两株耐铅镉真菌对土壤中铅镉赋存形态及小白菜吸收积累的影响

通过土培试验,研究接种耐铅镉真菌(产黄头孢霉Cephalosporium chrysogenum和头孢霉Cephalosporium SP.)对灭菌和未灭菌铅镉污染土壤上小白菜生长及铅镉赋存形态的影响.试验结果表明:接种两种耐重金属真菌可以降低或显著降低土壤中交换态铅镉、碳酸盐结合态铅镉和铁锰结合态铅镉,且显著增加土壤中有机结合态铅镉,因此降低了土壤中铅镉的活性;在灭菌和未灭菌铅镉污染土壤上接种两种真菌均能增加或显著增加小白菜的株高和鲜重,其中在未灭土壤中接种产黄头孢霉20 mL小白菜鲜重和株高最大,分别达到6.00 cm和3.22 g·株~(-1),在灭菌土壤上接种产黄头胞霉10 m L小白菜株高和鲜重最大,分别为10.66 cm和11.07 g·株~(-1);接种两种真菌可以显著降低未灭菌土壤上小白菜体内铅镉含量和累积量,在灭菌土壤上接种10 mL产黄头孢霉可以显著降低小白菜铅含量和累积量.     

施用沼渣和接种丛枝菌根真菌对甘草生长及矿质营养的影响

沼渣是厌氧发酵的残余物,可作为肥料施用,但因其含有一定量的重金属等有害物质可能导致环境污染风险.丛枝菌根(Arbuscular mycorrhiza,AM)真菌作为植物共生真菌,可以促进植物对矿质养分的吸收,同时能够通过不同途径减轻重金属对植物的毒害.本文采用甘草(Glycyrrhiza uralensis Fisch.)为供试植物开展盆栽试验,考察施用沼渣结合接种AM真菌对甘草生长和矿质营养的影响.试验结果表明,施用沼渣显著促进了植物生长,提高了植物生物量、磷含量和叶片叶绿素含量,与此同时提高了土壤有机质和磷、铬、铜、铅含量,并导致植物重金属含量显著升高.另一方面,AM真菌能够和甘草根系形成良好共生关系,但施用沼渣对菌根侵染表现出显著抑制作用.接种AM真菌促进了甘草生长、提高了根系磷含量及叶片叶绿素含量,同时显著降低了植株重金属含量至安全阈值以内.本试验表明,施用沼渣同时接种AM真菌可在促进甘草生长的同时阻控重金属污染风险,因而可作为沼渣安全利用的一种可行技术途径.     

降解褐煤菌种选育及降解产物研究

通过对分离自洗煤厂的一株青霉菌进行人工诱变,选育出一株具有较强降解褐煤能力的突变株．将褐煤加到平板培养的该菌株上,经过３６ ｈ 开始被降解．将该菌株用摇瓶培养３ ｄ ,其培养液也能降解褐煤．元素分析结果表明,降解物中 Ｈ、 Ｏ、 Ｎ 的元素质量分数（ ｗ／ ％ ） 比原煤均有所升高,而ｗ（ Ｃ）／ ％ 明显下降．降解产物的经验分子式可写为 Ｃ１００ Ｈ１４４ Ｏ５８ ．２ Ｎ１０ ．０ Ｓ１ ．１８ ,经凝胶过滤法测,定其 Ｍｒ 分布在（２ ～８） ×１０４ 之间; 其红外吸收光谱与原煤相比也有一定的变化． 这些结果说明生物降解过程中褐煤的组成和结构发生了一定的变化     

Biodegradation and bioconversion of cellulose wastes using bacterial and fungal cells immobilized in radiopolymerized hydrogels

