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一株产纤维素酶的耐热烟曲霉筛选及产酶条件研究 总被引:1,自引:0,他引:1
从土壤中分离和筛选到l株产纤维素酶能力较强的耐热真菌E4.通过菌株的形态特征和18S rDNA序列同源性比较,该菌株被鉴定为一种烟曲霉(Aspergillus fumigatus).实验结果表明,该菌株能在20℃以下生长,其最适和最高生长温度分别为40℃和55℃.该菌株的最佳产纤维素酶的基质为稻草,其最适产酶pH值为5.0,最适产酶温度为42℃.50℃摇瓶培养72h时可达到产酶最高峰,其羧甲基纤维素酶(CMCase)活和滤纸酶(FPA)活分别达到3.5U/mL和3.2U/mL.该菌株对稻草的降解效果较好,45℃液体摇床培养条件下在7d内对天然稻草的降解率达63.5%. 相似文献
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青霉P-1007产胞外酸性蛋白酶,其酶活可达1500u/g。该酶的最适温度为50℃,最适pH值为5.5;酶的pH稳定性和耐温性较好,在pH5.5,:50℃条件下保温8h,其相对酶活仍在83%以上;在pH值为5.5,60℃条件下水浴2h后,相对酶活为60%。不同金属盐对该酶酶活及不同氮源、碳源、温度、pH、含水量以及发酵时间对菌株产酶的影响试验结果表明:MnCl2,CuSO4均对该酶有激活作用,其他金属盐类对该酶有不同程度的抑制作用;添加黄豆粉(1%)和葡萄糖(1%)可使菌株产酶酶活分别提高71%和31%;培养温度为40℃以及培养基起始pH为7.0时产酶最高;含水量和发酵时间对产酶也有不同程度的影响。 相似文献
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产耐热纤维素酶菌株的分子鉴定及产酶条件优化 总被引:2,自引:0,他引:2
从温泉热源地区采集的水样中筛选出1株60℃生长的纤维素酶产生菌NR615。通过ITS序列及系统发育进化树的分析表明该菌株为烟曲霉(Aspergillus fumigatus)。该菌株在28~60℃生长较好。对菌体及产酶条件进行优化得出:初始pH6.5,碳、氮源分别为结晶纤维素、牛肉膏时有利于产酶。其产生的纤维素酶的最适反应温度65℃,最适pH5.0,且在50~70℃有一定稳定的活性。经过响应面分析优化培养基,发酵5 d时活力达到2.411 3 IU/mL。这些特征表明,该菌株是1株性能良好的耐热纤维素酶生产菌株。 相似文献
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产纤维素酶海洋菌株的分离及培养条件研究 总被引:1,自引:0,他引:1
从烟台近海处采集样品,用羧甲基纤维素钠刚果红培养基筛选得到一株高产纤维素酶的菌株,初步鉴定为革兰氏阴性芽孢杆菌。用羧甲基纤维素酶活测定法,确定了最佳酶促反应温度,并研究了培养时间、pH值,碳源、氮源等培养条件对菌体产酶的影响。结果显示,最适酶促反应温度为40℃,培养时间为54h,最适pH值为7.5,最佳碳源为羧甲基纤维素钠,最佳生长氮源为酵母膏,最佳产酶氮源为硫酸铵。与陆地纤维素酶产生菌相比,海洋纤维素产生菌所产纤维素酶具有低温催化的优势。 相似文献
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以甘啤3号大麦为原料,从中分离得到了2株生长能力较强的菌株,通过对该菌产生的β-葡聚糖酶、木聚糖酶、纤维素酶和糖化酶的酶活情况进行研究及生理生化鉴定得出该菌株为白地霉,分别为白地霉GQG28.1和白地霉GQG28.2。对筛选到的白地霉GQG28生长特性的初步研究表明,该菌最适生长温度为25℃,生长温度范围为5℃~37℃,其最适生长pH5.6,最低生长pH值为3.2,最高生长pH值为11.0,利用该白地霉制得麦芽综合指标为206.15,所制麦芽糖化力为308.5WK、α-氨基氮为186mg/100g、浸出物相对质量分数为87.1%。 相似文献
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该研究从酱香型高温大曲中筛选出产淀粉酶芽孢杆菌,对筛选菌株进行形态学观察、分子生物学鉴定以及高温驯化,并针对驯化前后所产淀粉酶进行酶学性质研究。结果表明,分离筛选到的产淀粉酶菌株Amy Z5为贝莱斯芽孢杆菌(Bacillus velezensis),在45℃培养条件下生物量及淀粉酶活性有较大幅度降低。菌株Amy Z5经高温驯化,生长温度提高至45℃,并缩短对高温环境的适应期,培养3 h时OD600 nm值即提高4.2倍。高温驯化后的菌株HTAmyZ5所产淀粉酶的最适反应温度从40℃提高至70℃,最适反应pH仍为3,在20~90℃及pH 1~7条件下酶活均能保持在60%以上,pH 9时仍有40%的酶活;最高酶活性提高了3.1倍,达到322.1 U/m L;但稳定性受到高温环境影响略有下降。该研究对酱香型大曲微生物高温发酵、原料高效持久利用及关键香气成分的形成均具有一定的参考意义。 相似文献
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纤维素酶高产菌筛选鉴定及酶学性质初步研究 总被引:2,自引:0,他引:2
该研究从土壤中筛选出一株纤维素酶高产菌株SP08,并通过菌落形态特征和ITS测序技术对菌株进行鉴定,最后通过酶促反应初步测定了该菌所产纤维素酶的性质。结果表明,筛选得到菌株SP08,经鉴定为康氏木霉(Trichoderma koningii),该菌株具有较高的纤维素酶产酶能力,培养60 h时纤维素酶活性即达(18.54±0.75),72 h时酶活达到最高(19.18±0.68)U/mL。酶学研究表明,菌株SP08所产纤维素酶最适温度和pH分别为50 ℃和5.5,在20~50 ℃及pH4.0~6.0时稳定性较高;Mg2+、Mn2+和Ca2+能够提高该酶活性,而Fe2+和Cu2+却对该酶具有抑制作用。 相似文献
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Figueroa-González I Quijano G Ramírez G Cruz-Guerrero A 《Journal of the science of food and agriculture》2011,91(8):1341-1348
Owing to their health benefits, probiotics and prebiotics are nowadays widely used in yogurts and fermented milks, which are leader products of functional foods worldwide. The world market for functional foods has grown rapidly in the last three decades, with an estimated size in 2003 of ca US$ 33 billion, while the European market estimation exceeded US$ 2 billion in the same year. However, the production of probiotics and prebiotics at industrial scale faces several challenges, including