鸭茅根际溶磷菌溶磷性和分泌植物生长素能力的研究

从鸭茅根际不同部位分离具有溶磷能力的菌株,通过溶磷圈法筛选出9株溶磷能力较强的菌株进行深入研究。利用钼蓝比色法测定其溶磷能力。结果表明：磷酸钙为磷源时溶磷量在109.47～270.40μg/mL,磷酸铝为磷源时溶磷量在0.00～25.86μg/mL。以磷酸钙为磷源进行动态研究,2次测定的溶磷量不同,测定最佳时间为9～12d。菌株分泌IAA测定结果显示,大部分菌株具有分泌IAA能力,加前体物质色氨酸时菌株分泌IAA能力较未加时大,菌株Da11、Da15在无前体物质条件下分泌IAA量分别达到10.60、10.69μg/mL。综合菌株的溶磷、分泌IAA,认为Da8、Da11、Da15、Da19和Da20等5个菌株具有较大的应用潜力。     

溶磷菌溶磷和分泌IAA特性及对苜蓿生长的影响

植物根际溶磷菌不仅可以提高植物对土壤磷素的利用率,同时可以促进根瘤菌的结瘤和固氮作用。利用液体培养法对5株溶磷菌的溶磷特性和分泌IAA能力进行研究,并通过盆栽试验研究接种溶磷菌对苜蓿(MedicagosativaL.)生长的影响。结果表明:各供试菌株溶磷能力差异较大,溶磷能力最强的是LM18(300.3 mg/mL);菌株都有分泌IAA特性,最大分泌量为17.95μg/mL(LM12)。接种溶磷菌后苜蓿株高、茎粗、干重、干鲜比和叶茎比都比对照明显增加。因此,溶磷能力和分泌IAA能力较强的菌株(LM12和LM18)可作为研制微生物肥料的优良菌株。     

甜高粱根际溶磷菌溶磷能力及菌株特性研究

利用蒙金娜培养基,从甜高粱根际分离具有溶磷能力的菌株,通过溶磷圈法筛选出5株溶磷能力较强的菌株,利用钼锑抗比色法和Salkowski比色法分别对溶磷特性与分泌IAA能力进行测定,结果表明,筛选的菌株分解磷酸钙的能力存在显著差异,溶磷量在107.26~233.95 μg/mL之间,各菌株均具有分泌IAA能力,IAA分泌量在15.23~27.79 μg/mL之间,接种溶磷菌后甜高粱株高、茎粗、干重都比对照明显提升。因此, 溶磷能力和分泌IAA能力较强的菌株(WD₅₁、WD₂₀) 可作为研制微生物肥料的优良菌株。     

三叶草根际溶磷菌溶磷及分泌IAA能力测定

为了获得优良的菌株资源,采用溶磷圈法、钼锑抗比色法和Spot、S2比色法,定性、定量测定了分离自三叶草根际10株溶磷细菌的溶磷和分泌植物生长激素(IAA)的能力,结果表明:各菌株在PKO无机磷培养液中的有效磷增量在106.63～666.01mg/L(P<0.05),菌株ls1-3有效磷增量最大;各菌株在蒙金娜有机磷培养液中的有效磷增量在0.32～58.42mg/L(P<0.05),菌株lhs11有效磷增量最大;有些菌株既能溶解无机磷,又能溶解有机磷,如菌株lhs4和lhs11;有些菌株能溶解无机磷,但无溶解有机磷的能力,如菌株ls1-3和ls1-5。除3个菌株(ls2-11、ls2-16和ls3-2)外,其他菌株都能分泌IAA,分泌量在0.36～20.39mg/L(P<0.05),菌株ls3-5分泌能力最强(20.39μg/mL)。菌株ls1-3、ls2-3、ls3-5、lhs4和lhs11有望作为研制微生物肥料的优良菌株。     

