黄孢原毛平革菌发酵稻草秸秆降解木质素的研究

研究利用黄孢原毛平革菌(Phanerochaete Chrysosporium Burdsall)对稻草秸秆进行固态发酵,在单因素基础上,通过正交试验得出稻草秸秆木质素的降解最优条件为6.5 g稻草,合成培养液12 m L,接种量0.8 m L(菌悬液浓度5×106CFU/m L),初始p H值4.5,测得木质素降解率为49.71%。采用扫描电镜SEM对发酵后10 d稻草表观形貌进行观察,结果清晰可见,发酵后稻草秸秆表面的空穴增多、增大,表面粗糙度增加,裂解现象明显。     

产漆酶菌株的筛选及其对烟秆降解效果的研究

为烤烟秸秆中木质素降解提供理论依据,丰富降解木质素的真菌资源。从腐殖质中分离高产漆酶的木质素降解真菌1株,对其进行形态学鉴定,并对其液态发酵产漆酶培养条件进行优化和对碳、氮源和Cu²⁺进行正交试验,最后测定了该株菌对烤烟秸秆的降解情况。结果表明：（1）该株真菌形态学鉴定为半知菌亚门,粘头霉属(Moniliales Gliocephalias sp.)命名为Z-1。基础培养基中产漆酶的最大值出现在液态发酵第4天,酶活为2.72 U/mL。（2）单因素试验中Z-1最适宜产酶发酵条件为：麦芽糖25 g/L、酵母膏10 g/L、Cu2 +浓度2.5 mmol/L。（3）正交试验中,培养基麦芽糖30 g/L、酵母膏12 g/L、Cu2 +浓度2.5 mmol/L处理产酶最高,酶活为3.24 U/mL,较基础培养基中高出18.89%。（4）液态发酵菌株对烟秆粉末降解30天后,失重率50%、木质素降解率39.39%、纤维素降解率36%。该株真菌产酶较高,对烤烟秸秆降解能力较强。     

木质素降解菌的筛选及对秸秆的降解研究

为筛选木质素高效降解菌,对筛选的方法体系进行了研究.结果表明,利用三种定性筛选平板结合定量的木质素磺酸钙降解的方法,能明显提高筛选效率,从16个菌株中筛选到3株对木质素有较强降解能力的菌株Tp1、Tf1与Ls21.为进一步验证所筛菌株的降解效果,选取其中综合性能较好的Tf1菌株(凤尾菇,Pleurotus sajor-caju),对小麦秸秆与玉米秸秆进行固态发酵试验,并以黄孢原毛平革菌(Phanerochaete chrysosporium)BKMF-1767作参照,结果表明,Tf1对小麦秸秆与玉米秸秆木质素的降解率分别为38.4%与47.7%,均高于参照菌株(分别为32.2%和34.6%).     

应用正交设计优选秸秆降解菌组合

为了探索利用正交设计筛选秸秆降解菌组合的方法,优选产纤维素酶和木质素酶的秸秆降解菌的组合。利用正交设计以玉米秸秆粉为发酵底物,检测分析不同组合的降解率及酶活;采用平板拮抗试验测定组合内菌株间的拮抗作用,检测筛选的效果。结果表明,降解菌不同组合之间玉米秸秆降解率存在着极显著的差异。筛选出最佳组合为A1B3C1D4E1F2G1,即接种量F-11为1 mL,XX-10为2.0 mL,G-09为1.0 mL,降解率超过对照10%以上。部分降解菌菌株之间存在一定的拮抗作用,秸秆降解率与组合内降解菌株的组成有关。正交试验设计是筛选秸秆降解菌最佳组合的一种有效方法,筛选出的降解菌最佳组合秸秆降解能力强,具有较好的开发利用价值。     

