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1.
Various inocula and grains were evaluated for carotenoid production by solid-state fermentation using Penicillium sp. PT95. Millet medium was more effective in both sclerotia growth and carotenoid production than other grain media. An inoculum in the form of sclerotia yielded higher sclerotia biomass compared to either a spore inoculum or a mycelial pellet inoculum. Adding wheat bran to grain medium favored the formation of sclerotia. However, neither the inoculum type nor addition of wheat bran resulted in a significant change in the carotenoid content of sclerotia. Among grain media supplemented with wheat bran (wheat bran:grain =1:4 w/w, dry basis), a medium consisting of rice and wheat bran gave the highest sclerotia biomass (15.10 g/100 g grain), a medium consisting of buckwheat and wheat bran gave the highest content of carotenoid in sclerotia (0.826 mg/g dry sclerotia), and a medium consisting of millet and wheat bran gave the highest carotenoid yield (11.457 mg/100 g grain).  相似文献   

2.
Sclerotia produced by a single isolate of Rhizoctonia solani AG3PT were buried in small plot experiments to investigate the effects of sclerotial production method, soil type and burial depth on sclerotial viability in field soil. The factor with the greatest effect on sclerotial viability, defined as the percentage of sclerotia germinating on agar following retrieval, in all experiments was the duration of burial. After 18 months, on average across all experiments, 20% of retrieved sclerotia were viable. A comparison between sclerotia produced in vitro on malt yeast extract agar and in vivo using micropropagated tubers in field soil found no significant differences between the two production methods on sclerotial viability. Burial in field soil at 20‐cm depth was found to significantly reduce sclerotial viability to 50% compared to 60% at 5 cm. In two pot experiments, amending the growing medium and soil with increasing inoculum densities of R. solani was found to increase stem number, stem canker and black scurf severity regardless of whether this soil‐borne inoculum was derived from mycelium or sclerotia. Black scurf incidence and severity were assessed 30–32 days posthaulm destruction and found to be similar for a range of sclerotial soil‐borne inoculum densities (1.0 × 10?1 g/kg d.w. soil to 6 × 10?3 g/kg d.w. soil). The significance of these findings in relation to pathogen survival, detection in soil and disease development is discussed.  相似文献   

3.
A glasshouse and field trial were conducted to evaluate foliar sprays of Contans® WG (Coniothyrium minitans) conidial suspensions for control of sclerotinia rot of carrot and infection of Sclerotinia sclerotiorum sclerotia by C. minitans. In the glasshouse trial, foliar sprays (1×104–108 conidia mL?1) decreased the viability of sclerotia recovered from diseased plants and increased infection by C. minitans. In the field trial, three successive foliar sprays applied at 14-day intervals failed to reduce foliage disease severity, but significantly reduced viability of sclerotia recovered from diseased plants/crop debris and increased infection by C. minitans. No significant differences in sclerotial viability or infection were observed between two conidial concentrations (2.4 and 4.8×106 conidia mL?1). Foliar sprays of Contans® WG have potential for reducing viability of sclerotia produced on diseased foliage.  相似文献   

4.
AIMS: To find a supplemental ingredient that can be added to routinely used growth media to increase conidial production and decrease aflatoxin biosynthesis in small sclerotial (S strain) isolates of Aspergillus flavus. METHODS AND RESULTS: Molasses was added to three commonly used culture media: coconut agar (CAM), potato dextrose agar (PDA), and vegetable juice agar (V8) and production of conidia, sclerotia, and aflatoxins by A. flavus isolate CA43 was determined. The effect of nitrogen sources in molasses medium (MM) on production of conidia, sclerotia and aflatoxins was examined. Water activity and medium pH were also measured. Conidia harvested from agar plates were counted using a haemocytometer. Sclerotia were weighed after drying at 45 degrees C for 5 days. Aflatoxins B(1) and B(2) were quantified by high-performance liquid chromatography. Addition of molasses to the media did not change water activity or the pH significantly. Supplementing CAM and PDA with molasses increased conidial production and decreased aflatoxins. Two-fold increased yield of conidia was found on MM, which, like V8, did not support aflatoxin production. Adding ammonium to MM significantly increased the production of sclerotia and aflatoxins, but slightly decreased conidial production. Adding urea to MM significantly increased the production of conidia, sclerotia and aflatoxins. CONCLUSIONS: Molasses stimulated conidial production and inhibited aflatoxin production. Its effect on sclerotial production was medium-dependent. Water activity and medium pH were not related to changes in conidial, sclerotial or aflatoxin production. Medium containing molasses alone or molasses plus V8 juice were ideal for conidial production by S strain A. flavus. SIGNIFICANCE AND IMPACT OF THE STUDY: Insight into molecular events associated with the utilization of molasses may help to elucidate the mechanism(s) that decreases aflatoxin biosynthesis. Targeting genetic parameters in S strain A. flavus isolates may reduce aflatoxin contamination of crops by reducing the survival and toxigenicity of these strains.  相似文献   

