共查询到19条相似文献，搜索用时 177 毫秒
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利用均匀设计法对Bacillus sp．ZJU318产酶的最佳培养基进行了快速优化研究。结果表明，其最适产酶培养基为：3．28％黄豆粉，0．023％蔗糖，0．075％K2HPO4，配制时的pH为12（灭菌后pH为8～9）；此外，其发酵的最佳条件为：发酵温度28℃，接种量20％，摇瓶装量20mL（250mL三角瓶）。在最适的发酵条件下，脂肪酶的发酵水平可达24．7U／mL。Bacillus sp．ZJU318脂肪酶作用的最适温度为45℃，40℃保温1h，活力几乎没有损失；但是，在50℃和60℃的条件下保温1h后，酶活降低得比较明显；酶作用的最适pH为9．0。在pH7～10，该脂肪酶较稳定，但是在酸性的环境中，酶的稳定性较低。 相似文献
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将改性硅藻土作为吸附剂用于处理印染废水,设计实验考察改性硅藻土用量、pH值、吸附时间等因素对印染废水中色度和CODcr的去除率的影响,并确定了改性硅藻土吸附印染废水中色度和CODcr的最佳条件。结果显示,最佳吸附条件为改性硅藻土加入量为0．8～1．0g／L,pH值6—9,室温条件下,处理时间为60min。处理后的印染废水中色度和0．8～1．0g／L浓度达到国家污水排放标准。 相似文献
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A2/O工艺即厌氧/缺氧/好氧生物脱氮除磷工艺是Anaerobic/Anoxic/Oxic的简称,因具有同时去除有机物、脱氮、除磷且处理成本较低而得到广泛应用。该工艺要求在厌氧、缺氧和好氧三种环境条件交替运行下将微生物菌群共存于同一污泥系统中,同时兼顾脱氮除磷效率,另外反硝化和聚磷菌释磷都需要有机碳源,而一般城市污水的COD/TN比值较低,这使得脱氮除磷效率因诸多因素影响而受到限制。因此要保证A2/O工艺的正常运行,产生最佳的处理效果,工艺条件就必须需要严格控制,但在实际操作中,严格控制这些条件是有一定难度的。为解决这一工艺运行中的内部矛盾,可以采取以下几种措施:包括对各个反应段溶解氧的监测及控制;根据实验数据调整污泥回流比并提高混合液回流比;针对碳源不足的情况适量补充碳源;采用控制污泥龄的方式,提高脱氮除磷处理效果。本文浅析了国内外有关的A2/O工艺改良与优化的技术和方法,介绍了倒置A2/O工艺、PASF工艺和UCT工艺,为工程实践提供参考。 相似文献
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东北地区8种毒蘑菇菌株生物学特性的研究 总被引：1，自引：0，他引：1
采用植物病理学及菌物学的研究方法对8个毒蘑菇菌株的生物学特性进行研究,结果表明：（1）白霜伞、绒白乳菇、厚环鹅膏、珊瑚菌、冠状环柄菇、鳞柄白鹅膏6菌株菌丝生长的最适温度为25℃,细鳞环柄菇和鹅膏菌2菌株菌丝生长的最适温度为20℃。（2）各菌株生长最适碳源,除珊瑚菌为麦芽糖,冠状环柄菇为木糖外,其它6菌株均为葡萄糖。（3）除白霜杯伞在无氮条件下生长最好外,其他7菌株生长最佳氮源均为蛋白胨。（4）各菌株生长最适pH值：鹅膏菌、厚环鹅膏、细鳞环柄菇、鳞柄白鹅膏、珊瑚菌为6．0。绒白乳菇和冠状环柄菇为7．0,白霜杯伞为7．5,均属于喜稍偏碱出坏境的菌株。 相似文献
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目的：测定谷丙甘氧酸胶囊中谷氧酸、丙氨酸、甘氧酸含量。方法：采用SS EXSIL ODS（250%＊4．6mm，5μm）色谱柱，0．05mol／L的醋酸钠溶液（pH6．4）：乙腈：水（70：15：5）为流动相的高效液相色谱法。结果：谷氧酸、丙氨酸、甘氨酸分别在132—308μg，48-112μg，24—56μg范围内线形良好（r=0．9998，0．9997，0．9996）；平均回收率分别为99．8％，99．8％，99．7；RSD分别为0．54％，0．62％，0．72％。结论：该方法简便快速，适用于谷丙甘氨酸胶囊中3组分含量的测定。’ 相似文献
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以抚仙湖的新鲜沉积物作为实验材料,进行内源性磷释放实验,分析沉积物上覆水及间隙水中磷酸盐含量在培养过程中随pH值、氧化还原电位(Eh)的变化情况。本研究分析结果表明,在好氧与厌氧的条件下,磷酸盐含量随pH值、Eh值的变化呈现先增后减的变化规律。然而,这样的变化规律不是pH或者Eh独立影响下产生的,而是二者共同影响下发生的。 相似文献
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苯酚降解菌株FY-6的初步鉴定及苯酚降解特性的研究 总被引：4，自引：0，他引：4
苯酚降解菌株FY-6经形态观察和生理生化反应鉴定为假单胞菌(Pseudomonas sp.).对不同温度、pH以及不同苯酚浓度培养基中菌株的生长和苯酚降解效率进行了研究.结果表明,FY-6菌株能在无机盐培养基中以苯酚为唯一碳源和能源进行生长,并同时对苯甲酸和萘有一定的降解作用.在温度为25～40℃、pH6～9和苯酚浓度400～1400 mg/L范围内,FY-6菌株的生长及苯酚降解效率均达到较高水平,因此,初步认定该菌株能适应较广泛的环境条件,并对苯酚浓度具较高的耐受性. 相似文献
