Mutants of Saccharomycopsis lipolytica defective in lysine catabolism.

Wild-type strains of Saccharomycopsis lipolytica are able to use lysine as a carbon or a nitrogen source, but not as a unique source for both. Mutants were selected that could not use lysine either as a nitrogen or as a carbon source. Some of them, however, utilized N-6-acetyllysine or 5-aminovaleric acid. Many of the mutants appeared to be blocked in both utilizations, suggesting a unique pathway for lysine degradation (either as a carbon or as a nitrogen source). Genetic characterization of these mutants was achieved by complementation and recombination tests.     

工业废水中阿特拉津降解细菌的遗传和生理多样性

【目的】通过遗传学和生理学实验,揭示分离自工业废水的阿特拉津降解细菌具有遗传和生理多样性,为阐明阿特拉津生物降解的分子机理和阿特拉津降解细菌在污染环境生物修复中的应用提供新见解。【方法】用普通PCR方法检测菌株的阿特拉津降解基因,分析其降解基因组成;用基因组重复序列PCR技术(rep-PCR)分析降解菌株的基因组类型;用Western blot方法检测菌株阿特拉津降解途径的第一个酶三嗪水解酶(TrzN);用不同氮源(阿特拉津、莠灭净、扑草净、西玛津、氰草净、阿特拉通和氰尿酸)和碳源(蔗糖、葡萄糖、麦芽糖、乳糖、柠檬酸钠、乙酸钠和琥珀酸钠)培养降解菌株,通过检测培养液的OD600值,证明菌株能够利用的氮源和碳源种类。【结果】对分离自工业废水的27个阿特拉津降解菌株所进行的阿特拉津降解基因PCR检测表明,其降解基因组成分别为trzN-atzBC、trzN-atzABC和atzADEF;通过rep-PCR实验将27个阿特拉津降解菌株分为7个群;Western blot结果表明,27个菌株中有24个含有三嗪水解酶TrzN;氮源利用实验表明,2个菌株能够利用所有7种氮源生长,其余25个菌株只能利用其中的2-6种;碳源利用实验表明,10个菌株能够利用所有7种碳源生长,其余17个菌株只能利用其中的3-6种。【结论】分离自某工业废水的27株阿特拉津降解功能菌存在相当广泛的遗传和生理学上的多样性,trzN-atzABC降解基因组成为首次发现。     

四株昭通乌天麻共生蜜环菌的生理生化特征及其分子鉴定

目的对4株昭通乌天麻(Gastrodia elata)共生蜜环菌(Armillaria mella)的生理生化活性进行研究,并鉴定其分类地位。方法通过测定不同碳源和氮源对蜜环菌生长以及胞外酶活性的影响,掌握该蜜环菌生理生化特性,再结合rDNA-IGS序列分析方法进行鉴定。结果不同蜜环菌需要不同的碳源、氮源。3种胞外酶中木聚糖酶活性最大,其次是羧甲基纤维素酶,漆酶活性最小。供试蜜环菌与云南、贵州地区天麻共生蜜环菌以及猪苓共生蜜环菌的亲缘关系比较远。结论蜜环菌能否作为天麻共生菌与其分类地位无关。     

Phenotypic characterization of the archaebacterial genus Sulfolobus: comparison of five wild-type strains.

Though amenable to routine manipulation and a popular subject of molecular genetic and biochemical studies on archaebacteria, the genus Sulfolobus has remained poorly described in phenotypic terms. To delineate their physiological capabilities and diversity, five laboratory strains, including type strains of the described species Sulfolobus acidocaldarius and S. solfataricus, were compared with respect to a variety of growth and biochemical parameters, including component profile of the surface-layer cell wall, inhibitors of growth, growth rate as a function of temperature and pH, and compounds used as sole sources of carbon or nitrogen. Motility and photoregulated production of an orange pigment were detected in all five strains tested. The results provide new criteria for distinguishing Sulfolobus strains as well as potential tools for the physiological and genetic manipulation of these extreme thermophiles.     