the search for economical and abundant raw materials for prebiotic production, the low-cost production of probiotics and the improvement of probiotic viability after storage or during the manufacturing process of the functional food. In this review, functional foods based on probiotics and prebiotics are introduced as a key biotechnological field with tremendous potential for innovation. A concise state of the art addressing the fundamentals and challenges for the development of new probiotic- and prebiotic-based foods is presented, the niches for future research being clearly identified and discussed. 相似文献
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常用消毒灭菌法及其机理与应用 总被引:3,自引:0,他引:3
介绍了采用消毒灭菌方法,有加热消毒法,紫外线辐射法和化学药剂消毒法。常用化学药剂有醛类、含氯消毒剂、醇类消毒剂以及高锰酸钾、生石灰等,阐释了消毒与灭菌两个概念的区别。 相似文献
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Wim Verbeke Federico J.A. Pérez-Cueto Marcia D. de Barcellos Athanasios Krystallis Klaus G. Grunert 《Meat science》2010
This paper presents the combined mid-term findings of the consumer research components of two EU Sixth Framework Programme integrated projects concerning meat, ProSafeBeef and Q-PorkChains. The consumer pillar of ProSafeBeef carried out eight focus group discussions in May 2008, in France, Germany, Spain and the UK. Q-PorkChains conducted a large-scale, web-based, consumer survey in January 2008 in Belgium, Denmark, Germany, Greece and Poland. The first project provides a set of qualitative data from a small cohort of focus groups and the second a set of quantitative data from a larger consumer sample. This paper draws together the main findings of both projects and provides a comprehensive overview of European citizens’ and consumers’ attitudes towards and preferences regarding beef and pork. In general, consumers consider meat to be a healthy and important component of the diet. Consumers support the development of technologies that can improve the health attributes of meat products and guarantee eating quality, but they have a negative view of what they see to be excessive manipulation and lack of naturalness in the production and processing of beef products. In the Q-PorkChains study consumer and citizen segments are identified and profiled. Consumer segments were built upon the frequency and variety of pork consumption. The citizen segments were built upon their attitudes towards pig production systems. Overall, the relationship between individuals’ views as citizens and their behaviour as consumers was found to be quite weak and did not appear to greatly or systematically influence meat-buying habits. Future studies in both projects will concentrate on consumers’ acceptance of innovative meat product concepts and products, with the aim of boosting consumer trust and invigorating the European beef and pork industries. 相似文献