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The buffering effect of acetate on hydrogen production during glucose fermentation by Ethanoligenens harbinense B49 was investigated compared to phosphate, a widely used fermentative hydrogen production buffer. Specific concentrations of sodium acetate or phosphate were added to batch cultures, and the effects on hydrogen production were comparatively analyzed using a modified Gompertz model. Adding 50 mM acetate or phosphate suppressed the hydrogen production peak and slightly extended the lag phase. However, the overall hydrogen yields were 113.5 and 108.5 mmol/L, respectively, and the final pH was effectively controlled. Acetate buffered against hydrogen production more effectively than did phosphate, promoting cell growth and preventing decreased pH. At buffer concentrations 100–250 mM, the maximum hydrogen production was barely suppressed, and the lag phase extended past 7 h. Therefore, although acetate inhibits hydrogen production, using acetate as a buffer (like phosphate) effectively prevented pH drops and increased substrate consumption, enhancing hydrogen production. 相似文献
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热带假丝酵母（Candida tropicalis）是长碳链二元酸发酵生产中的常用菌种,而热带假丝酵母突变株HP-2-48是一株高产DC12的优良生产菌株。本文对十二碳二元酸的发酵进行了研究,考察了青霉素钠盐、尿素、丙烯酸、pH值对菌体生长、产酸的影响并对其作用机制进行了讨论,并据此建立了长碳链二元酸新的发酵工艺。 相似文献
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探索催化剂的最佳制备条件及合成反应的最佳工艺条件,从而使C02和乙醇反应合成乙酸乙酯具有较高的选择性和收率。结果表明：用氢氧化钠作沉淀剂,采用共沉淀法制备Cu／Zn／A1／Co催化剂,沉淀时PH值为11,Cu、Zn、AI物质的量之比为9：8：15,加入Co的量为Cu、Zn、Al物质量总和的15％时制备所得的催化剂活性最好;在反应温度400℃,反应压力0．6MPa,乙醇与二氧化碳进料体积比为1：150,乙醇进料速度为0．3mL／min时合成反应最佳,此时乙醇的转化率为53．33％,乙酸乙酯的产率为9．77％,乙酸乙酯的选择性为18．33％。 相似文献
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Urinary abnormalities were evaluated in 100 renal stone patients with first episode of renal stone having age 22 to 45 years
from both sex and compared to 100 normal healthy control group having same age group from both sex. Twenty-four hours urinary
oxalate, calcium, uric acid, sodium, magnesium, phosphorus and citrate were estimated. The urinary pH was also determined.
In stone formers urinary oxalate, calcium, sodium and uric acid excretions were significantly higher when compared with control
group. Whereas citrate, phosphate and magnesium excretion were significantly lower in stone formers when compared with control.
The pH of urine in stone formers was lower than the controls. High dietary intake of purine rich diet causes elevated excretion
of uric acid, which leads to calcium oxalate crystal formation and precipitation. Other risk factors such as urinary oxalate,
calcium also related to formation of renal calculi.
