共查询到20条相似文献,搜索用时 15 毫秒
1.
Isabell Sommer 《当今生物学》2018,48(3):190-194
Why bread dough rises, although yeast cannot metabolize starch: Experiments with yeast Yeast is ideal for simple experiments to visualize metabolic processes, such as those known from baking bread, for example. Thus the metabolism of different sugars to carbon dioxide can be qualitatively demonstrated by inflating balloons or quantitatively by gas production in a fermentation tube (glass airlock for fermentation). The experiments presented can be used to answer the question of why yeast is added to bread dough even though it is not able to convert the starch present in the flour. 相似文献
2.
Sets of simulations of run-away fermentations were structured as two-level factorial experimental designs with parameters in a mathematical model as factors. By this technique it was possible to document the robustness and sensitivity of the model and to show why run-away fermentations may be difficult to control in practice. In an engineering approach to fermentation development it is beneficial to integrate simulation of fermentation experiments with real fermentation experiments in order to get a better planning and interpretation. 相似文献
3.
采用单因素试验和正交试验研究发酵培养基组成,优化Streptomyces sp. FIM-16-06产他克莫司的发酵条件,探讨摇瓶发酵的主要影响因子初始p H、装液量、转速等发酵参数的影响。确定了适宜的发酵培养基和发酵参数:6. 0%玉米淀粉、2. 0%黄豆粉、2. 0%葡萄糖和0. 5%玉米浆,初始pH 7. 5,装液量50 m L/500 m L三角瓶,种子菌龄48 h,接种量10%,摇床转速250 r/min,发酵温度27℃,发酵周期7 d。优化后的发酵水平较原生产工艺提高60%以上。他克莫司的优化发酵工艺为其工业化生产奠定了基础。 相似文献
4.
固定化对酵母细胞发酵产ATP能力的影响 总被引:1,自引:0,他引:1
通过试验对酵母菌细胞的固定化方法及固定化酵母细胞在发酵生产ATP方面的应用进行了探讨。综合固定化颗粒的性能指标(粒径、弹性和机械强度)和发酵产ATP的能力,通过正交试验对酵母菌细胞的包埋条件进行了优化,确定了固定化酵母细胞的较优组合为聚乙烯醇3.5%、海藻酸钠2%、CaCl23%及交联时间6h,发酵后ATP含量最高,达到0.716g/L。进一步发酵条件的试验证实,固定化能提高酵母菌细胞对温度适应范围,延长发酵生产周期,从而提高菌体的利用率。 相似文献
5.
S. S. Salek R. Kleerebezem H. M. Jonkers J. H. L. Voncken M. C. M. van Loosdrecht 《Applied microbiology and biotechnology》2013,97(6):2743-2752
Silicate minerals can be a source of calcium and alkalinity, enabling CO2 sequestration in the form of carbonates. For this to occur, the mineral needs to be first dissolved in an acidifying process such as the biological process of anaerobic fermentation. In the present study, the main factors which govern the dissolution process of an alkaline silicate mineral (wollastonite, CaSiO3) in an anaerobic fermentation process were determined. Wollastonite dissolution kinetics was measured in a series of chemical batch experiments in order to be able to estimate the required amount of alkaline silicate that can neutralize the acidifying fermentation process. An anaerobic fermentation of glucose with wollastonite as the neutralizing agent was consequently performed in a fed-batch reactor. Results of this experiment were compared with an abiotic (control) fed-batch reactor in which the fermentation products (i.e. organic acids and alcohols) were externally supplied to the system at comparable rates and proportions, in order to provide chemical conditions similar to those during the biotic (fermentation) experiment. This procedure enabled us to determine whether dissolution of wollastonite was solely enhanced by production of organic acids or whether there were other impacts that fermentative bacteria could have on the mineral dissolution rate. The established pH profiles, which were the direct indicator of the dissolution rate, were comparable in both experiments suggesting that the mineral dissolution rate was mostly influenced by the quantity of the organic acids produced. 相似文献
6.
