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1.
在正交预备试验得出有机废弃物分解产生CO2适宜条件的基础上,逐一进行单因子试验,以获得利用农业废弃物分解产生的CO2进行棚室栽培CO2施肥的最适发酵条件.结果表明,利用有机废弃物(稻草+猪粪)生物发酵产生CO2的最佳条件分别为:温度50℃、含水量70%、初始pH6.0~7.0.初始C/N比因发酵目的不同有较大变化,以堆肥为目的时为30/1,而以产生CO2为目的时,则以40/1为宜.在4个因素中,初始C/N比和含水量对CO2释放的影响较大,其次是温度,初始pH的影响最小.  相似文献   

2.
影响被孢霉产生含γ-亚麻酸油脂的几种因素   总被引:6,自引:0,他引:6  
对培养条件,如氮源种类、C/N比率、pH、种子种龄与接种量对被孢霉(Mortierellasp.)M14菌株的细胞生长和油脂形成的影响作了研究。结果表明,二级发酵优于一级发酵。M14菌株二级发酵时,种子种龄以49h为适,接种量宜大(30%)。无机氮源有利于不饱和脂肪酸的产生,有机氮源有利于细胞的增殖。低C/N比率有利于菌丝体产量的提高,提高C/N比率则能促进菌体细胞内的油脂合成。pH对菌体生长、油脂产生以及γ-亚麻酸含量都有显著的影响。  相似文献   

3.
粗糙脉孢菌(Neurospora crassa)木糖发酵的研究   总被引:8,自引:0,他引:8  
研究了不同通氧条件和培养基初始pH等对粗糙脉孢菌(Neurospora crassa)AS3.1602木糖发酵的影响。结果表明,粗糙脉孢菌具有较强的发酵木糖产生乙醇及木糖醇的能力。通气量对木糖发酵有较大的影响。乙醇发酵适合在半好氧条件下进行,此时乙醇的转化率达到63.2%。木糖醇发酵适合在微好氧的条件下进行,转化率达到31.8%。木糖醇是在培养基中乙醇达到一定浓度后才开始积累。培养基的初始pH对木糖发酵产物有较大的影响,乙醇产生最适pH5.0,木糖醇产生最适pH4.0。在培养基pH为碱性条件时,木糖发酵受到很大的抑制。初始木糖浓度对产物乙醇及木糖醇的产率有很大的影响。葡萄糖的存在会抑制木糖的利用,对乙醇和木糖醇的产生也有很大的影响。  相似文献   

4.
对新分离得到的能产生维生素C前体2-酮基-L-古龙酸(2-KGA)的优良菌株蛭弧菌J26,进行了一系列摇瓶发酵条件试验,通过添加一些其它有机碳源或其它氮源,可使蛭弧菌J26摇瓶发酵产生2-KGA由50-60mg/ml上升到70mg/ml以上,采用SMA探针技术的流加发酵摇瓶试验产生2-KGA可以达到83.9-91.7mg/ml。本文还对发酵时种子液的接种量、发酵初始精浓度、初始pH值等对产酸的影响,进行了比较研究,对摇瓶发酵全过程的单一菌体形态特征进行了电子显微镜观察。  相似文献   

5.
通过研究加工番茄污水污泥的有机污染物降解变化和好氧发酵条件(含水量、p H、C/N、含氧量和CO2)来确定番茄污水中有机污染物降解情况,从而优化加工番茄废水处理。结果表明:最佳生物好氧发酵条件为含水量60%~80%,C/N范围为5~10,氧气浓度10%,p H=6.5,污泥发酵15 h后,有机物降解速率达到平衡。  相似文献   

6.
枯草芽孢杆菌产β-甘露聚糖酶固体发酵条件的优化   总被引:1,自引:0,他引:1  
芽孢杆菌是产甘露聚糖酶的优良菌株,首次研究芽孢杆菌固体发酵条件的优化。以天然麸皮作为基本原料,研究利用枯草芽孢杆菌WY34固体发酵生产β-片露聚糖酶的发酵条件。最佳固体发酵培养条件为:麸皮5g,初始水分含量71%,初始pH7.0,接种量为2mL,1%Tween-80,0.4g魔芋粉,培养温度50℃。在最适条件下培养5d,甘露聚糖酶酶活高达7,650U/g干基,是未优化前酶活的2.78倍。  相似文献   

7.
[目的] 研究樟绒枝霉(Malbranchea cinnamomea) CAU521利用农业废弃物固体发酵产木聚糖酶的发酵条件.[方法]采用单因素试验法优化影响菌株产酶的各个条件,包括碳源种类、氮源种类、初始pH、初始水分含量、培养温度及发酵时间共6个因素.[结果]获得的最佳产酶条件为:稻草为发酵碳源、2%(W/W)的酵母提取物为氮源、初始pH 7.0、初始水分含量80%和发酵温度45℃.在此条件下发酵6d后木聚糖酶的酶活力达到13 120 U/g干基碳源.[结论]樟绒枝霉固体发酵产木聚糖酶的产酶水平高,生产成本低,具有潜在的工业化应用前景.  相似文献   

