Bioactive compounds and antioxidant activity exhibit high intraspecific variability in <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis> mushrooms and correlate well with cultivation performance parameters

Experimental data related with oyster mushroom production and nutritional properties usually derive from the examination of only one strain, and hence their representativeness/usefulness is questionable. This work aims at assessing intraspecific variability in Pleurotus ostreatus by studying 16 strains, under the same conditions, in respect to essential cultivation and mushroom quality aspects, and by defining the impact of intrinsic/genetic factors on such parameters. Hence, mushroom yield, earliness, crop length, biological efficiency, productivity, and their content in selected macro and microconstituents (e.g. fatty acids, sterols, individual phenolic compounds, terpenic acids, glucans) as well as their antioxidant properties (i.e., antiradical activity, ferric reducing potential, inhibition of serum oxidation) were assayed. The effect of intrinsic/genetic factors was evident, especially as regards earliness, yield of each production flush and mushroom weight, whereas biological efficiency was not particularly influenced by the cultivated strain. Moreover, phenolics, ergosterol and antiradical activity demonstrated significant variability among strains in contrast to what was observed for fatty acids, β-glucans and ferric reducing potential. The observed heterogeneity reveals the limitations of using a low number of strains for evaluating mushroom production and/or their content in bioactive compounds, and as evidenced, it is valuable for breeding and commercial purposes.     

大球盖菇“山农球盖3号”品种的选育

本研究收集了国内外28株大球盖菇菌株,通过SRAP分子标记技术和耐高温递进式循环驯化选择出2株适合的实验材料,采用原生质体融合、原生质体再生技术进行耐高温菌株初选,筛选出2株性状优良的耐高温菌株（S20菌丝耐高温、产量高;R10 I级菇比例高、子实体耐高温）,收集2菌株出菇后的孢子进行单孢杂交,在高温条件下通过多次继代培养和栽培实验,最终确定出J8L4（山农球盖3号）为最优耐高温高产菌株。该菌株能连续7d在最高料温达27-34℃、最高气温达40-47℃条件下生长良好,无杂菌污染,40d出菇,其产量达到14.56kg/m ²,生物转化率为91.03%,优质菇比例为66.21%。研究结果表明,通过多层次的驯化筛选和多项育种技术的综合使用,使得所选菌株的优良性状更显著,遗传稳定性更好。     

“食用菌产量和品质形成的分子机理及调控”项目简介——食用菌产业发展与技术创新的科学基础

食用菌以子实体为收获物,是优质蛋白的重要来源,我国重要的食物安全战略产业,已经成为我国粮、菜、果、油之后的第五大产值农作物,2013年产量3 169.68万吨（中国食用菌协会统计）,直接产值1 707亿元,间接产值6 828亿元,从业人口逾2 000万。我国食用菌产量已占全球总产量的75%以上。但是,与食用菌产业相关的基础科学研究严重匮乏,对产量和品质形成的关键科学问题研究的空白,严重制约着我国食用菌育种和栽培等产业技术的创新,导致单产低、质量差,产业链难以延长,产业效益持续下降,产业升级艰难。科学基础研究的缺乏,已经成为食用菌产业发展的瓶颈。2014年立项的国家重点基础研究发展计划（973）项目“食用菌产量和品质形成的分子机理及调控”（2014CB138300）,紧紧抓住困扰我国食用菌产业发展的科学问题,开展食用菌高效利用木质纤维素的分子机制、食用菌子实体形成发育的调控机理、食用菌温度响应的分子机制、食用菌活性物质及其合成代谢的分子基础和食用菌优异种质性状形成的遗传基础研究,拟阐释食用菌子实体形成的营养利用与遗传调控机制、食用菌抗逆性的温度响应机制和食用菌活性物质的合成代谢调控机理。构建食用菌科学理论体系,为食用菌产业关键技术创新奠定科学基础,为优质高产提供理论指导,为延长产业链,提高产业效益提供科学路径。     

Genetic distinctions among clinical and environmental strains of Vibrio vulnificus

