Effects of furfural on the growth and lipid production of oleaginous yeast Rhodotorula glutinis / 生物工程学报

In order to illustrate the effects of furfural, one of the most common inhibitory compounds in lignocellulosic hydrolysate, on oleaginous yeast Rhodotorula glutinis, we investigated the effects of different concentrations of furfural (0.1, 0.4, 0.6 and 1.5 g/L) on the biomass and lipid production of R. glutinis, as well as the effects of 1.0 g/L furfural on the utilization of glucose and xylose. Results showed that: when the furfural concentration reached 1.5 g/L, the lag phrase time was extended to 96 h, and the residual glucose was up to 17.7 g/L, with maximum biomass of only 6.6 g/L, which accounted for 47% of that in the basic medium (furfural-free), and the corresponding lipid content was reduced about 50%. Furfural showed lighter inhibitory degree on R. glutinis when xylose acted as the carbon source than glucose was the carbon source; more C18 fatty acids or unsaturated C18 fatty acids were generated in the presence of furfural.

Reflection on developing bio-energy industry of large oil company / 生物工程学报

China's energy supply becomes more serious nowadays and the development of bio-energy becomes a major trend. Large oil companies have superb technology, rich experience and outstanding talent, as well as better sales channels for energy products, which can make full use of their own advantages to achieve the efficient complementary of exist energy and bio-energy. Therefore, large oil companies have the advantages of developing bio-energy. Bio-energy development in China is in the initial stage. There exist some problems such as available land, raw material supply, conversion technologies and policy guarantee, which restrict bio-energy from industrialized development. According to the above key issues, this article proposes suggestions and methods, such as planting energy plant in the marginal barren land to guarantee the supply of bio-energy raw materials, cultivation of professional personnel, building market for bio-energy counting on large oil companies' rich experience and market resources about oil industry, etc, aimed to speed up the industrialized process of bio-energy development in China.

Progress on biodiesel production with enzymatic catalysis in China / 生物工程学报

This paper reports the progress of biodiesel production with enzymatic catalysis in Beijing University of Chemical Technology, one of the leaders in biodiesel R & D in China, which includes screening of high-yield lipase production strains, optimization and scale-up of the lipase fermentation process, lipase immobilization, bioreactor development and scale-up, biodiesel separation and purification and the by-product glycerol utilization. Firstly, lipase fermentation was carried out at industrial scale with the 5 m3 stirred tank bioreactor, and the enzyme activity as high as 8 000 IU/mL was achieved by the species Candida sp. 99-125. Then, the lipase was purified and immobilized on textile membranes. Furthermore, biodiesel production was performed in the 5 m3 stirred tank bioreactor with an enzyme dosage as low as 0.42%, and biodiesel that met the German biodiesel standard was produced. And in the meantime, the byproduct glycerol was used for the production of 1,3-propanediol to partly offset the production cost of biodiesel, and 76.1 g/L 1,3-propanediol was obtained in 30 L fermentor with the species Klebsiella pneumoniae.

Optimization of high-cell-density fermentation process for S-adenosyl-L-methionine production / 生物工程学报

Poor stability existed in the anaphase of the high-cell-density fermentation of Saccharomyces crevisiae for S-adenosyl-L-methionine (SAM) production in 5 L fermentor. To improve the fermentation stability, we studied the addition of diammonium hydrogen phosphate, sodium glutamate and adenosine disodium triphosphate into glucose feeding solution. Study of four fed-batch cultures showed that, after 34 h fermentation, when dry cell weight reached 100 g/L, the addition of 50 g pre-L-methionine and glucose feeding with 10 g/L adenosine disodium triphosphate was optimal for SAM production. Under this condition, after 65.7 h fermentation, both the dry cell weight and the yield of SAM reached the maximum, 180 g/L and 17.1 g/L respectively.

