产壳聚糖酶菌株的初步筛选

通过大量的筛选,获得了产壳聚糖酶较好的菌株Y2、Y4、Y8。其发酵液所产壳聚糖酶的酶活力分别为2．0U／ml,2．1U／ml,2．2U／ml。     

产壳聚糖酶内生真菌的筛选、鉴定及酶活力初步研究

植物内生真菌是挖掘不同类型壳聚糖酶及发现新酶的资源宝库。该研究从122株柑橘和血散薯内生真菌中筛选能产生壳聚糖酶的菌株,对其进行鉴定/初步研究酶活力影响因素,为后期其酶学性质及产壳聚糖酶内生真菌与宿主植物病害防御互作关系的研究奠定基础。通过透明圈法初筛结合液体发酵法进行复筛,得到2株可产生壳聚糖酶的内生真菌Stdif9和Stdif9-4,并发现Stdif9-4最高酶活力(0.968 U·mL^-1)显著高于Stdif9(0.780 U·mL^-1)。采用形态学和分子生物学结合的方法将菌株Stdif9-4鉴定为青霉属菌株,即Penicillium sp.Stdif9-4。通过DNS试剂法初步研究影响该菌株产壳聚糖酶活力的因素,发现不同培养时间对菌株壳聚糖酶活力具有显著影响,在培养96 h时,壳聚糖酶活力达到最大值。9种金属离子对菌株的酶活力具有不同影响,其中Mn²⁺和Ca²⁺对壳聚糖酶活力具有明显的激活作用;Ag⁺、Zn²⁺、Cd²⁺、Ba...     

产壳聚糖酶菌株的分离筛选及其诱变育种

利用以壳聚糖为唯一碳源的选择性培养基,从自然界中筛选得到一株壳聚糖酶活较高的菌株 ,其壳聚糖酶活为0.59U/mL.经初步鉴定,该菌株为芽孢杆菌属,以A表示.以该芽孢杆菌为出发菌株,经硫酸二乙酯(DES)诱变处理50 min后,筛选得到壳聚糖酶活明显提高的突变株DES-4,其壳聚糖酶活为1.60U/mL,是出发菌株的2.7倍.该突变株经连续传代5次后仍稳定产酶.研究表明,突变株DES-4的壳聚糖酶产生与芽孢形成之间关系密切,当芽孢充分形成后发酵液的壳聚糖酶活力不再增大.     

产壳聚糖酶菌株的发酵条件优化

方法:通过单因子实验,对保存的1株产壳聚糖酶的菌株C001进行发酵产酶条件优化,确定了最适产酶培养基组分.结果:温度30℃,发酵时间18h,pH5.5,接种量5%优化发酵条件后,产壳聚糖酶活力增长了37.4%.     

壳聚糖酶

<正>壳聚糖(Chitosan)是由N-乙酰葡糖胺(GlcN Ac)和葡糖胺(GlcN)通过β-1,4糖苷键相连接的多糖,与甲壳素、壳寡糖均被称为甲壳素类物质,被誉为继糖类、蛋白质、脂肪、维生素等生命元素之外的第六大生命物质。壳寡糖由于其生物相容性好、易于被人体吸收等优势,其商业产品已遍布各个领域,主要涉及功能性食品、药品、环保、化工等。通过化学方法降解壳聚糖制备壳寡糖的方法具有污染环境、产物不均一等缺点。利用生物酶法     

土壤中选育产壳聚糖酶菌株的研究

采用酶法降解壳聚糖具有反应条件易于控制、产物安全性高和环境污染少等独特的优越性。因此,筛选出高活力产壳聚糖酶菌株有着重要意义。该研究以不同地区采集土样分离出的1株细菌为出发菌株S,采用紫外线诱变（30W,20cm,5min）,经初筛和复筛及控温培养处理,获得了一株产壳聚糖酶较好的突变菌株,结果表明：所产酶活力达到3．47U/ml,酶活力提高近2倍,并具有较好的遗传稳定性,明显优于出发菌株,为发酵产壳聚糖酶的进一步研究提供了高产菌株。     

高产壳聚糖酶菌株的筛选及分类鉴定

目的：筛选一株高产壳聚糖酶的菌株。方法：通过形态学、生理生化及16S rDNA序列测定,对菌株进行分类鉴定。在培养基中以壳聚糖为唯一碳源,对长白山天池边的土样进行筛选。结果：获得一株产壳聚糖酶活力较高的菌株,最大酶活力达0．325U／ml。结论：经16S rDNA序列比对,该菌株与Beta proteobacterium的同源性高达99％。结合《伯杰细菌鉴定手册》（第九版）,将该菌株鉴定为Beta proteobacterium属的一个种,定名为Beta proteobacterium sp．T1。     