西北部分地区苦马豆根瘤菌的表型多样性研究

将采集自甘肃、新疆、宁夏等地区的苦马豆根瘤,经分离、纯化获得48株未知菌株,并选取7株参比菌株,进行唯一碳、氮源利用、对抗生素及染料抗性、耐盐性、初始pH生长、生长温度范围及酶活性等共113项生理生化测定;采用数值分类方法对未知根瘤菌进行表型多样性分析。结果表明：供试菌株在碳氮源利用、抗生素敏感性、抗逆性等方面存在着差异。该地区苦马豆根瘤菌具有较强的耐盐、耐碱能力,所有菌株均能在初始pH9~12的YMA培养基上生长,35%菌株可耐受6%的NaCl。从数值分类树状图可见,未知供试菌株在56%的相似水平上聚在一起,在72%的相似水平上分为5个表观群。群Ⅰ有39株菌,在74.6%相似水平聚合,中心菌株为CCNWGS0215;群Ⅱ有5株菌,在76%的相似水平聚合,中心菌株为CCNWGS0228;群Ⅳ有2株菌,在81.5%的相似水平聚合,群Ⅲ和群Ⅴ分别只有1株菌,它们与模式株分离,可能为潜在的新种。     

Plasmids specifying ε-caprolactam degradation in Pseudomonas strains

Abstract The large plasmid DNAs were found in several strains of Pseudomonas sp. capable of growing on ε-caprolactam as a sole source of carbon and nitrogen. The ability to grow on ε-caprolactam and ε-aminocaproic acid as sole sources of carbon or nitrogen and adipic acid as a sole source of carbon could be transferred in interspecies crosses. All transconjugants harboured corresponding large plasmid DNAs. It was suggested that the discovered plasmids possessed the genetic material controlling several consecutive reactions of ε-caprolactam catabolism yielding acetate and succinate.     

Utilization of γ-Aminobutyric Acid as the Sole Carbon and Nitrogen Source by Escherichia coli K-12 Mutants

Wild-type strains of Escherichia coli K-12 cannot grow in media with gamma-aminobutyrate (GABA) as the sole source of carbon or nitrogen. Mutants were isolated which could utilize GABA as the sole source of nitrogen. These mutants were found to have six- to ninefold higher activities of gamma-aminobutyrate-alpha-ketoglutarate transaminase (EC 2.6.1.19) and succinate semialdehyde dehydrogenase (EC 1.2.1.16) than those of the wild-type parent strains. Secondary mutants derived from these GABA-nitrogen-utilizing strains were able to grow on GABA as the sole source of carbon and nitrogen. They also grew faster on a variety of other carbon and nitrogen sources, and their growth was more strongly inhibited by different metabolic inhibitors than was that of the parent strains. The nature of the two mutations and the possible genes involved are discussed. A scheme of the pathway for GABA breakdown in E. coli K-12 is presented.     

Use of the A-2 elective medium for the differentiation of Aeromonas from related microorganisms]

The trial of culture medium A-2, proposed for the identification of Aeromonas on the basis of the nutritional utilization of gelatin as the only source of nitrogen and starch as the source of carbon in view of the limited content of mineral components in the medium, revealed that no other species of the family Vibronaceae grew in this medium, and it could be used in an additional test for the differentiation of vibrios from Aeromonas. A group of strains isolated from human feces, surface water and sewage was found to be incapable of growing in culture medium A-2; these strains, though having a number of characteristics in common with Aeromonas, differed from them in a number of additional tests.     

Genetic analysis of a region of the Rhizobium meliloti pSym plasmid specifying catabolism of trigonelline, a secondary metabolite present in legumes.

Genes controlling the catabolism of trigonelline, a secondary metabolite that is often present in legumes, are located on the pSym megaplasmid of Rhizobium meliloti. To investigate the role of bacterial trigonelline catabolism in the Rhizobium-legume symbiosis, we identified and characterized the R. meliloti RCR2011 genetic loci (trc) controlling trigonelline catabolism. Tn5-B20 mutagenesis showed that the trc region is a continuous DNA segment of 9 kb located 4 kb downstream of the nifAB and fdxN genes. Trc mutants fell into two classes according to their phenotype and location: (i) mutants carrying Tn5-B20 insertions in the right-hand part of the trc region were incapable of growing on trigonelline as the sole carbon and/or nitrogen source, and (ii) insertions in the left-hand part of the trc region resulted in delayed growth on trigonelline as the sole carbon and/or nitrogen source. No significant defect in nodule formation or nitrogen fixation was detected for mutants of either class. Screening of a set of R. meliloti strains from various geographical origins showed that all of these strains are able to catabolize trigonelline and show sequence homology between their megaplasmids and a trc probe.     

