广西沿海地区红树林根系土壤中放线菌的分离与鉴定

本研究通过分离纯培养,从广西北海及防城港红树林根系土壤中分离出放线菌并提取其总DNA,用放线菌通用引物对获得菌株的16SrDNA进行PCR扩增,对获得的扩增产物进行DNA序列测定及菌株鉴定。研究结果表明,从红树林根系土壤样品中分离出15株典型放线菌菌株。16SrDNA测序比对鉴定结果显示,15株典型放线菌菌株中有12株属于链霉菌属（Streptomyces）,是常见菌属;3株属于拟诺卡氏菌属（Nocardiopsis）,为稀有放线菌。本研究分离纯化获得15株典型放线菌,初步揭示了广西沿海地区红树林土壤中放线菌的多样性。     

糯红高粱苗期的内生酵母菌多样性分析

为揭示糯红高粱内生酵母菌多样性及筛选可利用菌株，本研究基于传统纯培养技术和Illumina MiSeq测序技术，研究杂交种金糯粱1号和地方种青壳洋根、茎和叶组织内生酵母菌的多样性，并对纯培养菌株产酶功能进行初筛。结果表明，分离纯化共获得36株内生酵母菌，其中金糯粱1号27株，青壳洋9株；根、茎、叶分别为6、7、23株。36株内生酵母隶属于1门3纲5目6科7属，担子菌门（Basidiomycota）为优势门，浅黄隐球酵母（Cryptococcus luteolus）为优势种，其中5株菌具有产4种酶的特性，隐球菌属（Cryptococcus）占比最多。基于酵母菌26S rDNA NL1F和NL2R区的高通量测序分析共检测到111个操作分类单元（OTU），隶属于2门83属，其中杂交种金糯粱1号和地方种青壳洋内生酵母菌群落多样性、群落结构不存在显著性差异，而不同组织间多样性、群落结构存在极显著性差异（P<0.001）。通过FUNGuild功能预测发现不同组织内生酵母菌的营养模式和生态功能群分为6种和16个，其中茎部独有功能群最多，叶部独有功能群最少。综上，糯红高粱不同品种和不同组织内生酵...     

酸性土壤中解磷菌的分离及其促生效果研究

酸性土壤中磷易被固定,磷的生物有效性极低。解磷菌对土壤中难溶性磷具有重要的增溶作用。虽然已有不少解磷菌方面的研究,但是主要集中于中性和石灰性土壤中钙磷的解磷菌报道,而关于酸性土壤中高效溶解铝磷的微生物报道较少。采用培养基和土培试验,首先对酸性土壤上不同植物（胡枝子、大豆、水稻）根际土壤中的解磷菌进行了分离,然后比较了它们对不同磷源（磷酸钙和磷酸铝）的溶解能力,最后研究了它们对大豆生长和磷吸收的影响。通过使用难溶性磷源（磷酸钙和磷酸铝）的固体培养基,分离得到5株优势菌株L1、S1、S2、R1和R2,经16S rRNA序列鉴定,L1属于阮杆菌属（Nguyenibacter）,S1和S2分别属于假单胞菌属（Pseudomonas）和沙雷氏菌属（Serratia）,R1和R2分别属于伯克氏菌属（Burkholderia）和雷尔氏菌属（Ralstonia）。菌株S1、S2、R1和R2对难溶性磷酸钙有较强的溶解能力,对磷酸铝的溶解能力较弱;菌株L1对磷酸铝表现出较高的溶解能力,对难溶性磷酸钙的溶解能力弱。联合接种菌株L1+S1对大豆生长和磷吸收表现出良好的促进效果,而单独接种L1和S1效果不显著。...     

甘蔗内生菌B9的鉴定及其促生长机制和定殖能力的研究

B9是一株分离于甘蔗品种"云蔗99-91"根部的内生菌,笔者对其种属鉴定与促生长机制开展研究,以期应用于甘蔗生产。试验通过传统方法与16S rRNA等看家基因片段测序对菌株进行分类鉴定;采用固体透明圈、酸性钼蓝比色法、火焰分光光度法、GFP荧光标记等方法测定与研究B9菌株固氮、溶磷、解钾、产IAA、嗜铁素等生物学活性及在甘蔗苗内的定殖情况;最后通过回接法研究菌液处理对玉米种子萌发与甘蔗幼苗生长发育的影响。结果表明B9菌属于芽孢杆菌属枯草芽孢杆菌(Bacillus subtilis),具有固氮、溶磷、解钾、产生IAA和嗜铁素的能力。用B9菌液处理后能提高玉米种子的发芽势与促进根芽组织生长,同时处理组甘蔗苗株在农艺性状与生理生化水平上明显优于无菌清水对照,并且发现B9菌能在甘蔗根茎叶内稳定定殖。本文鉴定了B9菌的种类和功能,阐明了B9菌的促生长机制和定殖能力,为开发生物菌肥并应用于生产提供理论依据。     

