scholarly journals Broad-Range and Binary-Range Acyl-Acyl-Carrier-Protein Thioesterases Suggest an Alternative Mechanism for Medium-Chain Production in Seeds

1997 ◽  
Vol 114 (2) ◽  
pp. 669-677 ◽  
Author(s):  
T. A. Voelker ◽  
A. Jones ◽  
A. M. Cranmer ◽  
H. M. Davies ◽  
D. S. Knutzon
2021 ◽  
Author(s):  
fangxiang hu ◽  
Weijie Cai ◽  
Junzhang Lin ◽  
Weidong Wang ◽  
Shuang Li

Abstract BackgroundSurfactin, a representative biosurfactant of popeptide mainly produced by Bacillus subtilis, consists of a cyclic heptapeptide linked to a β-hydroxy fatty acid chain. The functional activity of surfactin is closely related to the length and isomerism of the fatty acid chain. ResultsIn this study, the plant medium-chain acyl-carrier protein (ACP) thioesterase (BTE) from Umbellularia californica was overexpressed in a recombinant surfactin production strain based on B. subtilis 168. As a result, the surfactin yield after 24 h of cultivation improved by 23%, and the production rate increased from 0.112 to 0.177 g/L/h. The isoforms identified by RP-HPLC and GC-MS showed that the proportion of nC14-surfactin increased 6.4 times compared to the control strain. A comparison of further properties revealed that the product with more nC14-surfactin had higher surface activity and better performance in oil-washing. Finally, the product with more nC14-surfactin isoform had a higher hydrocarbon-emulsification index, and it increased the water-wettability of the oil-saturated silicate surface. ConclusionThe obtained results provide an original approach to modify the fatty acid chain of surfactin and further demonstrate the importance of the length and isomerism of the β-hydroxy fatty acid chain for the MEOR application of surfactin.


2014 ◽  
Vol 41 (1) ◽  
pp. 80 ◽  
Author(s):  
Yijun Yuan ◽  
Yinhua Chen ◽  
Shan Yan ◽  
Yuanxue Liang ◽  
Yusheng Zheng ◽  
...  

Coconut (Cocos nucifera L.) contains large amounts of medium chain fatty acids, which mostly recognise acyl-acyl carrier protein (ACP) thioesterases that hydrolyse acyl-ACP into free fatty acids to terminate acyl chain elongation during fatty acid biosynthesis. A full-length cDNA of an acyl-ACP thioesterase, designated CocoFatB1, was isolated from cDNA libraries prepared from coconut endosperm during fruit development. The gene contained an open reading frame of 1254 bp, encoding a 417-amino acid protein. The amino acid sequence of the CocoFatB1 protein showed 100% and 95% sequence similarity to CnFatB1 and oil palm (Elaeis guineensis Jacq.) acyl-ACP thioesterases, respectively. Real-time fluorescent quantitative PCR analysis indicated that the CocoFatB1 transcript was most abundant in the endosperm from 8-month-old coconuts; the leaves and endosperm from 15-month-old coconuts had ~80% and ~10% of this level. The CocoFatB1 coding region was overexpressed in tobacco (Nicotiana tabacum L.) under the control of the seed-specific napin promoter following Agrobacterium tumefaciens-mediated transformation. CocoFatB1 transcript expression varied 20-fold between different transgenic plants, with 21 plants exhibiting detectable levels of CocoFatB1 expression. Analysis of the fatty acid composition of transgenic tobacco seeds showed that the levels of myristic acid (14 : 0), palmitic acid (16 : 0) and stearic acid (18 : 0) were increased by 25%, 34% and 17%, respectively, compared with untransformed plants. These results indicated that CocoFatB1 acts specifically on 14 : 0-ACP, 16 : 0-ACP and 18 : 0-ACP, and can increase medium chain saturated fatty acids. The gene may valuable for engineering fatty acid metabolism in crop improvement programmes.


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