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141.
Singh OV 《Applied biochemistry and biotechnology》2006,135(1):43-57
Aspergillus niger ORS-4.410, a mutant of A. niger ORS-4, was generated by repeated ultraviolet (UV) irradiation. Analysis of the UV treatment dose on wild-type (WT) A. niger ORS-4, conidial survival, and frequency of mutation showed that the maximum frequency of positive mutants (25.5%) was obtained
with a 57% conidial survival rate after the second stage of UV irradiation. The level of glucose oxidase (GOX) production
from mutant A. niger ORS-4.410 thus obtained was 149% higher than that for WT strain A. niger ORS-4 under liquid culture conditions using hexacyanoferrate (HCF)-treated sugarcane molasses (TM) as a cheaper carbohydrate
source. When subcultured monthly for 24 mo, the mutant strain had consistent levels of GOX production (2.62±0.51 U/mL). Mutant
A. niger ORS-4.410 was markedly different from the parent strain morphologically and was found to grow abundantly on sugarcane molasses.
The mutant strain showed 3.43-fold increases in GOX levels (2.62±0.51 U/mL) using HCF-TM compared with the crude form of cane
molasses (0.762±0.158 U/mL).
The results reported herein were obtained while the author was working at the Department of Biotechnology, Indian Institute
of Technology, Roorkee-247667, India. 相似文献
142.
Dilute-acid softwood hydrolysate, with glucose and xylose as the dominant sugars was fermented to ethanol by co-cultures.
The strains used include Saccharomyces cerevisiae 2.535 (1#), Pachysolen tannophilis ATCC 2.1662 (2#), and recombinant Escherichia coli (3#) constructed in our laboratory carrying both pdc and adhB genes derived from Zymomonas mobilis. Before fermentation, the co-cultures were adapted for five batches. Observation under light microscope showed aggregation
of adapted strains, which could possibly improve their ability to degrade inhibitors. In addition, we tried to detoxify the
dilute-acid softwood hydrolysate with a combined method before fermentation. Our study showed that fermentation of detoxified
hydrolysate by adapted co-culture (1# + 2@) generated an exceptionally high ethanol yield on total sugar of 0.49 g/g, corresponding
to 96.1% of the maximal theoretical value after 48h; fermentation of detoxified hydrolysate by adapted co-culture (1# + 3#)
is faster (24h) and could reach a high ethanol yield (0.45 g/g total sugar). These experiments suggest that both adaptation
and detoxification significantly improve hydrolysate fermentation and ethanol production. 相似文献
143.
Lactic acid fermentation in cell-recycle membrane bioreactor 总被引:2,自引:0,他引:2
Traditional lactic acid fermentation suffers from low productivity and low product purity. Cell-recycle fermentation has become
one of the methods to obtain high cell density, which results in higher productivity. Lactic acid fermentation was investigated
in a cell-recycle membrane bioreactor at higher substrate concentrations of 100 and 120 g/dm3. A maximum cell density of 145 g/dm3 and a maximum productivity of 34 g/(dm3…h) were achieved in cell-recycle fermentation. In spite of complete consumption of substrate, there was a continuous increase
in cell density in cell-recycle fermentation. Control of cell density in cell-recycle fermentation was attempted by cell bleeding
and reduction in yeast extract concentration. 相似文献
144.
In this paper, a mathematical model for the lactic acid fermentation in membrane bioreactor is investigated. Firstly, continuous input substrate is taken. The existence and local stability of two equilibria are studied. According to Poincare-Bendixson theorem, we obtain the condition for the globally asymptotical stability of the equilibria. Secondly, using the Floquet’s theorem and small-amplitude perturbation method, we obtain the biomass-free periodic solution is locally stable if R2 < 1. The permanent conditions of the system are also given. Finally, our findings are confirmed by means of numerical simulations. 相似文献
145.
Dmitri Pismenni Vassili Kiritsenko Jaroslav Marhivka Mary-Liis Kütt Raivo Vilu 《Molecules (Basel, Switzerland)》2021,26(12)
Saccharides are the most common carbon source for Streptococcus thermophilus, which is a widely used bacterium in the production of fermented dairy products. The performance of the strain is influenced by the consumption of different saccharides during fermentation. Therefore, a precise measurement of the concentrations of saccharides in the fermentation media is essential. An 18-min long method with limits of quantitation in the range of 0.159–0.704 mg/L and with 13C labelled internal standards employing hydrophilic interaction chromatography coupled to mass spectrometric detection-(HILIC-LC-MS) allowed for simultaneous quantification of five saccharides: fructose, glucose, galactose, sucrose, and lactose in the fermentation samples. The method included a four-step sample preparation protocol, which could be easily applied to high-throughput analysis. The developed method was validated and applied to the fermentation samples produced by Streptococcus thermophilus. 相似文献
146.
The potential market for lactic acid as the feedstock for biodegradable polymers, oxygenated chemicals, and specialty chemicals
is significant. L-lactic acid is often the desired enantiomer for such applications. However, stereospecific lactobacilli
do not metabolize starch efficiently. In this work, Argonne researchers have developed a process to convert starchy feedstocks
into L-lactic acid. The processing steps include starch recovery, continuous liquefaction, and simultaneous saccharification
and fermentation. Over 100 g/L of lactic acid was produced in less than 48 h. The optical purity of the product was greater
than 95%. This process has potential economical advantages over the conventional process. 相似文献
147.
