新采收稻谷与仓储稻谷的霉菌菌相分析

采用传统培养法和宏基因组学技术对比了2017年新收获稻谷和将其仓储一年后稻谷中的真菌菌相差异。结果显示,稻谷中的真菌菌群由各类田间真菌转变为曲霉类和青霉类等仓储型真菌为主的优势菌群,并且两种方法的检测结果有着高度的一致性。可为稻谷在长距离运输期间的霉变防控提供重要的指导依据。     

Effect of pesticides on the seed-borne fungi and fungal succession on rice in Malaysia

Three fungicides (thiophanate methyl, thiram and 2-methoxyethyl mercury chloride) and two insecticides (carbaryl and malathion) were used to study the effects of each of the pesticides on the seed-borne fungi of rice. A total of over 40 species in 23 genera of fungi, including several pathogenic forms was isolated from the untreated flowers and seeds. Fewer fungi were encountered on flowers still enclosed within the sheaths and the largest number of fungi was isolated from seeds just before harvest. Storage of the seeds for 6 months eliminated a large number of field fungi that was originally present on freshly harvested rice seeds. The fungi that persisted on the stored seeds, however, were species reported to be capable of grain deterioration and mycotoxin production. With the pesticide-treated seeds, fewer fungi were isolated from those treated with thiram or 2-methoxyethyl mercury chloride than with any of the other chemicals. Species of Curvularia were isolated as the principal fungi on seeds treated with any of the chemicals.     

Contamination of freshly harvested Bambara groundnut (Vigna subterranea) seed from Mpumalanga,South Africa,with mycotoxigenic fungi

Freshly harvested Bambara groundnut (BGN) is occasionally consumed raw and can potentially become infected with mycotoxingenic field fungi. In this study, BGN samples were obtained from 12 farms in three districts of Mpumalanga in South Africa. Eight pooled samples were screened for multi-mycotoxin contamination using Ultra Performance Liquid-Chromatography tandem mass spectrometry (UPLC-MS/MS). To identify mycoflora, 12 samples were screened using conventional and molecular methods. Selected potential mycotoxin producing isolates were screened for mycotoxins using UPLC-MS/MS. No mycotoxins were detected on the freshly harvested BGN samples, but they were infected with various mycotoxin producing fungal species namely Aspergillus flavus (50%), Penicillium citrinum (25%), Penicillium oxalicum (17%), Penicillium citreoviridin (0.8%), and Fusarium verticillioides (0.8%). Following screening of selected fungal cultures, aflatoxin B₁ (0.4, 0.45 and 0.4 ppm) and fumonisin B₁ (0.7 ppm) were detected from A. flavus and F. verticillioides, respectively. Identification of mycotoxigenic fungi on freshly harvested BGN presents a potential health risk.     

基于形态特征和多基因序列鉴定储藏稻谷的优势真菌

稻谷储藏期间,真菌生长会影响稻谷质量,严重时会产生真菌毒素,引起食品安全问题。确定储藏期间稻谷的真菌群落组成并准确鉴定优势真菌,是实现有效防控危害真菌的前提,对于保障稻谷的品质和食品安全具有重要意义。基于此,利用传统的微生物分离培养方法,确定了不同地区粮仓内储存稻谷的真菌群落组成,并结合模式菌株和国际权威菌株序列,采用形态学观察及多基因联合系统发育分析方法准确鉴定我国储藏稻谷的优势种。结果表明,南方地区优势种为黄曲霉Aspergillus flavus、黑曲霉A. niger和蒙地曲霉A. montevidensis（阿姆斯特丹曲霉A. amstelodami）,北方地区优势种是多育曲霉Aspergillus proliferans和蒙地曲霉A. montevidensis。并阐述了南北方储藏稻谷主要优势种的详细鉴定过程及相关资料,为粮食中主要危害真菌物种的准确鉴定提供参考。     

