接种溶磷真菌对玉米和大豆根际细菌群落结构多样性的影响

Application of phosphate-solubilizing microorganisms （PSMs） has been reported to increase P uptake and plant growth. However, no information is available regarding the ecological consequences of the inoculation with PSMs. The effect of inoculation with phosphate-solubilizing fungal （PSF） isolates Aspergillus niger P39 and Penicillium oxalicum P66 on the bacterial communities in the rhizospheres of maize （Zea mays L. ‘Haiyu 6＇） and soybean （Glycine max Merr. ‘Heinong 35＇） was examined using culture-dependent methods as well as a culture-independent method, polymerase chain reaction-denaturing gradient gel electrophoresis （PCR-DGGE）. Compared with the control, the number of culturable microbes for soybean was significantly greater with P39, whereas for maize, the same was significantly greater with P66. In addition, a greater number of microbes were found in the rhizosphere of maize compared with soybean. The fingerprint of DGGE for 16S rDNA indicated that inoculation with PSF also increased bacterial communities, with the P66 treatment having higher numbers of DGGE bands and a higher Shannon-Weaver diversity index compared with P39; the composition of the microbial community was also more complex with the P66 treatment. Overall, complex interactions between plant species and exotic PSMs affected the structure of the bacterial community in the rhizosphere, but plant species were more important in determining the bacterial community structure than the introduction of exotic microorganisms.     

Utilization of Sparingly Soluble Phosphate by Red Clover in Association with Glomus mosseae and Bacillus megaterium

A pot experiment was conducted to investigate the mobilization of sparingly soluble inorganic and organic sources of phosphorus (P) by red clover (Trifolium pratense L.) whose roots were colonized by the arbuscular mycorrhizal (AM) fungus Glomus mosseae and in association with the phosphate-solubilizing (PS) bacterium Bacillus megaterium ACCC10010. Phosphate-solubilizing bacteria and rock phosphate had a synergistic effect on the colonization of plant roots by the AM fungus. There was a positive interaction between the PS bacterium and the AM fungus in mobilization of rock phosphate, leading to improved plant P nutrition. In dual inoculation with the AM fungus and the PS bacterium, the main contribution to plant P nutrition was made by the AM fungus. Application of P to the low P soil increased phosphatase activity in the rhizosphere. Alkaline phosphatase activity was significantly promoted by inoculation with either the PS bacterium or the AM fungus.     

Characterization of brushite as a re-crystallization product formed during bacterial solubilization of hydroxyapatite in batch cultures

Two strains of bacteria (Burkholderia sp., strain FeGL01, and Burkholderia caribiensis, strain FeGL03) were isolated from a Brazilian high phosphorus iron ore. The capacity of both strains to solubilize hydroxyapatite, Ca₅(PO₄)₃(OH), was assessed in plate and batch cultures. In batch cultures, the concentration of solution-P showed two kinetics: an initial one, characterized by a continuously increasing kinetics and a second one, characterized by oscillatory kinetics. To understand the nature of these oscillations, phosphatic residues in the spent broth were collected before, during and after the oscillations, and characterized using scanning electron microscopy (SEM), energy-dispersive X-ray chemical microanalyses (EDX) and X-ray diffraction (XRD). From these studies, it was found that drops in P concentration were related to the formation of an intermediate phosphate in the residues, identified as brushite, CaHPO₄·2H₂O. Later increase of available P in the solution was found to be a consequence of re-dissolution of brushite crystals previously formed. Re-crystallization of brushite was also detected in plate cultures after 12-14 days of incubation     

羊草根际解磷细菌数量及解磷强度的研究

对松嫩平原羊草不同生育时期根际解磷细菌的数量和解磷强度的动态变化进行了研究。研究发现,羊草不同生育时期根际和非根际解磷细菌数量均呈现单峰曲线的变化趋势,并在果后营养期达最高峰;无论是无机磷细菌还是有机磷细菌,均呈现明显的根际效应;有机磷细菌数量都比无机磷细菌要多;羊草不同生育时期解磷细菌的解磷强度也呈现单峰曲线的变化趋势,除果后营养期之外,其他各时期无机磷细菌的解磷强度都高于有机磷细菌。     

根际解磷微生物研究进展

综述植物根际解磷微生物种群分布和数量、解磷机制、解磷微生物与植物根系分泌的关系及解磷微生物对作物生长的影响等方面的研究进展,并展望解磷微生物的研究方向。     

6株解有机磷细菌的分离鉴定

从合肥市王小郢污水处理厂的污泥中筛选出6株能降解有机磷的细菌,对这6株茵株进行形态、生理生化性状测定,初步鉴定得出SI菌株为微杆菌属(Microbacterium),S2菌株为葡萄球菌属(Staphylococcus),S3(QY081102)菌株为假单胞菌属(Pseudomonas),S4菌株为不动杆菌属(Acinetobacter),S5菌株为黄色单胞菌属(Flavimonas),S6菌株为纤维单胞菌(Cellulomonas).对它们的解磷能力进行测定和比较,S3菌株的解磷能力最强,其D/d值为4.5,对卵磷脂的降解率为66%,进而对S3菌株进行了16S rDNA序列分析,确定其为产碱假单胞茵(Pseudomonas alcaligenes).     

