Evidence for limited species diversity of bacteriochlorophyll b-containing purple nonsulfur anoxygenic phototrophs in freshwater habitats

Thirteen new isolates of bacteriochlorophyll b-containing purple nonsulfur bacteria were isolated from four freshwater habitats using specific enrichment methods including the use of long wavelength filters and extincting dilution of the inoculum. The new isolates were compared with the type strain of Blastochloris viridis, strain DSM 133(T), as regards pigments, morphology, carbon nutrition, and phylogeny. All new isolates were budding bacteria, and phototrophic mass cultures were green, brown, or brown-green in color. The pattern of carbon sources photocatabolized were similar in all strains; however, sugars, both mono- and disaccharides, were widely used by the new isolates while they did not support growth of strain DSM 133(T). Phylogenetic analysis showed all new strains to cluster tightly with the type strain with the exception of one brown-colored strain and a mildly thermophilic strain. The results suggest that in contrast to purple nonsulfur bacteria containing bacteriochlorophyll a, those containing bacteriochlorophyll b may not be morphologically or phylogenetically diverse, and group into a tight phylogenetic clade distinct from all other anoxygenic phototrophs.     

Immunobiological properties of new unencapsulated <Emphasis Type="Italic">Bacillus anthracis</Emphasis> 363/11 strain

The results of a study on the immunobiological properties of a new, naturally attenuated, unencapsulated Bacillus anthracis 363/11 strain in comparison with the properties of the anthrax vaccine strain 55-VNIIVVIM, which is currently used in Russia and post-Soviet states, are presented in the article. Some differences in the phenotypes of the aforementioned strains are shown. The new strain caused lysis of sheep erythrocytes by α- but not by β-type; the strain had many more active proteinases and synthesized protocatechuic acid (PCA), in contrast to the vaccine strain. It was ascertained that immunization of animals by the new strain protects them from death after infection by field isolates of B. anthracis, while the 55-VNIIVVIM strain does not create this immunity. The data indicate that the new strain can be used to develop and improve anthrax prevention.     

Peptidoglycan compositions of a new strain of Arthrobacter crystallopietes during sphere-rod morphogenesis.

Arthrobacter crystallopoieties ATCC 15481 was used to isolate a new strain. designated Arthrobacter crystallopoieties EPSR-16, which had a mass doubling time in brain heart infusion broth and in glucose/salts/yeast extract medium of 30 min compared to 2.40 h for the parent strain in similar media. The growth rates for the new strain and for the parent were close to 12 h in glucose/salts medium. The new strain formed well-separated cocci and diplococci in glucose/salts medium, and upon nutrient shift-up all the cells in the population gradually changed into well-separated rods of regular shape. In the spherical state the cell wall peptidoglycan of the new strain contained lysine and no diaminopimelic acid. A gradual loss in lysine and a gain in diaminopimelic acid occurred during morphogenesis. Diaminopimelic acid became predominant in the cell wall during balanced growth in the rod state.     

一株烟酸羟基化转化菌株的筛选和鉴定

从南京地区的土壤中筛选到一株高效转化烟酸为 6_羟基烟酸的菌株NA_1。形态及生理生化特征测定结果表明 ,NA_1菌株与假单胞菌属 (Pseudomonas)中的恶臭假单胞菌 (P .putida)种的特征基本一致。测定了该菌株的16SrDNA序列并根据 16SrDNA构建了系统发育树 ;在系统发育树中 ,NA_1菌株与恶臭假单胞菌形成一个类群 ,序列同源性为 99%。因此将NA_1菌株鉴定为恶臭假单胞菌     

DM423菌株诱变前后对吡哌酸的耐药性测定

为了研制一种对腹泻病人疗效快,又不造成菌群失调的药物。我们确定吡哌酸与DM423菌联合应用。首先把DM423菌株诱变成耐药菌株,经多次诱变筛选结果是,耐药量比原菌株提高了2000倍,耐药性相对稳定,耐药株生物学特性与原菌株相同。定名为DM423-1菌株。     

Peptidoglycan compositions of a new strain of Arthrobacter crystallopoietes during sphere-rod morphogenesis

Arthrobacter crystallopoieties ATCC 15481 was used to isolate a new strain, designated Arthrobacter crystallopoieties EPSR-16, which had a mass doubling time in brain heart infusion broth and in glucose/salts/yeasts extract medium of 30 min compared to 2.40 h for the parent strain in similar media. The growth rates for the new strain and for the parent were close to 12 h in glucose/salts medium. The new strain formed well-separated cocci and diplococci in glucose/salts medium, and upon nutrient shift-up all the cells in the population gradually changed into well-separated rods of regular shape. In the spherical state the cell wall peptidoglycan of the new strain contained lysine and no diaminopimelic acid. A gradual loss in lysine and a gain in diaminopimelic acid occurred during morphogenesis. Diaminopimelic acid became predominant in the cell wall during balanced growth in the rod state.     