生物接触氧化法处理印染废水工艺细菌分析

以广东新会市德发废水处理厂为全对厌氧池和曝气池段细菌进行了分析,共分离出２７株菌株,分别属于４个属,其中芽胞杆菌和假单胞菌为优势菌株,约占总鉴定菌数的６０％。     

几株固氮芽孢杆菌的分离与鉴定

摘要： 从小麦（Triticum aestivum）、玉米（Zea mays）、黑麦草（Lolium sp.）和柳树（Salix sp.）的根际土壤中分离得到能在无氮培养基上生长的29株芽孢杆菌（Bacilli），通过固氮酶活的测定以及固氮酶结构基因 nifH 的PCR扩增得到7株固氮芽孢杆菌。对这7株固氮菌株进行了生理生化性状测定、16S rDNA序列分析(GenBank accession No. AY373358, AY373360,~AY373364和AY376876)、G+C mol%含量的测定及DNA-DNA杂交实验，结果表明，其中5株菌属于芽孢杆菌，另外2株菌属于类芽孢杆菌。在这7株被鉴定的菌株中，菌株T1被鉴定为Bacillus cereus；菌株G1、C4和C5被鉴定为B. megaterium；菌株W5的生理生化性状、16S rDNA和G+C mol%与Bacillus marisflavi 相近；G2的生理生化性状和16S rDNA 与Paenibacillus polymyxa 接近，但在基于16S rDNA的系统发育树中却与P. durus 聚在最小的分支内；T7可能是Paenibacillus属中的一个新种。     

蚯蚓粪中乳酸菌的分离及其在大肠杆菌O157：H7中的抗菌活性

本研究利用SL培养基从蚯蚓粪中分离到54株具有产酸性能的菌株,并以E.coli O157：H7（EDL933株）作为指示菌株,采用点种法检测分离菌株的抑菌活性。结果表明其中6个菌株对指示菌具有拮抗作用,通过形态特征,结合16S rDNA序列分析,初步鉴定该6个菌株分别为食物魏斯特菌（Listeria welshimeri）、乳酸片球菌（Pediococcus acidilactici）、短乳杆菌（Lactobacillus brevis）和格氏乳球菌（Lactococcus garvieae）。分离到的乳酸菌对E.coli O157：H7（EDL933株）具有显著的抑制作用,发酵温度和初始pH值影响发酵液的抑菌作用,优化环境因子可以促进拮抗菌对E.coli O157：H7的抑制作用。本研究为进一步分离抗菌产物用于人畜共患病的预防和治疗提供了理论依据。     

番茄内生拮抗细菌的分离鉴定及培养条件研究

针对番茄生产上灰霉病和叶霉病两大瘸害,为寻找安全、高效无污染的生防菌株及其最佳培养条件,本试验采用组织分离法从健康的番茄植株中分离出642个内生细菌菌株,并采用平板对峙法筛选出对番茄灰霉病菌和叶霉病菌拮抗作用强且稳定的两个菌株Thyy1和Jcxy8。通过形态学观察及生理生化特征测定,初步鉴定Jcxy8属环状芽孢杆菌（Bacillus circulans）,菌株Thhy1属枯草芽孢杆菌（Bacillus subtilis）。内生拮抗细菌在以豆饼粉为原料的6号培养基中生长速度快,发酵滤液对两种病原菌的抑制作用强。培养基初始pH值、培养时间、温度、通气量等对菌株生长及其抗菌物质的分泌有明显影响。以豆饼粉培养基、初始pH6．7、培养时问48h、温度30qc、并尽量增大培养通气量为菌株的最佳培养条件。     