Synthesis of biodiesel from crude oil by immobilized lipase / 生物工程学报

We used immobilized lipase from Candida sp. 99-125 to produce fatty acid methyl esters (FAMEs) from crude oil and methanol. We studied the effects of phospholipids on activity of immobilized lipase, reaction velocity, stability of immobilized lipase and the stability of immobilized lipase in crude and refined oil. Results showed that the activity of the lipase immersed in petroleum ether with 1% phospholipids dropped more quickly than the lipase in petroleum ether without phospholipids. When soybean oil was used without phospholipids as material, the FAMEs yield of 15 min was 26.2%, whereas the yield decreased to 12.4% when there were 5% phospholipids in the soybean oil. However when the phospholipids content was below 1%, the stability of the lipase did not change obviously. The lipase was stable when used to catalyze crude soybean oil and crude jatropha oil, after 10 cycles the FAMEs yield was still above 70%. This lipase showed great potential for industrial production of biodiesel from crude oil.

Immobilized lipase catalyzed synthesis of vitamin A plamitate / 生物工程学报

The synthesis of vitamin A plamitate in organic solvent with vitamin A acetate and ethyl palmitate with immobilized lipase from Candida sp. was studied. The influences of solvent, the molar ratio of substrates, the reaction temperature and time, and the water concentration were optimized and the best result was obtained by transesterification from 0.100 g vitamin A acetate and 0.433 g ethyl palmitic, at 30 degrees C, in 10 mL petroleum ether, containing 0.2% of water (V/V), with 1.1 g lipase. In these conditions, the yield of vitamin A palmitate reached 83% in 12 h. The immobilized lipase was reused about 5 batches.

Pre-L-methionine feeding strategy for S-adenosyl-L-methionine fermentative production / 生物工程学报

The yield of S-adenosyl-L-methionine (SAM) on high-cell-density fermentation by saccharomyces cerevisiae is mostly affected by the feeding strategy of pre-L-methionine. The mutant strain SAM0801 that could accumulate more SAM was used in this study. Six high-cell-density fermentation experiments in 5 L fermentor were investigated to get the optimal feeding time and amount of L-methionine. The results showed that when 40 g L-methionine was added in the fermentor after 30 h fermentation, a dry cell weight of 100 g/L was achieved. Under this condition, after 58 h fermentation, both the dry cell weight and the yield of SAM reached the maximum, 168 g/L and 14.48 g/L respectively.

Preparation of fast responsive, pH sensitive polyacrylic acid gel with different pore-forming agents / 生物医学工程学杂志

Five kinds of pore-forming agents, including PEG-400, chitosan, the polymer of chitosan and glutin, CaCO3 and NazCO3, were used in this experiment to prepare fast responsive and pH sensitive Polyacrylic acid (PAAc) gel which could be used as the material of punctum plug. The mechanism and effects of pore-forming agents on PAAc gel were studied; besides, the experiment also assessed the effects of the three most effective pore-forming agents on gel's water retention and swelling rate. The results showed that the most suitable dose levels of PEG-400, the polymer and Na2CO3 were 1 ml, 0.8 ml and 1 ml respectively, and PEG-400 was most effective with the same dosage; the gel with PEG-400 as pore-forming agent could finish more than 95% of the swelling process in just 5 minutes, it is suitable for use as punctum plug material.

Preparation of complex chitosan microcapsule and its application in controlled release of vitamin D2 / 生物医学工程学杂志

In this work a system which consists of chitosan (CS) microcores entrapped within enteric polymer is presented. Vitamin D2, used as a model drug, was efficiently entrapped within CS microcores using spray-drying and then microencapsulated into ethylic cellulose(EC). The morphology and release properties of microcapsules were tested. The influential factors of preparation conditions included molecular weight of chitosan, concentration of chitosan solution, concentration of acetic acid, loading of vitamin D2 were discussed. The results of in vitro release studies showed that the microcapsules prepared in this article could realize sustained release in intestine.