新疆不同来源金黄壳囊孢的多样性

为明确新疆不同寄主及地理来源的金黄壳囊孢(Cytospora chrysosperma)的多样性, 探讨种内亲缘关系和多样性差异。作者通过记录菌株在PDA培养基上的菌落颜色、形状、子实体形态等特征, 并应用Biolog-FF技术及ISSR分子标记技术, 比较了来自新疆5个地区5种寄主上的47株金黄壳囊孢的培养特征、生理生化特征及遗传多样性。结果表明47株金黄壳囊孢依据培养特征可划分为15种类型。不同类型菌株在碳源利用及代谢能力上存在差异, 各菌株对碳源的利用数量随着培养时间的增长逐渐增多。菌株882利用的碳源数量最多, 培养120 h可利用28种不同碳源, 碳源代谢能力中等; 菌株812-1利用的碳源数量最少, 培养120 h仅利用7种碳源, 代谢能力较低; 菌株1074-2、847、934、891-1、896、740具有单独利用碳源的能力。基于遗传相似性系数进行聚类分析, 结果显示遗传相似性系数为0.58时, 47个菌株被划分为两大类群, 其中第二类群菌株的培养特征为: 菌落白色、子实体较小且分布密集。供试金黄壳囊孢的多样性主要受自身遗传结构的影响, 不同寄主种类和地理来源对多样性的影响不显著。     

Utilization of carbon and nitrogen sources and acid/alkali production by cowpea rhizobia

Summary Sixteen slow-growing strains of rhizobia (15 cowpea rhizobia and oneR. japonicum) were examined to determine the effects of carbon and nitrogen sources on acid/alkali production in culture media. We found that the pH changes of the medium were more influenced by nitrogen sources than carbon sources (with the exception of ribose). When ammonium sulphate was used as a nitrogen source, all the cowpea rhizobia strains produced acid. When yeast-extract was used as a nitrogen source, however, a heterogenous pattern for acid/alkali production was found. The majority of the strains produced alkali from nitrate, glutamate and urea irrespective of carbon sources and acid from ribose irrespective of nitrogen sources.     

Trichosporon porosum comb. nov., an anamorphic basidiomycetous yeast inhabiting soil,related to the loubieri/laibachii group of species that assimilate hemicelluloses and phenolic compounds

Several isolates representing the genus Trichosporon were collected over a 6-year period from soils in The Netherlands. Based on classical growth tests with carbon and nitrogen compounds these were identical. Three of these (CBS 8396, CBS 8397 and CBS 8522) were subjected to molecular analysis of the D1/D2 region of the large subunit of rDNA. This confirmed that the three strains were identical, yet distinct from other members of the genus. Conspecificity was demonstrated with the type strain (CBS 2040) of Apiotrichum porosum Stautz (1931), with the exception that A. porosum, which had been isolated from exudate of a yew tree, differed morphologically from the soil strains. Based on the identity of DNA base sequences, morphology was not considered to be an adequate parameter to separate otherwise identical strains into two genera. Therefore, the new combination Trichosporon porosum is presented. Based on molecular sequence analysis, T. porosum may be related to T. sporotrichoides, within a weakly related clade that includes species such as Trichosporon laibachii and Trichosporon loubieri. The strains of T. porosum degrade phenolic compounds and hemicelluloses, which are characteristics with potential ecological importance in soil habitats. Characters distinguishing the nine species of the laibachii/loubieri group of species were listed. These include traditionally used tests as well as assimilation patterns of some aliphatic and phenolic compounds. Based on these tests, species such as Trichosporon multisporum and T. laibachii could be separated.     

A comprehensive synthesis unveils the mysteries of phosphate-solubilizing microbes

Phosphate-solubilizing microbes (PSMs) drive the biogeochemical cycling of phosphorus (P) and hold promise for sustainable agriculture. However, their global distribution, overall diversity and application potential remain unknown. Here, we present the first synthesis of their biogeography, diversity and utility, employing data from 399 papers published between 1981 and 2017, the results of a nationwide field survey in China consisting of 367 soil samples, and a genetic analysis of 12986 genome-sequenced prokaryotic strains. We show that at continental to global scales, the population density of PSMs in environmental samples is correlated with total P rather than pH. Remarkably, positive relationships exist between the population density of soil PSMs and available P, nitrate-nitrogen and dissolved organic carbon in soil, reflecting functional couplings between PSMs and microbes driving biogeochemical cycles of nitrogen and carbon. More than 2704 strains affiliated with at least nine archaeal, 88 fungal and 336 bacterial species were reported as PSMs. Only 2.59% of these strains have been tested for their efficiencies in improving crop growth or yield under field conditions, providing evidence that PSMs are more likely to exert positive effects on wheat growing in alkaline P-deficient soils. Our systematic genetic analysis reveals five promising PSM genera deserving much more attention.     