高产壳聚糖酶菌株的筛选及分类鉴定

目的在于筛选一株高产壳聚糖酶的菌株,通过形态学、生理生化及16SrDNA序列测定,对菌株进行分类鉴定。对长白山天池边的土样进行筛选,获得一株产壳聚糖酶活力较高的菌株,最大酶活力达0．325U／mL。经16SrDNA序列比对,该菌株与Beta proteobacterium的同源性高达99％。结合《伯杰细菌鉴定手册》（第9版）,将该菌株鉴定为Beta proteobacterium属的一个种,定名为Betaproteobac-tenure sp．T1。     

产壳聚糖酶菌株的筛选、鉴定及酶学特性分析

【目的】利用筛选培养基,从福建沿海潮间带泥样中分离筛选产壳聚糖酶的菌株,并研究菌株的产酶特性。【方法】通过形态学观察,结合26S rDNA序列进行分类鉴定,采用DNS法测定酶活力。【结果】筛选得到产壳聚糖酶的菌株KQ-1002与草酸青霉(Penicillium oxalicum)的同源性为99%,并初步鉴定为青霉属的一种。发酵培养的最适温度为30°C,最适碳源为1.0%水溶性壳聚糖,最适氮源为1.87%(NH4)2SO4,最适pH为6.0。该菌株液体发酵培养72 h产壳聚糖酶活性最高,经优化后最高产酶量为18 U/mL。纯化后的壳聚糖酶经SDS-PAGE分析其分子量约40 kD。酶促反应最适pH为5.0,最适反应温度为55°C,Km值为1.293 g/L。在离子浓度为1.0×10 3mol/L时,金属离子Cu2+、Hg2+、Ag+对酶的活性均有强烈的抑制作用。壳聚糖酶对不同底物及脱乙酰度的壳聚糖具有不同的降解作用。【结论】筛选获得产壳聚糖酶的真菌菌株KQ-1002的壳聚糖酶活力经优化后提高了约7倍,是一株具有研究和应用潜力的产壳聚糖酶菌株。     

壳聚糖酶产生菌的筛选及固定化细胞产酶

旨在筛选得到一株壳聚糖酶产生菌,并研究固定化细胞产酶的条件。在培养基中以壳聚糖为唯一碳源,对土壤样品进行筛选,获得一株无花果沙雷氏菌(Serratia ficaria CH-0203),该菌可被壳聚糖诱导产生壳聚糖酶。固定化细胞产酶的研究结果表明,多孔玻璃可以有效吸附CH—0203菌细胞。在最适发酵条件下(pH6．5,培养基与载体的总体积48ml,载体与培养基的比例为1．5g/4．0ml,吸附时间是20h-26h),发酵液酶活达到4．5U／ml,比游离细胞发酵提高了16％。采用半连续发酵的方式,固定化的细胞可以稳定发酵产酶120h左右。固定化细胞产酶的效率大大高于游离细胞。     

Screening of soil fungi for in vitro degradation of endosulfan

Intensive use of endosulfan has resulted in contamination of soil and water environments at various sites in Pakistan. This study was conducted to isolate efficient endosulfan-degrading fungal strains from contaminated soils. Sixteen fungal strains were isolated from fifteen specific sites by employing enrichment techniques while using endosulfan as a sole sulfur source, and tested for their potential to degrade endosulfan. Among these fungal strains, Chaetosartorya stromatoides, Aspergillus terricola, and Aspergillus terreus degraded both α- and β-endosulfan upto 75% in addition to ∼20% abiotic degradation of the spiked amount (100 mg l⁻¹) in the broth within 12 days of incubation. Biodegradation of endosulfan by soil fungi was accompanied by a substantial decrease in pH of the broth from 7.0 to 3.2. The major metabolic product was endosulfan diol along with very low concentrations of endosulfan ether. Maximum biodegradation of endosulfan by these selected fungal strains was found at an initial broth pH of 6, incubation temperature of 30°C and under agitation conditions. This study indicates that the isolated strains carried efficient enzyme systems required for bioremediation of endosulfan-contaminated soil and water environments.     

Desert soil fungi isolated from Saudi Arabia: cultivable fungal community and biochemical production