纤维素产氢菌的分离及不同秸秆处理方法的研究

为了增强生物方法对秸秆的利用能力,将秸秆较好地转化成氢能,本试验利用改良的Hungate厌氧滚管法及滤纸崩解法,从已得菌系JYB中,筛选得到1株能较好地降解纤维素产氢的细菌,并利用水热法、汽爆法等6种方法对秸秆进行预处理,以增强秸秆的产氢效果。结果表明：筛选得到菌株JYB-13,该菌可利用大量碳源产氢,产氢的最适条件为35℃,pH值8.5。对秸秆进行预处理,由产氢效果得知,该菌对2%硫酸处理后的秸秆降解效果最好,秸秆的降解率为53.1%,氢气含量达到37.2%。分析发酵前后秸秆的成分,可知该菌可以较好地利用纤维素和半纤维素,对木质素利用较少。     

降解稻草纤维素真菌的初步研究

从自然腐烂的稻草秸秆中分离筛选出126霉菌菌株,并从中筛选出10株降解稻草秸秆能力较好的菌株。其中以A242,A251降解秸秆纤维素能力较强;A321,B311降解秸秆半纤维素能力较强。A242,B311菌株的稻草粉发酵降解液中还原糖质量分数分别达到94.104 4,90.627 4 mg/g稻草粉;A321,B321菌株的稻草粉发酵降解液中木糖质量分数分别达到11.821 0,12.121 9 mg/g稻草粉。可综合其各自发酵的优势,将其作为初始菌株进行进一步的优化。     

高温木质素降解菌Geobacillus caldoxylosilyticus J16的筛选及其产酶发酵性质研究

从张家界、白云山采集到的朽木及落叶中,经分离、纯化后,获得了一株高温木质素降解菌,命名为地芽孢杆菌（Geobacillus caldoxylosilyticus J16）,此菌嗜热,耐高温,只降解木质素且不降解纤维素,对造纸业和可再生能源产业具有重要意义。本文通过对木质素中两种酶木质素过氧化物酶、锰过氧化物酶活性的研究,确定了木质素过氧化物酶的最适温度为65℃,最适PH为4,在55℃至70℃之间时酶活力较其他温度高且较稳定;锰过氧化物酶最是温度为60℃,最适pH为3在温度为55℃至65℃之间时,活力较其他温度高。作者发酵了黄豆杆、玉米杆、芝麻杆、油菜杆、锯末、小麦杆这六种农业废弃物,通过发酵前后的比较,说明了J16菌株对木质素降解的最大减少量为7.5%。上述数据显示此菌可以应用于废弃秸秆的处理和造纸厂污水的处理,对环保有重要意义.     

耐高温木质纤维素降解菌株的分离筛选、鉴定及降解工艺的研究

本研究旨在筛选出在高温条件下具有较强木质纤维素降解酶活性的细菌菌株,探究其降解秸秆木质纤维素的特性。从太白山林区温泉采集土壤样品并在高温条件下进行富集培养,利用脱色圈试验和比色法筛选出目标菌株,通过形态观察和16S rDNA序列分析鉴定菌株种类。对高温富集初筛所得菌株的纤维素酶、漆酶、木质素过氧化物酶和锰过氧化物酶活性进行测定。菌株X-08的纤维素酶活为0.02872 U/mL,菌株M-17的MnP、LiP和Lac酶活分别为51 U/mL、672 U/mL和192 U/mL。鉴定出菌株X-08为Anoxybacillus rupiensis,M-17为Geobacillus thermocatenulatus。采用双菌降解玉米秸秆,20天后木质素和纤维素的降解率分别达到24.51%和20.47%。研究结果为农业废弃物生物降解提供了新的细菌菌种资源,并为秸秆中木质纤维素的降解处理方法提供了新的思路。     