Vibrio vulnificus causes rare but frequently fatal septicemia associated with raw oyster consumption by persons with underlying hepatic or immune system dysfunction. The virulence potential of environmental reservoirs appears widely distributed, because most strains are virulent in animal models; however, several investigations recently demonstrated genetic divergence among strains from clinical versus environmental origin at independent genetic loci. The present study used PCR to screen DNA polymorphisms in strains from environmental (n = 35) or clinical (n = 33) sources, and genomic relationships were determined by repetitive extragenic palindromic DNA PCR (rep-PCR) typing. Significant (P < 0.01) association was observed for typical "clinical" or "environmental" polymorphism profiles based on strain origin. Most oyster isolates (88%), including all of those with the "environmental" profile, also formed a single rep-PCR genogroup. Clinical isolates within this group did not have the typical "clinical" profile. On the other hand, clinical isolates with the typical polymorphism profile were distributed among multiple rep-PCR genogroups, demonstrating greater genetic diversity than was evident by profiling genetic polymorphisms. Wound isolates were genetically distinct from typical blood isolates by all assays. Strains from an outbreak of wound infections in Israel (biotype 3) were closely related to several U.S. strains by rep-PCR, indicating potential reservoirs of emerging disease. Strains genetically related to blood isolates appeared to be relatively rare in oysters, as only one had the "clinical" polymorphism profile or clustered by rep-PCR. However, this study was not an extensive survey, and more sampling using rep-PCR for sensitive genetic discrimination is needed to determine the virulence potential of environmental reservoirs.     

Effects of the paedogenetic mushroom cecid, Heteropeza pygmaea (Diptera:Cecidomyiidae) on cropping of the cultivated mushroom (Agaricus bisporus)

When introduced into a mushroom crop at rates of 2, 20 or 200 larvae/tray (0.56 m²), the mushroom cecid, Heteropeza pygmaea, caused significant reductions in both yield and number of mushrooms in relation to the infestation level. The reductions were greater when the larvae were introduced at spawning rather than at casing. The yield and number of infested (unmarketable) mushrooms increased significantly in relation to the initial infestation level. Just two H. pygmaea larvae, introduced at spawning, resulted in cecid populations that caused a 12% loss in total yield in addition to a 7% loss due to spoilage. Loss assessment in the future, therefore, should take into account both yield suppression and spoilage. There was little effect of cecid infestation on flush timing and mushroom size was only affected in the fourth flush, when a significant reduction (27%) was shown at the highest infestation rate at spawning.     

Cultivation of different strains of king oyster mushroom (Pleurotus eryngii) on saw dust and rice straw in Bangladesh

Pleurotus eryngii is a popular mushroom due to its excellent consistency of cap and stem, culinary qualities and longer shelf life. In Bangladesh, where Pleurotus mushrooms are very popular, P. eryngii may take position among the consumers, but currently this mushroom is not cultivated in large scale there. In this study, 3 strains of P. eryngii such as Pe-1 (native to Bangladesh), Pe-2 (germplasm collected from China) and Pe-3 (germplasm collected from Japan) were cultivated on saw dust and rice straw and their growth and yield parameters were investigated. Pe-1 on saw dust showed the highest biological yield and efficiency (73.5%) than other strains. Also, the mycelium run rate and number of fruiting bodies were higher in Pe-1 than other two strains. The quality of mushroom strains was near about similar. On saw dust, the yield and efficiency were better than those cultivated on rice straw, however, on straw; the mushroom fruiting bodies were larger in size. This study shows the prospects of P. eryngii cultivation in Bangladesh and suggests further study in controlled environment for higher yield and production.     

Mushroom host influence on Lycoriella mali (Diptera: Sciaridae) life cycle

Lycoriella mali Fitch (Diptera: Sciaridae) infests mushroom crops early in the crop cycle. Recent observations in mushroom houses indicated a difference in emergence time and size of adult L. mali developing on various strains of commercial mushrooms. Samples of adult flies from isolated mushroom houses growing Portabella mushrooms were significantly heavier then those from oyster mushroom houses, whereas flies from shiitake mushroom houses were lightest in weight. Flies collected from isolated Portabella mushroom houses were reared on four strains and species of Agaricus and Pleurotus mushrooms. After the adults emerged, females were weighed, mated, and allowed to oviposit. The number of eggs laid increased as the weight of the female increased. Flies collected from isolated Portabella mushroom houses were reared on eight strains and species of mushrooms. Flies were reared for four generations on each host mushroom mycelium then switched to different host mushrooms. Overall, the hybrid strain of Agaricus bisporus (Lange) Imbach (Agaricales: Agaricomycetideae) was the most favorable host for L. mali, whereas the wild strain of A. bisporus was the least favorable host. Mushroom hosts influence developmental time, survivorship, weight, and reproduction of L. mali.     

