Amylase production by Aspergillus oryzae in a solid‐state bioreactor with fed‐batch operation using mussel processing wastewaters as feeding medium

BACKGROUND: The high oxygen availability in solid‐state cultures makes them especially suitable for fungal enzyme production. Glycogen‐rich mussel processing wastewaters have been used successfully as substrates for amylase production by Aspegillus oryzae in solid‐state cultures supported in polyurethane foam. The aim of this work was to study the fed‐batch mode in a scalable solid‐state bioreactor to extend the productive period and obtain high amylase production. Culture salinization due to the NaCl content of these wastewaters is the main drawback. RESULTS: Evaporation of the excess liquid added during feeding led to progressive salt accumulation. The effect of culture salinization on amylase production was analysed and mathematically modelled, and the IC₅₀ (65.4 g L^?1 of NaCl) was calculated. An optimum operation mode for this bioreactor was designed that included foam extrusion for removing the incubated medium, washing and a final recharge with fresh medium every 72 h of incubation. This procedure kept the salt concentration under IC₅₀ and increased the amylase production from 3000 to 12 000 UE g^?1. CONCLUSION: An operating mode with intermittent extrusions and washings of the support between feedings was found to be an appropriate procedure for preventing the accumulation of inhibitory compounds in fed‐batch solid‐state cultures. © 2012 Society of Chemical Industry     

Raw-Starch Degrading Amylase(s) Affect Enzyme-resistant Starch

Enzyme-resistant starch (RS) was degraded, in part, by amylase(s) that act on raw starch. The degradation (solubilization) was accompanied by changes in several characteristics (peak temperature and enthalpy) and, probably, by the presence of a lipid-amylose complex. The degradation resulted in a significant reduction in one of the two main contiguous peaks of RS around 155°C.     

荞麦制麦过程中的主要酶学特性

制造荞麦麦芽,并以荞麦麦芽为主料,研究了荞麦萌发的生化特性及萌发过程中制麦酶系活性变化的规律。考察了荞麦在发芽过程中α-淀粉酶、β-淀粉酶、多酚氧化酶、纤维素酶、蛋白酶在0~192 h酶活的变化情况,应用酶活分析方法确定了发芽的时间,找出了最适的发芽条件。结果表明,采用浸3断8的浸麦方式,浸麦及发芽温度为16℃,制麦6 d,所制备的荞麦麦芽酶活力最高。     

长期定位施肥对潮土分形维数的影响

试验选用1日龄健康肉用雏鹅108只，随机分为6组，分别饲喂玉米型饲粮、小麦型饲粮以及在小麦饲粮中添加不同浓度木聚糖酶的饲粮。结果表明：（1）小麦饲粮中添加0.2％和0.3％木聚糖酶能降低胃及十二指肠指数（P〉O．05）,添加量为0．2％时低于玉米组水平，添加0.3％木聚糖酶能降低空回肠及盲肠指数（P〉O．05）；添加0．1％和0．2％木聚糖酶时能降低肝脏指数（P〉O．05）,添加0.3％木聚糖酶时能降低胰腺指数（P〉O．05）。（2）在小麦饲粮中添加木聚糖酶能够改善肉鹅蛋白酶活性,添加量为0．2％时比小麦对照组高出34．38％（P〈O．01），效果最佳；木聚糖酶的添加同样能够改善肉鹅淀粉酶的活性，添加量为0．1％时比小麦对照组高出20.57％（P〈O．05），为最适添加量。     

紫甘薯β-淀粉酶提取纯化及稳定性的研究

对紫甘薯β-淀粉酶的稳定性进行了研究。结果表明紫甘薯β-淀粉酶在40～50℃有较好的热稳定性;在pH 5.0～7.0时有较好的稳定性,该酶对酸的耐受性相对较强而对碱的耐受性较弱。     

环保型棉织物退浆用胰酶的制备技术

研究从猪胰腺中提取适合纺织品退浆工艺要求的胰酶新工艺。使用猪十二指肠、胰酶粉为酶激活剂，异丙醇为提取溶剂，并用0．2％壳聚糖在10％条件下沉淀酶蛋白18h，制得酶制品中，淀粉酶活力可达92244个单位，收率达12％。该工艺简单易行，使用有机溶剂少，保护环境。产品酶活力高，适合退浆工艺要求。     

淀粉酶在文化纸中的应用

淀粉酶可以降解原淀粉液到任何所需的黏度,利用淀粉酶的这个特点,可以转化原淀粉液到适当的黏度,应用于文化纸的表面施胶中,从实验室小试和车间中试都得到了比较理想的效果。     

Enzyme activities,dietary fibre components and rheological properties of wholemeal flours from rye cultivars grown in Finland

Total and soluble dietary fibre, total and soluble pentosan and β‐glucan contents, activities of α‐amylase (EC 3.2.1.1) and endo‐β‐xylanase (EC 3.2.1.8) and viscous properties of aqueous suspensions of wholemeal flours during heating were determined in nine winter rye cultivars (Secale cereale L) grown in Finland in 1998–2001. There was marked annual and varietal differences in grain quality. In the rainy summer 1998 the yield was low, grains were small and dietary fibre content of the grains was high. Xylanase activity of the grains was high, which corresponded to the high content of soluble pentosans. In the dry summer of 1999, the pentosan content of the grains was low and β‐glucan content high. The effect of weather conditions and cultivar were also apparent in the differences in falling numbers, amylogram and swelling curve results. The two hybrid rye cultivars Esprit and Picasso had consistently highest falling numbers and amylogram peak viscosities. The activities of α‐amylase and xylanase had a moderate positive correlation with total pentosan content and the content of soluble pentosan. Xylanase activity had better correlation with the viscous properties of flour–water suspensions than α‐amylase. Surprisingly, α‐amylase activity had only a moderate negative correlation with falling number. Copyright © 2005 Society of Chemical Industry