8.
对瑞拉菌GAO-1-GR-2的发酵条件进行了单因素研究,通过正交试验设计对该菌株的培养基进行了筛选。并对其发酵条件进行了研究,结果表明:有机氮源以酵母粉和黄豆饼粉为宜;碳源以葡萄糖和饴糖最好,但考虑到发酵成苓,应选用葡萄糖2%。发酵培养基应呈中性,以采用自然pH为宜,pH超过8,或小于7,则会抑制发酵产物活性;通气量为1:0.5最好,能降低20%耗氧量;摇床转速140r/min,培养温度30℃,发酵周期72h。抗生素发酵原粉效价能达到4000μg/mL。  相似文献   

9.
从5龄家蚕肠道分离筛选得到一株产纤维素酶菌株BMC-2,以羧甲基纤维素酶(CMCase)比活力为响应值,通过Plackett-Burman试验设计、最陡爬坡试验和Box-Behnken试验设计对菌株BMC-2产纤维素酶发酵条件进行优化,结果表明,发酵时间、发酵温度、培养基初始pH和转速对CMCase比活力具有显著影响,其影响程度由大到小依次为发酵时间、培养基初始pH、发酵温度、转速.确定菌株BMC-2产纤维素酶最优发酵条件为:发酵时间94.35 h,发酵温度30.3℃,培养基初始pH 7.01,转速179 r/min.在此条件下, CMCase比活力理论值为25.801 U/mg,验证值为25.526 U/mg,较产酶条件优化前提高了1倍,预测模型可靠性高,可应用于菌株BMC-2产纤维素酶条件的优化.  相似文献   

10.
一个水解纤维素的嗜热厌氧菌新种   总被引:2,自引:0,他引:2  
本文报告了一株分解纤维素的嗜热厌氧菌。该菌株细胞革兰氏阴性,直或微弯杆状,大小0.2-0·6x1·5—9 0μm,以单端丛生鞭毛游动,形成端生膨大芽孢。可利用多种碳水化合物。在纤维素培养基中产生黄色。发酵纤维素的主要产物为乙醇、乙酸、CO2和H2。最适生长温度60℃,生长温度范围40—70℃;最适生长pH7.3—7.5。DNA中G+C含量为34mol%。经鉴定,它与已知的嗜热纤维素水解菌均有较大差别,定名为产黄纤维素梭菌(Clostridiumcelluloflavum sp.nov.)。  相似文献   

11.
Changes in organic C, total N, C:N ratio, activities of cellulase, xylanase and protease, and microbial population were determined during composting of different organic wastes such as mixture of sugarcane trash and cattle dung, press mud, poultry waste and water hyacinth biomass. There were losses of N in poultry waste and water hyacinth with the effect an initial increase in C:N ratio was observed which decreased later on due to decomposition. The activities of cellulase, xylanase and protease were maximum between 30 and 60 days of composting in various wastes. Similar trend was observed with respect to mesophilic bacterial and fungal population. Various quality parameters like C:N ratio, water soluble C (WSC), CO(2) evolution and level of humic substances were compared after 90 day composting. There was statistically significant correlation between C:N ratio and CO(2) evolution, WSC and humic substances. Significant correlation between CO(2) evolved and level of humic substances was also observed. The study shows that no single parameter can be taken as an index of compost maturity. However, C:N ratio and CO(2) evolved from finished compost can be taken as the most reliable indices of compost maturity.  相似文献   

12.
The Donnan ratio for chloride ion (rCl) was determined for human red cells in plasma utilizing 36Cl. The effect of altered PCO2 and pH on rCl was followed in two ways. CO2 partial pressure was varied (1-1.5% CO2 in O2; pH range 7.1-7.9) at 37.5 degrees C (isothermal); PCO2 and pH were also changed by altering temperature (range 5-45 degrees C) at constant CO2 content (temperature induced). At pH 7.4 and 37.5 degrees C, rCl was 0.631 +/- 0.0269 (SE, N = 5); isothermal drcl/dpH = -0.306 +/- 0.0234. When measured under conditions of variable temperature at constant CO2 content (pH range 7.3-7.9), drcl/dpH = .018 +/- 0.0232, significantly different from isothermal response (P less than 0.001). Hematocrit (H) changes with pH for conditions of initial H(7.4) of 0.45, under these conditions were also determined: isothermal dH/dpH = -0.031 +/- 0.0019; temperature induced, -0.004 +/- 0.0009. Temperature change alone at constant carbon dioxide content produces no significant change in distribution of chloride ions or water between erythrocyte and plasma compartments.  相似文献   

13.