5.
光是影响种子萌发和幼苗生长的关键因素.为理解不同树种种子萌发及幼苗生长对光梯度变化的响应机制,本文研究了不同光照强度(分别为自然光强的100%、60%、40%、15%和5%)对杉木和木荷种子萌发及幼苗生长的影响,探讨了两树种种子萌发和幼苗生长对光照响应的差异性.结果表明: 光照强度对两树种的种子萌发和幼苗生长均具有显著影响. 随着光照强度的减弱, 杉木种子萌发率增大,萌发指数增大,木荷种子萌发率和萌发指数则先增大后减小,在40%光照强度下达到最大值.两树种幼苗存活率在全光照(100%光照)下均为0,在5%~60%光照处理下则随着光照强度的减弱而显著降低.两树种幼苗根长、地径和株高对光梯度变化的响应趋势一致,随着光照强度的减弱,根长显著减小,地径和株高则先增大后减小,在5%光照强度下达到最小.随着光照强度的减弱,杉木幼苗根、茎、叶及总生物量降低,木荷幼苗生物量积累在15%~60%光照强度下较高, 5%光照强度下最小,且相同光照强度下,木荷幼苗各部分生物量均大于杉木.两树种幼苗应对低光环境时,表现出较大的茎和叶的生物量分配比,而根生物量比和根冠比降低.表明杉木苗期生长不耐阴,需要相对较强的光照,而木荷苗期具有较强的耐阴性,对弱光环境的适应性更强,能够在郁闭的林冠下定植和正常生长.  相似文献   

6.
AIMS: To investigate how linoleic acid affects conidial production and sclerotial development in a strictly mitotic Aspergillus parasiticus field isolate as related to improving biocompetitivity of atoxigenic Aspergillus species. METHODS AND RESULTS: We disrupted A. parasiticusDelta12-oleic acid desaturase gene (odeA) responsible for the conversion of oleic acid to linoleic acid. We examined conidiation and sclerotial development of SRRC 2043 and three isogenic mutant strains deleted for the odeA gene (DeltaodeA), either with or without supplementing linoleic acid, on one complex potato dextrose agar (PDA) medium and on two defined media: nitrate-containing Czapek agar (CZ) and Cove's ammonium medium (CVN). The DeltaodeA mutants produced less conidia than the parental strain on all media. Linoleic acid supplementation (as sodium linoleate at 0.3 and 1.2 mg ml(-1)) restored the DeltaodeA conidial production comparable to or exceeding the unsupplemented parental level, and the effect was medium dependent, with the highest increase on CVN and the least on PDA. SRRC 2043 and the DeltaodeA mutants were unable to produce sclerotia on CVN. On unsupplemented PDA and CZ, DeltaodeA sclerotial mass was comparable to that of SRRC 2043, but sclerotial number increased significantly to two- to threefold. Supplementing linoleic acid to media, in general, tended to decrease wild type and DeltaodeA sclerotial mass and sclerotial number. CONCLUSIONS: Linoleic acid stimulates conidial production but has an inhibitory effect on sclerotial development. The relationship between the two processes in A. parasiticus is complex and affected by multiple factors, such as fatty acid composition and nitrogen source. SIGNIFICANCE AND IMPACT OF STUDY: Conditions that promote sclerotial development differ from those required to promote maximum conidial production. Manipulation of content and availability of linoleic acid at different fungal growth phases might optimize conidial and sclerotial production hence increasing the efficacy of biocompetitive Aspergillus species.  相似文献   