Development of new strains and related SCAR markers for an edible mushroom, Hypsizygus marmoreus

New fast-growing and less bitter varieties of Hypsizygus marmoreus were developed by crossing monokaryotic mycelia from a commercial strain (Hm1-1) and a wild strain (Hm3-10). Six of the better tasting new strains with a shorter cultivation period were selected from 400 crosses in a large-scale cultivation experiment. We attempted to develop sequence characterized amplified region (SCAR) markers to identify the new strain from other commercial strains. For the SCAR markers, we conducted molecular genetic analysis on a wild strain and the eight most cultivated H. marmoreus strains collected from various areas in East Asia by randomly amplified polymorphic DNA. Ten unique DNA bands for a commercial Hm1-1 strain and the Hm3-10 strain were extracted and their sequences were determined. Primer sets were designed based on the determined sequences. PCR reactions with the primer sets revealed that four primer sets successfully discriminated the new strains from other commercial strains and are thus suitable for commercial purposes.     

Mycoplasma simbae sp. nov., Mycoplasma leopharyngis sp. nov., and Mycoplasma leocaptivus sp. nov., isolated from lions.

Mycoplasmas isolated from the throats of lions were shown to belong to three serotypes, all of which were serologically distinct from the previously recognized Mycoplasma and Acholeplasma spp. Eight mycoplasma colonies were cloned, including one from a leopard (strain LP), and were examined in detail for morphology, growth, and biochemical characteristics. The strains had the following properties: guanine-plus-cytosine contents of 37 mol% (strain LXT [T = type strain]), 28 mol% (strain LL2T), and 27 mol% (strain 3L2T) and a requirement for sterol. Strain 3L2T metabolized glucose, which was not metabolized by strains LXT and LL2T. Arginine and urea were not hydrolyzed. Strain LX (= NCTC 11724) is the type strain of a new species, Mycoplasma simbae; strain LL2 (= NCTC 11725) is the type strain of a second new species, Mycoplasma leopharyngis; and strain 3L2 (= NCTC 11726) is the type strain of a third new species, Mycoplasma leocaptivus.     

Theoretical considerations of cross-immunity, recombination and the evolution of new parasitic strains.

We explore the dynamics of multiple strains of a parasite in order to assess the conditions under which a novel strain, perhaps a mutant or migrant, may invade a population that already carries an endemic strain. Multiple strain dynamics can be modeled through coinfection or complete cross-immunity. We examine these three modes to discuss the relationships among cross-immunity, the basic reproductive rates of each strain, and the invasion of the new strain. Superinfection is more restrictive than coinfection in the proportion of parameters that allows invasion. The coinfection model is extended to allow haploid strains to undergo recombination within the host. We investigate the effects of recombination and cross-immunity on the invasion of new strains. Interestingly, although recombination is understood to generate diversity, it is not always advantageous.     

Effects of a hexokinase II deletion on the dynamics of glycolysis in continuous cultures of Saccharomyces cerevisiae

In glucose-limited aerobic chemostat cultures of a wild-type Saccharomyces cerevisiae and a derived hxk2 null strain, metabolic fluxes were identical. However, the concentrations of intracellular metabolites, especially fructose 1,6-bisphosphate, and hexose-phosphorylating activities differed. Interestingly, the hxk2 null strain showed a higher maximal growth rate and higher Crabtree threshold dilution rate, revealing a higher oxidative capacity for this strain. After a pulse of glucose, aerobic glucose-limited cultures of wild-type S. cerevisiae displayed an overshoot in the intracellular concentrations of glucose 6-phosphate, fructose 6-phosphate, and fructose 1,6-bisphosphate before a new steady state was established, in contrast to the hxk2 null strain which reached a new steady state without overshoot of these metabolites. At low dilution rates the overshoot of intracellular metabolites in the wild-type strain coincided with the immediate production of ethanol after the glucose pulse. In contrast, in the hxk2 null strain the production of ethanol started gradually. However, in spite of the initial differences in ethanol production and dynamic behaviour of the intracellular metabolites, the steady-state fluxes after transition from glucose limitation to glucose excess were not significantly different in the wild-type strain and the hxk2 null strain at any dilution rate.     