烟草根表可培养细菌群落组成及典型菌群的促生特性研究

植物微生物组是维护植物生长发育、提升抗逆防病的重要调控因素。为发挥植物微生物促进烟草生长、改善烟草根区微生态功能作用，本研究从烟草根表分离筛选可培养细菌组，并对不同菌株的促生能力进行测定。结果表明：①从烟草根表分离并鉴定出可培养菌株310株，隶属于31个属，其中主要为芽孢杆菌属(Bacillus)、假单胞菌属(Pseudomonas)；②对比分析发现假单胞菌属、芽孢杆菌属、寡养单胞菌属(Stenotrophomonas)和成对杆菌属(Dyadobacter)为4种供试土壤烟草根表共有的细菌类群；③对进一步筛选得到的16株菌株进行促生能力的测定，发现6株菌具有固氮能力，5株菌产铁载体，4株菌可溶解无机磷，4株菌产IAA；④盆栽试验验证16株菌株的促生效果，其中37.5% 的菌株对烟草生长具有显著促进作用，烟草株高、总鲜物质量和地下部干物质量分别比对照提高35.1%、27.9% 和30.7%。总之，从烟草根表分离获得多种具有促生能力的菌株，为未来构建促进烟草健康生长的复合菌剂提供了理论基础。     

番茄内生链霉菌S5的分离及其除草活性

采用植物内生放线菌分离方法从健康番茄（Lycopersicon esculentum）根中分离纯化出58株内生放线菌，从中挑选部分代表性菌株进行代谢产物除草活性检测，发现编号为S5的菌株的代谢产物对小麦（Triticum aesfivum L．）和绿豆（Phaseolus radiatus L．）种子的发芽有强烈的抑制作用，但对发芽后的幼苗生长无明显影响。以百喜草（Paspalum notatum）和狗牙根（Cynodon dactylon）为实验对象，证明S5菌株的代谢产物的确能抑制草籽的发芽，该活性具有潜在的除草效能。经初步鉴定，S5菌株为淡紫灰链霉菌淡青变种（Streptomyces lavendulaevar．glaucescens）。发酵条件实验结果表明，S5菌株在1％葡萄糖和0．3％牛肉膏的S培养基中，以2％接种量在pH7．0和25℃摇床培养，可得到最强的抑制种子发芽的生物活性。     

AM真菌对烟苗生长及某些生理指标的影响

在低浓度营养液条件下,利用漂浮育苗技术培育烟苗,于播种期、小十字期、生根期分别接种不同的AM真菌,研究了它们对烟苗生长、营养和某些生理指标的影响。结果表明,越早接种AM真菌,其侵染率越高;播种期接种,侵染率达到39.2%～59.6%。AM真菌的菌根效应因菌种(株)不同而异,接种球囊霉真菌（BEG-141）后,显著增加烟苗干重、磷含量、氮磷钾吸收量、叶绿素含量,以及根系硝酸还原酶、超氧化物歧化酶和几丁质酶活性。表明在漂浮育苗技术中,播种期接种适宜的AM真菌是培育壮苗的有效措施。     

Changes in acetylene reduction activities and effects of inoculated rhizosphere nitrogen-fixing bacteria on rice

Acetylene reduction activities (ARAs) of soils and rice plants during rice-growing season were monitored in temperate region in northeast China. This activity was significantly higher in rhizosphere soil than that in inter-row soil after rice seedlings were transplanted. The ARA was high for most of growing season, suggesting that the native N₂-fixing bacteria responded to rice roots very quickly. Sixteen strains of free-living N₂-fixing bacteria were isolated from three different soils. The ARAs of these strains were correlated with the averaged soil ARAs, suggesting that the isolated strains were likely the active flora responsive to rice roots. The strains were inoculated by soaking seedling roots into the liquid culture for 2 h, and the seedlings were transplanted into pots. Most strains tested did not show any growth-promoting effects except Azotobacter armeniacus and Azotobacter nigricans, which showed growth-promoting effects only at late rice growth stage and only when inoculated in combination but not separately. Present data indicated the promising future applications of these two strains in combination in the region, but further research is needed to understand the underlying mechanisms.     

Effect of fungal endophytes on morphological characteristics,nutrients content and longevity of plane trees (Platanus orientalis L.)