小麦储藏粉尘的变化与真菌生长

小麦储藏过程中,真菌在粮食中生长,会产生大量的孢子、菌丝及真菌分解物,它们可直接引起小麦中粉尘的变化。采用比浊法研究了13.3%、14.2%、15.7%、16.4%、18.2%水分的小麦在15、20、25、30℃下储藏90 d,粉尘的变化与真菌生长的关系。结果表明,13.3%和14.2%的小麦储藏90 d,未发现有真菌的生长,浊度值变化均处于一个较低的水平(小于0.250 A);15.7%、16.4%和18.2%水分的样品储藏中有部分检出有真菌的生长,初期浊度值在0.260~0.308 A,随着储藏时间的增加,被感染样品的真菌生长和浊度值的变化均呈上升趋势,两者有良好的相关性。在储粮过程中通过对小麦粉尘变化的检测,可对储粮真菌的生长进行预测。     

Identification of fungal contamination and determination of mycotoxigenic molds by micellar electrokinetic capillary chromatography in smoked paprika

The purpose of this work was to analyze the fungal contamination in smoked and unsmoked paprika processed from different cultivars of pepper and to investigate the ability of these and other mycotoxigenic molds to grow and synthesize mycotoxins in smoked paprika. Eighteen mycotoxins were evaluated using micellar electrokinetic capillary chromatography. No relevant differences were found in fungal contamination between smoked and unsmoked paprika. The number of yeasts obtained was low, ranging from 0.4 to 3.29 log CFU g(-1); most of the yeast strains were identified as Cryptococcus spp. followed by Candida spp. All mold counts were <4 log CFU g(-1). Aspergillus, Cladosporium, Penicillium, and Fusarium were the predominant hyphomycete genera. Six mycotoxins were identified in the extracts of several strains isolated from paprika and incubated on malt extract agar. Penicillium expansum followed by Penicillium citrinum and Penicillium raistrickii were the dominant mycotoxigenic fungi isolated. Most of themycotoxin-producing fungi produced detectable amounts of mycotoxins when grown on paprika agar.     

Toxigenic fungi associated with processed (green) coffee beans (Coffea arabica L.)

Processed (green) coffee beans from Coffea arabica in Brazil were assessed for the presence of Aspergillus and Penicillium species both before and after surface sterilisation, the aflatoxigenic and ochratoxigenic potential of the isolates and ochratoxin A levels. Contamination by Aspergillus and Penicillium species was found on 96% and 42%, respectively, of 45 samples from 11 localities. After disinfection with 1% sodium hypochlorite, the levels fell to 47% and 24%, respectively. One hundred and eighty isolates were identified to species level and comprised Aspergillus sections Circumdati (10 species), Flavi (3), Nigri (3), Versicolores (4), while two were teleomorphic species. Eight species of Penicillium were isolated. Within section Circumdati, 75% of the isolates produced ochratoxin A and all except Aspergillus elegans and Aspergillus insulicola have previously been reported to produce ochratoxin A. One-third of the 18 isolates of Aspergillus flavus produced aflatoxin B1 and B2. None of the isolates belonging to Aspergillus section Nigri or Penicillium produced ochratoxin A. Of the 40 bean samples analysed, 58% were infected with potentially ochratoxigenic fungi but only 22% of these were contaminated with ochratoxin A at levels that varied from 0.47 to 4.82 ng/g, with an average contamination level of 2.45 ng/g.     

TOXIGENIC FUNGI ISOLATED FROM LATE-SEASON PECANS

Of 1978 fungal colonies isolated on malt-salt agar from twenty 5-kg samples of pecans harvested late in the season, 39% were Cladosporium, 21% were Penicillium, 9% were Alternaria or Epicoccum, 8% Pestalotia or Monochaeta, 4% Trichothecium, 4% Aspergillus niger, and less than 2% were Fusarium, Phomopsis, Rhizopus, Aspergillus, and miscellaneous genera. Forty-four of 260 representative isolates were persistently toxic to day-old cockerels. Toxigenic Penicillium spp. included P. citrinum, P. terrestre, P. cyclopium, P. funiculosum, P. roquefortii, P. purpurogenum, P. rubrum, and P. rugulosum. Toxigenic isolates of other genera included Aspergillus fiavus, A. cervinus, Alternaria alternata, Trichothecium roseum, Pestalotia sp., and Fusarium spp. Additional key words are Carya illinoensis, mycotoxins.     

