ABSTRACT
To improve the productivity of L-phenyllactic acid (L-PLA), L-LcLDH1(Q88A/I229A), a Lactobacillus casei L-lactate dehydrogenase mutant, was successfully expressed in Pichia pastoris GS115. An NADH regeneration system in vitro was then constructed by coupling the recombinant (re) LcLDH1(Q88A/I229A) with a glucose 1-dehydrogenase for the asymmetric reduction of phenylpyruvate (PPA) to L-PLA. SDS-PAGE analysis showed that the apparent molecular weight of reLcLDH1(Q88A/I229A) was 36.8 kDa. And its specific activity was 270.5 U/mg, 42.9-fold higher than that of LcLDH1 (6.3 U/mg). The asymmetric reduction of PPA (100 mmol/L) was performed at 40 °C and pH 5.0 in an optimal biocatalytic system, containing 10 U/mL reLcLDH1(Q88A/I229A), 1 U/mL SyGDH, 2 mmol/L NAD⁺ and 120 mmol/L D-glucose, producing L-PLA with 99.8% yield and over 99% enantiomeric excess (ee). In addition, the space-time yield (STY) and average turnover frequency (aTOF) were as high as 9.5 g/(L·h) and 257.0 g/(g·h), respectively. The high productivity of reLcLDH1(Q88A/I229A) in the asymmetric reduction of PPA makes it a promising biocatalyst in the preparation of L-PLA.
Subject(s)
L-Lactate Dehydrogenase , Genetics , Lacticaseibacillus casei , Genetics , Phenylpyruvic Acids , Metabolism , Pichia , Genetics , Recombinant Proteins , Genetics , MetabolismABSTRACT
Objective: To screen the optimum conditions of proliferation, regenerated bud differentiation, and adventitious roots induction of Asarum heterotropoides petiole-derived callus so as to establish the effective system for callus proliferation and regeneration. Methods: Petiole-derived calli were subcultured in the proliferation medium supplemented with different concentration of 6-BA and NAA. Then green and compact calli were chosen to culture in differentiation medium with different exogenous hormones for the induction of regeneration bud and adventitious roots. After being acclimated, regenerated plants were transplanted. Results: The effective callus proliferation medium was 1/2 MS supplemented with 0.40 mg/L 6-BA and 0.10 mg/L NAA, then 1/2 MS medium supplemented with 0.4 mg/L 6-BA and 0.05 mg/L NAA was suitable for regenerated bud differentiation while regenerated buds grew better in 1/2 MS medium without any hormone. The medium of 1/4 MS supplemented with 0.25 mg/L IBA was best for the induction of adventitious roots. Conclusion: The optimum culture conditions of callus proliferation and differentiation in A. heterotropoides are determined to establish the regeneration system and obtain the regenerated plantlet successfully.
ABSTRACT
Cowpea is a crop of tremendous economic and ecological values particularly in sub-Saharan Africa, where over 80% of the crop is produced and consumed. Due to heavy attack by pests and diseases, actual yield does not exceed 20% of the crop’s potential in most of the production regions. Shortages of genes to combat biotic stresses in the germplasm and sexual incompatibility with wild relatives are major impediments in cowpea improvement. Genetic modification of cowpea with relevant genes can address these problems. Establishment of reproducible regeneration system is a prerequisite for genetic transformation of cowpea using transgenic technology. Cowpea is among the most recalcitrant crops for manipulation under In vitro condition especially via de novo process. However, strategies to regenerate cowpea under In vitro conditions have evolved steadily in the last three decades. In this review, we give a summary of cowpea regeneration work carried out so far and discussed approaches employed as well as challenges of developing efficient regeneration systems in cowpea.
ABSTRACT
Objective: To optimize the regeneration system of Rhodiola crenulata, to establish the optimal conditions for resistance screening, and to lay the foundation for the establishment of the efficient genetic transformation system of R. crenulata. Methods: The leaves of Rhodiola crenulata were used as explants. The influences of different ratios of 6-BA, NAA, and IAA in the medium on callus induction and growth conditions were observed, and the implant resistance of Kanamycin (Kan) and hygromycin (Hyg) was screened by gradient method. Results: MS + 3.0 mg/L 6-BA + 1.0 mg/L NAA + 700 mg/L L-Pro was the optimal medium for the differentiation of leaf adventitious bud and the differentiation ratio of adventitious bud reached 92%; MS + 700 mg/L L-Pro was the medium for adventitious roots; The best selection of genetic transformation system for R. crenulata was 200 mg/L Kan and 10 mg/L Hyg; Adding 10 mg/L Vc could effectively inhibit the phenolic substances secretion. Conclusion: The regeneration system of R. crenulata, is optimized, and the pressure of Kan and Hyg for genetic transformation system of R. crenulata is screened.
ABSTRACT
Object\ To establish a plantlet regeneration system of Rubus idaeus L for the purpose to obtain a large number of high quality seedling in a short time Methods\ Stem apex and part of the stem were used as the explant and the optimal culture media and conditions were selected by orthogonal design Results\ An optimum culture medium for the induction of callus, adventitious bud and root was obtained which can be carried out in the laboratory with comparative ease and good repeatability Conclusion\ A basic medium + BA 0 2 mg/L+NAA 1 0～1 5 mg/L was most suitable for the induction of callus; a medium + BA 1 mg/L+NAA 0 1～0 2 mg/L+GA 3 6～8 mg/L+CH 300 mg/L was good for the induction of bud; a medium +BA 1 mg/L+NAA 0 1 mg/L+GA 3 2 mg/L was suitable for propagation of the bud; and the basic medium+IBA 0 1 mg/L+NAA 0 5 mg/L was good for the induction of root
ABSTRACT
Object To establish an effective plantlet regeneration system of Aconitum carmichaeli Debx. for the purpose to obtain a large number of high quality seedling in a short time. Methods Leaves in vitro were tried as the explants and cultivated in different media with the various portion of hormones. Results The medium of MS+BA 1.0 mg/L+KT 0.5 mg/L+NAA 0.2 mg/L was the most suitable one for the induction of shoots; the medium of MS+BA 1.5 mg/L+NAA 0.1 mg/L was beneficial to the propagation of shoots; the medium of MS+BA 0.5 mg/L+NAA 0.1 mg/L was good for the elongation of shoots; and the medium of 1/2 MS without any hormone was suitable for the induction of roots. Conclusion Rapid propagation of A. carmichaeli could be achieved by tissue culture and this will lead to the possibility for its seedling in the industrial production.