Aims

The study aimed to find soil parameters that are best related to Se plant uptake for low Se soils with predominantly organic Se, and to explore the mechanisms that control Se bioavailability in the soils under study.

Methods

A pot experiment using nineteen soil samples taken from different fields of arable land (potato fields) in the Netherlands was conducted on summer wheat (Triticum aestivum L.). Selenium in wheat shoots and soil parameters, including basic soil properties, C:N ratio, inorganic selenite content, and Se and organic C in different soil extractions (0.01 M CaCl2, 0.43 M HNO3, hot water, ammonium oxalate, aqua regia) were analysed. Regression analysis was performed to identify soil parameters that determine Se content in wheat shoots.

Results

The regression model shows that Se:DOC ratio in 0.01 M CaCl2 soil extraction explained about 88 % of the variability of Se uptake in wheat shoots. Selenium uptake increased with Se:DOC ratio in CaCl2 extraction, which can be interpreted as a measure of the content of soluble Se-rich organic molecules. Selenium:DOC ratio in CaCl2 extraction and Se uptake increased towards higher soil pH and lower soil C:N ratio. The soil C:N ratio is also negatively correlated to Se:organic C ratio in other extractions (0.43 M HNO3, hot water, ammonium oxalate, aqua regia), indicating that at low soil C:N ratio soil organic matter is richer in Se. Contrarily, the soil pH is positively and strongly correlated to Se:organic C ratio in CaCl2 and hot water extractions, but only weakly correlated to Se:organic C ratio in other extractions.

Conclusions

Selenium-rich dissolved organic matter is the source of bioavailable Se in low Se soils with predominantly organic Se. The soil pH and quality of soil organic matter (i.e. soil C:N ratio) are the main soil properties determining Se bioavailability in these soil types.
  相似文献   

14.
高产洛伐他汀棒曲霉菌株的筛选、鉴定及发酵条件优化   总被引:1,自引:0,他引:1  
从不同生境(食品、土壤、空气、有机质等)收集到的自然发酵样品中分离得到150株曲霉属菌株.用高效液相色谱(HPLC)法检测发酵液中洛伐他汀(Lovastatin)含量,筛选获得1株稳定高产Lovastatin的曲霉菌株(编号:Ac-32).根据菌落形态特征并结合18 S rDNA测序,鉴定其为棒曲霉(Aspergillus clavatus).通过摇瓶发酵单因素实验优化了碳氮源种类、碳氮源含量、碳氮比(C/N)、发酵温度、初始pH、转速、种龄和接种量,确定了棒曲霉菌株Ac-32摇瓶发酵产Lovastatin的适宜条件为:乳糖为碳源、蛋白胨为氮源、碳源含量为100 g/L、氮源含量为12 g/L、碳氮比(C/N)为15:1.8、温度28℃、转速180 r/min、初始pH 5.2、种龄4 d、接种量6%.采用Minitab 17软件的P-B实验设计法,筛选对Lovastatin产量有显著影响的因素为:温度、pH、碳源含量和氮源含量.根据P-B实验结果,运用响应面法分析,确定棒曲霉菌株Ac-32产Lovastatin的最优条件为:碳源含量100 g/L,氮源含量11.8 g/L,温度28℃,pH 5.2.在此条件下,Lovastatin最高产量为236.221μg/mL.  相似文献   

15.
Mo M  Xu C  Zhang K 《Mycopathologia》2005,159(3):381-387
The effects of carbon and nitrogen sources, carbon-to-nitrogen ratio (C:N) and initial pH value on the growth and sporulation of the nematophagous fungus Pochonia chlamydosporia in liquid culture were examined. Among the 21 carbon sources and 15 nitrogen compounds tested, the optimal carbon and nitrogen sources for mycelial growth were sweet potato and L-tyrosine, and for sporulation were sweet potato and casein peptone. A C:N ratio of 10:1 at pH 3.7 gave the maximum yield of conidia and a C:N ratio of 40:1 at pH 6.8 gave the maximum biomass. The initial pH value had a significant effect on mycelial growth and conidial production, with the optimal ranges being 3.5–4.5 for sporulation and 5–6 for growth. Maximum conidial production was obtained at an initial pH of 4.0 and the maximum biomass at pH 6.0. The results also showed that the final pH after 7 days cultivation was always higher than the initial value. The variability in growth and sporulation of seven strains of P. chlamydosporia in liquid culture was also compared and discussed.  相似文献   