A new combination of O- and K-antigens of a Vibrio parahaemolyticus strain isolated from a patient with diarrhea

Vibrio parahaemolyticus strain 10260 was isolated from a patient with diarrhea. Biochemical and serological characters of the strain were analyzed. This strain possessed a new combination of O- and K-antigens. From the results of this study, the serotype of V. parahaemolyticus strain 10260 was proposed as O1:K20.     

A new marine microorganism strain L0804: taxonomy and characterization of active compounds from its metabolite

A new streptomyces strain designated L0804, producing antimicrobial substances, was isolated from marine mud in Qiangang, Jiangsu province, China. On the basis of cellular morphology, physiological and chemotaxonomic characterization and phylogenetic similarity of 16S rDNA gene sequences, the strain L0804 was identified as Streptomyces roseogilvus var. marine. However, the phylogenetic analysis indicated that strain L0804 represents a distinct phyletic line suggesting a new genomic species. Two antimicrobial compounds were isolated and purified from the strain L0804 culture broth using various separation procedures. The two active compounds were elucidated by HPLC, UV–VIS, IR and NMR spectroscopy. One was a mixture of at least three compounds belonging to alkaloids homologue, the other was griseoviridin. The antimicrobial activity and cytotoxicity of the two active compounds were compared. The results showed that strain L0804 was a new potential marine microorganism producing griseoviridin. Simultaneously, strain L0804 can also produce valuable substance of alkaloids homologue.     

Evidence of species succession during chlorobenzene biodegradation

We have previously reported the disappearance of a specific strain degrading chlorobenzene from a functionally stable bioreactor. In the present work, we investigated this species succession and isolated a new dominant strain, identified as Pandoraea pnomenusa sp. strain MCB032. A specific 16S rRNA-targeted oligonucleotide probe was designed and validated to identify strain MCB032 using fluorescence in situ hybridisation (FISH). The results confirmed the presence of strain MCB032 in samples collected over time, and showed that it was primarily located within the biofilm. Denaturing gradient gel electrophoresis (DGGE) provided evidence that the species succession occurred early in the operating period. The application of these biomolecular tools highlighted the remarkable stability of this new strain during the 15 months of reactor operation. The succession was attributed to the competitive kinetic behaviour of strain MCB032, which exhibited faster growth (micro(max) = 0.34 h(-1)) and higher substrate affinity (K(s) = 0.35 mg L(-1)) than strain JS150. Finally, this study contributed to the characterisation of the recently established Pandoraea genus, an emerging group in the biodegradation field.     

Development of a system of plasmid transfer in the strains Streptomyces avermitilis ATCC 31272 and Saccharopolyspora erythraea ATCC 11635 by the method of intergeneric conjugation

A new method of plasmid DNA transfer from the donor strain Escherichia coli S17-1 to the erythomycin-producing strain Saccharopolyspora erythraea and avermectin-producing strain Streptomyces avermitilis via intergeneric conjugation was proposed. The optimal parameters of the method were chosen for increasing the efficiency of crosses and ensuring easily reproducible results. The behavior of the multicopy plasmid pPM803 and the integration vector pTO1 along with a number of new plasmids specially created by us, was examined in these strains. A new plasmid vector (pSI60) capable of integrating into the chromosome of actinomycetes at the integration site of the temperate actinophage phi C31 was constructed. This vector possesses unique sites convenient for cloning and may be stably maintained in exconjugants of S. avermitilis and in the model strain Streptomyces lividans. The gene encoding resistance to spectinomycin and streptomycin was cloned into the vector pSI60 in this strain. For cloning in strain Sac. erythraea, vectors pSI261-280, which integrate into the chromosome via homology with the cloned DNA and can be stably maintained in exconjugants, were constructed.     

Evolutionary Invasion and Escape in the Presence of Deleterious Mutations

Replicators such as parasites invading a new host species, species invading a new ecological niche, or cancer cells invading a new tissue often must mutate to adapt to a new environment. It is often argued that a higher mutation rate will favor evolutionary invasion and escape from extinction. However, most mutations are deleterious, and even lethal. We study the probability that the lineage will survive and invade successfully as a function of the mutation rate when both the initial strain and an adaptive mutant strain are threatened by lethal mutations. We show that mutations are beneficial, i.e. a non-zero mutation rate increases survival compared to the limit of no mutations, if in the no-mutation limit the survival probability of the initial strain is smaller than the average survival probability of the strains which are one mutation away. The mutation rate that maximizes survival depends on the characteristics of both the initial strain and the adaptive mutant, but if one strain is closer to the threshold governing survival then its properties will have greater influence. These conclusions are robust for more realistic or mechanistic depictions of the fitness landscapes such as a more detailed viral life history, or non-lethal deleterious mutations.     

