中度嗜盐或耐盐放线菌生长对阴离子选择性研究*

长期以来Cl^-被作为主要阴离子来分离和培养中度嗜盐放线菌,但是盐湖中还含有NO3^-、SO4^2-、CO3^2-和HCO3^-等阴离子。培养基中只加入含有Cl^-的盐,不能完全模拟出自然界的环境,因此对中度嗜盐或耐盐放线菌的研究会有一定的限制。实验通过研究部分中度嗜盐或耐盐放线菌菌株生长对阴离子的选择影响,结果发现中度嗜盐或耐盐放线菌对部分阴离子如NO3^-和SO4^2-没有太大的选择性,Cl^-可以被NO3^-和SO4^2-所代替;但有些阴离子如CO3^2-和HCO3^-仅对拟诺卡氏菌属(Nocardiopsis)影响较小,对盐碱环境中的其他属的放线菌,如普氏菌属(Prauserella)、链单孢菌属(Streptomonospora)、糖单孢菌属(Saccharomonospora)等影响较大。     

嗜盐放线菌生物学特性初步研究*

通过对从新疆,青海等地采集的盐碱土样中分离获得的43株嗜盐或耐盐放线菌以及4株典型菌株的NaCl耐受实验,对不同浓度的Na^ ,K^ ,Mg^2 ,Ca^2 的选择性实验及pH耐受实验进行了研究。发现耐盐放线菌对Na^ ,K^ ,Mg^2 有广泛的适应性,只有少数耐盐放线菌能在较低浓度的CaCl2条件下生长;嗜盐放线菌对Na^ 有广泛的适应性,多数嗜盐放线菌生长所需的Na^ 可被K^ ,Mg^2 所替代,而不能被Ca^ 所替代,少数嗜盐放线菌的生长离不开Na^ ,对Na^ 有高度的专一性,是专嗜Na^ 的嗜盐放线菌,说明不同嗜盐放线菌对Na^ ,K^ ,Mg^2 ,Ca^2 的适应有选择性。因此,提出自然环境中是否也存在类似的专嗜K^ 或专嗜Mg^2 的嗜盐放线菌的推测。无论是嗜盐还是耐盐放线菌其pH生长范围都在6．0～10之间,生长最适pH7．0～8．0。另外,嗜盐放线菌的分布与分离地点也有一定的相关性。     

酸性和碱性土壤新分离的放线菌中线型和环型质粒的检测

从湖南、云南采集的19份酸性土壤样品分离到50株放线菌,在pH4.5和pH7.0的培养基上都能生长.从新疆、青海、云南的14份碱性土壤样品中分离到38株放线菌,在pH10.0和pH7.0的培养基上均能生长.因此,这些菌株属于中度嗜酸或中度嗜碱放线菌.利用脉冲电泳技术和普通凝胶电泳在其中12株放线菌中检测到线型质粒,其中3株放线菌中检测到环型质粒.这是首次在中度嗜酸和中度嗜碱的放线菌中报道线型和环型质粒.     

青海盐碱环境中具抗肿瘤活性放线菌的筛选和多样性研究

从我国青海省采集盐碱土样或泥样,用添加1.0~3.0mol/L NaCl的GPY琼脂培养基和ISP2琼脂培养基分离到145株典型放线菌菌株。采用6种肿瘤细胞株对分离菌株的发酵产物进行体外筛选,得到26株抗肿瘤活性阳性菌株(17.9%),19株为拟诺卡氏属(Nocardiopsis)菌株,7株为链霉菌属(Streptomyces)菌株。在抗肿瘤活性、形态特征、生理生化特性和全细胞水解物氨基酸组分分析等实验结果的基础上,选取差异较大的8株抗肿瘤活性阳性菌株进行16S rRNA基因序列测定和系统发育多样性分析。结果表明,2株属于链霉菌属(Streptomyces)的1个已知物种和1个潜在新种;6株属于拟诺卡氏菌属(Nocardiopsis),可能代表该属的4个新种。研究表明青海盐碱环境中存在产生抗肿瘤活性物质的重要放线菌资源,也提示其中蕴藏着较丰富的微生物多样性。     

美洲大蠊肠道耐热碱性蛋白酶产生菌筛选及其酶特性

昆虫肠道菌是重要的微生物资源.为拓展微生物酶资源菌种来源,本研究以含Na2 CO3和脱脂奶粉的培养基从美洲大蠊Periplaneta americana(L.)肠道中筛选产碱性蛋白酶的嗜碱细菌,进行形态学和16S rDNA序列鉴定,并分析温度、pH和Na2 CO3对菌株生长的影响;采用福林-酚法和SDS-PAGE酶谱法...     