地八角根际溶磷菌溶磷能力及菌株特性研究

采用PKO无机培养基,从地八角根际分离具有溶磷能力的菌株,通过溶磷圈法筛选出7株解磷能力较强的菌株进行深入研究。利用钼蓝比色法对菌株在液体培养条件下的溶磷能力进行测定,结果表明:筛选的菌株分解磷酸钙的能力差异不大,溶磷量在123.37～135.23μg/mL之间,各菌株的溶磷量与分泌有机酸量、培养介质pH值之间均不存在显著相关性;各菌株均具有分泌IAA能力,大多数菌落呈淡黄色或乳白色、不规则、不透明、扁平、无色素;除1株菌表现为中性外,其他6株表现为产碱性;所有菌株在以甘露醇、蔗糖、1/2甘露醇+1/2蔗糖、葡萄糖、木糖、麦芽糖取代蛋白胨的碳源培养基上均生长良好。其中,DBR2菌株经16SrDNA序列分析,初步鉴定为肠杆菌。     

高寒草地优势植物根际细菌促生特性及初步鉴定

筛选获得能促进高寒草地退化植被生长的优良耐低温植物根际促生细菌(PGPR)，能够丰富高寒草地优良菌株资源库。本研究以前期分离的18株细菌菌株为研究对象，采用乙炔还原法、钼锑抗比色法、Salkowski比色法和平板对峙法分别检测了18株菌株的固氮、溶磷、分泌植物生长激素(IAA)和抑制植物病原真菌的能力。结果表明：有14株菌均具有固氮、溶磷、分泌IAA特性，其中固氮酶活性为25.43～230.52nmol·(h·mL)^-1，溶有机磷量为66.90～115.06μg·mL^-1，溶无机磷量为9.22～380.28μg·mL^-1，分泌IAA量为12.45～71.71μg·mL^-1。其中2株菌编号为LMG2、LMJ2拮抗病原菌锐顶镰孢菌(Gibberella acuminata)效果显著，对其抑制率分别为30.75%和31.00%。综合比较各菌株特性，筛选出6株优良PGPR进行16S rRNA基因序列比对分析以确定其分类地位。经鉴定：菌株LMG2和LMJ2菌株与Pseudomonas piscium P50<...     

贵州黄壤地区葛藤根际溶磷细菌溶磷、分泌IAA及其它特性研究

从葛藤(Pueraria lobata)根际分离出8株具有较强溶解无机磷能力的菌株,溶磷圈法测定菌株的HD/CD值(溶磷圈直径HD,菌落直径CD)在2.14～6.73,液体振荡培养下菌株对磷酸钙的溶解量在72.28～159.15mg/L,菌株培养液pH值较初始培养基的pH值7.0均下降。菌株GTR2和GTR15溶解磷酸钙(分别为159.15mg/L、138.72mg/L)及分泌IAA能力(分别为12.71mg/L、14.44mg/L)均较大,且均为碱性菌株,能在甘露醇等多种碳源上较好生长。综合各菌株的溶磷及分泌IAA能力,菌株GTR2和GTR15有望成为高效微生物磷肥接种剂的优良菌种。     

高寒地区燕麦根际联合固氮菌研究Ⅱ固氮菌的溶磷性和分泌植物生长素特性测定

对分离自高寒地区燕麦根际的8株联合固氮菌株溶磷性和分泌植物生长素特性进行了测定,结果表明,菌株Azotobacter sp.ChO4、Azotobacter sp.ChO5和Azospirillus lipoferum ChO6具有溶磷能力,但溶磷强度差异较大 (83.8～103.5 μg/mL),Azospirillus lipoferum ChO6溶磷能力较Azotobacter sp.ChO5和Azotobacter sp.ChO4强;8株菌株均具有分泌植物生长素特性,但能力差异较大 (2.16～17.31 μg/mL),只有Pseudomonas sp.ChO3和Azospirillus lipoferum ChO6分泌IAA的浓度较高(大于10 μg/mL).研究认为,菌株Pseudomonas sp.ChO3、Azotobacter sp.ChO4、Azotobacter sp.ChO5、Azospirillus lipoferum ChO6和Azospirillus brasilense ChO8等在燕麦菌肥研制方面具有较大的开发潜力.     

