Effects of imazalil on sterol composition of sensitive and DMI-resistant isolates of Penicillium italicum

Imazalil differentially inhibited dry weight increase of 10-hour-old germlings of wild-type and DMI-resistant isolates ofPenicillium italicum in liquid malt cultures. EC₅₀ values ranged from 0.005 to 0.27 g ml^–1. In all isolates ergosterol constituted the major sterol (over 95% of total sterols) in the absence of the fungicide. Therefore, DMI-resistance cannot be associated to a deficiency of the C-14 demethylation enzyme in the ergosterol biosynthetic pathway. Imazalil treatment at concentrations around EC₅₀ values for inhibition of mycelial growth resulted in a decrease in ergosterol content and a simultaneous increase in 24-methylene-24,25-dihydrolanosterol content in all isolates. A correlation existed between the imazalil concentration necessary to induce such changes in sterol composition and the EC₅₀ values for inhibition of mycelial growth of the different isolates. The reason for the differential effects of imazalil on sterol composition in the variousP. italicum isolates may be due to decreased accumulation of the fungicide in the mycelium and to other yet non-identified mechanisms of resistance.Imazalil remt differentieel de toename in drooggewicht van 10-uur-oude gekiemde sporen van wild-type en DMI-resistente isolaten vanPenicillium italicum in vloeistofcultures van moutextract. De EC₅₀ waarden voor groei van de verschillende isolaten lopen uiteen van 0,005 tot 0,27 g ml^–1. In afwezigheid van het fungicide is in alle isolaten ergosterol het belangrijkste sterol (meer dan 95% van het totaal). DMI-resistentie kan daarom niet in verband staan met deficiëntie van het C-14 demethyleringsenzym in de ergosterol biosynthese. Imazalilbehandeling van mycelium bij concentraties rond de EC₅₀ waarde voor groeiremming, resulteerde bij alle isolaten in een afname van het ergosterolgehalte en een gelijktijdige toename van het gehalte aan 24-methyleen-24,25-dihydrolanosterol. Er bestaat dus een nauwe correlatie tussen de imazalilconcentratie die noodzakelijk is om vergelijkbare veranderingen in sterolsamenstelling te induceren en de EC₅₀ waarde voor remming van myceliumgroei van de verschillende isolaten. De differentiële effecten van imazalil op de sterolsamenstelling van de verschillendeP. italicum isolaten kunnen worden veroorzaakt door verminderde accumulatie van het fungicide in het mycelium en door andere, nog niet geïdentificeerde resistentiemechanismen.     

不同环境因素对青霉PT95菌核内类胡萝卜素稳定性的影响

将青霉PT95菌株发育成熟的菌核在不同环境条件下保存,结果发现:黑暗、低温、氮气、pH 6~8条件下有利于菌核内类胡萝卜素保持稳定。6种金属离子中,Fe3+、Fe2+、Al3+对类胡萝卜素稳定性影响最大,Mn2+的影响最小。氧化剂H2O2对PT95菌核中类胡萝卜素稳定性的影响不大,而还原剂Na2SO3的影响较大。     

采后硅酸钠处理对苹果梨青霉病的抑制

离体条件下,硅酸钠可抑制Penicillium expansum的菌丝生长,当浓度达到50 mmol/L时菌丝生长可被完全抑制.采用不同浓度的硅酸钠浸泡果实,可显著降低苹果梨损伤接种P.expansum的病斑面积,其中以200mmol/L的处理效果最好.硅酸钠处理可有效提高果实体内的过氧化物酶(POD)和多酚氧化酶(PPO)活性,促进过氧化氢(H2O2)和超氧化物阴离子(O2-)的产生,但对过氧化氢酶(CAT)和超氧化物岐化酶(SOD)活性的影响不大.由此表明,硅酸钠对梨果实青霉病的抑制与其的直接抑菌作用和诱导体内的抗性有关.     

两株纤维素降解真菌的分离鉴定及其产纤维素酶酶学性质的初步研究

从纤维素富集的环境中采集82个落叶层下面的土壤和腐朽的树木样品,经过初筛获得大约3500株纤维素降解真菌,二次筛选后得到16株纤维素酶活性较高的真菌.以Avicel为底物,测定16株纤维素降解真菌的粗酶活性,发现真菌菌株S10和X5对Avicel有明显的活性,分别为0.119IU/mL、0.025IU/mL.通过形态学观察和rDNA的ITS(内转录间隔区)序列分析,菌株S10被鉴定为针尾曲霉(Aspergillus aculeatus),菌株X5为草酸青霉(Penicillium oxalicum).对针尾曲霉S10和草酸青霉X5的粗纤维素酶的酶学性质进行初步研究,发现粗酶活性最高的最适pH值分别为5.0、6.0,最适反应温度分别为50～60℃、45～50℃.     

Fungal contamination of big-bale grass silage on Irish farms: predominant mould and yeast species and features of bales and silage

The extent of visible fungal growth and the identity of the predominant fungi causing spoilage of baled grass silage were recorded on 180 farms in Ireland. Fungal growth was evident on bales on 174 of the 180 farms visited and on 331 of the 360 bales examined. The mean proportion of surface area of bale, that was affected, was 0·06. Silage‐making method, storage characteristics and geographical location were significantly associated with the level of fungal contamination on bales. Fungal contamination was higher (P < 0·001) in bales where the surrounding polythene stretch‐film was visibly damaged compared with bales where the film appeared intact. A strong positive relationship was found between polythene film damage and dry‐matter content of the silage. The predominant fungus affecting the largest numbers of bales was Penicillium roqueforti. Other fungi frequently isolated included Schizophyllum commune, Pichia fermentans and Penicillium paneum. The distribution of individual fungi on bales was associated with geographical location, weather at harvest, and lactic and butyric acid concentrations of the silage. Penicillium roqueforti and P. paneum were more common on bales harvested in dry weather and with higher concentrations of butyric and propionic acids in the silage. Overall, a high incidence of visible fungal growth was recorded on bales throughout the country and the extent of colonization and fungal species occurring were not random.     