一株产右旋糖酐酶青霉的分离及酶的纯化和性质

[目的]从土壤中筛选到一株新的产右旋糖酐酶的真菌F1001,为酶法制备药用级右旋糖酐提供新的右旋糖酐酶产生菌株.[方法]通过形态特征和ITS rDNA序列分析方法鉴定菌株.利用硫酸铵盐析、Sepharose 6B凝胶柱纯化,得到纯度较高的酶蛋白.以右旋糖酐70 kDa为底物,对右旋糖酐酶酶学性质及催化机理进行研究.[结...     

Construction of a Stable alpha-Galactosidase-Producing Baker's Yeast Strain

Molasses is widely used as a substrate for commercial yeast production. The complete hydrolysis of raffinose, which is present in beet molasses, by Saccharomyces strains requires the secretion of alpha-galactosidase, in addition to the secretion of invertase. Raffinose is not completely utilized by commercially available yeast strains used for baking, which are Mel. In this study we integrated the yeast MEL1 gene, which codes for alpha-galactosidase, into a commercial mel baker's yeast strain. The Mel phenotype of the new strain was stable. The MEL1 gene was expressed when the new Mel baker's yeast was grown in molasses medium under conditions similar to those used for baker's yeast production at commercial factories. The alpha-galactosidase produced by this novel baker's yeast strain hydrolyzed all the melibiose that normally accumulates in the growth medium. As a consequence, additional carbohydrate was available to the yeasts for growth. The new strain also produced considerably more alpha-galactosidase than did a wild-type Mel strain and may prove useful for commercial production of alpha-galactosidase.     

Flexibacter japonensis sp. nov., a New Species That Produces a Novel Inhibitor of Human Leukocyte Elastase Isolated from Soil

This strain 758 of a new member of Flexibacter species isolated from a soil is a Gram-negative, nonflagellated, gliding, long rod or filamentous. The GC contents of the deoxyribonucleic acid of this strain is 49.8 mol %GC. The isolate can be distinguished from other Flexibacter species on the basis of physiological and biochemical properties and DNA relatedness data. Therefore, we propose a new species, Flexibacter japonensis, for this strain. The strain 758 is deposited to the Japan Collection of Microorganisms as JCM 9735. Received: 27 November 1995 / Accepted: 30 January 1996     

Taxonomy and chemical characterization of antibiotics of Streptosporangium Sg 10 isolated from a Saharan soil

A new actinomycete strain designated Sg 10, producing antimicrobial substances was isolated from an Algerian soil. Morphological and chemical studies indicated that strain Sg 10 belonged to the genus Streptosporangium. The comparison of its physiological characteristics with those of known species of Streptosporangium showed significant differences with the nearest species Streptosporangium carneum. Analysis of the 16S rDNA sequence of strain Sg 10 showed a similarity level ranging between 96.3% and 97.8% within Streptosporangium species, with S. carneum the most closely related. However, the phylogenetic analysis indicated that strain Sg 10 represent a distinct phyletic line suggesting a new genomic species. The antimicrobial activity of strain Sg 10 showed an antibacterial activity against Gram-positive bacteria as well as an antifungal one. Four active products were isolated from the culture broth using various separation procedures. On the basis of UV-VIS spectrometry, infrared spectroscopy and chemical revelations, the antibiotics were classified in the group of glycosylated aromatics.     

Bioinformatic analysis of structural proteins of paramyxovirus Tianjin strain

The amino acid sequences of the NP,P, M, F,HN and L proteins of the paramyxovirus Tianjin strain were analyzed by using the bioinformatics methods. Phylogenetic analysis based on 6 structural proteins among the Tianjin strain and 25 paramyxoviruses showed that the Tianjin strain belonged to the genus Respirovirus, in the subfamily Paramyxovirinae, and was most closely related to Sendal virus (SeV). Phylogenetic analysis with 14 known SeVs showed that Tianjin strain represented a new evolutionary lineage. Similarities comparisons indicated that Tianjin strain P protein was poorly conserved, sharing only 78.7%-91.9% amino acid identity with the known SeVs, while the L protein was the most conserved, having 96.0%-98.0% amino acid identity with the known SeVs. Alignments of amino acid sequences of 6 structural proteins clearly showed that Tianjin strain possessed many unique amino acid substitutions in their protein sequences, 15 in NP, 29 in P, 6 in M, 13 in F, 18 in HN, and 29 in L. These results revealed that Tianjin strain was most likely a new genotype of SeV. The presence of unique amino acid substitutions suggests that Tianjin strain maybe has a significant difference in biological, pathological, immunological, or epidemiological characteristics from the known SeVs.