The plane tree is one of the most frequently used street trees in urban landscape in Iran and some Mediterranean countries and some age-old ones are found in these countries. Endophytes are microorganisms which associate with healthy plant tissues, persisting without causing diseases symptoms in the host and normally benefitting them through improving plant ability to withstand environmental stresses. In this contribution, the hypothesis of fungal endophytes existence in the plane trees as well as their relationship with morphological characteristics of trees and nutrient elements of leaves were studied in the central part of Iran. The experiment was performed according to an unbalanced completely randomized design. Approximate age and height of plane trees were recorded and then the greenness and visual appearance were evaluated. Healthy shoots and bark pieces were collected and surface sterilized then placed in petri dishes containing PDA. The results showed that endophytes frequency were significantly greater in age-old trees (60.04%) than young ones (39.96%). Endophytes existence had a positive correlation with iron (Fe) and potassium (K) concentrations of the leaves, and trees height and circumference. Also, there was a positive correlation between the presence of fungal endophytes and improved visual appearance of plane trees. The results suggest that fungal endophytes association enhanced nutrient elements assimilation in trees contributing at least partly to elevated survival of age-old plane trees.     

Isolation and identification of potassium-solubilizing bacteria from tobacco rhizospheric soil and their effect on tobacco plants

Soil potassium supplementation relies heavily on the use of chemical fertilizer, which has a considerable negative impact on the environment. Potassium-solubilizing bacteria (KSB) could serve as inoculants. They convert insoluble potassium in the soil into a form that plants can access. This is a promising strategy for the improvement of plant absorption of potassium and so reducing the use of chemical fertilizer. The objectives of this study were to isolate and characterize tobacco KSB and to evaluate the effects of inoculation with selected KSB strains on tobacco seedlings. Twenty-seven KSB strains were isolated and identified through the comparison of the 16S ribosomal DNA. Among them, 17 strains belonged to Klebsiella variicola, 2 strains belonged to Enterobacter cloacae, 2 strains belonged to Enterobacter asburiae, and the remaining 6 strains belonged to Enterobacter aerogenes, Pantoea agglomerans, Agrobacterium tumefaciens, Microbacterium foliorum, Myroides odoratimimus, and Burkholderia cepacia, respectively. All isolated KSB strains were capable of solubilizing K-feldspar powder in solid and liquid media. K. variicola occurred at the highest frequency with 18 strains. Four isolates, GL7, JM3, XF4, and XF11, were selected for a greenhouse pot experiment because of their pronounced K-solubilizing capabilities. After being treated with the four KSB strains, plant dry weight and uptake of both K and nitrogen (N) by tobacco seedlings increased significantly. These increases were higher with the combination of KSB inoculation and K-feldspar powder addition. Isolate XF11 showed the most pronounced beneficial effect on plant growth and nutrient uptake by tobacco seedlings. Combining the inoculation of KSB and the addition of K-feldspar powder could be a promising alternative to commercial K fertilizer and may help maintain the availability of soil nutrients. Further studies are necessary to determine the effects of these bacterial strains on mobilization of potassium-bearing minerals under field conditions.     

Genetic diversity and potential for promotion of plant growth detected in nodule endophytic bacteria of soybean grown in Heilongjiang province of China

A total of 98 non-symbiotic endophytic bacterial strains isolated from soybean root nodules were classified into eight rDNA types in ARDRA analysis and 21 BOX types in BOX-PCR. The phylogenetic analysis of 16S rDNA identified these strains as Pantoea, Serratia, Acinetobacter, Bacillus, Agrobacterium, and Burkholderia. Limited genetic diversity was revealed among these bacteria since most of the strains (85.7%) were found in three very similar rDNA types corresponding to Pantoea agglomerans, and many strains shared the same BOX-PCR patterns. The inoculation of nodule endophytes had no significant effects on the growth and nodulation of soybean, but most of the strains produced indoleacetic acid (IAA), could solubilize mineral phosphate, and could fix nitrogen, implying that they are a valuable pool for discovering plant growth promoting bacteria. Our results demonstrated that the nodule endophytes were common in soybean and their diversity was affected by the plant's character and the soil conditions. The 99% similarities found in the nifH genes of Bradyrhizobium japonicum and of the endophytic Bacillus strains strongly indicated that horizontal transfer of symbiotic genes happened between the symbiotic bacteria and the endophytes.     