欧李(Cerasus humilis)内生固氮细菌筛选、鉴定及特性研究

为探究荒漠草原灌木欧李(Cerasus humilis)根系内生细菌固氮能力和其它特性。采用无氮培养基,从欧李根内分离获得20株内生固氮菌,并结合乙炔还原法测定固氮酶活性,钼锑抗比色法测定溶磷特性,Salkowski法测定分泌植物生长素(Indole acetic acid,IAA)能力,对筛选出固氮酶活性较高的菌株进行16S rDNA序列比对,确定其分类地位。结果表明,分离的内生固氮细菌均具溶磷和分泌IAA能力。所分离菌株固氮酶活性在31.45~424.81 nmol C₂H₄·h^-1·mL^-1之间(NS 25最高),解有机磷量在26.62~99.18 μg·mL^-1之间(YNS 4最高),溶无机磷量在1.10~20.31 μg·mL^-1之间(WNS 21最高),分泌IAA量在3.86~47.00 μg·mL^-1之间(NS 22最高)。10株固氮酶活性较高菌株经初步鉴定NS1 14-1和NS1 14-2为Bacillus pumilus,NS 25和NS 26为Bacillus paralicheniformis,YNS 1为Brevibacterium frigoritolerans,菌株WNS 21和NNS 15为Bacillus velezensis,NS 8为Paenibacillus catalpae,YNS 6为Cytobacillus firmus,NNS 19为Bacillus sp.。研究分离的内生固氮细菌具有溶磷和分泌IAA的能力,有望通过后续研制微生物菌剂为干旱地区植被恢复与生态重建发挥积极作用。     

联合固氮菌株分泌能力及其对燕麦的促生效应测定

测定了分离自草坪草和燕麦根际的固氮菌株的分泌植物生长素(IAA)能力及其对燕麦的促生效应。结果表明:11株固氮菌都能分泌IAA,其中加前体(色氨酸)浓度在2.16~22.3μg/mL的有9株浓度大于10μg/mL;不加前体浓度在0.81~13.8μg/mL的有6株浓度大于10μg/mL,有6株能够溶解有机磷,3株能够溶解无机磷,且溶磷强度在58~82μg/mL,1株既能溶解有机磷,又能溶解无机磷;试管试验中除了2株效果比对照差外,其他9株株高增加62.8%~142.8%、叶绿素增加2.78%~63.89%、地上植物量增加21.45%~150.48%、地下植物量增加2.04%~70.75%、总根长增加2.27%~41.27%、根表面积增加11.32%~84.9%;另外I017和I012两个菌株分泌激素能力较好,I016菌株综合能力较好。     

6株溶磷菌和4株固氮菌混合培养条件的研究

对6株溶磷菌和4株固氮菌混合培养,选择最适培养条件即温度,pH和盐分,为确定促生菌的最佳发酵条件和生态适应性评价提供依据。结果表明：溶磷菌和固氮菌单独培养或混合培养最适温度在25-35℃,混合培养较单独培养生长良好;溶磷菌和固氮菌单独培养或混合培养最适pH为6．5～7．5,在pH7．5～8．5偏碱性环境下,混合培养生长...     

饲料中无机磷和有机磷的测定方法

用分光光度法测定了饲料中的总磷、无机磷、有机磷的含量,将饲料样品处理成溶液,在酸性条件下,磷酸根离子与矾钼酸铵试剂形成黄色配合物,在420nm处测定吸光度,方法操作简便、快速、准确,回收率为97.4%～101.8%。     