The comparative effects of three formulations of diazinon on cropping of a hybrid and a non-hybrid strain of the cultivated mushroom Agaricus bisporus

Three formulations of diazinon: flowable granules (FG); wettable powder (WP); and emulsifiable concentration (EC), which are used for the control of mushroom pests, were compared for toxicity towards a hybrid and non-hybrid strain of the cultivated mushroom, Agaricus bisporus. With all formulations, yield and number of mushrooms were reduced according to dosage (linear trend). The EC was the most toxic and persistent formulation – equally so to both mushroom strains – and produced the most severe responses in all the parameters considered. The WP was the least toxic formulation. The hybrid strain was more susceptible to diazinon than the non-hybrid, but not markedly so.     

Modern aspects of mushroom culture technology

The production and culture of new species of mushrooms is increasing. The breeding of new strains has significantly improved, allowing the use of strains with high yield and resistance to diseases, increasing productivity and diminishing the use of chemicals for pest control. The improvement and development of modern technologies, such as computerized control, automated mushroom harvesting, preparation of compost, production of mushrooms in a non-composted substrate, and new methods of substrate sterilization and spawn preparation, will increase the productivity of mushroom culture. All these aspects are crucial for the production of mushrooms with better flavor, appearance, texture, nutritional qualities, and medicinal properties at low cost. Mushroom culture is a biotechnological process that recycles ligninocellulosic wastes, since mushrooms are food for human consumption and the spent substrate can be used in different ways.     

Advances in genetic analysis and biotechnology of the cultivated button mushroom, Agaricus bisporus

During the last decade several major breakthroughs have been achieved in mushroom biotechnology, which greatly enhanced classical mushroom breeding. DNA-based technologies such as restriction fragment length polymorphisms and randomly amplified polydisperse DNA sequences have allowed for a measure of genetic diversity, for the isolation of homokaryons, for the determination of inheritance of nuclear and mitochondrial markers, and for the production of a genetic linkage map. The recent availability of ready-to-use and affordable DNA technologies has resulted in a substantial increase in the number of Agaricus bisporus genes that have been identified and characterized. A major breakthrough was achieved in 1996 when the first successful and stable transformation system of A. bisporus was reported. Together, the availability of an increasing number of known genes and the possibility to produce transgenic mushrooms will result in a better understanding of the molecular, physiological and biochemical processes that are essential for mushroom production, shelf life and quality aspects such as flavor, texture and disease resistance. Some potential targets for strain improvement are discussed, such as the genes involved in brown discoloration, substrate utilization, carbon and nitrogen metabolism, and fruit body development. Received: 19 January 1999 / Received revision: 27 May 1999 / Accepted: 4 June 1999     

我国食用菌遗传学的发展及展望

食用菌遗传学是食用菌学科体系的重要分支之一,40年来我国食用菌遗传学研究紧密围绕为育种服务、最新分子生物学技术的应用和生产实践中的科学问题的解决等主题开展了众多科学活动.为了促进食用菌遗传学研究的系统性和全面性,本文梳理出9个方面的研究主题,主要包括食用菌种质资源调查和地方品种研究、食用菌农艺性状控制基因定位和分子辅助...     

Genetic Distinctions among Clinical and Environmental Strains of Vibrio vulnificus

Vibrio vulnificus causes rare but frequently fatal septicemia associated with raw oyster consumption by persons with underlying hepatic or immune system dysfunction. The virulence potential of environmental reservoirs appears widely distributed, because most strains are virulent in animal models; however, several investigations recently demonstrated genetic divergence among strains from clinical versus environmental origin at independent genetic loci. The present study used PCR to screen DNA polymorphisms in strains from environmental (n = 35) or clinical (n = 33) sources, and genomic relationships were determined by repetitive extragenic palindromic DNA PCR (rep-PCR) typing. Significant (P < 0.01) association was observed for typical “clinical” or “environmental” polymorphism profiles based on strain origin. Most oyster isolates (88%), including all of those with the “environmental” profile, also formed a single rep-PCR genogroup. Clinical isolates within this group did not have the typical “clinical” profile. On the other hand, clinical isolates with the typical polymorphism profile were distributed among multiple rep-PCR genogroups, demonstrating greater genetic diversity than was evident by profiling genetic polymorphisms. Wound isolates were genetically distinct from typical blood isolates by all assays. Strains from an outbreak of wound infections in Israel (biotype 3) were closely related to several U.S. strains by rep-PCR, indicating potential reservoirs of emerging disease. Strains genetically related to blood isolates appeared to be relatively rare in oysters, as only one had the “clinical” polymorphism profile or clustered by rep-PCR. However, this study was not an extensive survey, and more sampling using rep-PCR for sensitive genetic discrimination is needed to determine the virulence potential of environmental reservoirs.     