南通白蒲黄酒麦曲真菌群落结构研究

黄酒的主要产地是我国的上海、江苏、浙江等地区,南通白蒲黄酒是中国清爽型黄酒的典型代表,与上海和浙派黄酒在口味上具有明显的差异.麦曲作为黄酒发酵的粗酶制剂,是引起黄酒风味差异的主要原因之一.本实验运用传统分离培养方法,并运用ITS序列分析技术分析探讨了南通白蒲黄酒麦曲中的真菌群落结构,并与已报道的绍兴黄酒麦曲微生物群落结构进行了比较.经分离鉴定,南通白蒲黄酒麦曲中的主要丝状真菌为芽枝状枝孢霉、白曲霉、米曲霉、粒状青霉和产黄青霉,其含量分别为24％、25％、6％、18％和22％.与绍兴麦曲中的真菌种群(主要是伞枝犁头霉、米根霉、微小毛霉、米曲霉、烟曲霉和少量青霉)有较大差异.     

Toxigenic penicillia spoiling frozen chicken nuggets

Frozen chicken nuggets are classified as pre-prepared frozen meals. These products are convenient to consumers as they are easy to prepare and allow for long storage by freezing. Over the years, spoilage of frozen food products caused by fungi has been a continual problem for the food industry since mold can develop when frozen foods are allowed to attain temperatures of − 10 °C, or above. The growth of fungi on the food surface results in economic losses and represents a hazard to public health due to the possibility of mycotoxin production. The aim of this study was to identify the species of filamentous fungi involved in the spoilage of frozen chicken nuggets and determine their ability to produce mycotoxins under laboratorial conditions. A total of 7 samples of frozen chicken nuggets were analyzed by dilution plating in potato dextrose agar (PDA). These products had been returned by customers due to visible mold growth on their surface. The predominant species found were Penicillium glabrum, Penicillium polonicum, Penicillium manginii, Penicillium crustosum, Penicillium commune, and Penicillium solitum. Analysis of the profile of secondary metabolites was carried out in HPLC after growing the isolates in Czapek yeast autolysate agar (CYA) and yeast extract agar and sucrose (YESA) and extracting the extrolites with a solution of ethyl acetate, dichloromethane, methanol, and formic acid. Some isolates of these species showed an ability to synthesize mycotoxins such as cyclopiazonic acid citreoviridin, roquefortine C, penitrem A, and verrucosidin under standard conditions. Considering the occurrence of fungal spoilage in frozen food and the potential hazard involved, more studies on psychrophilic fungi growth in foods stored at low temperatures are necessary.     

Incidence of heat-resistant fungi in Nsukka, southern Nigeria

A total of 42 soil samples collected from different parts of Nsukka, Southern Nigeria, and 20 freshly plucked mango fruits were screened for the presence of heat-resistant fungi. Each soil sample, suspended in sterile water, and washings from each mango fruit were separately heated at 70 degrees C for 1 h before plating on double-strength potato dextrose agar containing chloramphenicol and incubating at approx. 28 degrees C. Approximately 98% of all soil samples and 17% of mango fruits contained heat-resistant fungi which were identified as Neosartorya fischeri, N. fischeri var. spinosa, Aspergillus flavus, Penicillium citrinum and Paecilomyces varioti which has not been reported in tropical soil. Neosartorya spp. were predominant and occurred in all positive samples. Fungal counts ranged from non-detectable to 200 colony-forming units per 10 g of soil. Most isolates appeared to grow faster at 35 degrees C than at 30 degrees C and 40 degrees C.     

Some biological and chemical characteristics of damaged corn

The predominant fungi isolated from damaged kernels of corn (maize) plated on agar media were species of Aspergillus (mainly A. glaucus) and Penicillium. Masses of spores and mycelium of Aspergillus, Penicillium, Cladosporium and Fusarium were present in the cavities of the embryo of many kernels from which no fungi grew. Some samples had a high percentage of blue-eye kernels, evidently caused mainly by A. restrictus and A. glaucus. The embryos of all damaged kernels were decayed to some extent by fungi. Weight averaged 51 · 7 lb/bu, not much below that of sound corn. Fat acidity values ranged from 90–324. No aflatoxin was found in any of the 24 samples tested.     

