固氮芽孢杆菌GD272的筛选鉴定及其固氮性能研究

对所选育出的一株固氮芽孢杆菌（编号为GD272）进行了形态、生理生化测定和接种效果研究。通过16S rDNA基因比对以及生理生化鉴定表明,该菌株属于芽孢杆菌Bacillus sp.。乙炔还原法测定显示该菌株具有较高的固氮酶活性;小白菜盆栽试验看出,接种GD272菌达到了施用化学氮肥的同等效果。菌株GD272在固氮微生物肥料生产中具有较好的开发应用前景。     

固氮球形芽孢杆菌与巨大芽孢杆菌的混合增效作用

球形芽孢杆菌Bs7与巨大芽孢杆菌Bm1 0 1混合培养时具有固氮增效作用。稀释 40 0倍的巨大芽孢杆菌的无菌上清液与球形芽孢杆菌共培养 ,同样能增强后者的固氮活性。Bs7(pAB5 76 )在纯培养时的nifA表达活性为 6 849 5Miller单位 ,与巨大芽孢杆菌上清培养液进行混合培养时的表达活性为 75 0 0 4Miller单位。上述结果表明 :某些微量非碳源的活性分泌物和某些固氮调节基因可能在固氮增效作用中起重要作用。在与水稻联合培养条件下 ,混合接种球形芽孢杆菌与巨大芽孢杆菌可以提高固氮菌在水稻根表的定殖能力     

芽孢杆菌与根瘤菌复合包衣对大豆结瘤固氮能力的影响

为了探究不同芽孢杆菌与根瘤菌复合包衣对大豆结瘤固氮的影响,通过盆栽试验,设置不接菌对照(CK)、根瘤菌单独包衣(R)、阿氏芽孢杆菌(RB)和胶质类芽孢杆菌(RP)2种促生菌分别与根瘤菌双包衣以及 3种菌混合包衣(RBP)共5个处理,测定大豆根瘤数量、干重、根瘤固氮酶活性及植株氮、磷、钾含量,筛选根瘤菌剂最佳组合。结果表明,接种菌剂的处理均能够促进大豆结瘤固氮,其中RB处理效果最好,能够获得最高的大豆植株干重、根瘤数量、根瘤干重、固氮酶活性、全氮含量,比CK分别提高51.80%、14.44%、53.33%、44.36%、25.61%,3种菌包衣并没有比双接种促生效果更好。相关性分析表明,根瘤干重与固氮酶活性、根瘤数量及植株干重都呈显著正相关关系,说明根瘤的质量可能比数量更能准确评价共生固氮效率。此结果为根瘤菌剂应用于机械化种植提供可能性,为进一步推广根瘤菌剂的规模化生产应用提供了科学依据。     

马铃薯内生固氮菌的分离及其促生特性研究

内生固氮菌是一类重要的植物促生菌,占据着植物组织内有利于营养供应和微环境适宜的生态位,能更好的发挥促生功能,促生机制包括固氮、解磷、产植物生长素、产ACC脱氨酶、产铁载体及拮抗病害等。本文从连作3年马铃薯根筛选获得8株内生固氮菌,其中短芽孢杆菌属(Brevibacterium)3株,芽孢杆菌属(Bacillus)3株和泛菌属(Pantoea)2株。促生特性研究发现:菌株Brevibacterium sp.GWR4具有较高固氮酶活性[16.206nmol C2H4/(mg蛋白质·h)],与圆褐固氮菌的固氮酶活性具有极显著性差异(P0.01);菌株Pantoea spp.GWR2、GWR3具有极高的产IAA能力,分别为186.07、162.21μg/m L,GWR2兼具产ACC脱氨酶活性[3.74μmol/(mg蛋白质·h)],GWR3兼具溶解无机磷的能力;菌株Brevibacterium sp.GWR5可以拮抗尖孢镰刀菌MLSOF(Fusarium xysporum)和茄病镰刀菌MLS-QB(Fusarium solani),兼具溶解有机磷和产IAA能力;Bacillus spp.GWR7、GWR8兼具固氮和产IAA能力。盆栽试验显示,分别接种Pantoea sp.GWR3,Brevibacterium spp.GWR4、GWR5和Bacillus spp.GWR7、GWR8后小白菜鲜重显著高于未接菌对照处理。可见,这5株菌兼具多种促生特性且对小白菜具有较好的促生效果,有望进一步研究开发成为微生物肥料生产菌种。     