Evaluation of indigenous potent mushroom growth promoting bacteria (MGPB) on Agaricus bisporus production

Mushrooms such as Agaricus bisporus, are cultivated for food worldwide. Fruit body initiation in Agaricus bisporus is a phase change from the vegetative to the reproductive stage which depends on the presence of a casing layer with particular physical, chemical and microbiological properties. The phase change is achieved practically by environmental manipulation and the presence of naturally occurring bacteria such as Pseuodomonas putida. In this study, 274 individual bacterial isolates were collected by screening the casing layer of 14 edible mushroom farms. The isolates were analysed with respect to biochemical properties, organic and inorganic phosphate solubilization, production of siderophore and growth in the presence of volatile compound of 1-octen-3-ol. It was found that approximately 97% of the strains were able to grow in the presence of 1-octen-3-ol and 36% were able to solubilize phosphorus. Among the isolates, 23 strains were selected as potent mushroom growth promoting bacteria (MGPB) for inoculation of the casing layer. Field experiments using these strains showed various promoting effects on production of mushroom. Finally, 2 strains (strains Bt4 and Ps7) showing the highest increase in A. bisporus production, were characterized as Pseuodomonas putida by molecular methods and identified as the best suited growth promoting inoculants for application in production farms for increasing the mushroom yield.     

Relative contribution of nematodes (Caenorhabditis elegans) and bacteria towards the disruption of flushing patterns and losses in yield and quality of mushrooms (Agaricus bisporus)

Laboratory tests of bacteria isolated from the body surface, or from the gut, of a saprophagous rhabditid nematode Caenorhabditis elegans infesting mushrooms (Agaricus bisporus) showed that some bacteria enhanced nematode reproduction and that others inhibited it. As some bacteria were shown to inhibit mycelial growth of the mushroom, the effects of Acinetobacter calcoaceticus var. anitratus, Enterobacter cloacae and Serratia liquefaciens, either alone or in combination with C. elegans, on the flushing patterns, quality and yield of A. bisporus (strain Horst U3) were studied. Bacteria alone had little effect on flushing patterns whereas C. elegans delayed the onset of mushroom production and significantly disrupted the growth pattern of crops, with mushrooms appearing more regularly and not within obvious flushes. Inoculation with bacteria resulted in ‘browning’ of mushrooms that was even more pronounced in C. elegans treatments. Characteristic distortion of sporophores was observed only in the presence of C. elegans. Nematodes commonly colonised sporophores. Bacteria affected the size of nematode populations both on the sporophores and in the casing. Significant yield loss occurred; up to 10% when bacteria were inoculated, up to 27.8% when C. elegans was inoculated, and up to 35% with both bacteria and nematodes. Synergism between C. elegans and A. calcoaceticus var. anitratus was observed; the combination resulted in significantly greater reduction in mushroom yield than any other treatment. It is concluded that bacteria contribute to yield loss and quality deterioration in A. bisporus but that the effects are far greater in the presence of C. elegans.     

Developments in breeding of Agaricus bisporus var. bisporus: progress made and technical and legal hurdles to take

True breeding of button mushrooms has hardly been done in the last decades, despite this species being one of the most cultivated mushrooms worldwide. Research done in the last 20 years has identified and characterised new germplasm and improved our understanding of the genetic base for some traits. A substantial collection of wild-collected strains is now available and partly characterised for a number of important traits such as disease resistance and yield. Most of the variations found in a number of important agronomic traits have a considerable heritability and are thus useful for breeding. Genetic marker technology has also developed considerably for this mushrooms in the last decade and used to identify quantitative trait loci (QTL) for important agronomic traits. This progress has, except for one example, not resulted so far into new commercially varieties. One of the reasons lies in the typical life cycle of the button mushroom Agaricus bisporus var. bisporus which hampers breeding. Joint investment is needed to solve technical problems in breeding. Special attention is needed for the protection of new varieties. Due to its typical life cycle, it is very easy to generate so called “look-a-likes” from protected cultivars by screening fertile single spore cultures. A consensus has been reached within the mushroom (breeding) industry to consider this method as the generation of essentially derived varieties as defined in plant breeding.

