Isolation and identification of toxigenic fungi from infected peanuts and efficacy of silver nanoparticles against them

Peanuts are vulnerable to fungal infections during long term storage. Fungi infecting peanuts are toxigenic and cause health hazards. The goal of this study was isolation and identification of fungi in peanuts and use of silver nanoparticles (AgNPs) to inhibit them. For this purpose firstly, we have isolated fungi from infected peanuts and identified on the basis of morphological and molecular study. Out of the total 54 fungal isolates, 47 were found to be Aspergillus spp. and other belongs to Penicillium spp. and Macrophomina phaseolina. Biochemical assay was performed to identify cultures of Aspergillus flavus from other species of this genus by inoculating it on Aspergillus Differentiation Medium (ADM). Thirty-one isolates were found to be A. flavus. Toxicity of Aspergillus spp. was evaluated on Yeast Extract Sucrose agar (YES) medium with an additive methylated β-cyclodextrin and nine isolates were found toxigenic. Secondly, AgNPs were synthesized from ten different plants and their characterization was performed using various analytical techniques such as UV–Visible spectrophotometer, Fourier Transform Infrared Spectroscopy, Zetasizer and Nanoparticle Tracking Analysis, etc. Further, antifungal potential of thus synthesized AgNPs was evaluated. All the synthesized AgNPs possess ability to inhibit fungal growth. Cymbopogon citratus leaf extract mediated AgNPs were found to have prominent antifungal potential against all test fungi and its minimum inhibitory concentration (MIC) was found to be 20 μg/ml. The biogenic approach proposed in the present study is eco-friendly, safe and economical viable. AgNPs also reported to have significant antifungal activity against toxigenic isolates of peanuts, hence such AgNPs can be effectively used for the management of toxigenic pathogens.     

Fate of ochratoxin A during wheat milling and some Chinese breakfast processing

To estimate the dietary intake of ochratoxin A (OTA), information on the fate during wheat processing is needed. The wheat contaminated with OTA at both levels (93.22 and 248.93 μg/kg) was artificially inoculated by Aspergillus ochraceus. Concentrations of OTA were 1.43–1.66 times higher in bran than whole wheat and 1.27–1.50 times higher in shorts than bran. A concentration reduction of 43.29–55.16% for OTA in flour was observed, with the final concentrations of 41.80 and 138.33 μg/kg in flour respectively. Whereas, OTA was not transferred or decomposed during milling, as the total amount of OTA in all milling fractions didn't decreased. The further losses of OTA were various depending on different processes. The concentration of OTA increased by 11–16% when the flour was processed into Chinese steamed bread (CBS), with the OTA concentrations of 49.2 and 161.35 μg/kg in CBS. It revealed fermentation and steaming increased the OTA levels in CBS. The loss of OTA was small in the Chinese fried bread sticks (CFBS) (38.84 and 129.02 μg/kg), being of 6.73–9.63%. A higher reduction of 23.27–23.92% for OTA was detected in the noodles processing, with the final concentration of 32.98 and 108.24 μg/kg in noodles respectively. The result revealed that the temperature, pH values and strains involved the processes exerted different effects. High temperature (180 °C) and alkaline condition (pH > 7) facilitated to the removal of OTA, while fermentation (with dry yeast) increased the OTA levels in products.     

Influence of pH and temperature variations on vapor phase action of an antifungal food packaging against five mold strains

An antifungal active food packaging containing cinnamon essential oil has been evaluated under different pH and temperature. Cinnamon essential oil was previously chosen among oregano, clove and their major components cinnamaldehyde, carvacrol and eugenol respectively. Minimal Inhibitory Concentration (MIC) and Minimal Fungicidal Concentration (MFC) were determined by macrodilution method against two strains of Aspergillus flavus as well as Aspergillus niger, Penicillium roqueforti and Penicillium expansum. Despite pH and temperature modified the growth rate of the molds, these variables did not affect the MIC and MFC values. The active food packaging, consisting of Polypropylene films coated with a formula containing 2%–6% cinnamon were produced and evaluated. The antifungal activity was studied against two A flavus, P roqueforti and P. expansum at different pH and temperature. The results highlighted the growth delay caused by the PP 2% in all cases. Total inhibition was obtained with higher amount of cinnamon. This fungicidal action was maintained beyond the 30 days of the experiments. Long-term properties were confirmed after 3 months. The fridge temperature did not hamper the antifungal action of the cinnamon volatile compounds. Finally, all these results demonstrated the high-performance of the antifungal packaging, what guarantee an efficient and durable antifungal protection.     