甘肃地区道地药材根际固氮微生物分离鉴定

为调研甘肃中药材种植区的固氮微生物资源,从党参、黄芪和当归3种药材种植地的根际土壤中分离具有固氮酶活性的微生物,单菌株纯化并进行分子生物学鉴定,最后通过乙炔还原法检测各菌株的固氮酶活性。结果表明:这3种作物的根际土壤中固氮微生物资源丰富,共分离得到28株具有固氮酶活性的菌株,经鉴定主要为根瘤菌属、芽孢菌属、单孢菌属、无色杆菌属和粘着箭菌属等,固氮酶活性为53.5 C_2H_2nmol·(h·ml)-1~295.3 C_2H_2nmol·(h·ml)~(-1),无色杆菌属的固氮酶活性较高。此研究为下一步筛选适合中药材生长的微生物固氮菌肥的菌种提供一定的理论依据。     

自生固氮菌的固氮能力及其对春小麦生长发育的影响

为挑选具有高固氮能力的自生固氮菌菌株, 用乙炔还原法对甘肃省春小麦和玉米等非豆科作物根际土壤中分离所得的13株菌进行固氮酶活性测定, 并通过盆栽试验对其进行春小麦肥效试验.结果表明:供试13株自生固氮菌对春小麦籽粒、生物产量及其构成因素均有一定促进作用, N6、N10、N13、N14、N27和N42 6株菌对春小麦产量的促进作用相对较高, 具有一定的应用前景, 有望成为微生物肥料研制的菌种.其中N13对春小麦的增产效果最为明显, 与施同量肥料(1/3N)的对照相比, 籽粒增产66.04%, 生物产量增产54.19%, 穗重增加47.65%, 穗粒数增多37.91%, 千粒重增加20.42%, 株高增加5.16%, 穗长增加21.89%, 且具有较强的固氮能力, 每盆固氮量为212.55 mg, 固氮酶活性也显著高于其他菌株, 达到139.79 nmol(C2H4)·h-1·mL-1.     

不同固氮菌对桉树生长指标的影响

通过调查和研究已经接种有固氮菌的桉树人工林,通过测定桉树胸径和树高、然后计算单株材积,旨在探讨接种固氮菌后对桉树人工林生长指标的影响。从实验结果可以看出:接种固氮菌可以有效的提高桉树胸径和树高的生长,同一树种接种不同的固氮菌株,对桉树促生的效果有明显差异性,其中促生效果最佳是固氮菌N2。     

盐爪爪根际产ACC脱氨酶菌株筛选及促生特性研究

为探究盐碱区生态环境改良方式,丰富产1-氨基环丙烷-1-羧酸(ACC)脱氨酶菌种资源,从新疆克孜勒苏柯尔克孜自治州盐碱地盐爪爪(Kalidium foliatum)根际土壤中筛选产ACC脱氨酶菌株,结合16S rRNA基因测序对优良菌株鉴定,通过盆栽接种试验验证其促生效果。结果从盐爪爪根际分离到26株产ACC脱氨酶菌株,酶活性为0.4～5.6 U·mg^-1,以PM14、PM16和PM24活性最高。经鉴定,菌株PM14、PM16和PM24分别归属肠杆菌属(Enterobacter)、赖氨酸芽孢杆菌属(Lysinibacillus)和假单胞菌属(Pseudomonas)。盆栽试验表明,接种3株菌对非盐碱胁迫下拟南芥地上(株高、地上干重)和地下(根长、根干重)部分生长均有明显促进作用;对盐碱土栽培小麦的地上部分(株高、茎粗、鲜重和干重、叶绿素含量)和根干重也有积极影响,尤以PM16最显著。PM14和PM16兼具解磷、固氮和分泌吲哚-3-乙酸(indole-3-acetic acid, IAA)的能力,PM24兼具固氮和分泌IAA的能力,均具有多种促生功能。本研究结果为盐...     

