ABSTRACT
The alkaline lipase gene of Penicillium expansum (PEL) was coloned into the yeast integrative plasmid pPIC3.5K, which was then transformed into His4 mutant yeast GS115. Recombinant Pichia strains were obtained by minimal olive oil-methanol plates screening and confirmed by PCR. The expression producus of PEL gene was analysis by SDS-PAGE and olive oil plate, the result indicated that PEL gene was functionally overexpressed in Pichia pastoris and up to 95% of the secreted protein. Recombinant lipase had a molecular mass of 28kD, showing a range similar to that of PEL, could hydrolyze olive oil and formed clear halos in the olive oil plates. Four different strategies (different media, pH, glycerol and methanol concentration) were applied to optimize the cultivation conditions, the activity of lipase was up to 260 u/mL under the optimal cultivation conditions. It is pointed out that the absence of the expensive biotin and yeast nitrogen base in the medium increased the lipase production. The possible reason of this result is absence of yeast nitrogen base increased the medium pH during cultivation, and PEL shows a higher stability at this condition. The lipase activity of the supernatant from the culture grown at pH 7 was higher than the one from the culture in the same medium at pH 6.0 is due to the pH stability of PEL too. The results also showed that the methanol and glycerol concentration had a marked effect on the production of lipase.
Subject(s)
Enzyme Stability , Fungal Proteins , Genetics , Metabolism , Genetic Vectors , Genetics , Hydrogen-Ion Concentration , Lipase , Genetics , Metabolism , Models, Genetic , Penicillium , Genetics , Pichia , Genetics , Metabolism , Plasmids , GeneticsABSTRACT
A cellulase high-yield strain was identified and named as Trichoderma longibrachiatum SSL by ITS sequence identification. The endoglucanase1 gene (eg1) encoding endo-l,4-?-D-glucanase I was ampli-fied by RT-PCR method, which including 1386 bp and encoding 461 amino acid. Sequence analysis showed that: This gene has a more 90% homology with the T. longibrachiatum eg1 gene. The eg1 gene encoding the mature peptide was inserted into the Pichia pastoris expression vector pPIC9K, which resulted in construc-tion of the recombinant expression plasmid, pPIC9k-eg1. The pPIC9k-eg1 was then introduced into the host Pichia pastoris GS115. After the induction of methanol, extracellular recombinant endoglucanase I from the supernatant of the recombinant Pichia pastoris strain reached 73 U/mL. A clear strengthening of the protein bands, whose molecular weight is about 58 kD, appeared in the SDS-PAGE.
ABSTRACT
The optimum condition of shaking-flask p roducing enzyme were the tempe rature 26℃,initial pH 6 4,fermentation period 19 hours,medium volume 15mL m e dium/300mL Flask.soymilk-clotting enzyme was obtained from ammonium sulfate p r ecipitation.The optimum temperature and pH for the soymilk-clotting activity wa s 70℃and 5 8.The enzyme was easy to lose activity in acid or alkaline circumst a nce.About 60% of the original activity remained after 1 hour at 60℃.Ca 2+ ,Fe 2+ , Mg 2+ ,Na +increased the clotting activity,whereas Zn 2+ ,Al 3+ ca use inhibition.
ABSTRACT
The optimum fermentation conditions of Asp.niger FS25 producing ?-glucanase was as follows,medium compositi on(g/100mL):barley flour 6,corn liquid 2,bran 0 8(NH 4) 2SO 4 0 4,FeSO 4 ?7H 2O 0 01,Na 2HPO 4?3H 2O 0 1,CaCO 3 0 5,MgSO 4?7H 2O 0 03;i nitial pH 5 0,cultivate temperature 32℃,50mL medium volume in 250mL triangle flask.The ?-glucanase activity of fermentation fluid reached 80 1u/mL,increa sing 84 1% contrasted to the initial.