Desert soils harbor fungi that have survived under highly stressed conditions of high temperature and little available moisture. This study was designed to survey the communities of cultivable fungi in the desert soils of the Arabian Peninsula and to screen the fungi for the potentially valuable antioxidants (flavonoids, phenols, saponins, steroids, tannins, terpenoids, and alkaloids) and enzymes (cellulase, laccase, lipase, protease, amylase, and chitinase). Desert soil was sampled at 30 localities representing different areas of Saudi Arabia and studied for physico-chemical soil properties. Five types of soil texture (sand, loamy sand, sandy loam, silty loam, and sandy clay loam) were observed. A total of 25 saprotrophic species was identified molecularly from 68 isolates. Our survey revealed 13 culturable fungal species that have not been reported previously from Arabian desert soils and six more species not reported from Saudi Arabian desert soils. The most commonly recorded genera were Aspergillus (isolated from 20 localities) and Penicillium (6 localities). The measurements of biochemicals revealed that antioxidants were produced by 49 and enzymes by 52 isolates; only six isolates did not produce any biochemicals. The highest biochemical activity was observed for the isolates Fusarium brachygibbosum and A. phoenicis. Other active isolates were A. proliferans and P. chrysogenum. The same species, for instance, A. niger had isolates of both high and low biochemical activities. Principal component analysis gave a tentative indication of a relationship between the biochemical activity of fungi isolated from soil and soil texture variables namely the content of silt, clay and sand. However, any generalizable relation between soil properties and fungal biochemical activities cannot be suggested. Each fungal isolate is probable to produce several antioxidants and enzymes, as shown by the correlation within the compound groups. Desert soil warrants further research as a promising source of biochemicals.     

木聚糖酶产生菌的选育及发酵条件研究

采用富集培养、透明圈平板筛选,从长期在其上堆放秸秆的土壤中分离到-株木聚糖酶产生菌黑曲霉C2。对该菌株进行紫外线诱变处理,然后采用自然选育的方法筛选到-株木聚糖酶高产菌株C2—56,并对该菌株的适宜发酵条件和酶学特性进行了初步研究。结果表明,C2—56三角瓶发酵酶活达656．8U／g,比出发菌株C2提高了140％;发酵条件以80％麸皮和20％玉米芯为培养基,采用3％接种量,在曲盘上发酵72h为宜,酶活达1750U／g;该菌株产生的木聚糖酶具有较差的热稳定性和较好的pH稳定性,适宜反应温度和pH分别为50℃和pH4．2。     

Four endoparasitic nematode destroying fungi isolated from Sand Ridge State Forest soil

A survey to determine the endoparasitic nematode destroying fungi located within Sand Ridge State Forest of Illinois was conducted from 1 January to 3 April 1973. A total of seven nematode destroying fungal species were isolated from the collected soil samples. Harposporium helicoides, H. crassum, H. lilliputanum are endoparasitic nematophagous fungi that have been isolated previously from the forest soil. Acrostalagmus gonoides, A. obovatus, Cephalosporium balanoides, and Monacrosporium cionopagum are nematophagous fungal species that had not been isolated previously from Illinois soil. Soil pH's and soil nutrient levels were not important in the isolation frequency of the collected endoparasitic nematode destroying fungi.     

The importance of sourcing enzymes from non-conventional fungi for metabolic engineering and biomass breakdown

A wealth of fungal enzymes has been identified from nature, which continue to drive strain engineering and bioprocessing for a range of industries. However, while a number of clades have been investigated, the vast majority of the fungal kingdom remains unexplored for industrial applications. Here, we discuss selected classes of fungal enzymes that are currently in biotechnological use, and explore more basal, non-conventional fungi and their underexploited biomass-degrading mechanisms as promising agents in the transition towards a bio-based society. Of special interest are anaerobic fungi like the Neocallimastigomycota, which were recently found to harbor the largest diversity of biomass-degrading enzymes among the fungal kingdom. Enzymes sourced from these basal fungi have been used to metabolically engineer substrate utilization in yeast, and may offer new paths to lignin breakdown and tunneled biocatalysis. We also contrast classic enzymology approaches with emerging ‘omics’-based tools to decipher function within novel fungal isolates and identify new promising enzymes. Recent developments in genome editing are expected to accelerate discovery and metabolic engineering within these systems, yet are still limited by a lack of high-resolution genomes, gene regulatory regions, and even appropriate culture conditions. Finally, we present new opportunities to harness the biomass-degrading potential of undercharacterized fungi via heterologous expression and engineered microbial consortia.     

10种多孔类真菌体外抗肿瘤活性的筛选

采用MTT法对10种多孔类真菌的发酵液和菌丝体提取物进行抗人肺癌细胞实验,测定培养基种类和培养时间对菌株抗肿瘤活性的影响。结果表明:PDA培养基培养的Onnia tomentosa和Ceizene unicolon的发酵液以及木屑马铃薯培养基培养的Formitopsis pinicola菌丝醇提物具有显著的抗肿瘤活性,其中Formitopsis pinicola菌丝醇提物浓度为500μg/mL时对肿瘤细胞的抑制率达到88．87%;且在不同的培养基中及不同的培养时间获得的菌丝醇提物的抗肿瘤活性变化不大。     

枯草芽胞杆菌甲壳素脱乙酰酶的筛选及酶学性质*

从海洋泥土中分离出产甲壳素脱乙酰酶菌株,确定该菌株为产碱属芽孢杆菌,其产酶适宜培养条件为：pH4．0,添加金属离子Ca^2 ,培养时间为80h,温度为350℃。所得甲壳素脱乙酰酶作用的最适温度为40℃～50℃,最适pH为4．5-5．0之间。