基于稻、麦秸秆工厂化栽培双孢蘑菇的理化性质变化研究

为研究稻、麦秸秆工厂化栽培双孢蘑菇(Agaricus bisporus)的差异,以60%稻草配方和100%麦草配方的培养料为栽培基质,研究发菌料在工厂化栽培双孢蘑菇过程中的p H、电导率、含水量、灰分、碳氮含量、C/N等理化性质及木质纤维素含量的变化情况。结果表明,与100%麦草配方相比,60%稻草配方栽培双孢蘑菇的培养料电导率、灰分含量较低,而第二潮菇后的碳氮含量迅速升高。三潮菇结束后,60%稻草配方的培养料纤维素与木质素的降解率低于100%麦草配方,而半纤维素的降解率差异不大。研究初步探明了稻、麦秸秆在双孢蘑菇栽培过程中的理化性质差异,为进一步利用稻秸秆工厂化栽培双孢蘑菇提供理论依据。     

秸秆降解菌系的筛选及其对酸碱度的响应

为给冷凉地区秸秆还田提供菌株资源,以常年处于低温环境的土壤与富含纤维素的腐烂物为菌源,以富集、继代培养方法筛选秸秆降解菌系和生产中主推的秸秆腐熟剂为试材,在15℃和20℃,pH 4.5、5.5、6.5、7.5、8.5、9.5条件下发酵秸秆,每隔24 h测定发酵液OD₆₀₀值,发酵15天测定滤纸酶、纤维素酶活性和秸秆降解率,探讨其对玉米秸秆的降解效果。结果表明,继代培养5~6代菌系分解纤维素的速度加快;15℃ 2种试材不同pH发酵液OD₆₀₀值第6天达到峰值,最高峰值均在pH 7.5;20℃ 2种试材不同pH发酵液OD₆₀₀值第7天达到峰值,秸秆降解菌系8号最高峰值为pH 8.5,秸秆腐熟剂最高峰值为pH 5.5。15℃ pH 8.5秸秆降解菌系8号滤纸酶活性显著高于秸秆腐熟剂;pH 7.5秸秆降解菌系8号纤维素酶活性显著高于秸秆腐熟剂;而秸秆腐熟剂纤维素酶活性在20℃ pH 4.5时高于秸秆降解菌系8号。15℃和20℃条件下,秸秆降解菌系8号pH 7.5秸秆降解率高,而秸秆腐熟剂为pH 4.5和pH 5.5秸秆降解率高;相同发酵条件下,秸秆降解菌系8号秸秆降解率显著高于秸秆腐熟剂。秸秆降解菌系8号降解秸秆适宜条件为中低温中性偏碱性,而秸秆腐熟剂为中温偏酸性。     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Reaction of tritordeum to Fusarium culmorum and Septoria nodorum

Summary Hordeum chilense is a wild barley extensively used in wide crosses in the Triticeae. It could be a valuable source of resistance to Fusarium culmorum and Septoria nodorum. Some H. chilense x Triticum spp. amphiploids, named tritordeums, were more resistant than the parental wheat line to these diseases, others were not. Average contents of ergosterol and deoxynivalenol (DON) suggested that resistance to colonization by Fusarium was the highest for Hordeum chilense, followed by tritordeum and wheat in decreasing order. In particular, the H. chilense genotypes H7 and H17 enhanced the wheat resistance to F. culmorum in its tritordeum offsprings. Resistance to S. nodorum in tritordeum was not associated with tall plant height. There is sufficient genetic variation for resistance to F. culmorum and S. nodorum among tritordeum to allow the breeding of lines combining short straw and resistance to both diseases.     