Summary The experiments on the fermentation of glucose to ethanol were carried out using the yeast Saccharomyces carlsbergensis W 34. The fermentation time could be reduced to 6 hours. Biomass degradation products such as cellobiose, dihydroxyacetone, glyceraldehyde, showed no or little effect on the fermentation rate. Hydroxymethylfurfural, furfural, methylglyoxal and lignin compounds such as phenol and vanillin inhibit the fermentation in the 1 to 10 mg/mL range very decisively. 相似文献
7.
啤酒酵母是啤酒酿造的灵魂,可以直接影响啤酒品质。在啤酒酿造过程中,由于啤酒酵母被多次传代和保藏,造成优良菌种发酵性能衰退等问题,导致发酵不彻底,影响最后啤酒的风味质量。为此以8株Lager型啤酒酵母为出发菌株,通过平板分离纯化获得80株分离菌株,再经过三角瓶发酵初筛和复筛、发酵罐中试发酵实验最终获得了8株发酵性能优良的啤酒酵母。其中,6株酵母可应用于酿造双乙酰含量低于0.1 mg/L的啤酒;3株酵母发酵度高于70%,适合酿造干啤酒;1株酵母发酵度低于50%,适合酿造低醇啤酒。在风味方面:1株酵母酿造的啤酒醇酯比为3.3,啤酒酯香味较突出;另1株酵母酿造的啤酒醇酯比为4.5,啤酒高级醇含量较高。8株经过选育的啤酒酵母发酵特征明显,便于精酿啤酒厂实际应用。 相似文献
8.
Summary Neural networks were compared to factorial experiments as techniques for designing fermentation media. The production of intracellular
oil byRhodotorula gracilis (Rhodosporidium toruloides) was used as a model system. Investigating three factors, the molasses, ammonium nitrate and yeast extract concentrations,
each at three concentrations, 27 experiments were required for a complete factorial expriment. In contrast, neural networks
could be trained on 10 experiments and predict the test experiments with reasonable accuracy. This represents a 63% saving
in the number of experiments that need to be conducted. Thus neural networks are a useful tool in developing fermentation
medium. 相似文献
9.
Cornelia List Zhaleh Hosseini Karin Lederballe Meibom Vassily Hatzimanikatis Rizlan Bernier-Latmani 《Environmental microbiology》2019,21(10):3548-3563
Iron is essential for most living organisms. In addition, its biogeochemical cycling influences important processes in the geosphere (e.g., the mobilization or immobilization of trace elements and contaminants). The reduction of Fe(III) to Fe(II) can be catalysed microbially, particularly by metal-respiring bacteria utilizing Fe(III) as a terminal electron acceptor. Furthermore, Gram-positive fermentative iron reducers are known to reduce Fe(III) by using it as a sink for excess reducing equivalents, as a form of enhanced fermentation. Here, we use the Gram-positive fermentative bacterium Clostridium acetobutylicum as a model system due to its ability to reduce heavy metals. We investigated the reduction of soluble and solid iron during fermentation. We found that exogenous (resazurin, resorufin, anthraquinone-2,6-disulfonate) as well as endogenous (riboflavin) electron mediators enhance solid iron reduction. In addition, iron reduction buffers the pH, and elicits a shift in the carbon and electron flow to less reduced products relative to fermentation. This study underscores the role fermentative bacteria can play in iron cycling and provides insights into the metabolic profile of coupled fermentation and iron reduction with laboratory experiments and metabolic network modelling. 相似文献
10.
11.
