绳状青霉P-19不同固体发酵浸提液对马铃薯镰刀菌根腐病病原菌的抑制作用

近年来,由镰刀菌引起的马铃薯根腐病严重影响我国马铃薯产业的发展。本研究通过比较不同发酵产物的抑菌活性,筛选绳状青霉Penicillium funiculosum P-19 菌株最适的固体发酵培养基配方,并通过平板对峙试验测定了其对马铃薯根腐病病原菌尖孢镰刀菌Fusarium oxysporum、接骨木镰刀菌F.sambucinum、茄病镰刀菌F.solani、木贼镰刀菌F.equiseti和锐顶镰刀菌F.acuminatum的抑制作用。结果表明,绳状青霉P-19对尖孢镰刀菌、接骨木镰刀菌、茄病镰刀菌、木贼镰刀菌、锐顶镰刀菌的抑制率分别为38.85%、45.07%、38.92%、28.13%、64.32%。不同培养基发酵后其浸提液对5种镰刀菌的拮抗作用存在较大差异,其中配方为甘草∶玉米粉∶木屑=5∶4∶1时发酵产物对尖孢镰刀菌的抑制率最高,为67.89%,板蓝根∶玉米粉∶木屑=3∶5∶2时对接骨木镰刀菌的抑制率最高,为67.00%,板蓝根∶玉米粉∶木屑=3∶5∶2时对茄病镰刀菌的抑制率为64.48%,甘草∶板蓝根∶葡萄皮渣∶玉米粉=2∶2∶10∶5时对木贼镰刀菌的抑制率为50.20%,甘草∶玉米粉∶木屑=3∶5∶2时对锐顶镰刀菌的抑制率达到78.25%。本研究为马铃薯镰刀菌根腐病的防控以及青霉菌生防制剂的开发和应用奠定了基础。     

桔青霉CR-2内切葡聚糖酶蛋白纯化研究初探

以高效纤维素分解菌桔青霉(Penicillium citrinum)CR-2菌株为材料,利用分子筛及离子交换技术纯化分离其内切葡聚糖酶蛋白,首次获得了电泳纯的桔青霉内切葡聚糖酶蛋白组分,大小为27.26 kDa,最适作用温度为60℃,最适作用pH为5。对研究桔青霉纤维素酶降解纤维素的作用机理以及该菌株的改造应用具有重要意义。     

Growth of Moulds and Production of Mycotoxins in Wheat during Drying and Storage

Abstract

Studies were carried out on the growth of mould and the production of mycotoxins in grain during drying and storage. Various amounts of forced ambient air, 800, 600, 400, 200 and 0 m³ (air)/(hour ton), were used to dry wheat, which contained 32% moisture at harvest. Samples for mycological examination and determination of mycotoxins and moisture content were taken weekly. At harvest the mould flora consisted of various field fungi with less than 10% Fusarium spp. An increasing proportion of Aspergillius and Penicillium spp. were recorded in the bins at 0 and 200 m³ (air)/h t. The mycotoxin analysis indicated that the Fusarium spp. were also metabolically active until at least five weeks after the grain was put into the store room. The concentration of deoxynivalenol (DON) reached about 10 mg/kg after three weeks in the bins with no air flow, and about 2 mg/kg in the bins at 200 m³ (air)/h t. The zearalenone concentration also increased considerably, to about 5 mg/kg, in the bins with no air flow. The present results show that drying of grains using forced ambient air may produce good conditions for growth of field fungi as well as storage fungi if the flow of air is too low.     

Evaluation of fungal epiphytes isolated from banana fruit surfaces for biocontrol of banana crown rot disease

Fungi isolated from the surface of banana fruits were evaluated for in vitro antagonism towards Lasiodiplodia theobromae. Thirteen fungi exhibiting pronounced growth inhibition of test pathogens were further tested for antibiosis against Thielaviopsis paradoxa, Colletotrichum musae, and Fusarium verticillioides. Clonostachys byssicola, Curvularia pallescens, Penicillium oxalicum, and Trichoderma harzianum were antagonistic to all test pathogens. Inhibition by C. pallescens and P. oxalicum to pathogens was at a distance, while C. byssicola and T. harzianum directly parasitized and killed the pathogens. The metabolites of C. byssicola, C. pallescens, and T. harzianum significantly affected the mycelial growth and conidial germination of the pathogens. In the artificial inoculation study, the antagonists survived and colonized banana fruits after 3 d. Interfungal parasitic relationship was observed between the antagonist and pathogen on artificial media and natural substrate. Postharvest application in the packing house showed that the incidence of crown rot in antagonist-treated banana was significantly lower when compared to fungicide and untreated control fruits.     

