The cell-surface display of the Flo1p anchor system with a flocculation functional domain was examined under various cultivation conditions. As a model system, lipase from Rhizopus oryzae with the pro sequence was genetically fused to the Flo1 short (FS) anchor (FSProROL) and displayed on the sake yeast cell-surface under the control of the SED800 promoter (pSED800). The nutrients and carbon source in the culture media affected the display of the fusion protein FSProROL on the sake yeast cell-surface. The lipase activity in whole cells cultivated in poor media, without peptone and/or yeast extracts, were higher than those cultivated in rich media. In addition, glucose and maltose were effective carbon sources for increasing the lipase activity in whole cells, and the addition of di- or tri-saccharide as the carbon source reduced the release of the lipase activity into the culture supernatants. The initial glucose concentration was found to influence the total lipase activity and it mainly affected the lipase activity in whole cells. Under the optimum condition, sake yeast was found to show high cell density and high lipase activity in short time cultivation. 相似文献
A carotenoid gene (crtR-B) from the green alga Haematococcus pluvialis, encoding β-carotene hydroxylase that was able to catalyze the conversion of β-carotene to zeaxanthin and canthaxanthin to
astaxanthin, was cloned into Chlamydomonas reinhardtii chloroplast expression vector p64D to yield plasmid p64DcrtR-B. The vector p64DcrtR-B was transferred to the chloroplast
genome of C. reinhardtii using micro-particle bombardment. PCR and Southern blot analyses indicated that crtR-B was integrated into the chloroplast genome of the transformants. RT-PCR assays showed that the H. pluvialiscrt R-B gene was expressed in C. reinhardtii transformants. The transformants rapidly synthesized carotenoids in larger quantities than the wild-type upon being transferred
from moderate to high-intensity white light. This research provides a foundation for further study to elucidate the possible
mechanism of photo-protection by xanthophylls and other carotenoids in high light conditions or through exposure to UV radiation. 相似文献
The use of halotolerant phosphate solubilizing bacteria as inoculants to convert insoluble phosphorus of salt-affected soils
to an accessible form is a promising strategy to improve the phosphorus ingestion of plants in salt-affected agriculture.
A total of four aerobic isolates with biggest clear halos on the 10% NaCl NBRIP medium plate containing tricalcium phosphate
were isolated from the rhizospheric soils of native plants growing on the wall of Dagong Ancinet Brine Well, located in Sichuan
of China. And these four isolates were classified to the same strain, named QW10-11, and closely related to Bacillusmegatherium var. phosphaticum DSM 3228 and B. megaterium ATCC 14581 according to their phenotype and 16S rRNA. However, the Molecular evolutionary evidences of 16S-23S rRNA ISR further
suggested that QW10-11, DSM 3228 and ATCC 14581 have respectively fall into the different sub-divisions in intra specific
phylogeny. Strain QW10-11 has significantly better ability of tricalcium phosphate solubilization than that of lecithin solubilization.
When it grows under pH 4.8–8.0, 24–33°C and 5–10% NaCl, it can exhibit the higher values of solubilized tricalcium phosphate
between 59.3 and 71.4 μg ml−1. Furthermore, its tricalcium phosphate solubilizing activity was associated with the release of organic acids. Taken together,
our results indicted that QW10-11 from the rhizospheric soils of halobiot of Dagong Ancinet Brine Well is attractive as efficient
phosphate solubilizing candidates in the salt-affected agriculture. 相似文献
Virus-like particles (VLPs) of the recombinant hepatitis B virus (HBV) core protein (HBc) are routinely used in HBV diagnostics worldwide and are of potential interest as carriers of foreign peptides (e.g., immunological epitopes and targeting addresses, and/or as vessels for packaged diagnostic and therapeutic nanomaterials). Despite numerous reports exploiting different expression systems, a rapid and comprehensive large-scale methodology for purification of HBc VLPs from yeast is still lacking. Here, we present a convenient protocol for highly efficient production and rapid purification of endotoxin-free ayw subtype HBc VLPs from the methylotrophic yeast Pichia pastoris. The HBc gene expression cassette along with the geneticin resistance gene was transferred to the P. pastoris genome via homologous recombination. A producer clone was selected among 2000 transformants for the optimal synthesis of the target protein. Fermentation conditions were established ensuring biomass accumulation of 163 g/L. A simple combination of pH/heat and salt treatment followed by a single anion-exchange chromatography step resulted in a more than 90% pure preparation of HBc VLPs, with a yield of about 3.0 mg per 1 g of wet cells. Purification is performed within a day and may be easily scaled up if necessary. The quality of HBc VLPs was verified by electron microscopy. Mass spectrometry analysis and direct polyacrylamide gel staining revealed phosphorylation of HBc at at least two sites. To our knowledge, this is the first report of HBc phosphorylation in yeast. 相似文献