A. M. Breure H. H. Beeftink J. Verkuijlen J. G. van Andel 《Applied microbiology and biotechnology》1986,23(3-4):245-249
Summary The influence of the adaptation procedure on the simultaneous fermentation of glucose and gelatin by putatively carbon-limited mixed anaerobic bacterial populations was investigated. In one series of experiments glucose, dissolved in a mineral salts solution, was fed to mixed populations of bacteria in anaerobic carbon-limited chemostat cultures maintained at different pH values and at 30°C. When, after reaching a steady state, the carbon substrate was switched to gelatin, growth ceased. However, when gelatin was added to the medium as a second carbon substrate, it was found in all cases that hydrolysis and fermentation of the protein proceeded to a limited extent (<30%) and that glucose continued to be completely metabolized. In a second series of experiments, bacterial populations were adapted to gelatin under comparable experimental conditions. After reaching a steady state, glucose was added to the medium as a second carbon substrate. Following establishment of the new steady state it was found that hydrolysis of gelatin was not inhibited but its fermentation was. It is concluded that anaerobic bacterial populations can loose their ability to degrade a protein substrate, depending on the adaptation procedure. 相似文献
12.
In this work, generalised additive models (GAMs) were used for the first time to model the fermentation of glutamate (Glu). It was found that three fermentation parameters fermentation time (T), dissolved oxygen (DO) and oxygen uptake rate (OUR) could capture 97% variance of the production of Glu during the fermentation process through a GAM model calibrated using online data from 15 fermentation experiments. This model was applied to investigate the individual and combined effects of T, DO and OUR on the production of Glu. The conditions to optimize the fermentation process were proposed based on the simulation study from this model. Results suggested that the production of Glu can reach a high level by controlling concentration levels of DO and OUR to the proposed optimization conditions during the fermentation process. The GAM approach therefore provides an alternative way to model and optimize the fermentation process of Glu. 相似文献
13.
14.
15.
混合菌群发酵秸秆可有效提高秸秆纤维的降解率及菌体蛋白的转化率,对拓广蛋白饲料来源、减少环境污染起到积极的作用。本研究以小麦秸秆为原料,在纤维素酶水解预处理的基础上,以米曲霉作为先导菌,进一步分解残留的粗纤维,为后期发酵提供充足的碳源。根据不同微生物的代谢特征和协同机理,试验确定了发酵阶段混合菌群的组成为:米曲霉、产朊假丝酵母和枯草芽胞杆菌;接种顺序为:先接种米曲霉,再接种产朊假丝酵母,最后接种枯草芽胞杆菌。正交试验表明,影响发酵主要因素的主次顺序为:秸秆与麸皮配比>接种比例>发酵时间>接种量>发酵温度;发酵的最适条件为:米曲霉的接种量2.5%,发酵12h后接入5%的产朊假丝酵母,继续发酵8h后接入2.5%的枯草芽胞杆菌,发酵温度为28℃,秸秆与麸皮的配比为4∶1,尿素添加量为1.2%;结合动力学分析,将混合菌群的发酵时间优化为35h,发酵产物中粗蛋白含量由原来的5.47%提高到25%左右。对最适发酵条件下的动力学过程进行了探讨,建立了以Logistic方程为基础的数学模型和动力学方程。本研究表明,混合菌群发酵秸秆提高了发酵产物中的粗蛋白含量。动力学分析对于了解发酵机理、掌握整个发酵过程中混合菌群生长的动态变化、优化发酵工艺具有重要的指导意义。 相似文献
16.
在单因素试验初步确定高产蛹虫草菌株发酵培养基的基础上,以蛹虫草茵丝体中腺苷含量为指标,进行11因素2水平Plackett—Burman试验设计试验,结合多元一次回归模型和F检验方法,筛选出发酵培养基中影响显著的组分酵母浸粉、蔗糖和维生素B1,采用旋转中心组合设计方法对这三个组分进行进一步优化,结合多元二次回归模型和响应面分析,获得高产蛹虫草菌株的最佳培养基(g/L):蔗糖18.85、蛋白胨10、酵母浸粉18.97、KH2PO,3、MgSO4 3、维生素Bl0.235、ZnCl20.011、(NH4)2S0410。验证试验结果表明蛹虫草腺苷得率较单因素优化获得的发酵培养基提高了26.91%。 相似文献
17.