新疆泥火山产酶嗜盐放线菌的筛选及多样性

[目的]了解新疆乌苏泥火山嗜盐放线菌及其产酶功能多样性.[方法]分别采用含有5%与10%NaCl的5种分离培养基,稀释平板涂布法对泥火山土壤样品进行分离;利用五种筛选培养基定性检测酶活性;在形态特征、耐盐性实验及16S rDNA基因测序的基础上进行系统发育学分析.[结果]获得嗜盐放线菌43株,极端嗜盐放线菌3株.4株嗜盐放线菌产脂肪酶,30株产半乳糖苷酶,27株产淀粉酶,6株产酯酶,4株产纤维素酶,1株同时产4种酶.系统发育学分析结果表明其中24株为拟诺卡氏菌属(Nocardiopsis),1株为链霉菌属(Streptomyces).产两种酶的菌株10006与Nocardiopsis exhalans(AY03600)相似性为96.64%(小于97%),可能是潜在的新种.[结论]本研究表明新疆乌苏泥火山中存在大量的产半乳糖苷酶及淀粉酶的嗜盐放线菌,所分离到的拟诺卡氏菌属产酶多样性比较高,并且潜藏着新的微生物资源.     

一株产碱极端嗜盐杆菌

从青海省大柴旦盐湖中分离到一株极端嗜盐杆菌。该菌株在培养过程中产碱,革兰氏阴性,细胞杆状,0．7-1.0×2-3μm,极生鞭毛运动,绝对好氧,以氨基酸作唯一碳源。不利用碳水化合物,生长所需盐(NaCl)浓度在1 2％以上,最适盐浓度为l 8％。生长pH范围6-l0,最适pH9。MgSO4·7H2Oo-3％对生长无明显影响。细胞蛋白质酸性,不含二氨莲庚二酸和胞壁酸,含甘油二醚键化合物,不具有色素。根据以上特征,将该菌株定为一个新种,定名为产碱嗜盐杆菌(Halobocierium haloalcaligenum n.sp.)。     

不同盐处理对玉米幼苗根系质子分泌及细胞膜透性的影响

以玉米品种郑单958为实验材料,分别用100 mmol/L NaCl、100 mmol/L KCl和50 mmol/L Na2CO3处理其幼苗3 d,研究不同盐类对玉米根系质子分泌和细胞膜透性的影响.结果表明:不同盐处理都显著抑制玉米幼苗根系的生长,抑制程度依次为Na2CO3>KCl>NaCl;不同盐处理均使玉米幼苗根系Na 含量显著增加,NaCl和Na2CO3处理显著降低根系K 含量而导致其Na /K 升高,但KCl处理却显著提高根系K 含量使其Na /K 降低;不同盐处理均能显著增加细胞膜透性而降低根系质子分泌能力,影响程度依次为Na2CO3>KCl>NaCl.研究发现,相同阳离子浓度条件下,KCl处理对玉米根系质子分泌的抑制作用强于NaCl,碱性盐的抑制作用大于中性盐;盐胁迫可能通过改变玉米幼苗根系质膜的稳定性来影响质子分泌,从而抑制根系生长.     

新疆塔里木盆地可培养嗜盐放线菌系统发育多样性

应用纯培养手段和基于16S rRNA基因序列的系统发育分析,对从塔里木盆地高盐环境土壤样品中分离的18株可培养嗜盐放线菌多样性进行了研究.实验结果表明,18株嗜盐放线菌可3个(GlycomycetaceaePseudonocardineae和Nocardiopsaceae),在有效发表的5个属的嗜盐放线菌中有4个属的嗜盐放线菌被分离到.多数菌株属于Actinopolyspora属(38.9%),Nocardiopsis属(27.8%)和Streptomonospora属(22.2%),是塔里木盆地高盐环境中嗜盐放线菌的优势类群.这些分离菌株中,菌株YIM 92370与最近种的相似性为92%,在Glycomycetaceae科内形成一个独立的分支,极有可能代表Glycomycetaceae科的一个新属.研究结果表明塔里木盆地高盐环境中存在有较为丰富的嗜盐放线菌系统发育多样性,并且潜藏着新类型的放线菌资源.     

松嫩平原碱化草甸朝鲜碱茅、獐茅耐盐碱特性的比较研究

本研究通过野外调查与室内实验相结合的方法,从生态学、生理学方面探讨了松嫩平原碱化草甸朝鲜碱茅和獐毛耐盐碱的特性,结果表明：两种植物均生长在含盐、潮湿而贫瘠的土壤上,朝鲜碱茅分布地段的土壤多含碱性盐(Na2CO3)。而獐毛所在地的土壤则多含中性盐(NaCl),这些体现出它们对盐碱适应性的差异。不同浓度的NaCl、Na2CO3胁迫对这两种植物的细胞膜透性、游离脯氨酸含量有明显影响。均以logistic曲线y=k/(1+ea-bx)或直线方程：y=a+bx形式较好地表达出来。说明朝鲜碱茅对NaCl的胁迫敏感,獐毛则对Na2CO3的胁迫敏感。两种植物在自然条件下的生态适应与实验条件下的生理适应相近。     

The Schizosaccharomyces pombe Pzh1 protein phosphatase regulates Na+ ion influx in a Trk1-independent fashion.