     

香菇双单杂交后代不同发育阶段酯酶同工酶研究

选用香菇野生株分别与栽培株及杂交株进行双单杂交 ,得到 8个杂交后代 ,且具有结实能力 ,分别对液培 2 0d杂交后代菌丝与液培原基酯酶同工酶进行了比较研究。结果表明 ,液培 2 0d菌丝菌株间酯酶同工酶酶谱显示出多样性 ,可以作为鉴定菌株的辅助遗传标记 ,而原基菌株间酯酶同工酶酶谱谱带较少 ,呈现趋同效应 ,不宜作为鉴定香菇菌株的辅助遗传标记。     

Applications of the rep-PCR DNA fingerprinting technique to study microbial diversity, ecology and evolution

A large number of repetitive DNA sequences are found in multiple sites in the genomes of numerous bacteria, archaea and eukarya. While the functions of many of these repetitive sequence elements are unknown, they have proven to be useful as the basis of several powerful tools for use in molecular diagnostics, medical microbiology, epidemiological analyses and environmental microbiology. The repetitive sequence-based PCR or rep-PCR DNA fingerprint technique uses primers targeting several of these repetitive elements and PCR to generate unique DNA profiles or 'fingerprints' of individual microbial strains. Although this technique has been extensively used to examine diversity among variety of prokaryotic microorganisms, rep-PCR DNA fingerprinting can also be applied to microbial ecology and microbial evolution studies since it has the power to distinguish microbes at the strain or isolate level. Recent advancement in rep-PCR methodology has resulted in increased accuracy, reproducibility and throughput. In this minireview, we summarize recent improvements in rep-PCR DNA fingerprinting methodology, and discuss its applications to address fundamentally important questions in microbial ecology and evolution.     

Lignocellulolytic enzyme activity,substrate utilization,and mushroom yield by <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis> cultivated on substrate containing anaerobic digester solids

Solid waste from anaerobic digestion of litter from the commercial production of broiler chickens has limited use as fertilizer. Its disposal is a major problem for digester operators who are seeking alternative use for anaerobic digester solids, also referred to as solid waste (SW). The use of SW as substrates for the cultivation of Pleurotus ostreatus strain MBFBL400 was investigated. Lignocellulolytic enzymes activity, substrate utilization, and mushroom yield were evaluated in ten different substrate combinations (SCs) containing varying amounts of solid waste, wheat straw, and millet. Nutritional content of mushrooms produced on the different substrates was also determined. Substrates containing 70–80% wheat straw, 10–20% SW, and 10–20% millet were found to produce the highest mushroom yield (874.8–958.3 g/kg). Loss of organic matter in all SCs tested varied from 45.8% to 56.2%, which had positive correlation with the biological efficiency. Laccase, peroxidase, and carboxymethylcellulase (CMCase) activities were higher before fruiting, whereas xylanase showed higher activities after mushroom fruiting. SW increased the nutritional content in mushrooms harvested, and the combination of wheat straw and SW with millet significantly improved mushroom yield. Our findings demonstrated the possibility of utilizing anaerobic digester solids in mushroom cultivation. The application of SW as such could improve the financial gains in the overall economy of anaerobic digester plants.     

Effects of Caenorhabditis elegans (Nematoda: Rhabditidae) on yield and quality of the cultivated mushroom Agaricus bisporus

Thirteen species of saprobic rhabditid nematodes (11 genera) were identified from samples of compost and casing material collected from mushroom farms in the British Isles. Caenorhabditis elegans, the most frequently found saprobe, was mass-produced monoxenically and its effects on the cultivated mushroom, Agaricus bisporus (strain U3) were studied. C. elegans did not multiply in well-prepared, pasteurised, spawned compost, whereas casing material proved to be a highly suitable environment for its reproduction. An initial casing inoculum of 10⁶ nematodes/crate of compost (7.5 kg), caused a significant reduction in mushroom yield. Losses in total mushroom yields of 11%, 20% and 26% were caused by initial inoculum rates of 10⁶, 10⁷and 2 × 10⁷ nematodes/crate, respectively. Yields were negatively correlated with the initial nematode inoculation level and regression equations were derived. The nematode treatments caused fewer mushrooms to be produced and an absence of the usual distinctive flushing patterns. C. elegans caused considerable deterioration in mushroom quality and characteristic distortion of mushrooms. Individual sporophores were mis-shapen, notched and had brown or violet coloured grills. Up to 3.8%, 6.7% and 10.8% of total weight and 3.5%, 5.4% and 8% of total numbers of mushrooms were distorted at the three highest nematode inoculum rates tested. Weights and numbers of distorted mushrooms were positively correlated with the initial nematode population. C. elegans commonly colonised sporophores.