Purification and characterization of a novel bacteriocin CAMT2 produced by Bacillus amyloliquefaciens isolated from marine fish Epinephelus areolatus

A novel bacteriocin named CAMT2 was produced by strain ZJHD3-06 which was isolated from the marine fish Epinephelus areolatus and identified as Bacillus amyloliquefaciens, Bacteriocin CAMT2 inhibits important food spoilage and food-borne pathogens such as Listeria monocytogenes, Staphylococcus aureus, Escherichia coli and Vibrio parahaemolyticus. Bacteriocin CAMT2 was purified by ammonium sulfate precipitation, gel filtration chromatography on Sephadex G-50 and reversed phase chromatography on a C₁₈ column. The molecular mass of the purified bacteriocin CAMT2 was about 20.0 kDa and N-terminal sequencing of the peptides revealed low similarity with existing antimicrobial peptides, as determined by an LC–MS/MS system. Bacteriocin CAMT2 was resistant for up to 100 °C and pH ranging 2–10, but lost its activity when treated with protease K. The bacteriocin also showed significant antimicrobial activity against L. monocytogenes in a meat model system. These obtained results suggest that bacteriocin CAMT2 has potential for use as a food biopreservative.     

Impact of grain size,Pr~(3+) concentration and host composition on non-contact temperature sensing abilities of polyphosphate nano- and microcrystals

In this article,varied praseodymium polyphosphate hosts:M~I(Li,Na K)Pr(PO_3)_4 microcrystals and LiLa_(1-x)Pr_x(PO_3)_4(x = 0.01-1)nanocrystals were successfully synthesized by the flux method and the coprecipitation technique,respectively.The size of stoichiometric nanocrystals of LiPr(PO_3)_4 was tuned by the te mpe rature of thermal treatment in range of 35-145 nm.In order to dete rmine the most suitable material for the non-contact optical thermometric applications,the temperature sensing measurements were carried out by using luminescence intensity ratio(LIR)of emission bands corresponding to the ~3 P_1→~3H_5 and ~3P_0→~3 H_5 electronic transitions of Pr~(3+) ions into the 123-423 K temperature range.The influence of the host material composition of M~Ⅰ(Li,Na,K)Pr(PO_3)_4 microcrystals on the sensitivity of luminescent thermometers was studied.It is found that the sensitivity of lithium praseodymium polyphosphate is the highest of all micropowders under investigation.Moreover,it is found that the nanocrystals reveal much higher relative sensitivity in respect to the microcrystalline counterparts.The highest sensitivity of LIR temperature sensing is found for LiPr(PO_3)_4 nanocrystals(35 nm grain size)in the whole temperature range,reaching 0.283%/K at 164 K.The impact of the average grain size on the sensitivity of LIR based thermometers of LiPr(PO_3)_4 nanocrystals was investigated.It is found that the reduction of the grain size from 145 to 35 nm results in the enhancement of the relative sensitivity from0.156 to 0.240%/K at 223 K.Additionally it is found that the high dopant concentration possesses favorable influence on the relative sensitivity of LiLa_(1-x)Pr_x(PO_3)_4 nanocrystalline luminescent thermometers.     

Enable high reversibility of Fe/Cu based fluoride conversion batteries via interfacial gas release and detergency of garnet electrolytes

Garnet-type Ta-doped Li₇La₃Zr₂O₁₂ (LLZTO) electrolyte suffers from unstable chemical passivation under air exposure, responsible for the poor interfacial wettability and conductivity with Li metal. Instead of conventional methods to remove surface contaminants by mechanical polishing, acid etching and high temperature reduction, herein we propose a simple strategy of interfacial gas release and detergency to smartly convert Li₂CO₃ passivation layer into ion-conductive Li₃PO₄ domains at mild temperature (∼200 ℃). The in-situ formation of PH₃ vapor and its phosphorization enables a dramatic decrease of Li/garnet interfacial resistance down to 2 Ω cm² at room temperature (RT). The improved interfacial wettability and conductivity endow the symmetric cells with ultra-stable galvanostatic cycling over 1500 h and high critical current density of 2.6 mA/cm². The high coulombic efficiency of Li plating enables a high reversibility of solid-state NCM811/Li cells even under a low N/P ratio (∼4) and high cut-off voltage of 4.5 V at RT. The prototype of fluoride-garnet solid-state batteries are successfully driven as rechargeable system (rather than widely known primary battery) with high conversion capacity (400 ∼ 500 mAh/g) and high-rate performance (251.2 mAh/g at 3 C). This interface infiltration-detergency approach provides a practical solution to the achievement of high-energy solid-state Li metal batteries.     

