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31.
为获得稻花鸡肉腐败菌的Arrhenius货架期预测模型,采用培养基初步筛选与16S rDNA全基因序列鉴定优势腐败菌,研究不同贮藏温度(25、4、0℃)下优势腐败菌和菌落总数的生长变化,通过化学反应动力学方程构建菌落总数、假单胞菌和沙雷氏菌货架期预测模型并进行验证。结果表明,稻花鸡肉在贮藏过程中逐渐占主导地位的优势腐败菌是假单胞菌属莓实假单胞菌和肠杆菌科沙雷氏菌属液化沙雷氏菌。稻花鸡肉25℃常温贮藏下货架期不超过0.5 d,腐败中后期沙雷氏菌占主导地位,4℃冷藏保鲜货架期不超过4 d,假单胞菌和沙雷氏菌均随贮藏时间的延长呈增长趋势,0℃冰温贮藏货架期不超过10 d,贮藏后期假单胞菌和沙雷氏菌差异性不显著。利用菌落总数、假单胞菌、沙雷氏菌3个指标建立货架期预测模型,3种货架期预测模型预测值与实测值对比,平均相对误差均在允许范围内,预测效果最佳的是假单胞菌货架期预测模型。菌落总数、假单胞菌和沙雷氏菌货架期预测模型均能对稻花鸡肉的货架期进行真实预测。 相似文献
32.
Xin Yuan Yu Liu Fan Cao Panliang Zhang Jian Ou Kewen Tang 《American Institute of Chemical Engineers》2020,66(9):e16292
Enzyme immobilization enhances the catalytic activity and stability of the enzyme, and also improves reusability. Metal–organic frameworks (MOFs), which possess diversified structures and porosity, have been used as excellent carriers for enzyme immobilization. Pseudomonas fluorescens lipase (PFL) has been successfully immobilized onto MOFs by covalent cross-linking to obtain a series of immobilized lipase (PFL@MOFs). PFL@MOFs are used for catalytic enantioselective hydrolysis of 2-(4-hydroxyphenyl) propionic acid ethyl ester enantiomers (2-HPPAEE) in aqueous medium and transesterification of 4-methoxymandelic acid enantiomers (4-MMA) in organic medium. The experimental results indicated that PFL@Uio-66(Zr) exhibits excellent enzymatic catalysis performances and high enantioselectives. In addition, to improve catalytic activity and reusability, PFL is modified by the polyethylene glycol (PEG) to prepare PEG-modified lipase (PFL-PEG), then PFL-PEG is immobilized onto Uio-66(Zr) to prepare PFL-PEG@Uio-66(Zr), demonstrating better reusability and catalytic activity compared with PFL@Uio-66(Zr). 相似文献
33.
Won Sun Park Jeonghan Lee Giyoun Na SaeGwang Park Su-Kil Seo Jung Sik Choi Won-Kyo Jung Il-Whan Choi 《International journal of molecular sciences》2022,23(3)
Inflammasomes are a group of intracellular multiprotein platforms that play important roles in immune systems. Benzyl isothiocyanate (BITC) is a constituent of cruciferous plants and has been confirmed to exhibit various biological activities. The modulatory effects of BITC on inflammasome-mediated interleukin (IL)-1β expression and its regulatory mechanisms in Pseudomonas aeruginosa (P. aeruginosa) LPS/ATP-stimulated THP-1 cells was investigated. Monocytic THP-1 cells were treated with phorbol myristate acetate (PMA) to induce differentiation into macrophages. Enzyme-linked immunosorbent assays (ELISA) were performed to measure the levels of IL-1β produced in P. aeruginosa LPS/ATP-exposed THP-1 cells. Western blotting was performed to examine the BITC modulatory mechanisms in inflammasome-mediated signaling pathways. BITC inhibited IL-1β production in P. aeruginosa LPS/ATP-induced THP-1 cells. BITC also inhibited activation of leucine-rich repeat protein-3 (NLRP3) and caspase-1 in P. aeruginosa LPS/ATP-induced THP-1 cells. Furthermore, we show that mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) activation in P. aeruginosa LPS was attenuated by BITC. These BITC-mediated modulatory effects on IL-1β production may have therapeutic potential for inflammasome-mediated disorders such as a nasal polyp. 相似文献
34.
Jéssica M.D.A. Câmara Magna A.S.B. Sousa Eduardo L. Barros Neto 《Journal of surfactants and detergents》2020,23(4):705-714
Studies about kinetics and modeling of production parameters for biosurfactants are essential to the development of efficient processes from an economic point of view. In this sense, this work evaluated the performance of four nonstructured models to explain the experimental data for biomass growth, substrate consumption, and rhamnolipid production using glycerol as carbon source and a Pseudomonas aeruginosa strain. The kinetic parameters of each model were estimated using a global search method known as genetic algorithm and numerical discretization of differential equations by the Runge–Kutta 4th order method. The main result of this study showed that the Monod model best represented the experimental data, with μmax values of 0.06 h−1, KS of 50.8 g L−1, YX/S of 0.43 g g−1, and YP/X equal to 0.017 g g−1. 相似文献
35.
