Recombined Microbial Fermentation For L-carnitine Production

L-camitine,also named vitamin BT,is an active compound found in animals and vegetal tissues,as well as in microorganisms.L-carnitine plays an important role in fatty acids metabolism.In recent years,L-carnitine has been increasingly used as a novel food additive and clinically applied in reducing blood fat,thus the demand of L-carnitine is increasing in worldwide market,and the development of manufacturing and detection methods are needed.Many microorganisms have the ability to be able to crotonobetaine,?-butyrobetaine,and D-carnitine into L-camitine.This article according to the analysis of production of L-carnitine in vivo of Escherichia coli and Pseudomonas,has capacity to transformed crotonobetaine and ?-butyrobetaine into L-carnitine and to transformed ?-butyrobetaine into L-carnitine in Escherichia coli and Pseudomonas,respectively.In order to further improve the yield of L-carnitine,Overexpression of some genes and delete some genes to improve the yield of L-carnitine in Wild type E.coli and Pseudomonas,get some stability of engineering bacteria to produce L-carnitine,in this paper,including the experimental method are:?Construction of the overexpression plasmid 28a-caiBCD and PACYCD-caiT-caiF in under the control of T7 promoter,then these plasmids were expressed in Escherichia coli BW25113AaceK and BL21(DE3),and these engineering strains were induced under with IPTG and anaerobic condition,the enzyme activity and cell were optimized,and then to transform crotonobetaine into L-camitine with the whole cell enzyme catalysis.?The construction of over expression plasmid 3087-bbd and overexpression of Pseudomonas pf5?cdh,then using this fermentation liquid with ?-butyrobetaine to produce L-carnitine.The final result:?Engineered strain of E.coli BW25113AaceK/28a-caiBCD+PACYCD-caiT-caiF(or BW25113AaceK/caiBCD+caiTcaiF for short),with induction by IPTG and anaerobic induction of 18h after cell growth of 2h,then produced 2.219 g/L L-carnitine in the conversion solution which contained 20 g/L of crotonobetaine,the molar conversion rate was about 13%.Engineered strain of E.coli BL21(DE3)/28a-caiBCD+PACYCD-caiT-caiF(or BL21(DE3)/caiBCD+caiT-caiF for short),with IPTG induction for 4h affter the cell growth of 2h,produced 8.5g/L L-camitine and the molar conversion rate was about 47%in the same conversion solution.It increased about 17-fold compared with wild type.?Pseudomonas engineering bacteria pf5?cdh/bbh carrying the plasmid of 3087-bbd,when using it for fermentation in Fermented liquid containing ?-butyrobetaine,the final yield was about 1.2g/L,but this yield its still improved compared to the wild type.