Disease resistance in protected crops and mushrooms

Summary Cultivars of tomatoes, cucumbers, lettuce and peppers have been bred for resistance to one or more pathogens. Some tomato and cucumber cultivars have resistance to a wide range of diseases. Resistance has been transient in many cases and a succession of cultivars with new genes or new combinations of resistance genes has been necessary to maintain control. There has been a number of notable exceptions and these have included durable resistance to such pathogens asFulvia fulva and tomato mosaic virus. With lettuce the resistance situation is complicated by the occurrence of fungicide resistant pathotypes. There are no strains ofAgaricus bisporus purposely bred for disease resistance.In protected flower crops only resistance to Fusarium wilt in carnations has been purposely bred but differences in disease resistance are apparent in cultivars of many ornamental crops. This is particularly so in chrysanthemums where there are cultivars with resistance to many of the major pathogens. Similar situations occur with other flower crops and pot plants. Cultivars of some species have not been systematically investigated for resistance.The need for genetic resistance will increase with the further reduction, in the limits on pesticide use and an increasing public awareness and importance of pesticide pollution.ADAS is an executive agency of the Ministry of Agiculture, Fisheries and Food and the Welsh Office.     

Genetic constitution and diversity in four narrow endemic redwoods from the family Cupressaceae

The genetic constitution and diversity of four relictual redwoods are discussed in this review. These include monotypic genera of the family Cupressaceae: coast redwood (Sequoia sempervirens), giant sequoia (Sequoiadendron giganteum), dawn redwood (Metasequoia glyptostroboides), and alerce (Fitzroya cupressoides). All four species are narrow endemics, share a number of common phenotypic traits, including red wood, and are threatened species. Fossil history suggests that the ancestors of redwoods probably originated during the Cretaceous and Tertiary periods and flourished thereafter for millions of years. Towards the end of the Tertiary period began their decline and struggle for existence that continued during the subsequent geologic upheavals and climate changes, until the survival of the present-day redwoods in the current restricted locations in the world (USA, China, and South America). Although two species, Sequoiadendron and Metasequoia, are diploids (2n = 22), and the other two are polyploids: Fitzroya a tetraploid (2n = 4x = 44), and Sequoia a hexaploid (2n = 6x = 66); they all share the same basic chromosome number x = 11. The genome size in the hexaploid Sequoia is one of the largest (31,500 MB) in the conifers, while the genome sizes of diploid Metasequoia and Sequoiadendron are about one-third (~10,000 MB) of Sequoia. Genetic diversity in the redwoods is lower than most other gymnosperms, except in Sequoia, which seems to rank near the upper quarter of the coniferous forest trees. Genomic research is sparse in the redwoods, and should be pursued for a better understanding of their genome structure, function, and adaptive genetic diversity.     

The induction in vitro of adventitious shoots in Rosa

Summary Adventitious shoots were formed on excised leaves, roots and callus of Rosa persica x xanthina and on excised leaves of R. laevigata and R. wichuraiana on culture media that included BAP and NAA as growth regulators. Shoots formed freely on freshly cultured callus of R. persica x xanthina but their production declined in successive cultures and ceased after twelve weeks. Transplantation to soil was improved by rooting plantlets in cellulose plugs in vitro and transferring plantlets to soil while still in the plugs.     

Distribution,ecology and reproductive biology of wild tomatoes and related nightshades from the Atacama Desert region of northern Chile

Over the past 20 years, several expeditions were made to northern Chile to collect populations of wild tomatoes (Solanum chilense, S. peruvianum) and allied nightshades (S. lycopersicoides, S. sitiens), and obtain information about their geographic distribution, ecology and reproductive biology. Restricted mainly to drainages of the Andean and the coastal cordillera, populations are geographically fragmented. The two nightshade species are rare and threatened by human activities. Adaptation to extreme aridity and soil salinity are evident in S. chilense and S. sitiens (the latter exhibits several xerophytic traits not seen in the tomatoes) and to low temperatures in S. lycopersicoides and S. chilense. All tested accessions are self-incompatible, with the exception of one S. peruvianum population collected at the southern limit of its distribution. Several distinguishing reproductive traits—anther color, attachment, and dehiscence, pollen size, and flower scent—suggest S. sitiens and S. lycopersicoides attract different pollinators than S. chilense and S. peruvianum. The four Solanum spp. native or endemic to Chile provide a variety of novel traits which, through hybridization and introgression with cultivated tomato, could facilitate development of improved varieties, as well as research on a variety of basic topics, including plant-pollinator interactions, abiotic stress responses, and evolution of reproductive barriers.     

