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181.
Pleurotus ostreatus mushroom mycelium was cultivated in submerged culture in shake-flask experiments with acid extract from peat and yeast extract
as nutrient sources. Different concentrations of water-diluted peat extract were tested in an attempt to overcome the effect
of growth inhibitors apparently present in nondiluted peat extracts. The best results were obtained with a ratio of one part
of peat extract diluted with one part of water. Several operating variables were studied to optimize the growth of mycelial
biomass ofP. ostreatus. The best results produced approximately 5 g/L dry biomass with a yield of 60% and an efficiency of 33%. These results were
obtained in 8 d at 5% (v/v) inoculum ratio, 28°C, pH of 5.0, and 150 rpm. 相似文献
182.
Summary A reversed-phase HPLC system for the quantification of recombinant DNA insulin precursors in yeast fermentation broth is described.
HPLC monitoring of the polypeptide can be achieved without interference from substrate components or proteins stemming from
the host cell, thus serving to determine the optimum harvesting time. Furthermore, it is demonstrated how different amino
acid links of the insulin A- and B-chains affect the chromatographic behaviour of the insulin precursor making it possible
to identify each precursor by its retention on the reversed phase support. 相似文献
183.
采用沉淀法制备了SnO2催化剂,以SnO2催化臭氧氧化降解糖蜜酒精废水脱色为探针反应,对催化剂的活性进行了评价.采用X射线衍射、红外光谱及热分析(TG-DSC)等技术对催化剂进行表征,研究了沉淀剂及焙烧温度等制备参数对SnO2催化臭氧氧化活性的影响.结果表明,SnO2催化剂对臭氧氧化降解糖蜜酒精废水脱色具有较高的催化活性,反应60 min后,糖蜜酒精废水的脱色率从单独臭氧氧化的43.04%提高到60.24%.沉淀剂对SnO2催化剂的活性影响很大,其中以氨水为沉淀剂制备的SnO2催化剂去羟基化反应程度高,所制得的催化剂活性最大.催化剂适宜的焙烧温度为723 K.SnO2吸附吡啶的红外光谱表明,催化剂表面存在L酸中心.臭氧在SnO2表面吸附的红外光谱表明,通过臭氧的末端氧原子与表面羟基及L酸中心成键,生成的活性氧可氧化降解糖蜜酒精废水. 相似文献
184.
Ahlawat S Mandhan RP Dhiman SS Kumar R Sharma J 《Applied biochemistry and biotechnology》2008,149(3):287-293
Pectinase production from Bacillus subtilis SS was optimized under solid-state fermentation (5,943 U/g of dry bacterial bran). The pectinase produced was stable in neutral to alkaline pH range at 70 degrees C; therefore, the suitability of this pectinase in pulp and paper industry was investigated. The enzyme pretreatment process was optimized, and a pectinase dose of 5 IU/g of oven-dried pulp (10% consistency) at pH 9.5 temperature 70 degrees C after 150 min of treatment gave the best pretreatment to the pulp. An increase of 4.3% in brightness along with an increase of 14.8 and 65.3% in whiteness and fluorescence, respectively, whereas a 15% decrease in the yellowness of the pretreated pulp were observed. There was a 5.85% reduction in kappa number and 6.1% reduction in permanganate number along with a reduction in the chemical oxygen demand value. Significant characteristics showed by pectinase open new possibilities of application of this cellulase-free enzyme in the pulp and paper industry by reducing the negative environmental impact of chemicals apart from improving the properties of paper. 相似文献
185.
Traditionally, as much as 80% or more of an ethanol fermentation broth is water that must be removed. This mixture is not
only costly to separate but also produces a large aqueous stream that must then be disposed of or recycled. Integrative approaches
to water reduction include increasing the biomass concentration during fermentation. In this paper, experimental results are
presented for the rheological behavior of high-solids enzymatic cellulose hydrolysis and ethanol fermentation for biomass
conversion using Solka Floc as the model feedstock. The experimental determination of the viscosity, shear stress, and shear
rate relationships of the 10 to 20% slurry concentrations with constant enzyme concentrations are performed with a variable
speed rotational viscometer (2.0 to 200 rpm) at 40 °C. The viscosities of enzymatic suspension observed were in range of 0.0418
to 0.0144, 0.233 to 0.0348, and 0.292 to 0.0447 Pa s for shear rates up to 100 reciprocal seconds at 10, 15, and 20% initial
solids (w/v), respectively. Computational fluid dynamics analysis of bioreactor mixing demonstrates the change in bioreactor
mixing with increasing biomass concentration. The portion-loading method is shown to be effective for processing high-solids
slurries. 相似文献
186.
Isci A Himmelsbach JN Pometto AL Raman DR Anex RP 《Applied biochemistry and biotechnology》2008,144(1):69-77
Simultaneous saccharification and fermentation (SSF) of switchgrass was performed following aqueous ammonia pretreatment.