Nutrient composition and food potential of Parkia roxburghii,a less known tree legume from northeast India

The nutrient compositions of Parkia roxburghii kernels and pods (i.e. tender, immature and mature) were determined. Protein content of the kernel was 29% and that of pods 13–19%. Similarly, fat content was highest (34%) in the kernel and ranged from 1–16% in the pods. Unsaturated acids Oleic, linoleic and linolenic acids made up 63–68% of the total fat in the pods as well as the kernels. The total essential amino acids amounted to 33%, 36% and 39% in the tender, immature, mature pods, respectively, and 42% in the kernels. The essential amino acid pattern of the kernel was comparable to the FAO/WHO/UNU (1985) amino acid requirement for preschoolers. However, the amino acid scores of the tender, immature and mature pods were 64, 84 and 92, respectively, with sulphur amino acids as the limiting amino acids in all the pod samples.     

基于电子舌和气相色谱-离子迁移谱分析脂肪添加量对中式香肠风味的影响

为提高中式香肠风味品质,研究不同脂肪添加量对中式香肠风味的影响,选取4 个不同脂肪添加量,即肥瘦肉质量比分别为0∶10、2∶8、3∶7、5∶5,以相同加工工艺制作中式香肠,采用电子舌和气相色谱-离子迁移谱（gas chromatography-ion mobility spectrometry,GC-IMS）分别对不同脂肪添加量的中式香肠滋味和挥发性风味物质进行分析,并根据挥发性组分的GC-IMS图谱结合主成分分析法分析不同样品间的差异。结果表明：随着脂肪添加量的增加,中式香肠水分含量显著降低（P＜0.05）,pH值降低,食盐及脂肪含量增加;电子舌味觉特征分析表明,不同脂肪添加量中式香肠的丰富性和咸味有显著差异,其他味觉特征无显著差异;GC-IMS分析表明,中式香肠中共检测出36 种挥发性物质,其中乙酸香叶酯、甲基胡椒酚、壬醛和二丁基硫醚等是主要特征风味物质。结合感官指标得出,脂肪添加量30%的中式香肠风味最佳,感官可接受度最好。     

不同产地菜籽油中微量元素的ICP-MS/MS法测定及统计比较

研究菜籽油中微量元素含量的分布规律及其与菜籽油产地之间的关系。采用电感耦合等离子体串联质谱(ICP-MS/MS)法测定了15种菜籽油中Be、Ti、Cr、Mn、Fe、Co、Ni、Cu、Zn、As、Se、Sr、Cd、Ba、Hg、Pb 16种微量元素的含量,将测定数据进行标准化处理后利用SPSS主成分分析与聚类分析对微量元素的分布进行评价。结果表明:菜籽油经煤油稀释后直接进样分析,在MS/MS模式下,分别选择O_2和NH_3/He为反应气,利用CRC技术消除了质谱干扰; Fe、Mn、Cu、Zn、Sr、Ba在0～500μg/kg范围内相关系数大于等于0. 999 8,其余10种分析元素在0～50. 0μg/kg范围内相关系数大于等于0. 999 6,16种元素的检出限为1. 05～20. 30 ng/kg;主成分分析结果显示累积方差的84. 487%来自前6个主成分,菜籽油的特征元素为Mn、Fe、Cu、Sr,聚类分析将15种菜籽油聚为3类,实现了不同产地菜籽油的初步判别。通过微量元素的主成分分析与聚类分析,可对菜籽油进行有效的产地溯源。     

Effects of pH on a fluorogenic vital dyes assay (4′,6′-diamidino-2-phenyl-indole and propidium iodide) for Cryptosporidium sp. oocysts

The fluorogenic vital dyes assay utilizing 4′,6′-diamidino-2-phenyl-indole (DAPI) and propidium iodide (PI) can be used for determining the viability of individual Cryptosporidium parvum oocysts isolated from environmental samples; however this assay can be affected by the pH of the oocyst suspending medium, resulting in formation of fluorescent yellow DAPI crystals at neutral or alkaline pH. Interference from DAPI crystals can lead to oocyst occlusion, making their viability assessment difficult or subjective. When the oocyst suspending medium is rinsed with HBSS adjusted to pH 4, DAPI crystallization is reduced or prevented without affecting oocyst staining characteristics with these two dyes or with fluorescein isothiocyanate conjugated anti-Cryptosporidium monoclonal antibody.