草酸青霉菌(P-o- 41)发酵液对小麦病害的诱导抗性作用

不同浓度的草酸青霉菌(P-o- 41)[1,2]发酵代谢物处理珊西烟的一张叶片,在另外的叶片上摩擦接种TMV,比较处理叶片与无菌蒸馏水对照叶片上的枯斑数.结果表明,稀释1 000倍的发酵代谢物处理及百万分之三十八的BTH处理与清水处理对照相比,枯斑抑制率(;)分别达到84.05;和79.96; ;对小麦白粉病的诱抗效果分别达到60.88; 和69.43; ;对小麦普通根腐病的抑制率在P0.01水平上达到显著差异,而平板圆盘测定结果表明,草酸青霉菌(P-o-41)发酵液对小麦根腐病菌无抑制作用.     

植物乳杆菌IMAUl0116产生抗娄地青霉活性物质培养基的优化

[目的]筛选对娄地青霉有较强抑菌活性的植物乳杆菌并提高其抗真菌活性。[方法]将活化后的植物乳杆菌IMAUl0116接种到MRs液体培养基中培养,采用双层平板点接法评价其抗娄地青霉菌的活性。[结果]单因素试验表明,以葡萄糖为碳源时,植物乳杆菌IMAUl0116对娄地青霉的抑制效果最好;植物乳杆菌以麦芽浸粉为氮源时,抑茵效果最好;抗真菌乳酸茵产生抗茵物质的最佳生长因子为玉米浆粉。植物乳杆菌IMAUl0116最佳培养基组成为：葡萄糖20/L＋麦芽浸粉20g／L＋玉米浆粉7/L＋适量无机盐。用优化培养基培养的植物乳杆菌IMAUl0116抑制娄地青霉菌产生的抑菌圈为18．6mm,用MRs培养基所产生的抑菌圈为15．0mm。[结论]植物乳杆菌IMAUl0116对娄地青霉有很好的抑制作用,有望在食品及饲料添加剂领域获得较好的应用。     

三种霉菌对生姜茎腐病的防效测定

试验利用哈茨木霉(Trichoderma harzianum)、绿色木霉(Trichoderma viride)和青霉(Penicillium spp.),采用菌丝体生长速率法和盆栽试验,测定了它们对生姜茎腐病(Pythiummyriotylum)的防治效果。结果表明:3种霉菌中青霉对生姜茎腐病的防治效果表现最佳,哈茨木霉次之,其室内抑菌率分别为50.97%和55.23%;盆栽防效分别高达74.83%和61.9%,显著高于绿色木霉,显示出了较高的开发应用价值。     

Three New and Eleven Known Unusual C25 Steroids: Activated Production of Silent Metabolites in a Marine-Derived Fungus by Chemical Mutagenesis Strategy using Diethyl Sulphate

Three new (1–3) and 11 known (4–14) C25 steroids with an unusual bicyclo[4.4.1]A/B ring system were isolated by tracing newly produced metabolites in the EtOAc extract of an antitumor mutant AD-1-2 obtained by the diethyl sulphate (DES) mutagenesis of a marine-derived Penicillium purpurogenum G59. HPLC-PDAD-UV and HPLC-ESI-MS analyses indicated that the G59 strain did not produce these metabolites and the production of 1–14 in the mutant AD-1-2 extract was caused by the activation of silent metabolites in the original G59 strain by DES mutagenesis. The structures of the new compounds, named antineocyclocitrinols A (1) and B (2) and 23-O-methylantineocyclocitrinol (3), including their absolute configurations were determined by various spectroscopic methods, especially the NMR and Mo₂-induced CD analyses. Compounds 1–3 provide the first examples of the C25 bicyclo[4.4.1]A/B ring steroids with the Z-configuration of 20,22-double bond. All of 1–14 weakly inhibited several human cancer cell lines to varying extents. These results provided additional examples for the successful application of the chemical mutagenesis strategy using DES to discover new compounds by activating silent metabolites in fungal isolates and supported also the effectiveness and usefulness of this new strategy.     

Prenylated Indolediketopiperazine Peroxides and Related Homologues from the Marine Sediment-Derived Fungus Penicillium brefeldianum SD-273

Three new indolediketopiperazine peroxides, namely, 24-hydroxyverruculogen (1), 26-hydroxyverruculogen (2), and 13-O-prenyl-26-hydroxyverruculogen (3), along with four known homologues (4–7), were isolated and identified from the culture extract of the marine sediment-derived fungus Penicillium brefeldianum SD-273. Their structures were determined based on the extensive spectroscopic analysis and compound 1 was confirmed by X-ray crystallographic analysis. The absolute configuration of compounds 1–3 was determined using chiral HPLC analysis of their acidic hydrolysates. Each of the isolated compounds was evaluated for antibacterial and cytotoxic activity as well as brine shrimp (Artemia salina) lethality.