5种催化裂化原料的裂化性能研究

利用XTL-5型提升管中试装置,对中国石油化工股份有限公司洛阳分公司催化裂化原料各组分的裂化性能进行了评价。结果表明:在完全相同的催化剂和操作条件下,减压蜡油、脱沥青油、常压重油、混合原料和拔头轻油浆的转化率分别为74.00%,69.91%,70.43%,67.16%和36.84%;其裂化性能从优到劣的顺序为:减压蜡油,脱沥青油(与常压重油相似),混合原料,拔头轻油浆;其中掺炼拔头轻油浆对催化进料的裂化性能影响很大,使催化裂化产品的分布明显变差。     

Screening of antifungal potentials of Lactobacillus helveticus KLDS 1.8701 against spoilage microorganism and their effects on physicochemical properties and shelf life of fermented soybean milk during preservation

This study investigated the screening of antifungal potential of Lactobacillus helveticus. L. helveticus KLDS 1.8701 showed strongest antifungal activity against Penicillium sp. of all provided strains, and antifungal activity was from organic acids and KLDS 1.8701 itself. Results of the impact of KLDS1.8701 on spoilage microorganisms in fermented soybean milk during the preservation period showed that it could inhibit Penicillium sp. and other spoilage microorganisms from the environment and the shelf-life of products were extended. The addition of KLDS 1.8701 has no significant effect on biochemical, rheological and sensory properties of fermented soybean milk. It also enhances total viable counts of Lactobacillus stains (L. helveticus + Lactobacillus bulgaricus)and didn't affect Streptococcus thermophiles. Thus, the use of L. helveticus KLDS 1.8701 as a bio-protective culture in other fermented products was suggested.     

Influence of emulsifier type on the antifungal activity of cinnamon leaf,lemon and bergamot oil nanoemulsions against Aspergillus niger

Only exiguous data are currently available on the antifungal properties of essential oil (EO) nanoemulsions against spore-forming microorganisms. The aim of this work is to develop physically stable nanoemulsion-based delivery systems for different EOs (cinnamon leaf, lemon, and bergamot), to exploit their antifungal properties against Aspergillus niger. The inhibition of mycelial radial growth and spore germination were used as indicators of antifungal activity of the nanoemulsions, which were prepared at 3 wt% EO, using non-ionic Tween 80 (T80) or anionic whey protein isolate (WPI) (1 wt%) as emulsifiers, and sunflower oil (1 wt%) as ripening inhibitor. The nanoemulsions were physically stable over seven days of accelerated aging at 35 °C.The minimal inhibitory concentration of free cinnamon leaf and of both citrus EOs were 0.35 and 5.50 μg/g, respectively. The encapsulation of cinnamon leaf EO in nanoemulsions significantly enhanced the inhibiting effect against A. niger mycelial growth and spore germination, with respect to the free EO. In contrast, for citrus EOs, the encapsulation in nanoemulsions generally decreased the antifungal activity, likely because of the nanoemulsion acting as a hydrophobic sink for the main constituents of citrus EOs. The emulsifier played a fundamental role in the resulting antifungal activity, with WPI-based nanoemulsions being more effective in inhibiting the mycelial growth and the spore germination of A. niger than T80-based ones. The antifungal action was correlated to the morphological alterations observed in A. niger, such as the loss of cytoplasm in fungal hyphae and hyphal tip. The results of this study show the importance of nanoemulsions design in the development of efficient and stable natural antifungal agents for food applications.     