Humic Acids Derived from Leonardite-Affected Growth and Nutrient Uptake of Corn Seedlings

Using organic fertilizer or soil amendment such as humic substances is an important component for sustainable agriculture. The objective of this study was to determine the effects of different factions of humic acids (HAs) on corn seedling growth and nutrient uptake. The experiment was carried out with both an agar culture in root boxes and a hydroponic culture to which 400 mg/L of different factions of humus acids, mixed HAs, and raw Leonardite were added. The experiments were repeated twice with three replications for each treatment. The results showed that applications of HAs significantly improved the leaf and root growth of corn seedlings compared with the control (no HA addition). In the agar culture, seedlings treated with HAs with relatively low molecular weights had more leaves and twice long of roots compared to control and other treatments. In the hydroponic culture, the mixture of three factions was the best treatment for both shoot and root growth of seedlings.     

半夏的组织培养及其成分比较

摘要：三叶半夏(Pinellia ternata Breit. )叶柄切段在含BA 0.5~2.0 mg/L和NAA 0.2 mg/L的MS培养基上，诱导小块茎的频率最高可达100%，小块茎用BA 2.0 mg/L+NAA 0.2 mg/L的MS培养基增殖，3周内增殖频率达16.9倍，小块茎易于生根移栽。应用组织培养技术大批量生产优质半夏种苗是可行的。组织培养和野生的块茎分别用80%甲醇、0.2 mol/L硫酸、去离子水提取内含物，经HPLC分析，比较其图谱表明, 组织培养块茎中各成分的总含量高于野生块茎，二者的主成分构成相似。     

铅胁迫对毛白杨组培生根苗生理生化及根尖细胞微管骨架的影响

用50μmol/L硝酸铅对毛白杨组培生根苗进行不同时间的处理,测定叶片超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）、抗坏血酸过氧化物酶（APX）4种抗氧化酶活性水平和丙二醛（MDA）含量的变化;并通过间接免疫荧光染色法观察根尖分生区细胞的微管骨架。结果显示：铅能使毛白杨叶片APX和POD活性出现...     

烤烟发酵有益细菌的分离筛选及优良菌株的鉴定

已有研究表明,利用从烟叶表面分离得到的微生物对烟叶进行发酵,可以改善烟叶的品质,在烟草生产中具有重要的应用潜力。本研究采用平板画线法,从烟叶、茶叶和笋干上分离得到细菌38株,并将这些菌株应用于烟叶发酵,根据烟叶化学成分和感官评吸对细菌处理的效果进行评价。结果发现,从烟叶上分离到的YX3、YX11和YX12等10个菌株可提高烟叶品质。对其中一个优良菌株（YX37）进行分子鉴定,结果表明其属于芽苞杆菌属。本研究结果证明了从烟叶表面分离烟叶发酵有益细菌的可行性和有效性,为细菌在烟草生产上的应用打下基础。     

The endophyte Enterobacter sp. FD17: a maize growth enhancer selected based on rigorous testing of plant beneficial traits and colonization characteristics

With the aim to select powerful microbial strains to be used for the enhancement of maize yield and resistance to abiotic and biotic stresses, we tested five endophytic bacterial strains previously isolated from maize roots. A range of different laboratory assays in regard to potential plant growth promotion was performed and strains were further evaluated for improving growth of five maize cultivars under axenic and natural soil conditions. Endophytic colonization was an additional component in our selection process as it is of high importance for an inoculant strain to efficiently colonize the plant environment. All strains had the potential to improve maize seedling growth under axenic conditions. Enterobacter sp. strain FD17 showed both the highest growth-promoting activity under axenic conditions as well as colonization capacity. FD17 was therefore selected for further plant tests in a net house, in which two different maize cultivars were grown in large pots until ripening and subjected to outdoor climatic conditions. Results showed that inoculation significantly increased plant biomass, number of leaves plant^?1, leaf area, and grain yield up to 39 %, 14 %, 20 %, and 42 %, respectively, as compared to the un-inoculated control. Similarly, inoculation also improved the photochemical efficiency of photosystem II (PSII) of maize plant and reduced the time needed for flowering. We also confirmed that strain FD17 is able to colonize the rhizosphere, roots and stems. Based on rigorous testing, Enterobacter sp. strain FD17 showed the highest potential to promote growth and health of maize grown under natural conditions. This study suggested that in vitro plant growth-promoting traits and potential of maize seedling growth promotion by bacterial endophytes could be used for the selection of potential inoculant strains subjected for further testing as bio-inoculant under field conditions.