分解蔗渣的研究Ⅱ.特异青霉YB-7纤维素酶的性质研究

对特异青霉（Ｐ．ｎｏｔａｔｕｍ）ＹＢ－７纤维素酶的一般酶学性质进行了研究。其最适酶作用条件为：ｐＨ５．０，５０℃，且在小于７０℃和ｐＨ４．０～９．０的范围内具有稳定性，ＣＭＣ、ＦＰＡ和β－葡萄糖苷酶活力变化范围有一定差别。甘油、葡萄糖和纤维二糖的最低抑制浓度（ｍｍｏｌ／Ｌ）分别为３．２５、２．４５和１．７１，其抑制系数分别为１．０１，２．３１和２．８０。８０％饱和度的硫酸铵可较完全地沉淀纤维素酶的有效成份。     

The use of sodium carbonate to improve curing treatments against green and blue moulds on citrus fruits

The effectiveness of curing oranges and lemons at 33 degrees C for 65h followed by storage under ambient and cold-storage conditions was investigated. This treatment effectively reduced the incidence of Penicillium digitatum (Pers) Sacc and P italicum Wehmer decay on inoculated and naturally infected oranges and lemons stored at 20 degrees C for 7 days. However, it failed to control green and blue mould infections on fruits placed in long-term cold storage, except green mould on oranges, which was effectively controlled. Dipping fruits in a sodium carbonate solution (20 g litre(-1)) for 2.5 min following a curing treatment at 33 degrees C for 65 h satisfactorily reduced green and blue mould incidence during subsequent long-term storage at 4 degrees C on oranges and at 10 degrees C on lemons. The efficacy was greater on injured fruits inoculated after the combination of treatments was applied, achieving a 60-80% reduction in decay in comparison with the curing treatment alone in all cases. A significant reduction of blue mould was also observed on fruits inoculated both before the treatments and on those re-inoculated after the treatments, demonstrating both protectant and eradicant activity. Thus, combining curing at 33 degrees C for 65 h with sodium carbonate treatment effectively controlled these post-harvest diseases on artificially inoculated citrus fruits and protected against re-infection. With naturally inoculated lemons, curing followed by sodium carbonate significantly reduced both green and blue mould incidence, but was not superior to curing alone. With naturally infected oranges, curing significantly reduced blue mould, but decay was not reduced further when followed by sodium carbonate treatment.     

甲磺隆污染土壤生物修复的初步探索

以14C-甲磺隆为例,通过投加优选菌株青霉(Penicillium sp.)和发酵有机肥,研究了污染土壤中甲磺隆除草剂的生物修复。结果显示,加入优选菌株Penicillium sp.或有机肥对甲磺隆污染土壤进行生物修复是可行的,Penicillium sp.或有机肥的引入,显著提高了土壤中甲磺隆残留物的降解速率,并大大减少了土壤中结合态甲磺隆残留物的形成,甲磺隆的降解半衰期由162.3 d降至42.5~51.6 d,56 d时其结合残留率仅为1.1%~4.6%,而对照土壤中结合残留率仍达到35.6%。     

马克斯克鲁维酵母对柑橘采后绿霉病的抑制效果

通过活体(in vivo)和离体(in vitro)试验,研究拮抗酵母菌株Kluyverom yces marxianus与不同浓度钼酸铵混合使用对柑橘采后绿霉病(Penicillium digitatum)的防治效果,以及钼酸铵对K.marxianus菌株生长和繁殖的影响.结果表明:不同浓度的钼酸铵对K.marxia...     

扬奇青霉α-半乳糖苷酶agl1基因在大肠杆菌中的表达与纯化研究

提取扬奇青霉总RNA,反转录合成cDNA,PCR扩增α-半乳糖苷酶agl1基因的编码区DNA序列,连接到原核表达载体pET28a(+)的多克隆位点,获得重组表达载体,转化大肠杆菌BL21,通过IPTG诱导获得agl1基因的特异性表达。结果表明:8mol/L尿素变性处理后的重组蛋白,经过Ni2+亲和柱纯化,SDS-PAGE检测该重组蛋白分子量约82ku,与预测结果相符。纯化的酶蛋白依次经过6、4、2mol/L和0mol/L尿素梯度透析复性后,α-半乳糖苷酶酶活为0.4U/mL。     

柑桔绿霉病拮抗细菌的筛选、鉴定及其抑制效果

从采集的柑桔园根际土壤中筛选得到1株对柑桔绿霉菌Penicillium digitatum具有较强拮抗活性的菌株HC-03.该菌株对柑桔绿霉菌、柑桔青霉菌Penicillium italicum、柑桔酸腐菌Geotrichum candidum等12种水果病原菌均有不同程度的拮抗作用,表现出广谱抗菌活性.菌落形态观察、生理生化特性分析及16S rDNA 序列测定和特异性PCR检测结果表明,该菌株为解淀粉芽孢杆菌Bacillus amyloliquefaciens.对沙糖桔的活体接种试验表明,菌株HC-03的发酵液、菌悬液及发酵滤液处理柑桔绿霉病的发生率均低于20%,病斑直径均在10mm以下.