Forgot your password?
New user?
New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems
CAS announces the release of SciFinder Scholar for Mac OS X
Press Releases
Press Releases
| Check out our New Publishers' Select for Free Articles |
Biochemical Engineering Journal (v.61, #)
Enhanced cephalosporin C production with a combinational ammonium sulfate and DO-Stat based soybean oil feeding strategy by Shengbing Duan; Guoqiang Yuan; Yanli Zhao; Hongfei Li; Weijia Ni; Meina Sang; Liming Liu; Zhongping Shi (pp. 1-10).
► Final CPC concentration reached 35.77g/L and DAOC stayed at 0.178g/L, DAOC/CPC was below 0.5% ensuring CPC products quality. ► Overall operation cost in CPC fermentation was relieved. ► Metabolic analysis revealed that a weakened carbon flux distribution in TCA was beneficial for reducing DOAC overflow.A novel substrates feeding strategy by coupling ammonium sulfate addition with soybean oil feeding was proposed for efficient cephalosporin C (CPC) production by Acremonium chrysogenum and testified in a 7L fermentor to maintain NH4+N concentration stably for normal mycelium differentiation. On the base of the coupling strategy, fermentation performance during main CPC production phase with different soybean oil feeding methods was compared. The results indicated that the modified DO-Stat soybean oil feeding strategy, namely, the method of adopting DO-Stat for soybean oil feeding and using O2-enriched air for aeration, could maintain CPC synthesis rate at an appropriately high level and reduce deacetoxycephalosporin (DAOC, the major by-product of CPC fermentation) accumulation simultaneously. The modified DO-Stat soybean oil feeding strategy could raise final CPC concentration up to a high level of 35.77g/L and lower DAOC concentration down to a level of 0.178g/L, so that the quality standard of CPC fermentation product could be satisfied by controlling DAOC/CPC ratio below 0.5%. The metabolic analysis revealed that a weakened carbon flux distribution in TCA was beneficial for reducing DOAC overflow.
Keywords: Acremonium chrysogenum; Antibiotic; Bioprocess monitoring; Cephalosporin C production; Fermentation; Optimization
Optimization of carbon and nitrogen sources for biomass and lipid production by Chlorella saccharophila under heterotrophic conditions and development of Nile red fluorescence based method for quantification of its neutral lipid content by Muge Isleten-Hosoglu; Idil Gultepe; Murat Elibol (pp. 11-19).
► We study growth, lipid and fatty acid composition of Chlorella saccharophila. ► Higher lipid content has been obtained under heterotrophic cultivation. ► We develop Nile red fluorescence spectrophotometric method. ► The principal fatty acids are oleic and linoleic acids.In this study, initially, the carbon and nitrogen source preferences of Chlorella saccharophila were examined in terms of biomass productivities under heterotrophic growth conditions. It was shown that C. saccharophila could actively utilize glucose and glycerol as carbon sources and bacteriological peptone as a nitrogen source. Secondly, the concentrations of nitrogen and carbon sources that were found to significantly influence the biomass productivity of heterotrophic C. saccharophila were further optimized by using Box–Behnken experimental design. Lastly, in a scale-up attempt, the medium consisting of 20g/L glucose and 1g/L bacteriological peptone was used in a 3L stirred tank bioreactor in which the final biomass concentration obtained was 7.7 fold higher than that of obtained under autotrophic conditions. Also, lipid content in heterotrophic cells of C. saccharophila was increased about 3 times compared to that of autotrophic cells. The principal fatty acids in heterotrophic C. saccharophila were oleic acid (C18:1) and linoleic acid (C18:2) constituting 34.4% and 30.1% of the total fatty acid contents, respectively. Moreover, a simple and rapid method determining the neutral lipid accumulation in C. saccharophila with spectrofluorimetry was developed and used easily for monitoring lipid accumulation in a stirred tank bioreactor.
Keywords: Microalgae; Heterotrophic culture; Batch processing; Optimization; Bioreactors; Lipid
Simultaneous purification and immobilization ofd-hydantoinase on the immobilized metal affinity membrane via coordination bonds by Yi-Miao Ko; Chih-I Chen; Chwen-Jen Shieh; Yung-Chuan Liu (pp. 20-27).