The exploration of genetic resources of Portuguese cabbage and kale for resistance to several Brassica diseases

Summary Twenty three accessions of nine Portuguese cabbage and kale land races from different geographic origins were tested at the seedling stage for resistance to several important brassica diseases. Resistance to downy mildew (Peronospora parasitica), expressed as necrosis of the cotyledon mesophyll, was found in all the accessions. Type A resistance to cabbage yellows (Fusarium oxysporum f. sp. conglutinans race 1) was present in most of the landraces. Resistance to clubroot (Plasmodiophora brassicae race 6) was found in one accession of the Portuguese tree kale. High resistance to blackleg (Leptosphaeria maculans) and white rust (Albuco candida) was not detected, although several accessions showed 20 to 30% of plants with intermediate expression of resistance. All Portuguese cole accessions were susceptible to blackrot (Xanthomonas campestris pv. campestris).     

Production and characterization of intergeneric diploid cybrids derived from symmetric fusion between Microcitrus papuana Swingle and sour orange (Citrus aurantium)

Plants were regenerated from intergeneric somatic hybridization between embryogenic protoplasts of Microcitrus papuana Swingle and leaf-derived protoplasts of sour orange (Citrus aurantium L.) via electrofusion. The regenerated plants were morphologically similar to the leaf parent in growth vigor, leaf and branch structure. FCM analysis showed that they were diploids. Simple-sequence-repeat (SSR) and cleaved-amplified-polymorphic-sequence(CAPS) were employed for hybridity characterization. SSR banding patterns of the regenerated plants were identical to the leaf parent, sour orange, indicating that they possessed nuclear component derived from sour orange. DNA amplification with chloroplast and mitochondrial universal primers, followed by restriction endonuclease digestion, revealed polymorphism between the fusion parents. Therefore, this method was used to determine the cytoplasmic compositions of the regenerated plants. Banding patterns for all the polymorphic primer/enzyme combinations of the regenerated plants were similar to those of the embryogenic parent, M. papuana, suggesting that only the cytoplasmic components derived from the embryogenic parent were present in the regenerated plants. FCM, SSR and CAPS demonstrated that intergeneric diploid cybrids have been successfully obtained by symmetric fusion. Related results concerning nuclear and cytoplasmic composition of previous diploid somatic hybrids and potential mechanism for regeneration of such kind of plants are discussed herein. This revised version was published online in July 2006 with corrections to the Cover Date.     

Breeding barriers between the cultivated strawberry, Fragaria × ananassa, and related wild germplasm

Five-hundred interspecific and intergeneric crosses were performed among accessions of the wild strawberries Fragaria vesca(2x), Duchesnea indica (8x), Potentilla tucumanensis (2x) and 9 genotypes of the cultivated strawberry, Fragaria×ananassa (8x), following an incomplete diallele mating design. Crosses between D. indica and F.×ananassa produced many putative hybrids when D. indica was used as female but a few achenes and plants when used as male; therefore, pollen-pistil compatibility relations were analyzed by fluorescence microscopy in this direction of the cross. Of the genotypic combinations, 78.6% were incompatible at the stigma level and 17.2% at the first third of the style. Only 3.6% were pollen-pistil compatible and produced fruits with achenes (seven did not germinate or originated short-lived plants and nine produced normal plants). F.vesca×F.×ananassa crosses produced 35 hybrid achenes but only 14% germinated, yielding short-lived plants; histological analyses revealed that inviable seeds had less developed (or collapsed) endosperms and smaller embryos than control plump F. vesca seeds. P.tucumanensis was only used as male, with negative results. These species and genera are partially isolated by a complex system of pre- and post-zygotic barriers. Knowledge of their nature would allow the breeder to devise strategies to put the genetic variability available in the group into a useful form. This revised version was published online in July 2006 with corrections to the Cover Date.