接种贝莱斯芽孢杆菌SW5菌株对发酵鳀鱼鱼露品质的影响

为探讨接种贝莱斯芽孢杆菌SW5菌株对发酵鳀鱼鱼露的影响,以贝莱斯芽孢杆菌SW5为唯一发酵菌株,以低值鳀鱼为原料,测定鱼露发酵过程中氨基酸态氮(AA-N)、挥发性盐基氮(TVB-N)、pH值、总酸含量,并使用顶空固相微萃取结合气相色谱-质谱联用仪(HS-SPME-GC-MS)测定发酵结束后发酵液的挥发性风味物质。结果表明,在发酵期间,利用SW5菌株发酵的处理组1在发酵第6天时AA-N含量最高,为0.76 g·100 mL^-1,达到市售二级鱼露标准。3种处理组和舟山商品鱼露中共检测出挥发性风味成分82种,主要是醇、酸、醛、酮、呋喃、烷烃及其他类化合物,接种组中的挥发性风味物质(40种)较未接种组(35种)有所增加。综上,接种贝莱斯芽孢杆菌SW5菌株发酵鱼露,能缩短发酵时间,增加风味物质种类,该菌株可用作海洋蛋白质源发酵精深加工的优良微生物菌株。     

根瘤菌与促生菌双接种对大豆生长和土壤酶活的影响

【目的】慢生大豆根瘤菌和胶质类芽孢杆菌单一菌株固氮或促生效果及机理已有较多研究,但两者双接种对作物的作用和增产机理尚未有所报道。本研究以慢生大豆根瘤菌5136与胶质类芽孢杆菌3016为研究对象,通过田间小区试验研究根瘤菌与促生菌不同施用模式对大豆生长和土壤酶活的影响,以期为开发新型高效复合菌剂提供理论依据。【方法】试验设对照(T1)、接种胶质类芽孢杆菌3016菌剂(T2)、接种慢生大豆根瘤菌5136菌剂(T3),胶质类芽孢杆菌3016和慢生大豆根瘤菌5136双接种(T4)和常规施肥(T5)5个处理,分别于大豆不同生育期调查大豆的农艺性状和结瘤状况,测定土壤酶活性,用BOX-PCR技术监测慢生大豆根瘤菌5136的占瘤率。【结果】1)在大豆成熟期,双接种(T4)处理的大豆单株分枝数、单株粒数、收获指数和产量均为最高,分别比T1高11.3%、9.7%、41.0%和9.3%,且单株空荚数最低,比T1降低了44.0%。2)在花荚期,双接种(T4)处理的占瘤率为25.4%,比T3处理高8.0%,且单株根瘤数和单株根瘤干重均为最高,分别比T1高41.6%和47.1%;说明双接种处理下,胶质类芽孢杆菌3016能够促进慢生大豆根瘤菌5136结瘤固氮。3)接种微生物菌剂均可不同程度地提高土壤酶活性,以双接种(T4)处理的效果最为显著,在大豆成熟期,土壤过氧化氢酶、脲酶和蔗糖酶活性均为最高,分别比对照高12.9%、8.9%和9.4%。4)相关性分析表明,土壤酶活性与大豆收获指数显著正相关或极显著正相关(P0.01或P0.05),其中过氧化氢酶与产量显著正相关;单株根瘤数和单株根瘤干重均与收获指数和蔗糖酶活性呈极显著正相关,与产量呈显著正相关。【结论】慢生大豆根瘤菌和胶质类芽孢杆菌双接种可以促进大豆生长,显著增加大豆的单株分枝数、单株粒数、收获指数和占瘤率,降低单株空荚数,增加大豆产量,同时可显著提高相关土壤酶活性,是一种节本增效的农艺措施。     

Synergistic effect of inoculating plant growth-promoting Pseudomonas spp. and Rhizobium leguminosarum-FB1 on growth and nutrient uptake of rajmash (Phaseolus vulgaris L.)

Plant growth-promoting bacteria (PGPB) Pseudomonas lurida-NPRp15 and Pseudomonas putida-PGRs4 possessing multiple plant growth-promoting traits were isolated from rhizoplane of pea and rhizosphere of garlic, respectively. The effects of individuals and combinations of Pseudomonas spp. with effective root nodulating symbiotic nitrogen fixing Rhizobium leguminosarum-FB1 on plant growth, nutrient uptake and yield of the rajmash plant were studied under greenhouse conditions. Bacterial inoculation resulted in significantly higher values for plant dry biomass, N, P, K, Zn and Fe contents as compared to the uninoculated control. Furthermore, dual inoculation of P. lurida-NPRp15 with R. leguminosarum-FB1 significantly increased root and shoot dry weight, nodulation, nutrient uptake, pod yield, and nutrient content of pods of rajmash VL63 compared to controls, single and triple inoculation. The results of the study indicate the potential of harnessing the benefit of plant growth-promoting and nitrogen-fixing microorganisms to improve the growth and yield of rajmash.     