溶磷菌在5种不同培养基中溶解磷矿粉的性能比较

通过小麦、苜蓿根际分离的4株溶磷菌(Lx81、Dm84、Jm92、Lx191)接种于PKO、SP、NBRIY、NBRIP、NBRIYP等5种培养基中测定菌落直径、溶磷圈大小、培养液有效磷含量、pH值及总有机酸含量的方法,研究溶磷菌在不同培养基上的生长情况和溶磷特性。结果表明:Lx81和Lx191在PKO培养基上的菌落直径最大,Dm84和Jm92在NBRIY培养基上的菌落直径最大;4菌株在NBRIP培养基中的溶磷量、总有机酸含量、pH下降值均显著高于其他培养基中的值。为了得到更多、更有效的溶磷菌株,在以后的工作中建议采用NBRIP培养基。     

乳白香青内生解磷菌的筛选鉴定及解磷特性研究

选择东祁连山高寒草地优势植物乳白香青为试验材料,分离和筛选内生解磷细菌,并对筛选的解磷细菌进行了鉴定,在此基础上,研究了其对玉米的促生作用。结果表明,从乳白香青植株中分离到4株内生解磷菌,解磷量(P₂O₅)为65.24～315.36 mg/L,其中菌株RA8的解磷能力最高;经形态特征、生理生化特性和16S rDNA 序列系统发育学分析,初步鉴定RA8为副球菌属细菌;RA8代谢产酸,但解磷能力与培养液的pH值之间无相关性,产生的非酸类代谢物质是其解磷的主要机制;RA8可以与土壤中的土著微生物互惠协作,增强RA8的解磷能力;经RA8处理的玉米在第70天和第100天生物量显著高于对照(P<0.05),第100天株高极显著高于对照(P<0.01),即RA8对玉米的生长有明显的促进作用。     

不同供磷水平对胡麻磷素养分转运分配及其磷肥效率的影响简

 以“坝选３号”胡麻为材料，研究了不施磷、低磷、中磷和高磷４ 个不同施磷（Ｐ_２Ｏ_５）水平（０，３５，７０ 和１０５ｋｇ／ｈｍ^２）对胡麻植株中磷素累积、转运、分配和磷肥利用效率的影响。结果表明，低磷、中磷和高磷水平时，胡麻各器官不同生育阶段磷素养分吸收和累积量的基本趋势一致，但其变化量与施磷量有极大关系。胡麻地上茎、叶、非籽粒和籽粒中，磷素的日增量增幅因器官而异；胡麻只有叶片中有磷素转移，中磷处理比低磷和高磷处理磷转移量增加５４．９３％～７３．８３％和８．１９％～１０．００％（P＜０．０５），籽粒中２０．４６％～３５．９３％ 的磷素是靠叶片转运而来。胡麻植株磷素累积主要在生殖生长阶段，占整个生育期总累积量的７９．０２％～９２．１７％。施磷（Ｐ_２Ｏ_５）量为７０ｋｇ／ｈｍ^２时磷肥表观利用率和农学效率最高，分别为２０．２２％～２０．５３％和７．３０～７．４４ｋｇ／ｋｇ。胡麻产量随施磷量增加而增加，增幅最高达２８．９６％～３１．４６％。结合产量与磷肥表观利用率和农学效率，本实验区同等肥力土壤条件下，以施磷（Ｐ_２Ｏ_５）量为７０ｋｇ／ｈｍ^２（中磷）为宜。     

江苏省部分桑园土壤溶磷菌的分布

针对江苏省内１１个不同地区的桑园土壤，分０ｃｍ～２０ｃｍ、２０ｃｍ－４０ｃｍ两个土层，分析了好氧的卵磷脂分解菌和磷酸钙分解菌的分布，同时分析与溶磷菌生长关系密切的土壤有机质和磷素含量。结果表明，好氧生长的卵磷脂分解菌和磷酸钙分解菌在各桑园的分布数量有较大差异，土壤溶磷菌总量在各桑园的分布顺序为无锡西漳＞海安双余＞镇江小牛山＞镇江石马＞金坛登冠＞宿豫＞如皋＞徐州＞江都曹王＞睢宁桃园镇＞射阳特庸；上层土样中菌含量明显高于下层土样，能分解卵磷脂和磷酸钙的菌类包含细菌、放线菌和真菌。     

The course of phosphorus excretion in growing pigs fed continuously increasing phosphorus concentrations after a phosphorus depletion.