以发酵液对镰刀菌孢子萌发的抑制率为指标,通过单因素试验,研究不同碳源、氮源、生长因子对灵芝S3发酵液抑菌活性的影响。运用响应面法,对各营养组分的含量进行优化。优化后碳源、氮源、生长因子含量分别为:乳糖3.04%,蛋白胨0.28%,VB1 0.0047%,抑菌率为91.71%,比基础发酵培养基增加了42.15%。发酵液作用12h后,光学显微镜下镰刀菌菌丝出现膨大和消融等畸变,并出现典型的“念珠状”形态;透射电镜显示镰刀菌孢子内出现大量空泡、原生质收缩,说明灵芝S3发酵液中的活性物质可有效抑制菌丝生长及孢子萌发。 相似文献
18.
A novel Sensor Reactor technology is presented which permits 13C labeling experiments for metabolic flux analysis during large-scale, semi-industrial, (fed-) batch fermentation processes deriving a series of flux maps that document fermentation courses in detail. The small-scale Sensor Reactor can be inoculated within 1.50-1.20s via a special inoculation unit with an inoculation volume accuracy of 1.025+/-0.021 L. The large-scale production reactor (here: 300 L) and the Sensor Reactor were run in parallel master/slave modes to control the current pH, temperature, pressure and dissolved oxygen values as changing set points for the Sensor Reactor. Using an automated pulsing technology, glucose pulses of 5 g/L could be realized within 0.51 s. The similarity of fermentations in the Sensor Reactor with the production process was demonstrated by studying L-lysine production with C. glutamicum during multiple, 'simulated' labeling experiments each lasting 2.5h. 'Real' labeling experiments are presented in Part II. 相似文献
19.
Impacts of main factors on bioethanol fermentation from stalk juice of sweet sorghum by immobilized Saccharomyces cerevisiae (CICC 1308) 总被引:1,自引:0,他引:1
In order to attain a higher ethanol yield and faster ethanol fermentation rate, orthogonal experiments of ethanol fermentation with immobilized yeast from stalk juice of sweet sorghum were carried out in the shaking flasks to investigate the effect of main factors, namely, fermentation temperature, agitation rate, particles stuffing rate and pH on ethanol yield and CO(2) weight loss rate. The range analysis and analysis of variance (ANOVA) were applied for the results of orthogonal experiments. Results showed that the optimal condition for bioethanol fermentation should be A(4)B(3)C(3)D(4), namely, fermentation temperature, agitation rate, particles stuffing rate and pH were 37 degrees C, 200rpm, 25% and 5.0, respectively. The verification experiments were carried out in shaking flasks and 5L bioreactor at the corresponding parameters. The results of verification experiments in the shaking flasks showed that ethanol yield and CO(2) weight loss rate were 98.07% and 1.020gh(-1), respectively. The results of ethanol fermentation in the 5L bioreactor showed that ethanol yield and fermentation time were 93.24% and 11h, respectively. As a result, it could be concluded that the determined optimal condition A(4)B(3)C(3)D(4) was suitable and reasonable for the ethanol fermentation by immobilized Saccharomyces cerevisiae. The conclusion in the research would be beneficial for application of ethanol fermentation by immobilized S. cerevisiae from stalk juice of sweet sorghum. 相似文献
20.
We propose a dynamic model of alcoholic fermentation in wine-making conditions. In this model, the speed at which CO(2) is released is related to the effects of the main factors involved in fermentation in wine-making conditions: temperature (which can vary within a predefined range) and nitrogen additions (which must not exceed the maximal authorized level). The resulting model consists of ordinary differential equations including numerous parameters that need to be identified and important interactions between explicative variables. These parameters were identified by uncoupling the effects of variables during specific experiments. The results were validated on another series of experiments in different conditions. 相似文献