Annually, great amounts of cellulose wastes, which could be measured in many billions of tons, are produced worldwide as residues from agricultural activities and industrial food processing. Consequently, the use of microorganisms in order to remove, reduce or ameliorate these potential polluting materials is a real environmental challenge, which could be solved by a focused research concerning efficient methods applied in biological degradation processes. In this respect, the scope of this chapter is to present the state of the art concerning the biodegradation of redundant cellulose wastes from agriculture and food processing by continuous enzymatic activities of immobilized bacterial and fungal cells as improved biotechnological tools and, also, to report on our recent research concerning cellulose wastes biocomposting to produce natural organic fertilizers and, respectively, cellulose bioconversion into useful products, such as: ‘single-cell protein’ (SCP) or ‘protein-rich feed’ (PRF). In addition, there are shown some new methods to immobilize microorganisms on polymeric hydrogels such as: poly-acrylamide (PAA), collagen-poly-acrylamide (CPAA), elastin-poly-acrylamide (EPAA), gelatin-poly-acrylamide (GPAA), and poly-hydroxy-ethyl-methacrylate (PHEMA), which were achieved by gamma polymerization techniques. Unlike many other biodegradation processes, these methods were performed to preserve the whole viability of fungal and bacterial cells during long term bioprocesses and their efficiency of metabolic activities. The immobilization methods of viable microorganisms were achieved by cellular adherence mechanisms inside hydrogels used as immobilization matrices which control cellular growth by: reticulation size, porosity degree, hydration rate in different colloidal solutions, organic and inorganic compounds, etc. The preparative procedures applied to immobilize bacterial and fungal viable cells in or on radiopolymerized hydrogels and, also, their use in cellulose wastes biodegradation are discussed in detail. In all such performed experiments were used pure cell cultures of the following cellulolytic microorganisms: Bacillus subtilis and Bacillus licheniformis from bacteria, and Pleurotus ostreatus, Pleurotus florida, and Trichoderma viride from fungi. These species of microorganisms were isolated from natural habitats, then purified by microbiological methods, and finally, tested for their cellulolytic potential. The cellulose biodegradation, induced especially by fungal cultures, used as immobilized cells in continuous systems, was investigated by enzymatic assays and the bioconversion into protein-rich biomass was determined by mycelial protein content, during such long time processes. The specific changes in cellular development of immobilized bacterial and fungal cells in PAA hydrogels emphasize the importance of physical structure and chemical properties of such polymeric matrices used for efficient preservation of their metabolic activity, especially to perform in situ environmental applications involving cellulose biodegradation by using immobilized microorganisms as long-term viable biocatalysts.     

菌根真菌在墨兰和建兰根中的感染特征及生理特性

从产于粤北山区的野生建兰报中分离出4株内生真菌,并对这些真菌在兰根上的感染特征及生理学特性进行了研究。结果表明,菌根真菌多数浸染植株根段离很尖3～18cm的根毛区,而根尖和新长出的根则很少被感染;几乎所有的老根都受过真菌的感染。真菌菌丝从兰报表皮侵入,通过表皮层进入皮层薄壁细胞内部形成菌丝团,而在表皮层并不进入细胞内,也不形成菌丝团。真菌感染极状整后第9天,皮层细胞内的菌丝团开始消解。所分离的菌株能利用大部分简单的有机碳源和氮源,能在营养成分不明确的天然介质中生长良好,但对硝酸盐的利用较差。     

北京市夏季空气微生物粒度分布特征

着重研究了夏季空气微生物的粒度分布特征,比较分析了北京市空气微生物粒度分布的变化状况.结果表明:空气细菌、空气真菌和空气放线菌的粒度分布特征各不相同, 并且不随着时间和空间的变化而变化.空气细菌呈偏态分布,大于2.0 μm的粒子约占总数的80.0%,小于1.0 μm的粒子最少,约占9.0%.空气真菌呈对数正态分布,1.0～6.0 μm的粒子约占70.0%,小于1.0 μm的粒子最少,约占5.0%.空气放线菌粒度分布与正态分布恰好相反,大于8.2 μm和小于1.0 μm的粒子约占60.0%;3.0～6.0 μm的粒子最少,约占10.0%.此外不同功能区优势真菌粒度分布规律基本一致.枝孢属(Cladosporium),青霉属(Penicillium)和曲霉属(Aspergillus)粒度主要分布在F3,F4和F5(1.0～6.0 μm)中,约占总数的85.0%,呈对数正态分布.而交链孢属(Alternaria)和无孢菌(nonsporing)主要分布在前4级(>2.0 μm),分别约占总数的90.0%和75.0%,呈偏态分布.在过去10年的城市化进程中,北京市空气微生物粒度分布的基本趋势没有变化,但是空气真菌粒度分布的峰值由原来的3.0～6.0 μm降低到2.0～3.0 μm.     