7.
通过培养试验,利用13C标记技术研究不同热解温度制备的生物质炭添加对杉木人工林土壤原有有机碳矿化的影响,为生物质资源有效利用和亚热带人工林固碳管理提供科学依据.生物质炭制备材料分别为木荷(阔叶树种)和杉木(针叶树种)凋落物,培养温度为25 ℃,时间为112 d.结果表明: 在整个培养阶段,与对照土壤相比,不同生物质炭添加对土壤原有有机碳矿化的影响均呈现先促进后抑制的规律,具体表现为杉木生物质炭处理仅在培养0~3 d表现为显著促进作用,在7~112 d均呈现为显著抑制作用,而木荷生物质炭处理则在培养0~14 d表现为促进作用,在28~112 d均表现为显著的抑制作用.培养结束时,3种杉木生物质炭(350、550和750 ℃)处理均显著抑制了土壤原有有机碳矿化,2种木荷生物质炭(350和550 ℃)处理也表现为显著的抑制作用.木荷生物质炭和杉木生物质炭的分解率介于0.8%~2.8%,随着热解温度的升高,生物质炭的分解率呈下降趋势,且同一热解温度下木荷生物质炭的分解率显著高于杉木生物质炭.上述结果表明,原材料和制备温度是生物质炭影响土壤原有有机碳矿化和生物质炭分解的重要因素.  相似文献   

8.
Water availability is an important environmental factor which has major effects on fungal activity. The effects of osmotic (KCl amended agar) and matric Polyethylene glycol ((PEG) 8000 amended agar) potentials over the range -0.1 to -5.0MPa on mycelial growth and conidial germination of eight isolates of the sclerotial parasite Coniothyrium minitans was assessed. The influence of soil water potential on the ability of three selected isolates (LU112, LU545, and T5R42i) to parasitise sclerotia of the plant pathogen Sclerotinia sclerotiorum was determined. For all eight C. minitans isolates, decreasing osmotic and matric potentials caused a reduction in mycelial growth and conidial germination. Isolates were more sensitive to decreasing matric potential than osmotic potential. Across the isolates, growth at an osmotic potential of -5.0MPa was 30-70% of the growth seen in the control, whereas less than 20% of the control growth was seen at the corresponding matric potential. Across all isolates no conidial germination was seen at matric potential of -5.0MPa. The C. minitans isolates varied in their sensitivity to decreasing water potentials. Mycelial growth and conidial germination of three isolates (LU112, Conio, and CH1) were more tolerant of low osmotic potential and matric potential with respect to mycelial growth. Isolates T5R42i and LU430 were least tolerant. In contrast, conidial germination of isolates Conio, LU545, and T5R42i were less sensitive to decreasing matric potential. Soil water potential was seen to affect infection and viability of sclerotia by the three C. minitans isolates. Isolate LU545 reduced sclerotial viability over a wider water potential range (-0.01 to -1.5MPa) compared with LU112 (-0.01 to -1.0MPa), with isolate T5R42i being intermediate. Indigenous soil fungi (Trichoderma spp. and Clonostachys rosea) were recovered from sclerotia but did not result in reduction in sclerotial viability. The relevance of these results in relation to biocontrol activity of C. minitans in soil is discussed.  相似文献   

