Latest Articles Include:
- Coenzyme Q10 production by Rhodobacter sphaeroides in stirred tank and in airlift bioreactor
Yen HW Shih TY - Bioprocess Biosyst Eng 32(6):711-716 (2009)
A higher Coenzyme Q10 (CoQ10) concentration of 25.04 mg/l was found in airlift bioreactor than the value of 18.11 mg/l obtained in stirred tank under the aerobic-dark cultivation of Rhodobacter sphaeroides. Aeration rate didn't show obvious impact to CoQ10 production in airlift bioreactor. The fed-batch operation in airlift bioreactor could increase the biomass concentration and led to the maximum CoQ10 concentration of 33.91 mg/l measured, but a lower CoQ10 cell content (3.5 mg CoQ10/DCW) was observed in the fed-batch operation as compared to the batch operation. To enhance the CoQ10 content, an aeration-change strategy was proposed in the fed-batch operation of airlift bioreactor. This strategy led to the maximum CoQ10 concentration of 45.65 mg/l, a 35% increase as compared to the simple fed-batch operation. The results of this study suggested that a fed-batch operation in airlift bioreactor accompanying aeration-change could be suitable for CoQ10 production. - Kinetic analysis of hybridoma cells viability under mechanical shear stress with and without serum protection
Legazpi L Laca A DÃaz M - Bioprocess Biosyst Eng 32(6):717-722 (2009)
The effect of a well-defined mild shear stress on hybridoma cell viability (HB-8852) in a serum-free culture medium has been analysed, and the role as shear protector of different concentrations of fetal bovine serum have been studied. Samples harvested from cultures in their late exponential growth phase, were subjected in a rheometer to a constant shear stress of 0.41 ± 0.02 Pa, and the evolution of viable and total cell concentrations was determined and compared with static controls. A simple segregated kinetic model for the viable and dead cells was used to know the effect of serum concentration on the specific cell growth and death rate of the cells. - MapsiDB: an integrated web database for type I polyketide synthases
Tae H Sohng JK Park K - Bioprocess Biosyst Eng 32(6):723-727 (2009)
Polyketides have diverse biological activities, including pharmacological functions such as antibiotic, antitumor and agrochemical properties. They are biosynthesized from short carboxylic acid precursors by polyketide synthases (PKSs). As natural polyketide products include many clinically important drugs and the volume of data on polyketides is rapidly increasing, the development of a database system to manage polyketide data is essential. MapsiDB is an integrated web database formulated to contain data on type I polyketides and their PKSs, including domain and module composition and related genome information. Data on polyketides were collected from journals and online resources and processed with analysis programs. Web interfaces were utilized to construct and to access this database, allowing polyketide researchers to add their data to this database and to use it easily. - Improved glutathione production by gene expression in Pichia pastoris
Fei L Wang Y Chen S - Bioprocess Biosyst Eng 32(6):729-735 (2009)
To utilize Pichia pastoris to produce glutathione, an intracellular expression vector harboring two genes (gsh1 and gsh2) from Saccharomyces cerevisiae encoding enzymes involved in glutathione synthesis and regulated by the glyceraldehyde-3-phosphate dehydrogenase (GAP) promoter was transformed into P. pastoris GS115. Through Zeocin resistance and expression screening, a transformant that had higher glutathione yield (217 mg/L) in flask culture than the host strain was obtained. In fed-batch culture process, this recombinant strain displayed high activity for converting precursor amino acids into glutathione. The glutathione yield and biomass achieved 4.15 g/L and 98.15 g (dry cell weight, DCW)/L, respectively, after 50 h fermentation combined with addition of three amino acids (15 mmol/L glutamic acid, 15 mmol/L cysteine, and 15 mmol/L glycine). - Production of succinate by a pflB ldhA double mutant of Escherichia coli overexpressing malate dehydrogenase
Wang W Li Z Xie J Ye Q - Bioprocess Biosyst Eng 32(6):737-745 (2009)
The gene encoding malate dehydrogenase (MDH) was overexpressed in a pflB ldhA double mutant of Escherichia coli, NZN111, for succinic acid production. With MDH overexpression, NZN111/pTrc99A-mdh restored the ability to metabolize glucose anaerobically and 0.55 g/L of succinic acid was produced from 3 g/L of glucose in shake flask culture. When supplied with 10 g/L of sodium bicarbonate (NaHCO3), the succinic acid yield of NZN111/pTrc99A-mdh reached 1.14 mol/mol glucose. Supply of NaHCO3 also improved succinic acid production by the control strain, NZN111/pTrc99A. Measurement of key enzymes activities revealed that phosphoenolpyruvate (PEP) carboxykinase and PEP carboxylase in addition to MDH played important roles. Two-stage culture of NZN111/pTrc99A-mdh was carried out in a 5-L bioreactor and 12.2 g/L of succinic acid were produced from 15.6 g/L of glucose. Fed-batch culture was also performed, and the succinic acid concentration reached 31.9 g/L with a yield of 1.19 ! mol/mol glucose. - Xylose reductase activity in Debaryomyces hansenii UFV-170 cultivated in semi-synthetic medium and cotton husk hemicellulose hydrolyzate
