fragments cause neurological disorders in Huntington's disease (HD), it is unclear how toxic htt fragments are generated and contribute to the disease process. Here, we report that complex NH2-terminal mutant htt fragments smaller than the first 508 amino acids were generated in htt-transfected cells and HD knockin mouse brains. These fragments constituted neuronal nuclear inclusions and appeared before neurological symptoms. The accumulation and aggregation of these htt fragments were associated with an age-dependent decrease in proteasome activity and were promoted by inhibition of proteasome activity. These results suggest that decreased proteasome activity contributes to late onset htt toxicity and that restoring the ability to remove NH2-terminal fragments will provide a more effective therapy for HD than inhibiting their production.     

Expression and localization of human lysozyme in the endosperm of transgenic rice

In order to understand the characteristics of recombinant protein expression and sublocalization in rice ( Oryza sativa L.) endosperm, we examined the expression level of human lysozyme protein and its subcellular location in transgenic rice seeds driven by rice glutelin and globulin promoters and signal peptides. A time course of human lysozyme expression during endosperm development was analyzed. The results showed that the expression profile of recombinant protein accumulation in endosperm paralleled that of the two storage proteins. Immunofluorescence microscopy revealed that human lysozyme and storage proteins co-localized to type-II protein bodies. Both promoter-signal peptide parings targeted recombinant protein to the protein bodies. In addition, a transgenic line with a higher lysozyme expression level exhibited morphologically different protein bodies with an unbalanced composition of lysozyme and native storage proteins. The high-level expression of recombinant protein distorted the trafficking and sorting of native storage proteins in rice endosperm and affected the expression of native storage protein.