This study constructs the immobilized metal affinity membrane (IMAM) via coupling of epichlorohydrin, iminodiacetic acid, and nickel ion on the regenerated cellulose membrane. Thed-hydantoin-hydrolyzing enzyme (DHTase) harboring a poly-His tagged residue was used as a model protein immobilized on the prepared IMAM. Various immobilization conditions were examined based on the yield of N-carbamoyl-d-p-hydroxyphenylglycine in batch reactions. The immobilization conditions were studied and the optimal conditions are as follows. By employing an IMAM with nickel ion of 155.5±5μmol/disc immersed in 0.1M Tris–HCl buffer pH 8 (with 0.8M sodium chloride) and immobilized time of 14h, a DHTase activity of 4.2±0.3U/disc was obtained. The immobilized DHTase membrane can achieve a larger pH and thermal tolerant range than that of free enzyme. Meanwhile, the stability test showed that 99% of enzyme activity could be retained after being repeated 15-times. The storage test also displayed 99% enzyme preservation after 7 weeks of storage.
Keywords: d; -Hydantoinase; Immobilized metal affinity membrane; Enzyme immobilization; Enzyme purification; Enzyme stability
Amyloid oligomer detection by immobilized molecular chaperone by Masafumi Sakono; Tamotsu Zako; Masafumi Yohda; Mizuo Maeda (pp. 28-33).
► Novel detection system of amyloid β (Aβ) oligomer which is known as causative agent of Alzheimer's disease (AD) is developed. ► Aβ oligomer detection is successfully achieved using a microplate covered with molecular chaperone which can interact with Aβ oligomer. ► We also demonstrate that at Aβ physiological concentrations this system specifically detects Aβ oligomers.Amyloid β (Aβ) oligomer is a known causative agent of Alzheimer's disease (AD). For early recognition of AD, development of an Aβ oligomer detection system is vital. We developed a novel detection system using the molecular chaperone, Prefoldin (PFD), which can specifically interact with amyloid oligomers. Aβ oligomer detection was achieved with a PFD-coated microplate, following the enzyme-linked immunosorbent assay (ELISA) technique. The results suggest that this system specifically detects Aβ oligomers at their physiological concentrations. The problematic nonspecific adsorption of Aβ to the microplate can be effectively blocked with 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer. This novel Aβ oligomer detection method may be applied for AD early recognition.
Keywords: Abbreviations; Aβ; Amyloid β; AD; Alzheimer's disease; ADDL; Aβ-derived diffusible ligand; ELISA; enzyme-linked immunosorbent assay; LTP; long-term potentiation; MPC; 2-methacryloyloxyethyl phosphorylcholine; PFD; PrefoldinAggregation; Amyloid beta; Biosensors; Bioseparations; Enzyme technology; Molecular chaperone
Ultrasound induced production of thrombinase by marine actinomycetes: Kinetic and optimization studies by Balakrishnan Naveena; Punniavan Sakthiselvan; Periyasamy Elaiyaraju; Nagarajan Partha (pp. 34-42).
► Marine actinomycetes found to be effective for thrombinase production. ► Low intensity ultrasonication increase the cell biomass, enzyme activity and even specific growth rate. ► Increase in salinity promotes better salt tolerance of isolate, cell growth and enzyme activity. ► Optimization by central composite design proved as significant for obtaining optimum conditions for bioprocess.A potent fibrinolytic protease (thrombinase) was isolated from marine actinomycetes which can be used for the treatment of myocardial infarction. Thrombinase producing actinomycetes were isolated from the marine water sample using fibrin plate assay. The spore morphology of the marine isolate was analyzed by light and scanning electron microscopy (SEM). Further the marine isolate was identified as Streptomyces venezuelae through biochemical tests and 16srRNA analysis. Effect of ultrasonication on cell concentration and enzyme activity was further determined and the maximum values 20.62mgmL−1 and 6.24FUmL−1, respectively were obtained under static condition. The maximum specific growth rate μm (h−1) of the marine isolate under static condition was evaluated as 0.554h−1 with ultrasonication by modified gompertz model using Matlab 7.0. Moreover effect of salinity on cell concentration and enzyme activity was also analyzed, the maximum biomass, 22.42mgmL−1 and maximum enzyme activity, 6.7FUmL−1 at 6% (w/v) salinity. Optimization was done further by response surface methodology (RSM) using central composite design (CCD) and it was found pH 7, temperature 35°C and salinity 6% (w/v) as optimum for maximum specific growth rate, 0.578h−1 and thrombinase activity, 8.34FUmL−1.
Keywords: Thrombinase; Marine actinomycetes; Optimization; Cell disruption; Growth kinetics; Microbial growth
Addition of HCl as a means to improve biogas production from protein-rich food industry waste by Anna Karlsson; Jörgen Ejlertsson (pp. 43-48).
