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INTRODUCTION Elastase is an enzyme that attacks and solubi-lizes elastin. As elastase can degrade elastin (Mori-hara, 1967) that other proteases cannot; it has broad applications in medical therapy, food processing and daily use chemicals industry. Considerable eff- orts were made to screen the elastase-producing strains, to study its pathogen effect and its charac-terizations (Tsuzuki and Oka, 1965; Tsai et al., 1988; Sharon et al., 1997; Ozaki and Shiio, 1975). Shiio, 1975). Reporte… 相似文献
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The production of elastase by Bacillus sp. EL31410 at various temperatures was investigated. In order to study the effect of temperature on elastase fermentation, different cultivation temperatures, ranging from 39 ℃ to 28 ℃, were evaluated in shake flask. The result indicated that 37 ℃ was best for cell growth at earlier stage; while maximum elastase activity was obtained when the cells were cultivated at 30 ℃. This result was verified by batch fermentation in 5-L bio-reactor under 37 ℃ and 30 ℃ temperature, respectively. The specific cell growth rate at 37 ℃ was higher than that at 30 ℃ during earlier stage of cultivation. The maximum value [5.5 U/(h-g DCW)] of elastase formation rate occurred at 24 h at 30 ℃ compared to 4.6 U/(h-g DCW) at 30 h at 37 ℃. Based on these results, two-stage temperature shift strategy and oscillatory temperature cultivation mode were evaluated in the next study. When compared to single temperature of 37 ℃ or 30 ℃, both two-stage temperature shift strategy and os 相似文献
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嗜热酶的稳定机制和稳定策略的研究进展 总被引：1，自引：0，他引：1
来源于嗜热菌的嗜热酶具有热稳定性和嗜热性。嗜热酶与对应的中温酶序列具有高度的序列同源性、高度相似的三级结构和催化机制。在简单总结了嗜热酶的生化和分子特性后,本文重点讨论了嗜热酶稳定的分子机制和提高蛋白质稳定性的策略。嗜热酶稳定的分子机制包括:氨基酸组成特性、蛋白质分子内的作用力、蛋白质构型的影响、锚定N末端和C末端、环的缩短和固定、翻译后修饰。提高蛋白质热稳定性的策略包括:蛋白质工程策略(序列一致概念、理性设计、定向进化、多肽链延伸和计算模型)、化学修饰法、添加保护剂提高酶的稳定性。 相似文献
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An efficient culture medium producing a bacterial elastase with high yields was developed further following preliminary studies by means of response surface method. Central composite design (CCD) and response surface methodology were applied to optimize the medium constituents. A central composite design was used to explain the combined effect of three medium constituents, viz, glucose, K2HPO4, MgSO4@7H2O. The strain produced more elastase in the completely optimized medium, as compared with the partially optimized medium. The fitted model of the second model, as per RSM,showed that glucose was 7.4 g/100 ml, casein 1.13 g/100 ml, corn steep flour 0.616 g/100 ml, K2HPO4 0.206 g/100 ml and MgSO4@7H2O 0.034 g/100 ml. The fermentation kinetics of these two culture media in the flask experiments were analyzed. It was found that the highest elastase productivity occurred at 54 hours. Higher glucose concentration had inhibitory effect on elastase production. At the same time, we observed that the glucose consumption rate was slow in the completely optimized medium, which can explain the lag period of the highest elastase production. Some metal ions and surfactant additives also affected elastase production and cell growth. 相似文献
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INTRODUCTION β-1,3-1,4-glucan is the major cell wall compo-nent of barley and other cereal endosperms. It consistsof a polymer of glucose monomers joined by β-1,3-and β-1,4-glycosidic bonds in an irregular fashion(Woodward et al., 1983; Edney et al., 1991). Due toits unique structure, barley β-glucan can be dissolvedin water in high molecular mass and resulting in ahigh viscosity solution. The high-molecular-massβ-glucan released during mashing causes severe fil-tration problems and… 相似文献
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The optimization of cultural conditions for β-glucanase production by Bacillus subtilis ZJF-1A5 was investigated in flask trials. Temperature had gre at effect on β-glucanase production which maximized at optimal temperature of 37 ℃ and decreased significantly when temperature was over 37℃.Charge quantity af fected β-glucanase production significantly. Adding oxygen vector N-dodec ane or acetic ether benefited β-glucanase production, but it depended on the conc entrat ion and charge quantity. The results of fractional factorial design showed that age and size of inoculum and shaking speed were the key factors affecting β -gluc anase production and the cultivation time span to reach the highest β-gluc anase activity. The optimal cultural conditions for β-glucanase production obtai ned wi th CCD were as follows: inoculum age and size (16 h, 3.82%(v/v)), shaking speed 2 10 r/min, charge quantity of 30 mL in 250 mL flask and initial pH 7.0, cultured at 37℃ for 50 h. Repeated experimental results accorded with those predicted b y a second-order polynomial model. The amount of β-glucanase, α-amylase and neut ral protease produced by B subtilis ZJF-1A5 was associated partially with c ell g rowth. Those three enzymes' activities increased following the cell growth and i ncreased significantly when cells entered the stationary phase. 相似文献
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INTRODUCTION Butyric acid has several potential applications in industry. Its applications in the foodstuffs and beverage industries are widespread. It may be used as the pure acid in the dairy industry, or in the form of esters as a food additive to increase fruit fragrance. Furthermore, butyric acid could also have some important physiological functions. For example, butyric acid esters are the character-impact flavors in tropic fruits and dairy products (Centeno et al., 2002; Watson e… 相似文献
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INTRODUCTIONβ 1 ,3 1 ,4 glucanisthemajorcellwallcom ponentofbarleyandothercerealendosperm ,andconsistsofpolymersofglucosemonomersjoinedbyβ 1 ,3 andβ 1 ,4glycosidicbondsinanon regularfashion (Woodwardetal.,1 983 ;Edneyetal.,1 991 ) .High molecular mas… 相似文献