Allelopathic effect of phenolic acids from humic solutions on two spruce mycorrhizal fungi:Cenococcum graniforme andLaccaria laccata

The aim of this investigation was to determine the impact ofp-hydroxyacetophenone,p-hydroxybenzoic acid, catechol, and protocatechuic acid on respiration of two spruce mycorrhizal fungi:Laccaria laccata andCenococcum graniforme. These phenols are produced byVaccinium myrtillus,Athyrium filixfemina, andPicea abies, predominant species of spruce forests in the Alps, and they are also present in humic solutions at 10^–10 M or 10^–5 M. Respiration of the two fungi was inhibited by the four phenolic acids, even at concentrations ranging from 10^–5 M to 10^–7 M. These data show phenolic acids from humic solutions have biological activity at extremely low concentrations, suggesting a contribution ofV. myrtillus, A. filixfemina, andP. abies to allelopathic inhibition of mycorrhizal fungi.     

Flavonoids released by carrot (Daucus carota) seedlings stimulate hyphal development of vesicular-arbuscular mycorrhizal fungi in the presence of optimal CO2 enrichment

Carbon dioxide has been previously identified as a critical volatile factor that stimulates hyphal growth ofGigaspora margarita, a vesiculararbuscular mycorrhizal fungus, and we determined the optimal concentration at 2.0%. The beneficial effect of CO₂ on fungal development is also visible in the presence of stimulatory (quercetin, myricetin) or inhibitory (naringenin) flavonoids. Sterile root exudates from carrot seedlings stimulate the hyphal development ofG. margarita in the presence of optimal CO₂ enrichment. Three flavonols (quercetin, kaempferol, rutin or quercetin 3-rutinoside) and two flavones (apigenin, luteolin) were identified in carrot root exudates by means of HPLC retention time. Flavonols like quercetin and kaempferol are known to have stimulatory effects on hyphal growth ofG. margarita.     

Biodiversity,Phylogeny, and Antifungal Functions of Endophytic Fungi Associated with Zanthoxylum bungeanum

This study investigated the biodiversity, phylogeny, and antifungal activity of endophytic fungi isolated from Zanthoxylum bungeanum. A total of 940 isolates obtained were grouped into 93 morphotypes, 43 species, and 23 genera, which were authenticated by molecular identification based on rDNA internal transcribed spacer (ITS) sequence analysis. A high diversity of endophytic fungi from Z. bungeanum are observed with high species richness S (43), Margalef index D′ (6.1351), Shannon–Wiener index H′ (3.2743), Simpson diversity index D_s (0.9476), PIE index (0.9486), and evenness Pielou index J (0.8705) but a low dominant index λ (0.0524). Significant tissue specificity of the endophytic fungi was observed in Z. bungeanum, and the highest species richness and diversity indexes were obtained in the stem. Phylogenetic analyses of the 93 endophytic isolates were carried out by the neighbor-joining (NJ) method to demonstrate their evolutionary processes. Antifungal activities of endophytic fungi were assayed and eight endophytic isolates showed strong and long-lasting inhibition against host pathogenic fungi Fusarium sambucinum and Pseudocercospora zanthoxyli. Here, for the first time, we systematically demonstrate the biodiversity, phylogeny, and antifungal activity of endophytic fungi associated with Z. bungeanum and reveal the value of sampling different tissues of a given plant to obtain the greatest endophyte species diversity, which might offer a framework for further investigation and utilization of endophytic fungi as aunique source of interesting and useful bioactive compounds.     