9.
In order to evaluate the potential use of Phoma exigua isolate PFC 2705 (PFC2705) as a biological control agent for salal (Gaultheria shallon), effect of cultural and environmental parameters on growth, conidia production, and pathogenicity of P. exigua were characterized in studies conducted under laboratory and greenhouse conditions. Within a range of 5-30°C, the optimum growth and germination temperature range was 20-25°C. The effect of pH on mycelial growth and conidial germination was not significant from pH 5 to 10. Fluorescent light significantly enhanced sporulation of the fungus on most agar media tested, yet was not necessary for growth. The type of culture media significantly affected mycelium growth, sporulation, and conidia germination. Age of mycelia used as inoculum affected the disease severity on salal. PFC2705 suppressed the growth of mature salal plant by inciting lesions on leaves, branch tips, and axillary buds and caused 56% death of the total biomass above ground. Characteristics such as easy inoculum production, wide range of growth environments, and high infectivity on salal increased the potential of P. exigua as a biocontrol agent for management of salal.  相似文献   

10.
L Ferraro  F Fatichenti  M Ciani   《Process Biochemistry》2000,35(10):1125-1129
Sequential grape juice fermentation first with immobilized Candida stellata and then with an inoculum of Saccharomyces cerevisiae was carried out at pilot scale and under non-sterile conditions in order to evaluate the dynamics of yeast microflora and their influence on the analytical profile of wine. Non-Saccharomyces yeast were adequately controlled while S. cerevisiae wild strains were consistently present after 3 days of fermentation and could compete with the inoculated S. cerevisiae strain. However, the metabolism of immobilized C. stellata cells strongly influenced the analytical profile of wines with a consistent increase in glycerol (70%) and succinic acid content in comparison with values for a S. cerevisiae fermentation control.  相似文献   

11.
以木荷和杉木为试验材料,模拟异质和同质两种森林土壤养分环境,设计单植、两株纯植和两株混植3种栽植方式,开展盆栽试验研究木荷与杉木混交造林增产及木荷生长竞争优势形成的原因.结果表明: 与同质养分环境相比,异质养分环境中木荷与杉木混植时两树种均具有较高的苗高和干物质积累量,且木荷竞争优势明显,这与其根系可塑性强有关.混植的木荷各径级细根大量增生,其根系总长度、表面积和体积比杉木高80%~180%.木荷细根在垂直方向上采用了补偿性的生长策略,即除占据富养表层外,还在低养分斑块中大量增殖以获得更大的竞争优势.木荷与杉木的细根在土壤中的拓殖深度不同,生态位分化,缓解了两树种根系对养分的强烈竞争,提高了混植产量.纯植的木荷由于根系自我识别作用,抑制了根系的生长,使得纯植产量较低.细根在空间上错开和均匀分布可能是木荷纯林结构稳定的原因之一.建议在生产中采用块状整地和表层施肥等措施,改善土壤养分分布状况,营建混交林促进木荷和杉木生长,而对已营造的木荷人工纯林,可以及时调控林分密度促进林木生长.  相似文献   

12.
初步研究了外源β-胡萝卜素和光照对青霉PT5菌株菌核分化和类胡萝卜素产率的影响。结果表明,在培养基中加入外源β-胡萝卜素后,PT5菌株渗出液出现的时间、菌核出现的时间延迟了,但菌核成熟的时间没变。培养基中的外源β-胡萝卜素浓度越大,其渗出液、菌核出现的时间越迟。外源β-胡萝卜素亦能降低PT5菌株的脂质过氧化水平和菌核中的类胡萝卜素含量。高氧胁迫的光照培养条件有利于PT95菌株的菌核分化和色素在菌核中的积累;与低氧胁迫的黑暗培养条件相比,其菌核生物量和类胡萝卜素产率分别增加了18.7%和101%。以上实验结果表明,若想获得高的菌核生物量和类胡萝卜素产率,应该尽可能在高氧胁迫、无抗氧化剂存在的条件下培养PT5菌株。  相似文献   