Effects of co-inoculation of Bradyrhizobium japonicum SAY3-7 and Streptomyces griseoflavus P4 on plant growth,nodulation, nitrogen fixation,nutrient uptake,and yield of soybean in a field condition

ABSTRACT

Co-inoculation of nitrogen-fixing bacteria with plant growth-promoting bacteria has become more popular than single inoculation of rhizobia or plant-growth-promoting bacteria because of the synergy of these bacteria in increasing soybean yield and nitrogen fixation. This study was conducted to investigate the effects of Bradyrhizobium japonicum SAY3-7 and Streptomyces griseoflavus P4 co-inoculation on plant growth, nodulation, nitrogen fixation, nutrient uptake, and seed yield of the ‘Yezin-6’ soybean cultivar. Nitrogen fixation was measured using the acetylene reduction assay and ureide methods. Uptake of major nutrients [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] was also measured. This study showed that single inoculation of SAY3-7 significantly increased shoot biomass; nodulation; Relative Ureide Index (RUI %), percent nitrogen derived from N fixation (% Ndfa); N, P, K, Ca, and Mg uptakes; during the later growth stages (R3.5 and R5.5), compared with control. These observations indicate that SAY3-7 is an effective N-fixing bacterium for the plant growth, nodulation, and nitrogen fixation with an ability to compete with native bradyrhizobia. Co-inoculation of SAY3-7 and P4 significantly improved nodule number; nodule dry weight; shoot and root biomass; N fixation; N, P, K, Ca, and Mg uptake; at various growth stages and seed yield in ‘Yezin-6’ soybean cultivar compared with the control, but not the single inoculation treatments. Significant differences in plant growth, nodulation, N fixation, nutrient uptake, and yield between co-inoculation and control, not between single inoculation and control, suggest that there is a synergetic effect due to co-inoculation of SAY3-7 and P4. Therefore, we conclude that Myanmar Bradyrhizobium strain SAY3-7 and P4 will be useful as effective inoculants in biofertilizer production in the future.     

华北冬绿肥作物二月兰的营养特征研究

二月兰可作为冬季绿肥作物引入华北地区农田种植,与春玉米等作物形成良好的粮肥复种体系,在华北地区有着广阔前景.本试验调查分析了二月兰从返青到成熟的养分含量及累积状况,结果表明,二月兰植株体的养分含量较高,盛花期其干物质氮、磷、钾含量分别为2.99％、0.42％和2.99％,且产量较高.二月兰对氮、钾的累积量大,对磷的累积量较小.盛花期二月兰的养分已累计完成了总量的86.3％～94.0％,是进行翻压的最适宜时期.二月兰的养分累积过程符合Logistic方程y=k/(1 +ae-bx),氮、磷、钾最大累积速率出现的先后顺序为磷最早、氮次之、钾最晚.     

壳聚糖对NaCl胁迫下菜用大豆结瘤固氮的影响

【目的】研究壳聚糖对盐胁迫抑制菜用大豆结瘤固氮的缓解效应,为进一步探讨壳聚糖抗逆机理提供新的线索。【方法】以蛭石为基质,以菜用大豆‘特早王’–根瘤菌共生体系为研究对象,采用人工气候箱培养,研究NaCl胁迫下壳聚糖对菜用大豆根瘤形成、生物固氮的影响。菌种为与‘特早王’共生匹配性较好的快生根瘤菌N18。接种后的植株进行如下4个处理:1)叶面喷施清水,根部浇灌无氮营养液(CK);2)叶面喷施壳聚糖水溶液,根部浇灌无氮营养液(CTS);3)叶面喷施清水,根部浇灌溶有NaCl的无氮营养液(Cl);4)叶面喷施壳聚糖水溶液,根部浇灌溶有NaCl的无氮营养液(CTS+Cl)。上述各处理施用的水或水溶液均为无菌水配制,NaCl处理的浓度为50 mol/L,CTS处理的适宜浓度为200 mg/L。接种30天后,将大豆植株取出,用清水将根部蛭石冲洗干净后,立即测定根瘤固氮酶活性、根瘤数及根瘤鲜重,然后测定根瘤豆血红蛋白含量和根系活力,最后测植株干重和全氮量。【结果】氯化钠胁迫下,植株干重显著下降,与CK相比降幅达49%,喷施壳聚糖后(CTS+Cl),降低幅度显著减小,但依然显著低于CK (P <0.05)。无盐条件下,与CK相比,壳聚糖处理(CTS)增加植株干重的效果不明显。喷施壳聚糖显著增加了菜用大豆的根瘤数、根瘤鲜重、植株含氮量、根系活力、豆血红蛋白含量及固氮酶活性(P <0.05)。NaCl胁迫显著抑制了菜用大豆的结瘤固氮作用,其中根瘤数、根瘤鲜重分别较CK下降了79%、90%,而壳聚糖处理(CTS+Cl)使菜用大豆在盐逆境下的结瘤数、根瘤鲜重、植株全氮含量、根系活力、豆血红蛋白含量及固氮酶活性等均显著回升,增幅分别达对照的29%、20%、17%、48%、19%、21%,但均显著低于CK。【结论】非NaCl胁迫下,喷施壳聚糖可以显著促进菜用大豆结瘤,提高豆血红蛋白含量及固氮酶活性,最终增加植株含氮量。在NaCl胁迫下,外源壳聚糖可以显著缓解氯化钠胁迫导致的对根系活力和结瘤固氮的影响。因此,叶面喷施壳聚糖是促进菜用大豆结瘤固氮和生长的有效措施。     