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The objectives of the current study were to investigate the relationship between body condition score (BCS) and dairy form and changes in genetic parameters for BCS and dairy form within and across lactations and age. Body condition score and dairy form were obtained from the Holstein Association USA, Inc. Records were edited to include those cows classified between 24 and 60 mo of age and between 0 and 335 d in milk (DIM). A minimum of 20 daughters per sire and 15 cows per herd-classification visit were required. The dataset consisted of 135,178 records from 119,215 cows. Repeatability, multiple trait, and random regression models were used to analyze the data. All models included fixed effects for herd-classification visit, age within lactations 1, 2, and 3 or higher, and 5th-order polynomials for DIM. Random effects included sire and permanent environment for all models. Random regression models included age at classification nested within sire or DIM and lactation number nested within sire. Genetic variance for both BCS and dairy form was lowest in early lactation and highest in midlactation. Genetic correlations within and across lactations were high. The genetic correlation between DIM 0 in lactation 1 and DIM 305 in lactation 3 was estimated to be 0.77 for BCS and 0.60 for dairy form. The genetic correlation estimate between 30 mo of age at classification and 50 mo of age at classification was 0.94 for both dairy form and BCS. The repeatability models appeared to generate accurate evaluations for BCS or dairy form at all ages and stages of lactation. 相似文献
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果蔬可以提供营养, 有利于人类健康, 而果蔬的后熟及其与环境的相互作用会影响果蔬采后的质量和安全。对果蔬生物学过程的了解和掌握是减少果蔬采后损失和保障果蔬采后质量和安全的关键。在过去的10多年, 基于组学技术的系统生物学在了解果蔬后熟及其与环境相互作用的分子机制方面得到了越来越多的应用。本文对此做了细致的总结, 指出了存在的不足, 并提出了未来的发展方向。 相似文献
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《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2013,30(12):2190-2200
ABSTRACTAlthough consumption of eggs is an essential part of our diet, limited information is available for table eggs other than those laid by hens. The aim of our study was to determine concentrations of polychlorinated dibenzofurans (PCDD/Fs), dioxin-like (DL-) and non-dioxin-like (NDL) polychlorinated biphenyls (PCBs) in ostrich eggs and meat available on the Polish market, in order to obtain baseline information on the current status of these pollutants in comparison to poultry products. Obtained data were compared with the binding EU limits set for chicken eggs and meat. The levels of individual PCDD/Fs and PCBs congeners varied considerably. The percentage share of total WHO toxic equivalency factor (WHO-TEQ) content indicates the dominant role of PCDD/Fs. High concentrations of PCDD/F and DL-PCBs, in the range of 0.85–74.48 pg WHO-TEQ g?1 fat, were found in ostrich eggs; this exceeds the maximum level permitted for chicken eggs by a factor of up to 15. Eight of the 11 egg samples exceeded the action level for hen eggs. Although the ostrich meat concentrations of PCDD/Fs do not exceed the limit established for poultry muscle (1.75 pg g?1 fat), average contents of PCDD/Fs exceeded almost four times the levels in chicken and turkey muscle. Human exposure was evaluated and the resulting risk was characterised. Taking into account the low average consumption of ostrich eggs, the resulting exposure to dioxins for the general population can be considered as negligibly low. However, the individuals who frequently consume such eggs may be at risk of elevated exposure. Although ostrich products are not consumed frequently, such data are nevertheless useful for food safety purposes. 相似文献