13.
Differential scanning calorimetry, circular dichroism, and visible absorption spectrophotometry were employed to elucidate the structural stability of thermophilic phycocyanin derived from Cyanidium caldarium, a eucaryotic organism which contains a nucleus, grown in acidic conditions (pH 3.4) at 54°C. The obtained results were compared with those previously reported for thermophilic phycocyanin derived from Synechococcus lividus, a procaryote containing no organized nucleus, grown in alkaline conditions (pH 8.5) at 52°C. The temperature of thermal unfolding (td) was found to be comparable between C. caldarium (73°C) and S. lividus (74°C) phycocyanins. The apparent free energy of unfolding (ΔG[urea]=0) at zero denaturant (urea) concentration was also comparable: 9.1 and 8.7 kcal/mole for unfolding the chromophore part of the protein, and 5.0 and 4.3 kcal/mole for unfolding the apoprotein part of the protein, respectively. These values of td and ΔG[urea]=0 were significantly higher than those previously reported for mesophilic Phormidium luridum phycocyanin (grown at 25°C). These findings revealed that relatively higher values of td and ΔG[urea]=0 were characteristics of thermophilic proteins. In contrast, the enthalpies of completed unfolding (ΔHd) and the half-completed unfolding (ΔHd)1/2 for C. caldarium phycocyanin were much lower than those for S. lividus protein (89 versus 180 kcal/mole and 62 versus 115 kcal/mole, respectively). Factors contributing to a lower ΔHd in C. caldarium protein and the role of charged groups in enhancing the stability of thermophilic proteins were discusse.  相似文献   

14.
菌核是核盘菌Sclerotinia spp.在土壤中的主要存活形式和菌核病的主要初侵染源,在土壤中可存活8年以上,其数量和存活状况直接影响着菌核病的发生和危害程度。本研究以雪腐核盘菌Sclerotinia nivalis菌株SS-TB为材料,分析了菌核萌发的影响因素、致死温度以及土壤温度对菌核存活的影响。结果表明,未成熟菌核较成熟菌核更容易萌发;菌核萌发的最佳温度为20-25℃、pH为3.0-4.0、土壤含水量为20%-45%。菌核长时间浸泡水中对其存活不利,浸泡30d以后,存活率开始急剧下降,至47d时存活率为0。雪腐核盘菌菌核具有较强的耐高温特性,随着温度和处理时间的增加,菌核萌发率呈下降趋势。菌核在水浴中85℃ 5min、80℃ 10min、75℃ 10min、70℃ 30min、65℃ 120min、60℃ 180min时全部丧失活力。在土壤温度30℃和35℃处理5周、40℃和45℃处理4周时菌核全部失去活力。该研究结果为通过水旱轮作和土壤高温处理来防治西洋参菌核病提供了理论基础。  相似文献   

15.
Effects of sixteen chemical pesticides on conidial germination of C. thromboides and P. nouryi were investigated at two concentrations (R and 0.2R, where R=the lowest manufacture's recommended concentration for field use). Of the fungicides tested, propamocarb hydrochloride did not significantly affect conidial germination of C. thromboides, but at R it completely inhibited conidial germination of P. nouryi. At 0.2R of procymidone, iprodione, haloxyfop-methyl and fenoxaprop-p-ethyl, conidia of C. thromboides had some germination after 24 h, although they entirely restricted conidial germination of the fungus at the concentration of R. Tribenuron-methyl, one herbicide, had no adverse effect on conidial germination of C. thromboides and P. nouryi after 6 h at the two concentrations, whereas the other seven herbicides were strongly antagonistic to P. nouryi, except for carfentrazone-ethyl at 0.2R.  相似文献   

16.
We previously observed secretion of native-type Streptomyces mobaraensis transglutaminase (MTGase) in Corynebacterium glutamicum by co-expressing the subtilisin-like protease SAM-P45 from S. albogriseolus which processes the pro-region. In the present study, we have used a chimeric pro-region consisting of S. mobaraensis and Streptomyces cinnamoneus transglutaminases for the production of MTGase in C. glutamicum. As a result, secretion of MTGase using the chimeric pro-region is increased compared to that using the native pro-region.  相似文献   