Antioxidant and anti food-borne bacterial activities of extracts from leaf and different fruit parts of Myristica fragrans Houtt

The main products of Myristica fragrans are the dried seed (nutmeg) and aril (mace), which are used as spices or condiments to flavor foods. In this study, its leaf and different parts of fruit (pericarp, aril, seed-kernel and shell) were compared for their total phenolic content, antioxidant and anti food-borne bacterial capacities. The 80% methanol extracts of aril, seed-kernel and shell shared the highest total phenolic content with shell extract acted as the greatest primary antioxidant, by having the highest ferric reducing antioxidant power (FRAP) activity (EC₅₀ 9.7 ± 0.1 μg/mL), β-carotene-bleaching activity (EC₅₀ 21.5 ± 2.7 μg/mL) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity (EC₅₀ 160.9 ± 13.9 μg/mL), whereas the pericarp extract exhibited highest secondary antioxidant activity as a metal chelator (EC₅₀ 75.6 ± 14.4 μg/mL). Only the aril and seed-kernel extracts were found to inhibit the food-borne bacteria with the lowest minimum inhibition concentration of 50 μg/mL, against Staphylococcus aureus (ATCC12600) and Bacillus cereus (ATCC10876). Our findings suggest the possibility of using the aril and seed-kernel extracts as natural food preservative and other parts as a new source of natural antioxidant for food and pharmaceutical industries.     

Antibacterial activity of Borago officinalis and Brassica juncea aqueous extracts evaluated in vitro and in situ using different food model systems

The present study was undertaken to characterize the antibacterial activity of the aqueous extracts (AEs) obtained from the leaves of Borago officinalis L. and Brassica juncea L. The antagonistic activity was evaluated against several bacteria (42 strains of Listeria monocytogenes, 35 strains of Staphylococcus aureus, 38 strains of Enterobacter spp. and 18 strains of Salmonella enterica) commonly associated with foodborne diseases by paper disc diffusion method. The susceptibility to the plant extracts was strain specific. Thirty-five strains (7 L. monocytogenes, 11 S. aureus, 1 S. Enteritidis, 1 S. Veneziana, 7 Enterobacter hormaechei, 5 Enterobacter cloacae, 1 Enterobacter sakazakii and 2 Enterobacter amnigenus) were sensitive to both AEs. The activity of B. juncea AE towards the Gram-positive strains was generally higher than that observed for B. officinalis (45 and 22 strains inhibited by B. juncea and B. officinalis, respectively), while an opposite trend was registered against the Gram-negative strains (22 and 35 strains inhibited by B. juncea and B. officinalis, respectively). The highest inhibition was displayed by B. juncea AE against E. sakazakii 23A. B. officinalis AE showed the same minimum inhibitory concentration (MIC) (10 mg/mL) for the majority of the most sensitive strains, while the MIC of B. juncea AE was different for each bacterial species and the lowest concentration was registered to inhibit enterobacteria (3.1 mg/mL). After 1-year storage in different thermal conditions (room temperature, 4 °C and −20 °C), both AEs lost their inhibitory power. The extracts did not show cellular toxicity when tested against sheep erythrocytes. Hence, B. officinalis and B. juncea AEs were effective as natural antibacterial substances. AEs were tested in situ in three food model systems (meat, fish and vegetable) at two concentrations, but only when added at a concentration 10-fold higher than that showing definite efficacy in vitro (100 and 31 mg/mL for B. officinalis and B. juncea, respectively), they inhibited the growth of the sensitive strains, even though the cells were still viable after 24 h. The influence of AEs on the volatile organic compounds (VOCs) composition of the food models was analysed by gas chromatography/mass spectrometry. The different levels of alcohols, aldehydes, esters, hydrocarbons, ketones and phenol registered, showed a consistent effect of B. officinalis and B. juncea AEs on the VOCs of the food models. However, the sniffing assay found only B. juncea AE impacting consistently the final aroma of the food models.     

Effects of different plant hormones for microbial degradation of PASHs and diesel under aerobic conditions

The effects of plant hormones for biodegradation of polycyclic aromatic sulfur heterocycles(PASHs)and diesel fuel were studied.Indole butyric acid(IBA)and gibberellin were found to promote biodegradation of DBT and diesel,respectively.Concentrations of plant hormones,pH,temperature,soil moisture and substrate concentrations were optimized in microbial metabolic processes.Two main factors including temperature and IBA concentration were determined by factor analysis in DBT biodegradation.And soil moisture and diesel concentration were important factors in diesel biodegradation.Binding sites between cell surface and DBT or diesel components were performed by molecular operating environment(MOE).This study suggested that plant hormones could be applied to effectively remove pollutants in environment.     