Sampaio FC de Faria JT Coimbra JS Lopes Passos FM Converti A Minin LA - Bioprocess Biosyst Eng 32(6):747-754 (2009)
To develop a new enzymatic xylose-to-xylitol conversion, deeper knowledge on the regulation of xylose reductase (XR) is needed. To this purpose, a new strain of Debaryomyces hansenii (UFV-170), which proved a promising xylitol producer, was cultivated in semi-synthetic media containing different carbon sources, specifically three aldo-hexoses (d-glucose, d-galactose and d-mannose), a keto-hexose (d-fructose), a keto-pentose (d-xylose), three aldo-pentoses (d-arabinose, l-arabinose and d-ribose), three disaccharides (maltose, lactose and sucrose) and a pentitol (xylitol). The best substrate was lactose on which cell concentration reached about 20 g l−1 dry weight (DW), while the highest specific growth rates (0.58–0.61 h−1) were detected on lactose, d-mannose, d-glucose and d-galactose. The highest specific activity of XR (0.24 U mg−1) was obtained in raw extracts of cells grown on d-xylose and harvested in the stationary growth phase. When grown on cotton husk ! hemicellulose hydrolyzates, cells exhibited XR activities five to seven times higher than on semi-synthetic media. - Comparative study on the influence of dissolved oxygen control approaches on the microbial hyaluronic acid production of Streptococcus zooepidemicus
Liu L Du G Chen J Wang M Sun J - Bioprocess Biosyst Eng 32(6):755-763 (2009)
Three different dissolved oxygen (DO) control approaches were proposed to improve hyaluronic acid (HA) production: a three-stage agitation speed control approach, a two-stage DO control approach, and an oxygen vector perfluorodecalin (PFC) applied approach. In the three-stage agitation speed control approach, agitation speed was 200 rpm during 0–8 h, 400 rpm during 8–12 h, and 600 rpm during 12–20 h. In the two-stage DO control strategy, DO was controlled at above 10% during 0–8 h and at 5% during 8–20 h. In the PFC applied approach, PFC (3% v/v) was added at 8 h. HA production reached 5.5 g/L in the three-stage agitation speed control culture model, and 6.3 g/L in two-stage DO control culture model, and 6.6 g/L in the PFC applied culture model. Compared with the other two DO control approaches, the PFC applied approach had a lower shear stress and thus a higher HA production was achieved. - Penicillin acylase immobilization depending on macromolecular crowding and catalysis in aqueous–organic medium
Xue J Wang A Zhou C Shen S - Bioprocess Biosyst Eng 32(6):765-772 (2009)
To enhance penicillin acylase (PA) performance, it was immobilized in mesocellular silica foams (MCFs) depended on macromolecular crowding and applied to catalysis in non-aqueous medium. Ficoll 70, dextran 10,000, dextran 40,000 and bovine serum albumin were co-assembled with PA. It was observed that specific activity of PA assembled in MCFs with dextran 10,000 in 80% cyclohexane (v/v) was 233.2 U/mg, 200% as that of PA assembled in MCFs in 80% cyclohexane and 323.5% as that of free PA in full aqueous medium. As content of alkane increased, activity of PA in MCFs with macromolecules varied slightly. In addition, PA co-immobilized with dextran 10 in MCFs retained 58.2% of its initial activity after heating at 50°C for 4 h, 1.2 times higher than that of PA immobilized alone in MCFs. The results showed that macromolecular crowding was favorable for immobilization of PA and its catalysis in suitable aqueous–organic medium. - Maximizing filamentous phage yield during computer-controlled fermentation
Grieco SH Lee S Dunbar WS Macgillivray RT Curtis SB - Bioprocess Biosyst Eng 32(6):773-779 (2009)
Filamentous phage such as M13 and fd consist of a circular, single-stranded DNA molecule surrounded by several different coat proteins. These phages have been used extensively as vectors in phage display where one of the phage coat proteins is genetically engineered to contain a unique peptide surface loop. Through these peptide sequences, a phage collection can be screened for individual phage that binds to different macromolecules or small organic and inorganic molecules. Here, we use computer-controlled bioreactors to produce large quantities of filamentous phage in the bacterial host Escherichia coli. By measuring phage yield and bacterial growth while changing the growth medium, pH and dissolved oxygen concentration, we found that the optimal conditions for phage yield were NZY medium with pH maintained at 7.4, the dO2 held at 100% and agitation at 800 rpm. These computer-controlled fermentations result in a minimum of a tenfold higher filamentous phage production! compared to standard shake flask conditions. - Improving neural network prediction of effluent from biological wastewater treatment plant of industrial park using fuzzy learning approach