Belkacemi Khaled Turcotte Ginette Halleux Damien de Savoie Philippe 《Applied biochemistry and biotechnology》1998,(1):441-462
Lignocellulosic materials derived from forages, namely timothy grass, alfalfa, reed canary grass, and agricultural residues,
such as corn stalks and barley straw, were pretreated using ammonia fiber explosion (AFEX) process. The pretreated materials
were directly saccharified by cellulolytic enzymes. Sixty to 80% of theoretical yield of sugars were obtained from the pretreated
biomasses. Subsequent ethanolic fermentation of the hydrolysates byPachysolen tannophilus ATCC 32691 resulted in 40-60% of theoretical yield after 24 h, based on the sugars present in the hydrolysates. The uptake
of sugars was not complete, indicating a possible inhibitory effect onP. tannophilus during the fermentation of these substrates. 相似文献
148.
《Arabian Journal of Chemistry》2022,15(12):104315
The green and high-value recycling of shrimp shell and straw remains a worldwide problem. This study aimed to investigate the potential utilization of a fermentation broth (FB) which contains shrimp shell and straw as a new source for preparation of biodegradable films. Aureobasidium pullulans and Photobacterium sp. LYM-1 were used in the fermentation. The cellulase activity was 115.92 U/mL and chitinase activity was 17.89 U/mL in FB. The polysaccharides concentration in FB was 1.05 mg/mL after 7 days of fermentation. An eco-friendly PVA-reinforced FB biodegradable film (FBBF) was successfully prepared and the effect of different plasticizers and surfactants on the mechanical, structural, and impermeability properties of the film was determined. The formation of new bonds between PVA and FB was proved by FTIR spectroscopy. The FBBF containing 0.25 % (w/v) glycerol and 0.01 % (v/v) tween-20 showed better strength properties. Elongation and water-swelling properties were highly improved by adding 0.2 % (m/v) citric acid. According to FE-SEM images, the smooth and tight surface of citric acid added FBBF was observed. Interestingly, the FBBF film showed good heat/moisture capacity, antifungal, and degradation properties. This report reveals a new green, and high-value recycling of straw and shrimp shell by the co-fermentation with A. pullulans and Photobacterium sp. LYM-1. It is also a novel way for the preparation of biodegradable film. 相似文献
149.
Junker BH Hesse M Burgess B Masurekar P Connors N Seeley A 《Applied biochemistry and biotechnology》2004,119(3):241-277
Culture pelleting and morphology has a strong influence on process productivity and success for fungal and filamentous bacterial
cultures. This impact is particularly evident with early phase secondary metabolite processes with limited process definition.
A compilation of factors affecting filamentous or pelleting morphology described in the literature indicates potential leads
for developing process-specific control methodologies. An evaluation of the factors mediating citric acid production is one
example of an industrially important application of these techniques. For five model fungal and filamentous bacterial processes
in an industrial fermentation pilot plant, process development strategies were developed and effectively implemented with
the goal of achieving reasonable fermentation titers early in the process development cycle. Examples of approaches included
the use of additives to minimize pelleting in inoculum shake flasks, the use of large-volume frozen bagged inoculum obtained
from agitated seed fermentors, and variations in production medium composition and fermentor operating conditions. Results
were evaluated with respect to productivity of desired secondary metabolites as well as process scalability. On-line measurements
were utilized to indirectly evaluate the cultivation impact of changes in medium and process development. Key laboratory to
pilot plant scale-up issues also were identified and often addressed in subsequent cultivations. 相似文献
150.
K. C. Thomas S. H. Hynes A. M. Jones W. M. Ingledew 《Applied biochemistry and biotechnology》1993,43(3):211-226
Very high gravity (VHG) wheat mashes containing more than 300 g of dissolved solids per liter were prepared and fermented
with active dry yeast at 20, 25, 30, and 35°C with and without yeast extract as nutrient supplement. At 20°C, mashes with
38% (w/v) dissolved solids end-fermented without any nutrient supplementation and maximum ethanol yields of 23.8% (v/v) were
obtained. With increasing temperatures, the sugar consumption decreased. Addition of yeast extract stimulated the rate of
fermentation at all temperatures, but did not increase the total amount of sugar consumed. The stimulatory effect of yeast
extract on cell multiplication decreased with increasing sugar concentration, and virtually no difference in cell number was
observed between yeast extract-supplemented and unsupplemented mashes at sugar concentrations above 33% (w/v). The fermentative
capacity of the yeast (expressed as maximum specific rate of sugar consumption) remained the same at all sugar concentrations
in unsupplemented mashes, but decreased in yeast extract-supplemented mashes at sugar concentrations below 33% (w/v). When
the sugar concentration was above 33% sugar (w/v), the fermentative capacity in yeast extract-supplemented mashes was greater
than that observed in unsupplemented samples. 相似文献