17.
A study on the survival of Lecanicillium lecanii conidia in storage at room temperature was carried out. Firstly, drying methods of conidia powder were compared. Vacuum-freeze drying (VFD) was more suitable for drying conidia as compared to vacuum drying (VD) at room temperature. Vacuum-freeze drying for 24-h resulted in a water content of 5.4%, and a viability, determined as germination of conidia in 2% glucose solution after16 h, was 90.3% and the infection in greenhouse whitefly, Trialeurodes vaporariorum was about 94.7% at a dose of 1×108 conidia/mL. Secondly, the factors influencing viability of conidia stored at room temperature were evaluated in the laboratory. Temperature was the most critical factor influencing conidial storage stability, among the tested factors affecting survival of conidia stored at room temperature for 6 months. Both conidial germination and infection of hosts decreased with storage temperature increasing from 15 to 35°C, and at 35°C the survival of stored conidia for 6 months was near zero. The moisture content of the conidial powder was another major factor influencing viability of stored conidia at room temperature. Conidial powder dried to about 5% moisture content showed higher viability than non-dried conidial powder. For the carriers, clay and charcoal were more suitable for storage of L. lecanii conidia at room temperature. At a room temperature of 25°C, L. lecanii conidia which were dried to 5% water content and mixed with clay or charcoal could retain about 50% survival after 6 months' storage.  相似文献   

18.
刘奇正  屈珊  谭方河  董彩虹 《菌物学报》2021,40(12):3157-3168
外源营养袋的应用是国内羊肚菌大田栽培成功的关键技术之一,但其作用机理和影响因素一直没有得到充分的解析。本研究首先于室内建立一个外源营养模型,确认模型中外源营养模块可以向外输出营养,且被梯棱羊肚菌菌丝利用。通过模型实验发现,外源营养添加到贫瘠培养基时,菌体生物量的增加显著高于营养丰富的培养基;在梯棱羊肚菌生长的不同阶段添加外源营养,菌核形成位置不同,并影响生物量的增加,在菌核起始阶段添加,主培养基的生物量增加最多;外源营养的添加位置、块数等因素在本模型中没有检测到对生物量的影响。外源营养使用聚丙烯袋包裹和不包裹比较发现,包裹组的主培养基内生物量增速和总量低于无包裹组,而外源营养块内趋势相反,但最终两组之间外源营养块与主培养基内生物量总和没有显著差异。使用滤纸和铝箔包裹外源营养时,对生物量的影响和聚丙烯袋材质没有显著差别。外源营养碳氮比20:1时,最有利于主培养基生物量的积累。本研究建立的外源营养研究模型得到的结论与大田栽培有较好的一致性,通过模型发现了实际栽培中不容易观察到的现象,有助于对外源营养袋作用机理进行深入研究。  相似文献   

19.
互花米草入侵下湿地土壤碳氮磷变化及化学计量学特征   总被引:1,自引:0,他引:1  
为阐明外来物种入侵对生态系统的改变,对闽江河口区本土植物短叶茳芏和不同入侵年限的互花米草湿地土壤总碳(TC)、总氮(TN)、总磷(TP)含量进行了测定与分析.结果表明: 互花米草入侵后0~50 cm深度各层土壤TC、TN和TP含量均有不同程度的增加,其中TC、TN的变化比较一致,而TP的变化滞后;TC的增加引起土壤C/N持续增加,而TP是调节互花米草入侵过程中湿地土壤C/P和N/P的关键因子,C/P和N/P的变化基本一致.土壤TC、TN、TP的变化受到土壤盐度、容重、含水量和黏粒组成的影响,而它们之间计量比主要受土壤盐度、粒径组成的影响;C/N和C/P对互花米草湿地的土壤固碳效应具有良好的指示作用.互花米草入侵引起生物量和湿地生境改变,导致土壤碳氮磷含量及其生态化学计量比发生显著变化,且随入侵时间延长表现出不同的变化特征.  相似文献   

20.
<正>川西缺齿鼩(Chodsigoa hypsibia)(De Winton andStyan,1899)和小纹背鼩鼱(Sorexbedfordiae)(Thomas, 1911)同属于劳亚食虫目(Eulipotyphla)鼩鼱科(Soricidae)。缺齿鼩鼱属(Chodsigoa,Kastschenko, 1907)全世界目前已知10个物种(Wilson and Mittermeier, 2018; Chen et al., 2022),其中川西缺齿鼩为中国特有,  相似文献   

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