处理乙硫醇废气生物滤池中微生物的初步鉴定

生物滤池是废气生物处理的主要技术之一 ,其生物相包括细菌和真菌 .对于疏水性有机物质 ,真菌具有更高的处理效率 ,而且真菌对环境的适应性也比细菌强 .本研究采用生物滤池处理含乙硫醇废气 ,通过对生物滤池填料上附着的微生物进行分离鉴定表明 ,初步判定分离出的菌株分别为常现青霉、宛氏拟青霉、文氏曲霉和顶孢头孢霉 .     

海南西沙试验站大气霉菌群落初步调查

目的 筛选西沙试验站大气环境优势菌种,进行西沙试验站装备敏感菌研究。方法 采用撞击法进行大气霉菌采样,用统计学法计算出不同试验场地真菌数量,结合形态学法与ITS1-5.8S-TIS2或26SrDNA D1/D2区序列分析法鉴定菌种,并用SPSS初步探讨大气真菌与环境因素的关系,分析西沙试验站装备敏感菌。结果 西沙试验站优势种为Aspergillus aculeatus、Penicillium citrinum、Pithomyces sacchar、变红镰孢霉Fusarium incarnatum、Cladosporium oxysporum和Cladosporium oryzae,影响西沙试验站大气霉菌群落结构的重要环境因素是相对湿度和风速,贮存在西沙试验站的装备容易长霉,多种材料有不同的敏感菌,尤其是涂层样件和橡胶类材料。结论 西沙试验站大气环境中存在种类繁多的霉菌。     

Cellular damage of plant pathogenic fungi by antifungal compounds produced by Bacillus spp. isolates

The use of microorganisms as biological control agents (BCAs) has become an effective alternative to chemical means of controlling plant pathogens. The antagonistic and inhibitory activity of 71 Bacillus spp. strains, which were isolated from different Mexican sites, were tested against several phytopathogen fungi, Fusarium oxysporum, Fusarium equiseti, Fusarium avenaceum, Bipolaris spp. and Alternaria spp. From the antagonism study, the strain ELI149 showed a marked inhibition of growth against all tested fungi; therefore crude metabolites from this strain were extracted using ethyl acetate and amberlite resin and probed against the same fungi as well as strains of Mucor sp., Penicillium spp. and Paecilomyces spp. The results indicated that amberlite was more suitable for extraction of secondary metabolites with antifungal activity. Finally, observation of cell damage in the tested pathogenic fungi showed marked morphological changes on reproductive structures in all tested fungi indicating that antibiosis was the mechanism of the antagonistic effect. These results suggest that metabolites from the Bacillus strains have a wide spectrum of antibiotic activities, which can be used as biocontrol agents for controlling fungal plant diseases of agricultural importance.     

Screening for plants and rhizospheral fungi with bioremediation potency of petroleum-polluted soils in a Tehran oil refinery area

The contamination of soils by toxic and/or hazardous organic pollutants, especially with crude oil, is a widespread problem. This study was conducted in a petroleum-contaminated area in a Tehran oil refinery to find petroleum-resistant plants and their rhizospheral fungal strains with bioremediation potency. The plants growing in the oil-polluted area were collected and determined taxonomically. Root samples of the plant species were collected from a polluted area and fungal strains determined by laboratory methods and taxonomical keys. The growth ability of the isolated fungal strains was studied in media containing 1%–15% crude oil. Results showed that seven plant species were of the highest density in the contaminated area: Alhagi persarum, Hordeum marinum, Peganum harmala, Phragmites australis, Prosopis farcta, Salsola kali, and Senecio glaucus. The root-associated fungi were isolated and showed that the fungal variation in the oil-polluted area is higher than that in a non-polluted area. The growth assay of isolated fungal strains showed that all studied fungal strains were able to form colonies at the applied concentrations but Alternaria sp. and Rhizopus sp. were the most resistant ones. Some plants were resistant to oil pollution, which also had positive effects on the fungal strains.