Effects of Root Plant Growth Promoting Rhizobacteria Inoculations on the Growth and Nutrient Content of Grapevine

The objective of this study was to evaluate the effects of seven nitrogen (N₂)-fixing and/or phosphorus (P)-solubilizing and siderophore-producing microorganism based bio-fertilizers in single and triple strain combinations isolated from the acidic rhizospheric soil of native tea, grapevine, and wild red raspberries. As a result of this study, bacterial efficiency was found to be variable and depended on the bacterial strains and evaluated growth parameters. Plant growth-promoting rhizobacteria (PGPR) has improved macro- and micro-nutrient concentrations in grapevine leaves, and stimulated plant growth. Triple inoculation and single inoculation based bio fertilizers were found to stimulate overall plant growth, including shoot and leaf weight, main shoot length, leaf ground index, chlorophyll, nitrogen, zinc and iron content of grapevine cv ‘Italy’. Bio-fertilizers increased the nutrients such as nitrogen, zinc and iron concentrations and consequently increased the chlorophyll content of the leaves.     

不同改良剂对旱地苹果园壤土团聚体和水分的影响

为对比研究植物根际促生菌(枯草芽孢杆菌、胶质芽孢杆菌)和苹果树枝生物炭的施加对黄土丘陵区山地苹果园粉质壤土团聚体含量、稳定性以及土壤水分的影响,采用田间定位试验,设置4个处理:施加65 t/hm²生物炭(BC)、20 t/hm²枯草芽孢杆菌(PGBS)、20 t/hm²胶质芽孢杆菌(PGBM)和对照(CK)。湿筛法获得土壤各粒径团聚体含量,并计算水稳性团聚体的平均重量直径(MWD)、几何平均直径(GMD)和分形维数(D)。结果表明:BC、PGBS和PGBM处理有机碳含量(SOC)较CK提升18.04%~206.91%,全氮(TN)含量较CK提升6.11%~66.56%。分析表明,BC、PGBS和PGBM处理0—60 cm土层>0.25 mm团聚体含量显著增加;各处理分形维数D较CK均降低,MWD、GMD均高于对照CK,大小顺序为PGBS>PGBM>BC,施加改良剂可以增加土壤团聚体的稳定性。各处理0—60 cm土层土壤饱和导水率和土壤含水量均得到提升。施加生物炭和植物根际促生菌可以显著提升土壤有机碳和全氮含量,增强土壤结构稳定性,提升土壤含水量,生物炭处理对于土壤有机碳和全氮含量的提升优于植物根际促生菌,但植物根际促生菌施用对土壤结构稳定性的提升更佳。     

不同播期对华北地区二月兰生长及养分吸收的影响

通过小区试验研究了华北地区不同播期对二月兰(Orychophragmus violaceus)生长发育、养分吸收和产量的影响。结果表明,播期推迟会造成二月兰的出苗数、越冬数、养分累积量和产量下降,以9月14日播种为最高,其鲜草产量达到20 925 kg/hm2,氮、磷、钾累积量分别达到51.59、6.95和93.44 kg/hm2,种子产量达到667 kg/hm2;但植株的氮、磷含量有随播期推迟而上升的趋势。播期推迟会导致二月兰生育期延迟,表现为收获时二月兰秸秆和种子的含水量增加。本试验条件下,综合考虑二月兰在华北地区的最适播期为9月14日。     