白腐真菌染料脱色菌株的筛选及一色齿毛菌脱色条件的研究

以平皿培养方式对采集自中国和芬兰的白腐真菌菌株降解6种不同结构的人工染料的能力进行了筛选研究。在40株菌株中,黑管孔菌Bjerkandera adusta Y5012,一色齿毛菌Cerrena unicolor Y5002,硬毛粗盖孔菌Funalia trogii Y4997,香栓孔菌Trametes suaveolens D8325和云芝栓孔菌Trametes versicolor Y4946对刚果红、橙黄G、茜素红、结晶紫、中性红和亚甲基蓝均显示出较强的脱色能力。对一色齿毛菌Cerrena unicolor Y5002的液体培养脱色条件进行了研究,其最适碳源和氮源分别为蔗糖和麦芽浸粉;在不同橙黄G浓度下均获得较高的脱色率,因此浓度为500mg/L的橙黄G未对该菌的脱色能力产生抑制作用,而浓度为400mg/L茜素红则对其脱色作用产生明显抑制。对菌丝生物量和染料脱色率的研究表明,在不同碳源和氮源条件下,两者之间具有明显的正相关性。     

Symbiotic competence, genetic diversity and plasmid profiles of Egyptian isolates of a Rhizobium species from Leucaena leucocephala (Lam.) Dewit

L.D. KUYKENDALL, D.M. SWELIM, F.M. HASHEM, S.M. ABDEL-WAHAB AND N.I. HEGAZI. 1996. There is considerable interest in improving nitrogen fixation in tropical legume trees to increase soil fertility, particularly in developing countries. To provide information needed for the development of improved strains, characterization of strains of Leucaena -nodulating Rhizobium was performed. Thirteen strains were isolated from root nodules of Leucaena leucocephala grown in different geographical regions in Egypt. Plasmid DNA profile groups, including identification of symbiosis-controlling plasmids, were defined. Symbiotic competence was determined in plant tests and some strains were perhaps more symbiotically proficient at fixing nitrogen with L. leucocephala than were reference strains. The genetic diversity of these strains was determined by RFLP analysis of total DNAs using, as probes, six arbitrarily selected cosmid clones from a gene library of strain TAL 1145, a well-characterized reference strain. There were four plasmid profile groups which did not correlate with either symbiotic competence or RFLP analysis. RFLP analysis, unlike plasmid profiles, permitted a determination that all 13 Egyptian strains were evidently homogeneous and quite distinct from previously studied Leucaena -nodulating Rhizobium as represented by reference strains.     

Influence of amino acids on nitrogen fixation ability and growth of Azospirillum spp

The utilization of amino acids for growth and their effects on nitrogen fixation differ greatly among the several strains of each species of Azospirillum spp. that were examined. A. brasiliense grew poorly or not at all on glutamate, aspartate, serine, or histidine as the sole nitrogen and carbon sources. Nitrogen fixation by most A. brasiliense strains was inhibited only slightly even by 10 mM concentrations of these amino acids. In contrast, A. lipoferum and A. amazonense grew very well on glutamate, aspartate, serine, or histidine as the sole nitrogen and carbon sources; nitrogen fixation, which was measured in the presence of malate or sucrose, was severely inhibited by these amino acids. It was concluded that growth on histidine as the sole source of nitrogen, carbon, and energy may be used for the taxonomic characterization of Azospirillum spp. and for the selective isolation of A. lipoferum. The different utilization of various amino acids by Azospirillum spp. may be important for their establishment in the rhizosphere and for their associative nitrogen fixation with plants. The physiological basis for the different utilization of glutamate by Azospirillum spp. was investigated further. A. brasiliense and A. lipoferum exhibited a high affinity for glutamate uptake (Km values for uptake were 8 and 40 microM, respectively); the Vmax was 6 times higher in A. lipoferum than in A. brasiliense. At high substrate concentrations (10 mM), the nonsaturable component of glutamate uptake was most active in A. lipoferum and A. amazonense.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of amino acids on nitrogen fixation ability and growth of Azospirillum spp.