► The pH of anaerobic digestion process was reduced from 8.0 to 7.8. ► A ∼50% increase in methane yield was achieved. ► Levels of acetate, propionate and iso-butyrate were reduced. ► The positive effects are likely related to decreased concentration of NH3.The effect of pH on the production of biogas during anaerobic digestion of a protein-rich substrate, containing mainly slaughter house waste, was investigated. Four laboratory scale reactors (4L liquid volume) with an organic load of 3.5g volatile solids (VS) L−1 reactor volume day−1, and a hydraulic retention time 24 days were run under mesophilic conditions in semi-continuous mode for 64 days. Two of the reactors were pH-regulated (target pH was 7.6 and 7.8, respectively) by adding HCl, while the other two reactors were operated as controls (pH 8.0). By the end of the experiment the pH-controlled reactors produced 0.6L of methane gVSadded−1day−1, while the controls produced 0.4L. The gas produced did in all cases have a CH4 – content of about 65%. The improvement in process performance in the pH-regulated reactors, compared to the controls, was also reflected in lower final levels of acetate, propionate, isobutyrate and 2-metylbutyrate. The laboratory-scale study showed that lowering the pH by 0.2–0.4 units by adding HCl to the reactors increased the methane yield with about 50%, indicating a considerable increase of the microbial ability to utilise the organic material for biogas production.
Keywords: Anaerobic digestion; Slaughter house waste; pH-control; Ammonia; Volatile fatty acids; Process improvement
Decolourisation and detoxification of rayon grade pulp paper mill effluent by mixed bacterial culture isolated from pulp paper mill effluent polluted site by Ram Chandra; Rachna Singh (pp. 49-58).
Display Omitted► This manuscript described bacterial consortium with three bacteria showing potential ligninolytic activity. ► The consortium capable for decolourisation & detoxification of rayon grade pulp paper mill effluent at high pollution load. ► The metabolic products during detoxification is also reported which is new information. ► This information will be useful to understand the mechanism of bacterial detoxification of pulp paper mill effluent. ► The developed consortium would be useful in various biotechnological applications.This study deals with the decolourisation and detoxification of rayon grade pulp paper mill effluent by mixed culture of three bacterial strains having ligninolytic enzyme activity. These strains were identified as IITRP1 Pseudochrobactrum glaciale (FJ581024), IITRP2 Providencia rettgeri (GU193984) and RCT2 Pantoea sp. (FJ755943) based on 16S rRNA gene sequencing. The results showed that mixed culture effectively reduced colour 96.02%, chemical oxygen demand (COD) 91% and biological oxygen demand (BOD) 92.59% of the pulp paper mill effluent within 216h of the incubation period. Maximum enzyme activity for lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase were recorded at 48, 72 and 144h of the incubation period, respectively. The high performance liquid chromatography (HPLC) analysis of bacterial degraded samples showed 90% reduction of lignin and chlorophenol compared to the untreated sample. Further, gas chromatography–mass spectroscopy (GC–MS) analysis revealed that majority of the compounds present in the untreated sample were completely removed and only few metabolites were generated after bacterial treatment. The toxicity assessment of the pulp paper mill effluent on Vicia faba L. showed 40% reduction after bacterial treatment. However, untreated effluent sample showed inhibition of seed germination and α-amylase activity.
Keywords: Abbreviations; BOD; biological oxygen demand; COD; chemical oxygen demand; DO; dissolved oxygen; GC–MS; gas chromatography–mass spectroscopy; HPLC; high performance liquid chromatography; LiP; lignin peroxidase; MnP; manganese peroxidase; OD; optical density; RGP; rayon grade pulp; TDS; total dissolved solid; TIC; total ion chromatogramRayon grade pulp; Chlorophenol; Peroxidases; Laccase; Seed germination test; GC–MS
Hydrogen and ethanol production in anaerobic fluidized bed reactors: Performance evaluation for three support materials under different operating conditions by Aruana Rocha Barros; Edson Luiz Silva (pp. 59-65).