We have previously shown that fission yeast encodes a PPZ-like phosphatase, designated Pzhl, which is an important determinant of cation homeostasis. pzh1 delta mutants display increased tolerance to Na+ ions, but they are hypersensitive to KC1 [Balcells, L., Gómez, N., Casamayor, A., Clotet, J. & Ari?o, J. (1997) Eur. J. Biochem. 250, 476-483]. We have immunodetected Pzh1 in yeast extracts and found that this phosphatase is largely associated with particulate fractions. Cells defective in Pzh1 do not show altered efflux of Na+ or Li+ ions, but they accumulate these cations more slowly than wild-type cells. K+ ion content of pzh1 delta cells is about twice that of wild-type cells, and this can be explained by decreased efflux of K+. Therefore, Pzh1 may regulate both Na+ influx and K+ efflux in fission yeast. To test the possible relationship between K+ uptake, Na+ tolerance and Pzh1 function, we deleted the trk1+ gene, which encodes a putative high-affinity transporter of K+ ions. trkl delta mutants grew well even at relatively low concentrations of KCl and did not show significantly altered content or influx of K+ ions. However, they showed a Na(+)-sensitive phenotype which was greatly intensified by deletion of the sod2+ gene (which encodes the major determinant for efflux of Na+ ions), and clearly ameliorated by deletion of the pzh1 phosphatase, as well as by moderate concentrations of KCl in the medium. These results suggest that Trk1 does not mediate the effect of Pzh1 on NaCl tolerance and that fission yeast contains efficient systems, other than Trk1, for uptake of K+ ions.     

等渗NaCL和KCL胁迫对高梁幼苗生长和气体交换的影响

本文比较研究了等渗NaCl和KCl胁迫下,高粱幼苗生长及叶片离子含量、质膜相对透性和有关气体交换参数的变化。结果表明,在低浓度NaCl和KCl胁迫7天时,高粱生长、含水量和质膜相对透性与对照相比没有明显变化,而净光合速率、蒸腾速率和气孔导度已明显下降,叶肉细胞间隙CO2浓度明显增加。NaCl胁迫下叶片Na+含量成倍增加,而K+和Ca2+含量无明显变化。KCl胁迫时叶片K+含量明显增加,Ca2+含量明显下降,而Na+含量没有明显变化。随着NaCl或KCl浓度的增加,幼苗生长和叶片含水量明显下降,质膜透性和细胞间隙CO2浓度明显增加,净光合速率、蒸腾速率和气孔导度进一步下降。 NaCl胁迫下叶片Na+含量进一步增加,K+和Ca2+进一步下降,而KCl胁迫下叶片K+含量进一步 增加,Na+和Ca2+含量进一步下降。KCl对高粱生长抑制、质膜透性、Ca2+含量下降及光合气体交换参数的影响均明显大于等渗的NaCl。     

等渗NaCl和KCl胁迫对高粱幼苗生长和气体交换的影响

本文比较研究了等渗ＮａＣｌ和ＫＣｌ胁迫下,高粱幼苗生长及叶片离子含量、质膜相对透性和有关气体交换参数的变化。结果表明,在低浓度ＮａＣｌ和ＫＣｌ胁迫７天时,高粱生长、含水量和质膜相对透性与对照相比没有明显变化,而净光合速率、蒸腾速率和气孔导度已明显下降,叶肉细胞间隙ＣＯ２浓度明显增加。ＮａＣｌ胁迫下叶片Ｎａ＋含量成倍增加,而Ｋ＋和Ｃａ２＋含量无明显变化。ＫＣｌ胁迫时叶片Ｋ＋含量明显增加,Ｃａ２＋含量明显下降,而Ｎａ＋含量没有明显变化。随着ＮａＣｌ或ＫＣｌ浓度的增加,幼苗生长和叶片含水量明显下降,质膜透性和细胞间隙ＣＯ２浓度明显增加,净光合速率、蒸腾速率和气孔导度进一步下降。ＮａＣｌ胁迫下叶片Ｎａ＋含量进一步增加,Ｋ＋和Ｃａ２＋进一步下降,而ＫＣｌ胁迫下叶片Ｋ＋含量进一步增加,Ｎａ＋和Ｃａ２＋含量进一步下降。ＫＣｌ对高粱生长抑制、质膜透性、Ｃａ２＋含量下降及光合气体交换参数的影响均明显大于等渗的ＮａＣｌ。     