薰衣草产酚酸内生真菌的分离及产物初步鉴定

利用人工种植的薰衣草及无锡本地采集的相同品种薰衣草,对其各组织内生真菌进行分离、纯化。分别分离得到18和23株内生真菌。对所筛选出的菌株进行固态发酵,并对其发酵培养产物进行提取。通过化学反应的方法从野外采集薰衣草内生真菌中筛选出一株产酚酸的菌株,并通过分子生物学方法对其进行初步鉴定,并对其固态发酵提取物进行初步研究。研究结果表明了薰衣草内生真菌的多样性,为通过微生物固态发酵产酚酸类物质提供理论和实验基础。     

竹叶兰内生真菌的分离鉴定及其抗氧化活性研究

本文采用经典的植物内生菌分离方法,从两种不同产地的竹叶兰植株的根、茎及叶片部位中共分离出16株可培养的内生真菌,其中4种真菌分离自云南省西双版纳地区的竹叶兰,12种真菌分离自广西省百色市的竹叶兰。根据形态学观察和ITS基因序列同源性分析,大致分为7类,其中Phanerochaete sp.、Phyllosticta capitalensis、Diaporthe sp.、Hypoxylon sp.、Nodullsporium sp.、Chaetomium nigricolor各一株,其余10个菌株均属于Colletotrichum sp.,说明Colletotrichum sp.为竹叶兰内生真菌的一大优势种。通过对其中5种内生真菌的抗氧化活性进行测定(DPPH自由基清除法、Fe~(3+)还原能力法及H_2O_2自由基清除法),得到具有较强抗氧化活性的2种菌株BSSF-2及YNLF-1(对DPPH自由基的清除率≥80%),经鉴定菌株BSSF-2为Colletotrichum karstii,菌株YNLF-1为Phanerochaete sp.。本研究结果表明,药用植物内生真菌在寻找新型抗氧化药物的方面具有广阔前景。     

菌剂混施对各粒径矸石性质及苜蓿生长的影响

矿区矸石山由于养分贫瘠、微生物活性低,复垦难度高。微生物修复技术目前已成为矿区生态复垦的研究热点。为明确哈茨木霉菌(TH)、胶质芽孢杆菌(BM)与丛枝菌根真菌(AMF)3种菌剂在不同粒径煤矸石(大粒径(5~10 mm)、中粒径(2~5 mm)、小粒径(0~2 mm))中的复垦效果,设置单施、双菌混施、三菌混施及对照共8个处理,进行盆栽试验,测定紫花苜蓿生长指标、基质养分含量和基质微生物指标。结果表明,单施处理中,丛枝菌根真菌(AMF)对不同粒径基质综合改良效果最佳,总体上能显著提升紫花苜蓿的生长指标和不同粒径基质养分含量,将紫花苜蓿生物量提高了17.39%~40.43%。菌剂混施处理对不同粒径基质综合改良效果均好于单施处理,其中TH和BM混施、TH和AMF混施对基质过氧化氢酶、蔗糖酶、有效磷、MBC的提升表现出了强烈的互补效果,BM和AMF对基质碱解氮、有效磷、速效钾、MBC质量分数、磷酸酶、蛋白酶活性表现出了强化作用。各处理对小粒径基质的综合改良效果均优于大、中粒径基质,原因在于基质粒径越小,比表面积越大,越有利于微生物附着生长;同时,小粒径基质的孔隙较小,小孔隙保存水分的时间长于大孔隙。各处理中,TH+BM+AMF,AMF+TH,TH+BM分别为大、中、小粒径基质综合改良效果最佳的处理,分别将紫花苜蓿生物量提升了82.61%,86.69%,126.39%,对紫花苜蓿的根长、生物量和基质MBN质量含量均具有协同作用。综合来说,TH,BM,AMF菌剂混施技术可以作为矸石山一种良好的复垦技术,建议根据矸石山中煤矸石粒径大小选用相应的菌剂混施处理。     

云南省常见新鲜野生食用菌中硒含量调查

目的 调查云南省常见新鲜野生食用菌中硒含量水平。方法 收集云南省9个州市常见新鲜野生食用菌共计26个品种189件, 按照GB 5009.93-2017 《食品安全国家标准 食品中硒的测定》中原子荧光光谱法测定所采集的新鲜野生食用菌中的硒含量。结果 189件新鲜野生食用菌中有188件样品中检出硒, 检出率为99.5%, 硒含量范围为0.5~2670 μg/100 g, 平均值为126.0 μg/100 g, 中位值为35.0 μg/100 g, 其中硒含量最高的是昆明的干巴菌, 为2670 μg/100 g。结论 本研究为云南省常见新鲜野生食用菌中硒含量评价提供基础数据。     