Pai TY Wang SC Chiang CF Su HC Yu LF Sung PJ Lin CY Hu HC - Bioprocess Biosyst Eng 32(6):781-790 (2009)
Three types of adaptive network-based fuzzy inference system (ANFIS) in which the online monitoring parameters served as the input variable were employed to predict suspended solids (SSeff), chemical oxygen demand (CODeff), and pHeff in the effluent from a biological wastewater treatment plant in industrial park. Artificial neural network (ANN) was also used for comparison. The results indicated that ANFIS statistically outperforms ANN in terms of effluent prediction. When predicting, the minimum mean absolute percentage errors of 2.90, 2.54 and 0.36% for SSeff, CODeff and pHeff could be achieved using ANFIS. The maximum values of correlation coefficient for SSeff, CODeff, and pHeff were 0.97, 0.95, and 0.98, respectively. The minimum mean square errors of 0.21, 1.41 and 0.00, and the minimum root mean square errors of 0.46, 1.19 and 0.04 for SSeff, CODeff, and pHeff could also be achieved. - Characterization of a thermostable alkaline protease produced by marine Streptomyces fungicidicus MML1614
Ramesh S Rajesh M Mathivanan N - Bioprocess Biosyst Eng 32(6):791-800 (2009)
Totally 191 different marine actinomycetes were isolated from 256 different marine samples collected from the Bay of Bengal and its associated Pulicat lake and Pichavaram mangrove, India. Among them, 157 produced caseinase, 113 produced gelatinase and 108 produced both the protease enzymes. An isolate coded as MML1614 was selected for further study as it exhibited high proteolytic activity. The MML1614 was identified as Streptomyces fungicidicus based on polyphasic taxonomical approach including 16S rRNA sequence analysis. The culture conditions were standardized for the growth and protease production in S. fungicidicus MML1614. The protease was isolated from a 6-day-old culture filtrate of S. fungicidicus MML1614 and partially purified up to 4.5-fold. The protease was optimally active at pH 9 and 40 °C and it was stable up to pH 11 and 60 °C. PMSF and NaCl inhibited the enzyme activity up to 22 and 11%, respectively. The partially purified protease removed the blood! stain more effectively when combined with different detergents than the detergents alone. - Control of continuous fed-batch fermentation process using neural network based model predictive controller
Kiran AU Jana AK - Bioprocess Biosyst Eng 32(6):801-808 (2009)
Cell growth and metabolite production greatly depend on the feeding of the nutrients in fed-batch fermentations. A strategy for controlling the glucose feed rate in fed-batch baker's yeast fermentation and a novel controller was studied. The difference between the specific carbon dioxide evolution rate and oxygen uptake rate (Qc − Qo) was used as controller variable. The controller evaluated was neural network based model predictive controller and optimizer. The performance of the controller was evaluated by the set point tracking. Results showed good performance of the controller. - N-removal performance and underlying bacterial taxa of upflow filter bioreactor system under different dissolved oxygen and internal recycle conditions
Laobusnanant P Lee SH Anceno AJ Ghosh GC Kim DJ Pathak BK Shipin OV - Bioprocess Biosyst Eng 32(6):809-818 (2009)
Biological N-removal treatment of piggery wastewater in the upflow anaerobic–anoxic–aerobic floating filter (UA3FF) bioreactor based on the concept of nitritation–denitritation was studied along with the changes in internal recycle ratio and dissolved oxygen concentration (DO). Consecutive changes in the recirculation ratio between the anoxic and aerobic reactors has resulted in abundance and composition shifts of N-cycling bacteria as well as other bacterial groups, reflecting different survival strategies across (bio/physico)chemical milieu. The DO concentration was optimized to achieve nitritation in the aerobic reactor and denitritation in the anoxic reactor. Optimal nitritation–denitritation (270 and 130 g NO2−–N produced or reduced/m3 filter media/day) was obtained at DO of 1.0–1.5 mg/l, inter-reactor recirculation ratio of 1:1–2:1, HRT of 24 h, pH of 7.6 ± 0.3, and temperature of 28 ± 4 °C. Since only well known nitrifying and denitrifying tax! a were found, nitritation–denitritation was likely carried out by these bacteria rather than the yet unidentified novel taxa. Archaeal nitrifiers recently discovered to be important in the global N-cycle were not detected. - Xylanases from Aspergillus niger, Aspergillus niveus and Aspergillus ochraceus produced under solid-state fermentation and their application in cellulose pulp bleaching