NaCl胁迫对小麦幼苗生长、叶绿素含量及Na^＋、K^＋吸收的影响

对宁夏地区种植的几个春小麦品种和国内外引进的抗盐小麦材料的幼苗进行不同浓度NaCl胁迫处理,结果表明：NaCl胁迫对小麦幼苗地上部生长抑制显著,而对地下部生长影响较小;NaCl胁迫对小麦幼苗的胁迫主要是离子伤害,而渗透胁迫不明显;随NaCl浓度的增加,叶绿素含量显著下降,同时植株中Na^ 含量增加,K^ 含量下降,K^ /Na^ 降低;不同品种对不同浓度NaCl的胁迫反应不同。     

Bioenergetic properties of alkalophilic Bacillus sp. strain C-59 on an alkaline medium containing K2CO3.

Alkalophilic Bacillus sp. strain C-59 could grow well on an alkaline medium containing K2CO3, as well as Na2CO3, but did not grow on K+-depleted medium. Right-side-out membrane vesicles, energized in the absence of Na+, however, could not take up [14C]methylamine actively, while vesicles equilibrated with 10 mM NaCl actively took up [14C]methylamine. The uptake of [14C]serine was also stimulated by the addition of Na+, and the imposition of a sodium gradient caused transient uptake. These results indicated that an Na+/H+ antiporter was involved in pH homeostasis and generation of an electrochemical sodium gradient in strain C-59 even though a growth requirement for Na+ was not evident. The efflux of 22Na+ from 22Na+-loaded vesicles was more rapid at pH 9.5 than at pH 7 in the presence of an electron donor. On the other hand, vesicles at pH 7 showed more rapid efflux than at pH 9.5 when the antiporter was energized by a valinomycin-mediated K+ diffusion potential (inside negative).     

Protein phosphatase type 2B (calcineurin)-mediated, FK506-sensitive regulation of intracellular ions in yeast is an important determinant for adaptation to high salt stress conditions.

To assess the physiological function of Ca(2+)-dependent protein phosphatase (PP2B) in the yeast Saccharomyces cerevisiae, the phenotypes of PP2B-deficient mutants were investigated. Although PP2B was dispensable for growth under normal conditions, the mutations did, however, cause growth inhibition under certain stress circumstances. The growth of the mutants was inhibited by NaCl and LiCl, but not by KCl, CaCl2, MgCl2 or nonspecific osmotic stresses. Upon shift to high NaCl medium, intracellular Na+ levels of both wild type yeast and the mutants initially increased at a comparable rate. However, internal Na+ in wild type cells started to decline more rapidly than the mutant cells during cultivation in high NaCl medium, indicating that PP2B is important in maintaining a gradient across the membrane. The protection against salt stress was achieved, at least in part, by the stimulation of Na+ export. The maintenance of a high level of internal K+ in high NaCl medium was also PP2B-dependent. In the presence of the immunosuppressant FK506, the growth behaviour and intracellular Na+ and K+ of wild type cells in high NaCl medium became very similar to those of the PP2B-deficient mutant in a manner dependent on the presence of the FK506 binding protein.     

Relationship between xylem ion concentration and bean growth responses to short-term salinisation in spring and summer

Bean plants, Phaseolus vulgaris L. cv. Contender, were grown in the spring and summer seasons to study the relationship between xylem Na+/Cl-, transpiration rate, and salt tolerance. Eight-day-old seedlings were transplanted to 50% modified Hoagland solution with 1 mM NaCl. Four days after transfer, one of two treatments was applied: a control of 1 mM NaCl or a treatment of 25 mM NaCl every two days to reach a final treatment concentration of 75 mM NaCl. Plants were sampled on the fourth day after the final salt concentration was reached, eight days after the salinisation treatment began. Relative growth rate was 2.6-fold greater in summer than in spring. However, while no differences were found between treatments in spring, summer salt-treated plants had growth rates that were 31% lower than those of controls. In summer, CO2 assimilation, stomatal conductance, and transpiration rate of salinised plants declined with respect to controls. Leaf Na+ and trifoliolate leaf Cl- were higher in salt-treated plants in summer, although root Na+ was significantly higher in spring. Moreover, in summer salinity inhibited Ca2+ and K+ uptake and changed its distribution. Summer salt-treated plants had an average of 17-fold higher xylem Na+ during the daily cycle, while xylem Cl-, only in the afternoon, showed higher values (1.5-fold) compared to spring-grown plants. Our results suggest that the faster growth response to salt in summer-grown bean was at least partly due to an increase in xylem Na+ independent of the transpiration rate and possibly related to an increase in xylem Na+ influx or/and Na+ recirculation.