河南烟叶仓储期优势霉菌的分离鉴定及防霉剂的筛选

对来自河南产区仓储烟叶中的主要霉菌进行了分离、鉴定,并测定了防霉剂对优势霉菌的抑制作用.结果表明,河南烟叶样品中霉菌数量以曲霉最多,其次是青霉.山梨酸钾、丙酸钙、双乙酸钠、脱氢醋酸钠、对羟基苯甲酸乙酯和富马酸二甲酯对黄曲霉、黑曲霉和桔青霉这3种优势霉菌均有明显的抑霉作用.     

Production of secondary metabolites by some terverticillate penicillia on carbohydrate-rich and meat substrates

Most terverticillate penicillia isolated from dry-cured meat products are toxigenic, but their ability to produce hazardous metabolites on meat-based substrates is not well known. The production of extrolites by selected terverticillate penicillia isolated from dry-cured ham has been studied on carbohydrate-rich media (malt extract agar, Czapek yeast autolysate agar, rice extract agar, and rice), meat extract triolein salt agar, and ham slices. Chloroform extracts from the selected strains grown on malt extract agar were toxic for the brine shrimp (Artemia salina) larvae and VERO cells at a concentration of 2 mg/ml, but 0.02 mg/ml produced no toxic effect. Analysis by high-pressure liquid chromatography (HPLC) coupled with photodiode array detection (DAD) or with mass spectrometry (MS) and an atmospheric pressure chemical ionization (APCI) source revealed different biologically active metabolites: cyclopiazonic acid and rugulovasine A from Penicillium commune; verrucosidin, anacine, puberuline, verrucofortine, and viridicatols from Penicillium polonicum; arisugacin and viridicatols from Penicillium echinulatum; and compactin and viridicatols from Penicillium solitum. Most of these metabolites, including the amino acid-derived compounds, were produced in the media containing high levels of carbohydrates. High concentrations of nitrogen compounds in the medium does not imply a greater production of the metabolites studied, not even those derived from the amino acids. However, molds growing on dry-cured ham are able to synthesize limited amounts of some secondary metabolites, a fact not previously reported. The combination of HPLC coupled with DAD and MS-APCI was useful for identification of closely related terverticillate Penicillium species from dry-cured ham. These techniques could be used to characterize the risk associated with the potential production of secondary metabolites in cured meats.     

Antimicrobial activity of vanillin against spoilage microorganisms in stored fresh-cut mangoes

The antimicrobial activity of vanillin against four bacteria (Pantoea agglomerans, Aeromonas enteropelogenes, Micrococcus lylae, and Sphingobacterium spiritovorun), four fungi (Alternaria sp., Aspergillus sp., Penicillium sp., and Fusarium sp.), and three unidentified yeasts isolated from spoiling fresh-cut mango slices was verified in laboratory media adjusted to pH 5.0. MICs of vanillin against the fungi (12.5 to 13.3 mM), bacteria (10 to 13.3 mM), and yeasts (5.0 to 6.7 mM) indicated that all the test species were sensitive to the antimicrobial effects of vanillin. Fresh-cut mango slices were dipped for 1 min in solutions containing 40 and 80 mM vanillin before being packaged in rigid trays and stored at 5 and 10 degrees C to verify the effects of vanillin on the development of the spoilage microflora. Microbiological analysis for up to 14 days of storage revealed that treatment with 80 mM vanillin significantly delayed (P < 0.05) the development of total aerobic bacteria and yeast and mold populations. Vanillin may be a practical preservative for processing fresh-cut mango.     

Spoilage fungi and their mycotoxins in commercially marketed chestnuts

A nationwide survey was carried out to assess mould spoilage of Castanea sativa nuts sold in Canadian grocery stores in 1998-99. Morphological and cultural characters, along with secondary metabolite profiles derived from thin-layer chromatography, were used to sort and identify fungi cultured from nut tissue. Three mycotoxigenic fungi dominated (Penicillium crustosum, Penicillium glabrum/spinulosum and Penicillium discolor) and were isolated at frequencies of 67.1%, 18.6% and 17.7%, respectively, from a total sample size of 350 nuts. Another mycotoxin producer, Aspergillus ochraceus was also isolated, but at a much lower frequency. HPLC and diode array detection were used to confirm the suspected presence of the mycotoxins penitrem A, chaetoglobosin A and C, emodin and ochratoxin A in extracts prepared from naturally infected nut tissue. To the best of our knowledge, this is the first time emodin has been found in a naturally contaminated food source.     