A balance study was performed in order to quantify the effect of continuously increased phosphorus (P) intake on faecal and urinary P excretion. The aim was to quantify the level of intake where regulatory P excretion becomes relevant for comparative digestibility measurements on P, and when the pig adapts its urinary P excretion to increased P intake. Phosphorus intake of growing pigs was continuously increased on a daily basis starting at a marginal level and P excretion via faeces and urine was continuously followed for 92 days. Two semi-synthetic diets were prepared with different proportions of Na2HPO4 resulting in 2.4 (diet 1) and 6.3 (diet 2) g P/kg DM. Concentration of Ca was adapted to achieve a Ca supply approximately 3.1 fold the digestible P supply. Six castrated male crossbred pigs (31 kg BW) were kept individually in metabolism crates after they had undergone a 14 d P depletion period during which they were fed diet 1 solely. Pigs received 1.04kg of diet 1 per day throughout the experiment, and each day the amount of feed and P supplied to pigs from diet 2 was increased by 12 g and 69 mg, respectively. ME supply was approximately 2.4 fold maintenance and average daily BW gain of pigs during the entire experiment was 690 +/- 30 g. While intake increased linearly, faecal excretion of P and Ca increased non-linearly and could be best described by third order polynomial functions. The proportion of ingested P not excreted via faeces followed a quadratic type of curve with a maximum of 81% at 25 days on experiment and P intake of 4.0 g/d. Thereafter, the proportion decreased continuously. The digestibility of P from diet 2, determined by the slope ratio technique, was constant and not affected by P intake up to a P intake of 5 g/d. Renal P excretion did not exceed inevitable losses until day 60 and increased exponentially thereafter when body P reserves were restored. It is concluded, that an adaptation to surplus P supply occurred earlier on the intestinal than on the renal level. While faecal P excretion appeared regulated depending on the actual requirement for P retention, the regulation via urine depended on the P status of the pig. Once the renal P excretion of growing pigs exceeds a level of 25 mg/d, intake of digestible P cannot be regarded sufficiently low to measure P digestibility as a capacity of the feedstuff.     

Relative bioavailability of phosphorus in inorganic phosphorus sources fed to growing pigs

The relative bioavailability of P in 5 sources of inorganic P was determined using growing pigs. The 5 sources of inorganic P were dicalcium phosphate (DCP), monocalcium phosphate (MCP) containing 50% MCP (MCP50), MCP containing 70% MCP (MCP70), MCP containing 100% MCP (MCP100), and monosodium phosphate (MSP). A total of 11 diets were formulated. The basal diet was formulated to contain 0.10% P, and 10 additional diets were formulated by adding 0.07 or 0.14% P from each of the 5 P sources to the basal diet. Growing pigs (n = 44; initial BW: 16.8 ± 4.3 kg) were individually housed and randomly allotted to the 11 experimental diets. Feed was provided on an ad libitum basis throughout the 28-d experimental period. At the conclusion of the experiment, all pigs were killed, and 4 bones (i.e., the third and fourth metacarpals on both front feet) were harvested. Bone-breaking strength, bone ash, and Ca and P concentrations were determined. The concentration of bone ash increased (P < 0.05) as MCP50, MCP70, MCP100, or MSP were added to the basal diet, and the concentration of bone P also increased (P < 0.05) as MCP70, MCP100, or MSP were added to the basal diet. The relative bioavailability of P in each of the feed phosphates was determined using slope ratio methodologies based on breaking strength, and expressed relative to MSP. The slope of the regression line for diets containing MSP or MCP100 was steeper (P < 0.05) than the slope for pigs fed the diet containing DCP, but not different (P > 0.05) from that of pigs fed diets supplemented with MCP50 or MCP70. In conclusion, P in MSP and MCP100 is more bioavailable than P in DCP, but there were no differences within MCP sources.