Single-stranded DNA (ssDNA)-binding protein (SSB) plays a crucial role in DNA replication, repair, and recombination as well as replication fork restarts. SSB is essential for cell survival and, thus, is an attractive target for potential antipathogen chemotherapy. Whether naturally occurring products can inhibit SSB remains unknown. In this study, the effect of the flavonols myricetin, quercetin, kaempferol, and galangin on the inhibition of Pseudomonas aeruginosa SSB (PaSSB) was investigated. Furthermore, SSB was identified as a novel quercetin-binding protein. Through an electrophoretic mobility shift analysis, myricetin could inhibit the ssDNA binding activity of PaSSB with an IC50 of 2.8 ± 0.4 μM. The effect of quercetin, kaempferol, and galangin was insignificant. To elucidate the flavonol inhibition specificity, the crystal structure of PaSSB complexed with the non-inhibitor quercetin was solved using the molecular replacement method at a resolution of 2.3 Å (PDB entry 7VUM) and compared with a structure with the inhibitor myricetin (PDB entry 5YUN). Although myricetin and quercetin bound PaSSB at a similar site, their binding poses were different. Compared with myricetin, the aromatic ring of quercetin shifted by a distance of 4.9 Å and an angle of 31° for hydrogen bonding to the side chain of Asn108 in PaSSB. In addition, myricetin occupied and interacted with the ssDNA binding sites Lys7 and Glu80 in PaSSB whereas quercetin did not. This result might explain why myricetin could, but quercetin could not, strongly inhibit PaSSB. This molecular evidence reveals the flavonol inhibition specificity and also extends the interactomes of the natural anticancer products myricetin and quercetin to include the OB-fold protein SSB. 相似文献
36.
Pinon A Alexandre V Cupferman S Crozier A Vialette M 《International journal of cosmetic science》2007,29(2):111-119
The influence of ethanol on the behaviour of Pseudomonas aeruginosa and Staphylococcus aureus strains was evaluated throughout this study. Strains of different origin were used: collection, clinical and industrial strains were selected. Concentrations of ethanol from 0 to 20% (v/v) were evaluated by automated optical density measurements and by enumeration. When growth conditions were observed, predictive microbiology models were used to assess quantitatively for the ethanol effect. Primary modelling of kinetics was performed to determine growth rate values; secondary modelling was performed on these growth rates as influenced by ethanol, and minimum inhibitory concentrations of ethanol were determined for each strain. Staphylococcus aureus strains were more resistant to ethanol than P. aeruginosa strains, in growth conditions as well as in inactivation conditions. Furthermore, clinical S. aureus strains were more resistant than the collection strain. The method was promising for management of microbiological safety in cosmetics. 相似文献
37.
38.
铜绿假单胞菌是包装饮用水中污染风险较大的一种条件致病菌。科学规范的检验方法标准能够为包装饮用水中铜绿假单胞菌的监测提供良好的技术保障。GB 8538-2016 《食品安全国家标准 饮用天然矿泉水检验方法》是我国包装饮用水中铜绿假单胞菌检测主要依据的食品安全标准。本文对该标准“57 铜绿假单胞菌”部分存在的问题进行了分析,对方法涉及的培养基、试剂以及滤膜进行质量控制的必要性和质控方法进行了阐述,以期为完善包装饮用水中铜绿假单胞菌的检验工作提供参考。 相似文献
39.
假单胞菌(Pseudomonas spp.)的生长繁殖是影响冷却牛肉货架期的重要因素。为确定假单胞菌为冷却牛肉的特定腐败菌并建立其货架期预测模型,将屠宰后的冷却牛肉4 ℃贮藏,测定了假单胞菌数量与菌落总数、挥发性氨基氮(TVBN)值、颜色明度值(L*)及感官评定分值等品质指标,并确定了冷却牛肉的假单胞菌腐败限控量。将冷却牛肉分别置于0 ℃、5 ℃、10 ℃、15 ℃、20 ℃和25 ℃条件下进行假单胞菌计数,建立Gompertz方程的初级生长模型和二级模型,并进行了模型的验证,建立了货架期预测模型。研究表明,Gompertz预测模型能有效预测4~25 ℃条件下假单胞菌在冷却牛肉中的生长情况,在0 ℃、5 ℃和10 ℃温度条件下,对牛肉货架期进行验证,与实际货架期相比偏差<1 d,表明货架期预测模型适用。 相似文献
40.
目的建立食品中椰毒假单胞菌酵米面亚种实时荧光PCR检测方法。方法根据椰毒假单胞菌酵米面亚种16S~23S rRNA基因片段序列,用Oligo7设计一对特异性引物和一个TaqMan探针,摸索最佳退火温度,最佳引物和探针浓度,建立椰毒假单胞菌酵米面亚种实时荧光PCR检测方法。通过对唐菖蒲伯克霍尔德氏菌以及22种其他标准菌株进行实时荧光PCR检测,验证本法的特异性和抗干扰性。同时从菌液浓度和DNA浓度水平上进行研究,确定该检测方法的灵敏度。结果用该方法检测23种菌,除唐菖蒲伯克霍尔德氏菌外,其他22种细菌均为阴性。抗干扰性试验显示杂菌对检测结果不影响,本法抗干扰能力强。通过灵敏度试验的研究,确定本法检测椰毒假单胞菌酵米面亚种的菌液灵敏度为1×10~2 CFU/mL,DNA灵敏度为250 fg/μL。结论本试验设计的引物和探针具有较强特异性、抗干扰性以及灵敏度,该方法具有很好的研究价值和应用前景。 相似文献