Endophytic bacterial diversity in Korean kimchi made of Chinese cabbage leaves and their antimicrobial activity against pathogens

The diversity of bacterial endophytes associated with Chinese cabbage (CC) leaves from two cultivation areas in Korea, namely, Seosang-gun (SS) and Haenam-gun (HN), and from a laboratory transgenic plant (TP) was investigated. A total of 5.76 log CFU/g isolates were identified from the interior leaves of the three cultivars of CC, which were grouped into 5.08, 5.36, and 5.34 log CFU/g from SS, HN, and TP samples, respectively. Phylogenetic analysis based on the 16S rRNA sequences indicated that the isolates belonged to four major phylogenetic groups: high-G + C Gram-positive bacteria (HGCGPB), low-G + C Gram-positive bacteria (LGCGPB), Proteobacteria, and Bacteroidetes. The most predominant group of species in the leaves of the SS, HN and TP CC cultivars were LGCGPB (50%), LGCGPB (65.2%), and HGCGPB (43%), respectively. A total of 23 bacterial genera were identified from the three cultivars of Chinese cabbage. Most extracellular hydrolytic enzyme-producing colonies among the isolates belong to the genus Bacillus those were predominant in the HN cultivars. In addition, some isolates especially Bacillus sp. (TPL08), Bacillus subtilis (SSL16, HNL10) exhibited potential activity as biocontrol agents against food-borne pathogenic bacteria and phytopathogenic fungi tested in this study. This study first revealed the endophytic bacterial communities in leaves of Chinese cabbage (main ingredients of kimchi) grown in Korea.     

Studies on surface activity of petroleum sulfonates prepared from extracts of solvent refining

Petroleum sulfonates with the active substance content from 21 to 32.5 % wt were prepared from four extracts of solvent refining by phenol and N-methylpyrrolidone (oil side streams II and III) in laboratory conditions. Their average molecular weight, composition, and surface activity were evaluated using a rotating drop test. The sulfonated products were characterized by NMR, IR spectroscopy, and HPLC methods.     

Effects of five ashes on the stability of petroleum coke water slurry

The effects of five main ingredients (i.e. SiO₂, Al₂O₃, Fe₂O₃, CaO and MgO) of coal ash on the stability of petroleum coke water slurry (PCWS) were investigated in this paper. The results showed that the stability of PCWS could be improved tremendously by the appearance of a small quantity of CaO in the PCWS, while the other 4 ashes had little impact. When the apparent viscosity was 1000 mPa·s, the PCWS with CaO dosage of 0.3 wt% would possess the solid concentration of 68.0%, the flow characteristic exponent of 0.78, and the water separation rate of 3.4%.     

各种因素对水泥石抗压强度的影响

使用美国 EG&G CHANDLER 公司研制的 4265 型超声波强度测定仪,考察了未加砂水泥浆和加砂水泥浆 24 h 内的强度发展趋势,以及 CH20L 高温水泥浆体系各组分用量对加砂水泥浆 24 h 内抗压强度的影响。结果发现,CH20L 未加砂水泥浆强度呈对数曲线发展,CH20L 加砂水泥浆强度呈二级台阶走势发展,且未加砂水泥浆 24 h 内的强度发展比加砂水泥浆快;早强剂和降失水剂用量的增加及pH 值的升高使加砂水泥石 24 h 强度有所增大,缓凝剂和分散剂用量的增加及水泥浆密度的减小使水泥石 24 h 强度有所减小;不同批样水泥由于化学成分等的差异导致其水泥石强度发展曲线不同。     

植物酚类钻井液处理剂的电导特性研究

通过实验研究了混合态的兴安落叶松植物酚类钻井液处理剂的电导特性,提出了利用配位一电导滴定曲线来计算混合态植物酚类化合物及其改性产物中组分的相对含量的新方法,并根据电导滴定曲线的变化规律,分析了混合态植物酚类改性产物的电化学特性,进而解释了用纯化的单酚或多酚的理化性质难以解释的酚类油田化学品的一些使用特性。     