Switchgrass was soaked in aqueous ammonium hydroxide (30%) with different liquid–solid ratios (5 and 10 ml/g) for either 5
or 10 days. The pretreatment was carried out at atmospheric conditions without agitation. A 40–50% delignification (Klason
lignin basis) was achieved, whereas cellulose content remained unchanged and hemicellulose content decreased by approximately
50%. The Sacccharomyces cerevisiae (D5A)-mediated SSF of ammonia-treated switchgrass was investigated at two glucan loadings (3 and 6%) and three enzyme loadings
(26, 38.5, and 77 FPU/g cellulose), using Spezyme CP. The percentage of maximum theoretical ethanol yield achieved was 72.
Liquid–solid ratio and steeping time affected lignin removal slightly, but did not cause a significant change in overall ethanol
conversion yields at sufficiently high enzyme loadings. These results suggest that ammonia steeping may be an effective method
of pretreatment for lignocellulosic feedstocks. 相似文献
187.
Dutra JC da C Terzi S Bevilaqua JV Damaso MC Couri S Langone MA Senna LF 《Applied biochemistry and biotechnology》2008,147(1-3):63-75
The aim of this study was to monitor the biomass growth of Aspergillus niger in solid-state fermentation (SSF) for lipase production using digital image processing technique. The strain A. niger 11T53A14 was cultivated in SSF using wheat bran as support, which was enriched with 0.91% (m/v) of ammonium sulfate. The addition of several vegetable oils (castor, soybean, olive, corn, and palm oils) was investigated
to enhance lipase production. The maximum lipase activity was obtained using 2% (m/m) castor oil. In these conditions, the growth was evaluated each 24 h for 5 days by the glycosamine content analysis and digital
image processing. Lipase activity was also determined. The results indicated that the digital image process technique can
be used to monitor biomass growth in a SSF process and to correlate biomass growth and enzyme activity. In addition, the immobilized
esterification lipase activity was determined for the butyl oleate synthesis, with and without 50% v/v hexane, resulting in 650 and 120 U/g, respectively. The enzyme was also used for transesterification of soybean oil and ethanol
with maximum yield of 2.4%, after 30 min of reaction. 相似文献
188.
Thomsen MH Holm-Nielsen JB Oleskowicz-Popiel P Thomsen AB 《Applied biochemistry and biotechnology》2008,148(1-3):23-33
To have all-year-round available feedstock, whole-crop maize is harvested premature, when it still contains enough moisture
for the anaerobic ensiling process. Silage preparation is a well-known procedure for preserving plant material. At first,
this method was applied to obtain high-quality animal feed. However, it was found that such ensiled crops are very suitable
for bioenergy production. Maize silage, which consists of hardly degradable lignocellulosic material, hemicellulosic material,
and starch, was evaluated for its potential as a feedstock in the production of bioethanol. It was pretreated at low severity
(185 °C, 15 min) giving very high glucan (∼100%) and hemicellulose recoveries (<80%)—as well as very high ethanol yield in
simultaneous saccharification and fermentation experiments (98% of the theoretical production based on available glucan in
the medium). The theoretical ethanol production of maize silage pretreated at 185 °C for 15 min without oxygen or catalyst
was 392 kg ethanol per ton of dry maize silage. 相似文献
189.
190.
Clavulanic acid is a naturally occurring antibiotic produced by Streptomyces clavuligerus. The present work reports on clavulanic acid production by Streptomyces clavuligerus MTCC 1142 using one-factor-at-a-time and L25 orthogonal array. The one-factor-at-a-time method was adopted to investigate the effect of media components (i.e., carbon
source, nitrogen source and inoculum concentration) and environmental factors such as pH for clavulanic acid production. Production
of clavulanic acid by Streptomyces clavuligerus was investigated using seven different carbon sources (viz. glucose, sucrose, modified starch, rice-bran oil, soybean oil, palm oil, and glycerol) and six different nitrogen sources
(viz. peptone, yeast extract, ammonium chloride, ammonium carbonate, sodium nitrate and potassium nitrate). A maximum yield of
140 μg/mL clavulanic acid was obtained in the medium containing soybean oil as a carbon source and yeast extract as nitrogen
source. Subsequently, the concentration of soybean flour, soybean oil, dextrin, yeast extract and K2HPO4 were optimized using L25 orthogonal array method. The final optimized medium produced 500 μg/mL clavulanic acid at the end of 96 h as compared to
140 μg/mL before optimization. Synthesis of precursor molecules as a metabolic driving force is of considerable importance
in antibiotic synthesis. Attempts to increase the clavulanic acid synthesis by manipulating the anaplerotic flux on C3 and C5 precursors by supplementing the medium with arginine, ornithine, proline, valine, leucine, isoleucine, pyruvic acid and á-ketoglutarate
were successful. Supplementing the optimized medium with 0.1 M arginine and 0.1 M leucine increased the yield of clavulanic acid further to 1100 μg/mL and 1384 μg/mL respectively. 相似文献