ABSTRACT
The diatom Nitzschia laevis is a good alternative source of eicosapentaenoic acid (EPA). Besides strategies for high cell density culture, EPA productivity may be further improved by herbicides. The effect of the herbicide quizalofop-p-ethyl on the growth and EPA production was studied in this paper. As the solvent of the herbicide, DMSO was proved to inhibit the growth and EPA production of N. laevis. The concentration of DMSO in the medium should not exceed 0.2%. Quizalofop-p-ethyl could cause morphology damage to the N. laevis cells. With the increasing concentration of quizalofop-p-ethyl from 0 mmol/L to 0.4 mmol/L, the dry cell weight production decreased, while at the same time, the lipid content of the dry cell mass increased. When treated with 0.1 mmol/L quizalofop-p-ethyl, the EPA content increased from 3.00% to 3.58% (of dry cell weight, DW), and the proportion of EPA (20:5) in total fatty acids (TFA) increased from 25.15% to 32.88% . These results indicated that the herbicide quizalofop-p-ethyl could stimulate the accumulation of EPA; therefore it might be useful for selecting algae colonies that overproduce EPA.
Subject(s)
Culture Media , Culture Techniques , Diatoms , Metabolism , Eicosapentaenoic Acid , Herbicides , Pharmacology , Propionates , Pharmacology , Quinoxalines , PharmacologyABSTRACT
In order to provide plenty of information about the relationship between its structure and function,the structure of a novel housefly pupae D-galactose binding lectin with the molecular weight 55kDa and immune acitivity was analyzed preliminarily.In the first place,oligosaccharide chain was confirmed to be existed in this kind of novel housefly pupae lectin by the method of gel staining,and then its structure was analyzed with the help of protein sequencing instrument,spectrophotometer color contrast,?-elimination reaction,infrared spectroscopy and atomic force microscopy.This kind lectin was a global-shaped monomer with the diameter 75 nm or so and the protein and oligosaccharide content 97.36% and 2.1% respectively.Peptide chain and oligosaccharide chain was linked by O-glycoside bond with the N-terminal blocked and the sugar ring alpinum type.All above was the reliable theory for further analysis of structure.
ABSTRACT
The study was to develop cis-dichlorodiammineplatinum(DDP)-loaded formulations using a novel type of self-assembled compound composed of block copolymers synthesized by poly(?-glutamic acid)(?-PGA).For the potential of targeting liver cancer cells,D-galactose was conjugated on the prepared ?-PGA.In vitro,DDP can be released from the resulting conjugate in PBS:there was a burst release during the first 8 h,then followed by sustained release.DDP could be easily incorporated into poly(?-glutamic acid)-D-galactose esterifiable derivative through a covalent bond.The yield of DDP incorporation into the esterifiable derivative was 9.4%～10.2%.In vitro experiments conclusively established that the poly(?-glutamic acid)-D-galactose esterifiable derivative-Cisplatin Complex Compound(?-D+-DDP)was much less toxic to normal cell lines than DDP only.The surviving rate of cells treated with ?-D+-DDP compound is higher than those treated with free DDP.Also it has obvious antitumor efficiency on human liver tumor BEL-7402 cells.HE staining indicated that the ?-D+-DDP compound make the BEL-7402 apoptosis.These results indicated that the conjugation of DDP to the esterifiable derivative reduced its cytotoxicity activity,but retains its antitumor activity in vitro.In conclusion,the ?-D+-DDP compound could be used as a potential clinic antitumor drug.The ?-PGA obtained by fermentation can be used as a valuable drug carrier system.
ABSTRACT
This thesis aimed at the Bacillus natto TK-1 screened out from Natto.The lipopeptide was purified using Thin-Layer Chromatography(TLC),and investigated its anti-tumor activity.After acid precipitation and methanol extraction,the lipopeptide was separated on TLC.Then the authors get the monomer surfactin which molecular weight is 1036Da through the High performance liquid chromatography(HPLC),electro spray ionization-mass spectrometry(ESI-MS) and infrared(IR).MTT method was implied to testify the anti-tumor activity of the purified sample from TLC.The results indicated a concentration and time-dependent relationships.After 48h,their IC50 were 40 mg/L.The detection with inverted microscope fluorescence microscope displays that the surfactin will cause a series of Morphological changes to the cells.In TUNEL experiment,the authors noticed that surfactin has the ability to induce apoptosis,besides this inhibition shows an obvious time-dependent relationship.
ABSTRACT
Fermentation for Eicosapentaenoic Acid(EPA) production by Nitzschia laevis at various temperature between 10℃ and 30℃ was investigated and the dynamics characteristics during fermentation process were also analyzed.Based on the results,a varying temperature nursing method of two stage control strategy is proposed:During the first stage,which comprises the delay phase and the initial index phase,the temperature is maintained at 25℃;then the temperature is shifted to 20℃ and kept up till the end of the fermentation process.By this method,a EPA content of 6.0% and a yield of 291.60 mg/L have been gained.These are 24.07% and 18.81% higher than that of fixed temperature(25℃) fermentation,respectively.
ABSTRACT
Response Surface Methodology was applied to optimize the culture components for lipopeptide production by Bacillus natto TK-1. In the first step, two level factorial design of Plackett-Burman was used to evaluate the influence of six related factors. It showed that three factors playing the important roles in the medium, including peptone, yeast extract powder and CaCl_2. The path of steepest ascent was used to approach the optimal region of the fermentation conditions subsequently. In the third step, the concentrations of those three main factors were further optimized by using Box-Behnken and Response Surface Analysis. By solving the quadratic regression model equation, the optimal concentrations of the variables were determined as: peptone 1.73%, yeast extract powder 0.063 %, CaCl_2 1.385?10-4mol/L. Under the optimal culture conditions, the diameter of haemolysis zone increased 29.3 % than before. HPLC analysis showed the precise production of lipopeptide was 30.2% higher than preliminary culture. Furthermore, at three batches cultivation, the experiment values under the optimal conditions agreed with the predictive values. It showed that Response Surface Methodology was proper and a good choice for optimization.