不同类型裂缝对气井产能影响

在低渗、特低渗气藏开发过程中,裂缝对气井的产能和稳产能力起着主导作用。选取了某低渗气田在不同沉积微相下的含有裂缝的岩心进行了专门的实验研究。详细分析了半充填缝、未充填缝的应力敏感,评价了裂缝宽度随有效应力的变化以及其对产能的贡献差异。实验研究表明:未充填缝的应力敏感性较强,对气井初期产能贡献较大;半充填缝的应力敏感性较弱,对气井中后期产能起主导作用;特低渗气藏产量在很大程度上取决于未充填缝与充填缝的比例。     

Effect of different molecular weight amphiphilic polymers on emulsifying behavior

Abstract

Amphiphilic polymers applied in oil fields are polymer mixtures with different molecular weight. Stability of O/W emulsion prepared by amphiphilic polymers with different molecular weight was studied by stability analyzer. The difference in stability was clarified according to the external phase and interfacial properties. Results showed that PI(micro-molecular polymer) formed a tighter network structure in solution which exhibit higher viscoelasticity and more resistant to shear; and was more favorable to the emulsion stability than PII(macro-molecular polymer) due to higher surface activity. This work provides references for the molecular weight distribution optimization of amphiphilic polymer.     

Influences of ripening stages and extracting solvents on the polyphenolic compounds,antimicrobial and antioxidant activities of blueberry leaf extracts

This study investigated polyphenols, antimicrobial and antioxidant activities of blueberry leaf extracts harvested at three fruit ripening stages (immature, semi-mature, and commercial-mature) and extracted by three solvents (95% ethanol, 70% acetone, and 100% methanol). Quercetin, kaempferol, gallic, protocatechui, caffeic, vanillic, syringic, p-coumaric, and ferulic acids were identified in the extracts with varied amount depending on ripeness stage and extraction solvent. Protocatechui and ferulic acids were not detected at semi-mature samples, and none protocatechui, syringic and p-coumaric acids in ethanol-extracts from commercial-mature samples. All extracts exhibited antimicrobial activity against Escherichia coli and fungi, but only semi-mature and commercial-mature samples were against Listeria monocytogenes and Staphylococcus aereus. Methanol- and acetone-extracts had higher polyphenol content, DPPH and reducing power than those of ethanol-extracts, whereas opposite trend was observed in ORAC values. These results indicated the potentials of using blueberry leaf extracts as natural antimicrobial and antioxidant substance for food applications.     

Phytochemical screening and corrosion inhibitive behavior of Pterolobium hexapetalum and Celosia argentea plant extracts on mild steel in industrial water medium

Preliminary phytochemical screening was carried out for methanolic extracts of Pterolobium hexapetalum (PH) and Celosia argentea (CA). Methanolic extracts of PH and CA were studied as corrosion inhibitors for mild steel in industrial water medium using mass loss and electrochemical techniques. The adsorption of both PH and CA extracts on mild steel surface followed Langmuir isotherm. The electrochemical impedance spectroscopy (EIS) measurements showed that the charge transfer resistance increases with increasing concentration of extracts. Various thermodynamic parameters were evaluated and discussed. Scanning electron microscopy (SEM) was used to analyze the surface adsorbed film. Further, antioxidant activity of the plant extracts was determined and correlated with the results obtained with inhibition efficiency.     

国产AH-90重交通道路沥青的感温性研究

以SHRP试验方法为主要手段，研究了几种有代表性的国产AH-90重交通道路沥青的感温性，通过对沥青在不同老化阶段，不同温区下的感温性指标的研究，表明老化对不同沥青的感温性影响程度差别不大，沥青在低温区的感温性与高中温区的感温性有些不同，国产的AH-90重交通道路沥青具有良好的感温性。     

不同提取剂对紫罗兰马铃薯花青素提取含量的影响

目的讨论不同提取剂对紫罗兰马铃薯花青素含量的影响,并对其稳定性做了初步的探讨。方法分别采用柠檬酸-磷酸氢二钠溶液和1.5mol/L HCl-95%乙醇作为提取剂,提取64、67和70号紫罗兰马铃薯的鲜薯和干粉花青素,紫外分光光度法测定其含量。结果不同提取剂影响了花青素的含量;放置时间和温度均可引起花青素的降解;1.5mol/L HCl-95%乙醇作为提取剂具有较高的提取率和稳定性。结论不同提取剂对紫罗兰马铃薯花青素的提取含量、稳定性均有较大影响。