► The biological production of hydrogen and ethanol was evaluated in AFBR. ► The AFBRs contained polystyrene (R1), grounded tire (R2), and PET (R3). ► The best performance was achieved with reactor R2 (2.11molH2mol−1 glucose). ► The R3 showed a better performance for ethanol concentration (1941.78mgL−1).The objective of this study was to evaluate the influence of different support materials (polystyrene – R1, grounded tire – R2 and polyethylene terephthalate (PET) – R3) on producing hydrogen and ethanol using three anaerobic fluidized bed reactors. Each reactor had a total volume of 4192cm3 and was fed with media containing glucose as the carbon source (4000mgL−1) with an influent pH around 5.0 and an effluent pH of about 3.5, a hydraulic retention time (HRT) of 8–1h at a temperature of 23±2°C, with thermal treatment of the inoculum. For hydrogen production, the best performance was achieved with R2 (2.11molH2mol−1 glucose), providing the highest H2 content in biogas (60%). In all reactors, the predominant soluble metabolites were acetic acid, butyric acid, lactic acid and ethanol, with small amounts of propionic acid. The reactor R2 produced more acetic and butyric acid (434.74 and 1013.61mgL−1, respectively). However, reactor R3 showed a better performance for ethanol concentration (1941.78mgL−1).
Keywords: Acid fermentation; Hydrogen production; Ethanol production; Anaerobic fluidized bed reactor; Support material
Simulation of ex vivo bone marrow culture: Application to chronic myeloid leukaemia growth model by Chi Yip Joan Ma; Nicki Panoskaltsis; Robin Kumar; Xiao Yun Xu; Athanasios Mantalaris (pp. 66-77).
► Development of a numerical model to investigate the advanced aspects of haematopoiesis. ► Regulatory effects of growth factors on the production of chronic myeloid leukaemia cells. ► Purpose-designed scaffold placed inside a perfused bioreactor.The three-dimensional (3-D) architecture of the bone marrow (BM) supports the renewal, maintenance, proliferation and differentiation of haematopoietic stem cells (HSCs). Efforts have been made towards the reconstruction of an ex vivo HSC culture system, which could have several potential applications, such as the detailed understanding of normal and leukaemic haematopoiesis and expansion of haematopoietic stem cells for use in bone marrow transplantation (BMT). In this paper, a numerical model has been developed to investigate the advanced aspects of haematopoiesis, the regulatory effects of growth factor granulocyte colony-stimulating factor (G-CSF), thrombopoietin (TPO) and erythropoietin (EPO) on the production of chronic myeloid leukaemia (CML) cells within a purpose-designed scaffold placed inside a perfused bioreactor. A multi-lineage cellular growth model of haematopoietic cells was incorporated in order to mimic the complexity of the diseased BM. The simulation results demonstrate that different combinations and concentrations of cytokines can alter the self-renewal, differentiation, and proliferation of CML cells and this effect is also dependent upon operation conditions and scaffold properties. The numerical model presented here enables the optimisation of scaffold design parameters and mass transfer environment necessary for developing a suitable ex vivo haematopoietic system.
Keywords: Computational fluid dynamics; Chronic myeloid leukaemia; Bioreactors; Growth kinetics and mass transfer
Recovery and separation of surfactin from pretreated Bacillus subtilis broth by reverse micellar extraction by Ruey-Shin Juang; Huei-Li Chen; Shu-Chi Tsao (pp. 78-83).
► The use of 40mM TOA reverse micelles can extract 98% of 2.9g/L surfactin at pH 6.5. ► Purity of surfactin recovered from TOA micelles by ethanol–NaCl solution reaches 91%. ► The use of 5mM Aliquat 336 micelles can extracts 92% of 3.0g/L surfactin at pH 9.0. ► Stripping of surfactin from Aliquat 336 micelles is hindered due to complex formation. ► TOA reverse micelles are recommended as the separating media for this purpose.The recovery and purification of surfactin from the fermentation broth of Bacillus subtilis ATCC (American Type Culture Collection) 21332 by extraction and stripping (back extraction) using reverse micelles was studied. Prior to extraction, the broth was precipitated by acid (HCl) at pH 4 and the precipitate was then dissolved in alkaline (NaOH) solution at pH 11. The effects of the type and concentration of surfactant, phase volume ratio, initial aqueous pH, and the presence of co-solvents on the extraction as well as the effects of the type and concentration of added inorganic salt and ethanol on the stripping were studied. It was shown that, in the absence of co-solvents, the extraction efficiency of 3.0g/L surfactin from the pretreated broth by reverse micelles of 40mM tri- n-octylamine (TOA) and 5mM Aliquat 336 in n-hexane was more than 92%. The concentrations of the added inorganic salt (ammonium sulfate and sodium chloride) in the strip solution were also optimized. The purity of recovered surfactin from the TOA reverse micelles was higher than 90% when the strip solution contained 0.43M of sodium chloride in water.
Keywords: Separation; Surfactin; Fermentation; Liquid–liquid extraction; Reverse micelles; Cationic surfactants