16.
The conditions of polysaccharide production by the fungus Ganoderma lucidum were optimized. The maximal yield of endopolysaccharides and exopolysaccharides was observed at 25–30°C, initial pH of culture medium 4.0–6.0, and at a C:N ratio of 18:1 and 25:1, respectively. The greatest yield of mycelium was reached at a more intensive aeration, and the maximal yield of polysaccharides was observed at a less intensive aeration. The optimal ratio between fungus growth and polysaccharide production was observed at 100 rpm and an aeration of 1.0– 1.5 1/1 medium·min.Translated from Prikladnaya Biokhimiya i Mikrobiologiya, Vol. 41, No. 2, 2005, pp. 194–199.Original Russian Text Copyright © 2005 by Babitskaya, Shcherba, Puchkova, Smirnov.  相似文献   

17.
According to the theory of optimal nitrogen partitioning within a leaf, the chlorophyll (Chl) a/b ratio is expected to increase when leaf N content decreases. Here, we report the first empirical support for this prediction. The Chl a/b ratio increased while Chl content decreased in response to N limitation in photosynthetic cotyledons and leaves of seedlings of four tropical woody species in the Bignoniaceae. The responses of all four species were in the same direction, but differed in magnitude. For Tabebuia rosea, the species that exhibited the greatest increase in Chl a/b ratios (up to values of 5.9), detailed photosynthetic characteristics were also examined. Light and N availability were positively correlated with the light- and CO2-saturated photosynthetic O2 evolution rate, as well as with leaf carboxylation capacity (Vcmax) and electron transport rate (Vj). Severe N limitation and high light did not cause chronic photo-inhibition (i.e. no change in quantum yield or in dark-acclimated Fv/Fm). The observed change in the ratio of Vcmax to leaf N in response to N availability was consistent with likely functional reasons for change in the Chl a/b ratio. Adjustment of the Chl a/b ratio was apparently an integral feature of acclimation to high light conditions and low N availability.  相似文献   

18.
Based on the curvilinear relationship between leaf nitrogen content and the initial slope of the response of CO(2) assimilation (A:) to intercellular CO(2) concentrations (C:(i)) in apple, it is hypothesized that Rubisco activation state decreases with increasing leaf N content and this decreased activation state accounts for the curvilinear relationship between leaf N and CO(2) assimilation. A range of leaf N content (1.0-5.0 g m(-2)) was achieved by fertilizing bench-grafted Fuji/M.26 apple (Malus domestica Borkh.) trees for 45 d with different N concentrations, using a modified Hoagland's solution. Analysis of A:/C:(i) curves under saturating light indicated that CO(2) assimilation at ambient CO(2) fell within the Rubisco limitation region of the A:/C:(i) curves, regardless of leaf N status. Initial Rubisco activity showed a curvilinear response to leaf N. In contrast, total Rubisco activity increased linearly with increasing leaf N throughout the leaf N range. As a result, Rubisco activation state decreased with increasing leaf N. Both light-saturated CO(2) assimilation at ambient CO(2) and the initial slope of the A:/C:(i) curves were linearly related to initial Rubisco activity, but curvilinearly related to total Rubisco activity. The curvatures in the relationships of both light-saturated CO(2) assimilation at ambient CO(2) and the initial slope of the A:/C:(i) curves with total Rubisco activity were more pronounced than in their relationships with leaf N. This was because the ratio of total Rubisco activity to leaf N increased with increasing leaf N. As leaf N increased, photosynthetic N use efficiency declined with decreasing Rubisco activation state.  相似文献   

19.
Effect of environmental parameters on the biodegradation of oil sludge.   总被引:24,自引:0,他引:24  
A laboratory study was conducted with the aim of evaluating and optimizing the environmental parameters of "landfarming", i.e., the disposal by biodegradation in soil of oily sludges generated in the refining of crude oil and related operations. Oil sludge biodegradation was monitored by CO2 evolution and by periodic analysis of residual hydrocarbons. The parameters studied were soil moisture, pH, mineral nutrients, micronutrients, organic supplements, treatment rate, teratment frequency, and incubation temperature. Oil sludge biodegradation was optimal at a soil water-holding capacity of 30 to 90%, a pH of 7.5 to 7.8, C:N and C:P ratios of 60:1 and 800:1, respectively, and a temperature of 20 degrees C or above. Addition of micronutrients and organic supplements was not beneficial; sewage sludge interfered with hydrocarbon biodegradation. Breakdown of the saturated hydrocarbon (alkane and cycloalkane) fraction was the highest at low application rates, but higher application rates favored the biodegradation of the aromatic and asphaltic fractions. An application rate of 5% (wt/wt) oil sludge hydrocarbon to the soil (100,000 liters/hectare) achieved a good compromise between high biodegradation rates and efficient land use and resulted in the best overall biodegradation rate of all hydrocarbon classes. Frequent small applications resulted in higher biodegradation than single large applications. Two 100,000-liter/hectare (255 barrels per acre) or four 50,000-liter/hectare oil sludge hydrocarbon applications per growing season seem appropriate for most temperate zone disposal sites.  相似文献   

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