Phosphate-solubilizing microorganisms associated with the rhizosphere of mangroves in a semiarid coastal lagoon

 The phosphate-solubilizing potential of the rhizosphere microbial community in mangroves was demonstrated when culture media supplemented with insoluble, tribasic calcium phosphate, and incubated with roots of black (Avicennia germinans L.) and white [Laguncularia racemosa (L.) Gaertn.] mangrove became transparent after a few days of incubation. Thirteen phosphate-solubilizing bacterial strains were isolated from the rhizosphere of both species of mangroves: Bacillus amyloliquefaciens, Bacillus licheniformis, Bacillus atrophaeus, Paenibacillus macerans, Vibrio proteolyticus, Xanthobacter agilis, Enterobacter aerogenes, Enterobacter taylorae, Enterobacter asburiae, Kluyvera cryocrescens, Pseudomonas stutzeri, and Chryseomonas luteola. One bacterial isolate could not be identified. The rhizosphere of black mangroves also yielded the fungus Aspergillus niger. The phosphate-solubilizing activity of the isolates was first qualitatively evaluated by the formation of halos (clear zones) around the colonies growing on solid medium containing tribasic calcium phosphate as a sole phosphorus source. Spectrophotometric quantification of phosphate solubilization showed that all bacterial species and A. niger solubilized insoluble phosphate well in a liquid medium, and that V. proteolyticus was the most active solubilizing species among the bacteria. Gas chromatographic analyses of cell-free spent culture medium from the various bacteria demonstrated the presence of 11 identified, and several unidentified, volatile and nonvolatile organic acids. Those most commonly produced by different species were lactic, succinic, isovaleric, isobutyric, and acetic acids. Most of the bacterial species produced more than one organic acid whereas A. niger produced only succinic acid. We propose the production of organic acids by these mangrove rhizosphere microorganisms as a possible mechanism involved in the solubilization of insoluble calcium phosphate. Received: 21 April 1999     

石灰性土壤解磷细菌的鉴定及其对土壤无机磷形态的影响

【目的】从北方石灰性土壤中分离筛选解磷细菌,对其进行鉴定,并测定其解磷能力,为筛选高效稳定的解磷菌株提供参考。【方法】采集陕西杨凌地区白菜、葡萄、猕猴桃3种植物根际土样,采用稀释涂布法分离土壤解磷细菌,对分离到的细菌进行革兰氏染色,观察菌落形态及颜色,测定其生理生化性质,并结合16SrRNA法对其进行鉴定;测定各菌株在固体及液体培养基中的解磷能力大小;分析浇灌无机解磷细菌发酵液后石灰性土壤中无机磷形态及其含量的变化。【结果】共分离筛选得到10株解磷细菌,其中2株为有机解磷细菌(Y1和Y2),4株为无机解磷细菌(W1、W2、W3和W4),其余4株既能分解有机磷,也能分解无机磷,为双解磷细菌(WY1、WY2、WY3和WY4);分离到的10株解磷细菌为革兰氏阴性菌,其中WY1和Y2为短杆菌,其余均为杆菌。生理生化性质及16S rRNA序列分析结果表明,10株菌株中8株属于芽孢杆菌属(Bacillus),其中WY2、W1、W2、W3与腊状芽孢杆菌相似,WY3和W4与苏云金芽孢杆菌相似,WY4与巨大芽孢杆菌相似,Y2与Bacillus aryabhattai相似;WY1和Y1分别与耐寒短杆菌、杨氏柠檬酸杆菌相似。不同类型解磷细菌在固、液体培养基中解磷能力不同;高效液相色谱分析结果表明,筛选得到的无机解磷细菌部分分泌草酸,部分分泌酒石酸。石灰性土壤浇灌无机解磷细菌发酵液后,Ca8-P、Ca2-P含量增加,Fe-P含量减少,Al-P、Ca10-P、O-P含量变化不大。【结论】石灰性土壤中解磷细菌具有物种多样性,无机解磷细菌能使石灰性土壤中可利用有效磷含量增加。     

一种新型廉价吸附剂对低浓度 氨氮的吸附特征研究

采用旱伞草为试验原料,通过简单的炭化处理工艺制取一种新型廉价的吸附剂。研究了炭化旱伞草在不 同氨氮浓度下吸附时间、投加量、吸附温度、pH、粒径等因素对其去除效果的影响,并采用傅立叶红外光谱分析对该 种吸附剂及吸附氨氮前后官能团的变化进行检测分析。结果表明院吸附剂制取的最佳炭化温度为450益,炭化时间 40 min;最佳工艺条件为吸附时间60 min,吸附剂投加量为1.50 g,吸附温度30益,pH 为6~8,旱伞草粒径为420~841 滋m。傅立叶红外光谱分析结果表明炭化后旱伞草中含有丰富的羟基和氨基,并与水中氨氮发生氧化反应,使氨氮得 到去除。