基于高通量测序技术分析霉变核桃仁真菌多样性

目的:研究核桃仁在适宜霉变条件(温度25 ℃、相对湿度85%)下的真菌侵染过程,揭示其霉变过程中真菌群落的结构与真菌群落样性变化。方法:采用Illumina Miseq高通量测序方法分析核桃仁霉变过程中的真菌群落组成和多样性。结果:子囊菌门是核桃样品霉变的主要真菌门类,相对丰度在27.41%~99.98%范围,其次是担子菌门,相对丰度在0.01%~32.56%范围。在真菌属水平上,霉变过程中的主要优势种群为镰孢菌属、链格孢属、赤霉属与曲霉属。1周内核桃仁的霉变过程可大致分为Ⅰ期(0~2 d)、Ⅱ期(3~4 d)、Ⅲ期(5~7 d)3个时期,Ⅱ期与Ⅰ期相比镰孢菌属出现明显的富集,Ⅲ期与Ⅱ期相比镰孢菌属、链格孢属与曲霉属出现明显的富集,Ⅲ期与Ⅰ期相比镰孢菌属、链格孢属与曲霉属出现明显的富集。结论:核桃仁霉变过程中真菌微生物群落的变化分为3个时期,真菌多样性呈下降趋势,镰孢菌属、链格孢属与曲霉菌属是其霉变的优势真菌种群。     

基于高通量测序探究东北粳稻储藏期间真菌群落的演替

为探究不同初始水分的东北粳稻在模拟实仓环境储藏的条件下,稻谷中真菌群落随储藏时间的演替变化。选取水分在14.50%~15.50%的稻谷HW和13.50%~14.50%稻谷LW,进入模拟储藏实验。结果表明,在第一和第二储藏期高水分稻谷HW水分含量由15.50%降低至15.09%,低水分稻谷LW水分含量由14.21%降低至13.59%,直至第三储藏期保持平稳。基于可操作性分类单元（Operational Taxonmic Units,OTUs）的物种分类分析,两种水分的稻谷真菌群落经历了不同的演替变化。高水分稻谷在每个储藏期,真菌群落都发生了明显演替,稻瘟病菌（Magnaporthe_grisea）、金黄色蝶形担孢酵母（Papiliotrema_aurea）、弯孢菌（Curvularia_inaequalis）、黑孢霉（Neosetophoma_samararum）、汉纳酵母菌（Hannaella_sinensis）在储存结束时成为了最终的优势菌种。低水分稻谷在第二储藏期真菌群落发生明显演替,优势菌种为弯孢菌（Curvularia_inaequalis）、汉纳酵母菌（Hannaella_sinensis）、Hannaella_zeae。     

草莓致腐霉菌的鉴定及其产毒能力研究

目的调查草莓表面主要致腐真菌,并研究其是否产生毒素。方法对草莓真菌进行分离,综合利用菌落形态学观察、显微生殖观察、真菌ITS序列系统发育学分析鉴定真菌;利用高效液相色谱法检测腐烂草莓及真菌发酵液中赭曲霉毒素A(ochratoxin A,OTA)的含量。结果 4种毛霉属真菌和1种青霉属真菌可引起草莓腐烂,经分子鉴定分别为易脆毛霉菌、卷枝毛霉菌、多枝毛霉菌、根毛霉菌和草酸青霉菌。腐烂的草莓和毛霉发酵液检测不出OTA,但青霉菌发酵液中检测出OAT毒素存在。结论真菌是致草莓腐烂的主要诱因,毛霉菌在腐烂过程中占主导地位,但产毒素的青霉菌与其共生,应加强草莓及制品的风险监测。