基于传统培养法和高通量测序技术分析新疆红枣中真菌多样性

目的 揭示新疆红枣中真菌多样性, 有效防控红枣病害的发生。方法 采用高通量测序技术与传统微生物培养法对红枣进行真菌群落结构分析, 利用Huang模型比较分离的有害真菌的生长。结果 高通量测序结果表明, 优势菌属为链格孢属（Alternaria）、曲霉属（Aspergillus）、枝孢属（Cladosporium）和青霉属（Penicillium）, 传统微生物分离测序鉴定的真菌群落为曲霉属（Aspergillus）、链格孢属（Alternaria）、青霉属（Penicillium）、枝孢属（Cladosporium）和踝节菌属（Talaromyces）。在马铃薯葡萄糖琼脂培养基和红枣琼脂培养基上, 产黄青霉的生长速率最小, 赭曲霉的迟滞时间最长, 链格孢霉和黄曲霉在这两种培养基上的生长速率相关性较好。结论 红枣的主要致病菌是曲霉属和链格孢属。     

Mycotoxins in South African traditionally brewed beers

Traditionally brewed alcoholic beverages are regularly consumed by most ethnic black South Africans. Maize and barley, both of which are used for producing locally brewed alcoholic beer, are frequently contaminated by mycotoxin-producing moulds. The study was undertaken to investigate whether these toxins are present in raw grains and the traditional beers imbibed by the local black African population. It was established that the raw ingredients (sorghum, sorghum malt grains, maize grits), commercially produced traditional beers (Utshwala and Utshwala special) and home-brewed beers (Umqombotha, Isiqatha, Imfulamfula) were contaminated by bacteria and fungi (both yeasts and moulds). The contaminating moulds were isolated and identified. The contaminated samples were analysed for aflatoxins B 1 , B 2 , G 1 and G 2 , zearalenone, citrinin, deoxynivalenol, and ochratoxin A using a multi-mycotoxin thin-layer chromatography screening method and the toxins were quantified by high-performance liquid chromatography. Grain samples were infected by Aspergillus flavus , A. alliaceus , A. clavatus , Penicillium spp., Rhizopus spp. and Mucor spp. Sorghum malt grain samples contained the toxin zearalenone. No mycotoxin-producing fungi were present in the fermented beers but two of six commercial beer samples contained aflatoxins (200 and 400 μgl -1 ) and 45% (13 of 29) of the home-brewed beers had zearalenone (range 2.6-426 μg l -1 ) and/or ochratoxin A (3-2340 μg l -1 ).     

传统发酵食品-浆水中微生物的分离与初步鉴定

通过对浆水中的微生物进行分离培养及数量测定，查明了浆水中的优势菌为乳酸菌及酵母菌，其次尚有少量放线菌，霉菌为污染菌。从不同样品中分离得到了2株乳酸菌、3株酵母菌，1株放线菌及2株霉菌，通过对其形态、培养特征及生物学特性的研究，初步鉴定2株乳酸菌分属于乳杆菌属（Lactobacillus）和明串珠菌属（Leaconostoc）；3株酵母菌分属于酒香酵母属（Brettanomyces）、隐球酵母属（Cryptococcus）及裂殖酵母属（Schizosaccharomyces）；放线菌属于诺卡氏菌属（Nocardia）；2株霉菌分属于青霉属（Penicillium）和曲霉属（Aspergillus）。     

Mycotoxin production and postharvest storage rot of ginger (Zingiber officinale) by Penicillium brevicompactum

Twenty naturally infected ginger (Zingiber officinale) rhizomes displaying visible mold growth were examined to identify the fungi and to evaluate the presence of fungal secondary metabolites. Penicillium brevicompactum was the predominant species isolated from 85% of the samples. Mycophenolic acid was identified from corresponding tissue extracts. Because mycophenolic acid is a potent immunosuppressant and synergistic mycotoxicosis studies involving human consumption have not been carried out on this metabolite, spoilage of commercially marketed produce caused by P. brevicompactum is a concern. This is the first reported occurrence of mycophenolic acid in commercially sold plant food products.