The utilization of amino acids for growth and their effects on nitrogen fixation differ greatly among the several strains of each species of Azospirillum spp. that were examined. A. brasiliense grew poorly or not at all on glutamate, aspartate, serine, or histidine as the sole nitrogen and carbon sources. Nitrogen fixation by most A. brasiliense strains was inhibited only slightly even by 10 mM concentrations of these amino acids. In contrast, A. lipoferum and A. amazonense grew very well on glutamate, aspartate, serine, or histidine as the sole nitrogen and carbon sources; nitrogen fixation, which was measured in the presence of malate or sucrose, was severely inhibited by these amino acids. It was concluded that growth on histidine as the sole source of nitrogen, carbon, and energy may be used for the taxonomic characterization of Azospirillum spp. and for the selective isolation of A. lipoferum. The different utilization of various amino acids by Azospirillum spp. may be important for their establishment in the rhizosphere and for their associative nitrogen fixation with plants. The physiological basis for the different utilization of glutamate by Azospirillum spp. was investigated further. A. brasiliense and A. lipoferum exhibited a high affinity for glutamate uptake (Km values for uptake were 8 and 40 microM, respectively); the Vmax was 6 times higher in A. lipoferum than in A. brasiliense. At high substrate concentrations (10 mM), the nonsaturable component of glutamate uptake was most active in A. lipoferum and A. amazonense.(ABSTRACT TRUNCATED AT 250 WORDS)     

基于微生物同化作用的D-丙氨酸生产工艺研究

以L-丙氨酸为唯一碳氮源,从采集的若干土壤中初筛出能够降解L-丙氨酸的菌株;再以D-丙氨酸为唯一碳氮源,复筛出降解L-丙氨酸而不降解D-丙氨酸的菌株。依据菌种对DL-丙氨酸的不对称降解活性,筛选出具有最高的L-丙氨酸降解活性的菌株,并对菌株同化L-丙氨酸的反应条件进行了研究。结果表明:编号为ALA-D82的菌株具有最高的降解L-丙氨酸的能力,经鉴定为酵母菌属。在30℃,控制pH6.0,通气比1:1(V/V)和转速900 r.min-1的条件下,L-丙氨酸降解的速度最大。在最适条件下,1500 g DL-丙氨酸分两部分添加入7 L的反应液中。反应72 h后溶液中的L-丙氨酸被完全降解,提取得到D-丙氨酸晶体,产率和光学纯度分别达到92.13%和99%。     

Positive selection of antibiotic-producing soil isolates.

Stepwise discriminant analysis was used to identify the most powerful selective substrates which could be used to formulate media capable of enriching for antibiotic-producing soil isolates. This was achieved by characterizing a collection of 74 soil bacteria, including eubacteria and actinomycetes, according to their ability to produce antibacterial antibiotics and their growth responses to 43 physiological and nutritional tests. The characters which were selective for actinomycetes relative to eubacteria included growth on proline (1%, w/v) and humic acid (0.1%) as sole sources of both carbon and nitrogen, growth on nitrate as a nitrogen source, and growth at pH 7.7-8.0. Growth on proline (1%) and humic acid (0.1%) as sole carbon/nitrogen sources, growth on asparagine as a nitrogen source, and growth in the presence of vitamins were among the characteristics which allowed antibiotic-producing actinomycetes to be differentiated from non-antibiotic-producing strains. Several simple isolation media which incorporated the selective substrates identified by discriminant analysis succeeded in increasing the proportion of actinomycetes isolated from soil samples. Furthermore, the percentage of isolates capable of antibiotic production was considerably increased.     

Physiological and biochemical contributions to the taxonomy of the genus Prototheca

Prototheca zopfii (12 strains) is able to use glucose, fructose, propanol, glycerol, and acetate as sources of carbon for growth. One of the strains is biochemically (utilization also of galactose and mannose), and two strains are morphologically slightly different.Two strains can be identified as P. wikerhamii. They exhibit good growth with glucose, fructose, galactose, trehalose, propanol, glycerol, acetate, and glutamate as sources of carbon. P. spec. 263-2 grows only with glucose and acatate. P. zopfii and P. wickerhamii are able to use urea, glycine, and glutamate as sources of nitrogen. P. spec. 263-2, on the other hand, cannot utilize these organic nitrogen compounds for growth.Four strains of Chlorella protothecoides are able to use glucose, fructose, galactose, and acetate as sources of carbon for growth in the dark. Three of them utilize also mannose, trehalose, and glutamate. Two strains can grow with glycerol, and one is able to use lactose. — Urea and glycine can serve as sources of nitrogen for the four strains of C. protothecoides. Glutamate supports growth of three strains, and one strain is able to use nicotinamide.