Hypocitraturia is the main cause of renal calculi along with hypomagnesiuria and hypophosphaturia in the patient of Marathwada
region. On the basis of urinary abnormalities further stone formation in the patient can be prevented by dietary modifications. 相似文献
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BackgroundBiosurfactants are surface active molecules produced by microorganisms which have the ability to disrupt the plasma membrane. Biosurfactant properties are important in the food, pharmaceutical and oil industries. Lactic acid bacteria can produce cell-bound and excreted biosurfactants.ResultsThe biosurfactant-producing ability of three Lactobacillus strains was analyzed, and the effects of carbon and nitrogen sources and aeration conditions were studied. The three species of lactobacillus evaluated were able to produce biosurfactants in anaerobic conditions, which was measured as the capacity of one extract to reduce the surface tension compared to a control. The decreasing order of biosurfactant production was L. plantarum>Lactobacillus sp.>L. acidophilus. Lactose was a better carbon source than glucose, achieving a 23.8% reduction in surface tension versus 12.9% for glucose. Two complex nitrogen sources are required for growth and biosurfactant production. The maximum production was reached at 48 h under stationary conditions. However, the highest level of production occurred in the exponential phase. Biosurfactant exhibits a critical micelle concentration of 0.359 ± 0.001 g/L and a low toxicity against E. coli. Fourier transform infrared spectroscopy indicated a glycoprotein structure. Additionally, the kinetics of fermentation were modeled using a logistic model for the biomass and the product, achieving a good fit (R2 > 0.9).ConclusionsL. plantarum derived biosurfactant production was enhanced using adequate carbon and nitrogen sources, the biosurfactant is complex in structure and because of its low toxicity could be applied to enhance cell permeability in E. coli.How to cite: Montoya Vallejo C, Florez Restrepo MA, Guzmán Duque FL, et al. Production, characterization and kinetic model of biosurfactant produced by lactic acid bacteria. Electron J Biotechnol 2021;53. https://doi.org/10.1016/j.ejbt.2021.06.001 相似文献
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长白山地区蒙古栎光合特性 总被引：15，自引：0，他引：15
基于单叶尺度上的光强－光合响应以及CO2－光合响应测定，对长白山地区蒙古栎成树和幼树的光合特性分别进行了研究．结果表明，蒙古栎成树的光补偿点（Lcp）为21μmol/m2/s，光饱和点（Lsp）为1564μmol/m2/s，表观量子效率（a）为0.045μmol/mol；幼树的Lcp、Lsp、a以及CO2补偿点、饱和点分别为29μmol/m2/s、1581μmol/m2/s、0.049μmol/mol、73μmol/mol、625μmol/mol．幼树和成树具有相似的光响应特征，但前者的光合同化能力要高于后者．蒙古栎具有典型的喜光性，但对高光的利用效率要低于弱光． 相似文献
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A. Ahmed A. K. Pendse S. K. Rajpurohit P. P. Singh 《Indian journal of clinical biochemistry : IJCB》1992,7(2):171-178
Acid challenge test was carried out on 87 subjects (37 normal and 50 radiologically proven stone formers) to assess their renal acidification capacity. NS were given three doses viz. 75, 100 and 150 mg NH4Cl/Kg body weight while the SF were tested with only 150 mg dose which was found to be an adequate dose. Ammonium chloride was given in gelatin capsules with breakfast and hourly urine samples were collected for next 7 hours. pH, creatinine, calcium, inorganic phosphorus, citrate, titrable acid and ammonium were analysed in all the samples. The incidence of renal tubular acidosis (RTA) in NS, tested with 75 mg and 100 mg/kg doses of ammonium chloride, was 50% and 10% respectively while it was nil and 24% respectively in NS and SF tested with 150mg/kg dose. Complete RTA was detected in one SF. No significant difference was observed in urinary profile of NS and SF except that the hourly titrable acid excretion was lower in later. A comparison between with and without RTA SF revealed that titrable acid and phosphate excretion decreased in RTA defect. Overall data indicate that (a) RTA was an etiologic factor in one fourth of the SF; (b) an oral acid challenge test is a good adjunct to detect this condition and (c) acid challenge increases calcium, phosphate and titrable acid excretion and decreases citrate. 相似文献
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《Electronic Journal of Biotechnology》2014,17(6):262-267
BackgroundThe Tibetan pig is a pig breed with excellent grazing characteristics indigenous to the Qinghai–Tibet plateau in China. Under conditions of barn feeding, 90% of its diet consists of forage grass, which helps meet its nutritional needs. The present study aimed to isolate and identify a cellulolytic bacterium from the Tibetan pig's intestine and investigate cellulase production by this bacterium. The study purpose is to provide a basic theory for the research and development of herbivore characteristics and to identify a source of probiotics from the Tibetan pig.ResultsA cellulolytic bacterium was isolated from a Tibetan pig's intestine and identified based on morphological, physiological, and biochemical characteristics as well as 16S rRNA analysis; it was designated Bacillus subtilis BY-2. Examination of its growth characteristics showed that its growth curve entered the logarithmic phase after 8–12 h and the stable growth phase being between 20 and 40 h. The best carbon source for fermentation was 1% corn flour, while 2% peptone and yeast powder compound were the best nitrogen sources. The initial pH during fermentation was 5.5, with 4% inoculum, resulting in a high and stable amount of enzyme in 24–48 h.ConclusionsThe isolated BY-2 strain rapidly grew and produced cellulase. We believe that BY-2 cellulase can help overcome the shortage of endogenous animal cellulase, improve the utilization rate of roughage, and provide strain sources for research on porcine probiotics. 相似文献