Betini JH Michelin M Peixoto-Nogueira SC Jorge JA Terenzi HF Polizeli ML - Bioprocess Biosyst Eng 32(6):819-824 (2009)
This study describes the production of xylanases from Aspergillus niveus, A. niger, and A. ochraceus under solid-state fermentation using agro-industrial residues as substrates. Enzyme production was improved using a mixture of wheat bran and yeast extract or peptone. When a mixture of corncob and wheat bran was used, xylanase production from A. niger and A. ochraceus increased by 18%. All cultures were incubated at 30 °C at 70–80% relative humidity for 96 h. For biobleaching assays, 10 or 35 U of xylanase/g dry cellulose pulp were incubated at pH 5.5 for 1 or 2 h, at 55 °C. The delignification efficiency was 20%, the brightness (percentage of ISO) increased two to three points and the viscosity was maintained confirming the absence of cellulolytic activity. These results indicated that the use of xylanases could help to reduce the amount of chlorine compounds used in cellulose pulp treatment. - Production and characterization of lipopeptide biosurfactant by a sponge-associated marine actinomycetes Nocardiopsis alba MSA10
Gandhimathi R Seghal Kiran G Hema TA Selvin J Rajeetha Raviji T Shanmughapriya S - Bioprocess Biosyst Eng 32(6):825-835 (2009)
A sponge-associated marine actinomycetes Nocardiopsis alba MSA10 was screened and evaluated for the production of biosurfactant. Biosurfactant production was confirmed by conventional screening methods including hemolytic activity, drop collapsing test, oil displacement method, lipase production and emulsification index. The active compound was extracted with three solvents including ethyl acetate, diethyl ether and dichloromethane. The diethyl ether extract was fractionated by TLC and semi-preparative HPLC to isolate the pure compound. In TLC, a single discrete spot was obtained with the Rf 0.60 and it was extrapolated as valine. Based on the chemical characterization, the active compound was partially confirmed as lipopeptide. The optimum production was attained at pH 7, temperature 30°C, and 1% salinity with glucose and peptone supplementation as carbon and nitrogen sources, respectively. Considering the biosurfactant production potential of N. alba, the strain cou! ld be developed for large-scale production of lipopeptide biosurfactant. - Enhanced docosahexaenoic acid production by reinforcing acetyl-CoA and NADPH supply in Schizochytrium sp. HX-308
Ren LJ Huang H Xiao AH Lian M Jin LJ Ji XJ - Bioprocess Biosyst Eng 32(6):837-843 (2009)
Docosahexaenoic acid (DHA) production in Schizochytrium sp. HX-308 was evaluated by detecting enzymatic activities of ATP:citrate lyase (EC 4.1.3.8), malic enzyme (EC 1.1.1.40) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) at different fermentation stages. According to the analysis, a regulation strategy was proposed which reinforced acetyl-CoA and NADPH supply at a specific fermentation stage. DHA content of total fatty acids was increased from 35 to 60% by the addition of 4 g/L malic acid at the rapid lipid accumulation stage. Total lipid content also showed an apparent increase of 35% and reached 19 g/L when 40 mL ethanol/L was added at the late lipid accumulation stage. - Identification and cloning of a gene encoding dichloromethane dehalogenase from a methylotrophic bacterium, Bacillus circulans WZ-12 CCTCC M 207006
Wu S Zhang H Yu X Chen J - Bioprocess Biosyst Eng 32(6):845-852 (2009)
The gene dehalA encoding a novel dichloromethane dehalogenases (DehalA), has been cloned from Bacillus circulans WZ-12 CCTCC M 207006. The open reading frame of dehalA, spanning 864 bp, encoded a 288-amino acid protein that showed 85.76% identity to the dichloromethane dehalogenases of Hyphomicrobium sp. GJ21 with several commonly conserved sequences. These sequences could not be found in putative dichloromethane (DCM) dehalogenases reported from other bacteria and fungi. DehalA was expressed in Escherichia coli BL21 (DE3) from a pET28b(+) expression system and purified. The subunit molecular mass of the recombinant DehalA as estimated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis was approximately 33 kDa. Subsequent enzymatic characterization revealed that DehalA was most active in a acidic pH range at 30°, which was quite different from that observed from a facultative bacterium dichloromethane dehalogenases of Methylophilus sp. strain DM11. The Mic! haelis–Menten constant of DCM dehalogenase was markedly lower than that of standard DCM dehalogenases.
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