Azoarcus sp. strain KH32C affects rice plant growth and the root-associated soil bacterial community in low nitrogen input paddy fields

ABSTRACT

Excessive input of nitrogen fertilizer causes nitrogen pollution in aquatic environments. Utilizing microbial inoculants seems to be effective in decreasing the extent of nitrogen fertilizer application. Genome sequencing analysis of Azoarcus sp. strain KH32C, which was isolated from a paddy-upland rotation paddy field in Japan, showed that the strain may interact with plants. In this study, we examined the effect of inoculation of rice seeds with strain KH32C as a bacterial inoculant in paddy fields without nitrogen fertilization. Rice of three cultivars inoculated with strain KH32C were cultivated in paddy fields with different soil carbon and nitrogen levels. We investigated the growth rate of rice plants and the elemental composition of brown rice. In addition, the bacterial community structures in the rice root-associated soil were examined using molecular genetic analysis. KH32C inoculation resulted in an increase in the rice plant growth rate in the early growth phase with cultivar Nipponbare. Elemental composition analysis showed that the zinc concentration in brown rice of Nipponbare was increased by KH32C inoculation. KH32C inoculation affected the bacterial community in Nipponbare root-associated soil. The community of potential plant growth-promoting bacteria, the majority of which were in the class Alphaproteobacteria, had relatively high abundance in the early growth stage after KH32C inoculation. Our results indicated that strain KH32C can be utilized as a bacterial inoculant with the effect of promoting rice growth and enhancing the zinc content of rice grains in low nitrogen input paddy fields.     

含ACC脱氨酶活性的复合菌株提高苜蓿抗盐碱能力研究

为探究含ACC脱氨酶活性的复合菌株对盐碱胁迫下紫花苜蓿的促生效果,以3株含ACC脱氨酶活性的植物根际促生菌拜式不动杆菌Y-2(Acinetobacter beijerinckii)、粘质沙雷氏菌BC-3(Serratia marcescens)和产气肠杆菌CE-1(Enterobacter aerogenes)为供试菌株,通过菌株拮抗反应测试,筛选可以混合使用的菌株,测定单菌株和复合菌株的耐盐碱特性和促生特性,并进行盐碱土盆栽试验,评价其对紫花苜蓿的促生效果。结果表明,复合菌株Y-2+CE-1和BC-3+CE-1间无拮抗反应,可以混合使用,在p H值为10和盐浓度为7%的条件下生长良好。单菌株和复合菌株均具有ACC脱氨酶活性、分泌植物生长素(IAA)能力和溶磷能力,且复合菌株的促生特性优于单菌株。此外,接种单菌株和复合菌株均能不同程度地促进紫花苜蓿的生长,其中复合菌株Y-2+CE-1和BC-3+CE-1促生效果显著,与对照相比,株高、根长、地上干重、根干重分别提高20.3%和20%、51.4%和45.9%、47%和36.4%、68.8%和52%,且促生效果优于单菌株。可见,含ACC脱氨酶活性的复合菌株能缓解盐碱胁迫,对紫花苜蓿具有明显的促生效果。本研究结果为研制复合菌肥,治理和利用盐碱地奠定了理论基础。     

玉米根际高效固氮菌Sphingomonas sp. GD542的分离鉴定及接种效果初步研究

固氮微生物菌种选育是固氮微生物肥料生产应用的基础。本研究从玉米根际土壤分离到1株高效固氮菌株GD542,菌体短杆状,0.4μm×1.0～1.5μm,革兰氏阴性;固氮酶活性为5.046nmol(C2H4)·h-1·mg-1(蛋白);利用碳源较广泛,抗逆性较强,既可在4℃低温生长,也可以在37℃下生长,耐盐性高达10%。16SrDNA序列分析结果表明,该菌株与鞘氨醇单孢菌Sphingomonas azotifigens的16SrDNA序列有高达96%的同源性,结合形态特征和生理生化特征等,将其初步鉴定为鞘氨醇单孢菌Sphingomonas sp.。接种小白菜的温室盆栽试验表明,菌株GD542具有很好的固氮效能,与无氮对照相比,接种GD542处理植株干重增加206%,含氮量增加230%,达到统计学显著差异水平,开发应用前景较好。