Antigenic activity of emmonsia crescens mutants

The antigenic properties of 3 UV mutants of Emmonsia crescens Emmons et Jellison 1960 were compared with the original wild strain, further with other 13 E. crescens strains, with E. parva, E. brasiliensis, E. ciferrina and Chrysosporium pannorum.For this purpose the strains were used for the immunisation of 70 rabbits. The formation of specific IgM- and IgG-antibodies was examined in their blood by means of several serologic reactions, and the capability of sensitizing the organism was proved by means of skin tests.All strains stimulated the formation of specific antibodies and sensibilised the macroorganism but in various extent. The differences in the antigenic activity was found not only among the single species but also among the single strains of the same species.All three mutants of E. crescens induced the formation of the specific antibodies but weaker than the virulent strains. They elicited, however, stronger and better reliable skin reactions than the virulent strains.The dimorphic fungus Emmonsia crescens Emmons et Jellison 1960 a causative agent of adiaspiromycosis is variable as in the saprophytic as in the parasitic phase of the life cycle. The cultures of strains isolated from different host animals can be morphologically disparate (13). They grow at various rates and they form the adiaspores of different sizes (1, 2, 19).The mutants of E. crescens induced by UV radiation possess especially a much greater variability: they differ from the wild strain by the morphology of the colony, by the rate of the growth, by the conidiation and by the virulence (6), which is associated with the capability of conversion in the morphologically perfect adiaspores (7). The size of these adiaspores in the granulomas of the hosts is in correlation with the growth rate of the mycelial stage of the mutants in vitro (5).We were interested in the antigenic properties of E. crescens mutants. Thereupon we tried to determine the. antigenic activity of avirulent mutants as well as those with a significantly decreased virulence and compare it a) with the original wild strain, b) with the different strains of E. crescens and c) with the strains of related species: E. parva, E. brasiliensis, E. ciferrina and Chrysosporium pannorum.     

Adiaspiromycosis Due to <Emphasis Type="Italic">Emmonsia crescens</Emphasis> is Widespread in Native British Mammals

Adiaspiromycosis caused by Emmonsia crescens is primarily a respiratory disease affecting small mammals, especially members of the Families Rodentia, Carnivora and Mustelidae. Although isolated reports exist of adiaspiromycosis in free-living British wildlife, the extent of infection in wild animals in the UK, and the significance of any associated pathology are unclear. Here, we report the results of histopathological examination of lungs of free-living wild mammals from the south–west UK coupled with digestion of lung material in potassium hydroxide followed by centrifugation and microscopic examination for the presence of adiaspores. The combined results showed that almost one-third (27/94, 28.7%) of animals examined had evidence of infection with E. crescens. Attempts to culture E. crescens from infected lungs were unsuccessful. However, E. crescens could be confirmed as the causative agent by PCR amplification and sequencing of DNA from adiaspores micro-dissected from animal lungs. The prevalence of adiaspiromycosis was largely independent of animal species or precise geography. Adiaspore burdens in most animals were low, consistent with transient exposure to E. crescens. However, burdens in several animals suggested heavy or repeated exposures to E. crescens, and were considered sufficient to have significantly impaired respiratory function. Finally, since E. crescens is apparently widespread in UK mammals and the first UK human case of adiaspiromycosis was reported recently, we present data obtained using a previous isolate of E. crescens demonstrating that both the mycelial and adiaspore phases of the organism are susceptible to amphotericin B, voriconazole, itraconazole and caspofungin.     

Strain diversity and host specificity in a specialized gut symbiont of honeybees and bumblebees

Host‐restricted lineages of gut bacteria often include many closely related strains, but this fine‐scale diversity is rarely investigated. The specialized gut symbiont Snodgrassella alvi has codiversified with honeybees (Apis mellifera) and bumblebees (Bombus) for millions of years. Snodgrassella alvi strains are nearly identical for 16S rRNA gene sequences but have distinct gene repertoires potentially affecting host biology and community interactions. We examined S. alvi strain diversity within and between hosts using deep sequencing both of a single‐copy coding gene (minD) and of the V4 region of the 16S rRNA gene. We sampled workers from domestic and feral A. mellifera colonies and wild‐caught Bombus representing 14 species. Conventional analyses of community profiles, based on the V4 region of the 16S rRNA gene, failed to expose most strain variation. In contrast, the minD analysis revealed extensive strain variation within and between host species and individuals. Snodgrassella alvi strain diversity is significantly higher in A. mellifera than in Bombus, supporting the hypothesis that colony founding by swarms of workers enables retention of more diversity than colony founding by a single queen. Most Bombus individuals (72%) are dominated by a single S. alvi strain, whereas most A. mellifera (86%) possess multiple strains. No S. alvi strains are shared between A. mellifera and Bombus, indicating some host specificity. Among Bombus‐restricted strains, some are restricted to a single host species or subgenus, while others occur in multiple subgenera. Findings demonstrate that strains diversify both within and between host species and can be highly specific or relatively generalized in their host associations.     

Yeast species associated with spontaneous wine fermentation of Cabernet Sauvignon from Ningxia,China

The eastern base of the Helan Mountains in Ningxia is a fast developing wine production area in China. Of urgent necessity to the Ningxia wine industry is to be able to produce wines with typical regional characteristics. It is well known that autochthonous yeast species and strains play an important role in introducing local character or terroir into the winemaking practice. The aim of this study was to investigate indigenous yeast species diversity and preselect desirable S. cerevisiae strains in the Ningxia region. Four hundred wine-related yeast colonies were isolated from Cabernet Sauvignon musts in three vineyards at the beginning, middle and final stages of spontaneous fermentations. Yeast species were first classified according to colony morphologies on Wallerstein Laboratory Nutrient Agar (WL) and confirmed by sequencing of the D1/D2 domain of the 26S rRNA gene. Nine unique colony morphology types were profiled on WL agar and three new types were found. After sequence analysis of representative colonies from each WL group, nine yeast species were identified, namely H. uvarum, H. occidentalis, M. pulcherrima, C. zemplinina, H. vineae, I. orientalis, Z. bailii, P. kluyveri and S. cerevisiae. The non-Saccharomyces yeasts appeared mainly in the early stage of the fermentation while H. uvarum, I. orientalis and P. kluyveri were able to remain in the final stage. Fourty-six S. cerevisiae isolates were preselected according to physiological characteristics and twelve strains with valuable fermentation properties were obtained.     

A rapid identification method for aflatoxin-producing strains ofAspergillus flavus andA. parasiticus by ammonia vapor

The colony reverse of aflatoxin (AF)-producing strains ofAspergillus flavus andA. parasiticus turned pink when their cultures were exposed to ammonia vapor. The color change was visible for colonies grown on media suitable for AF production such as potato dextrose, coconut, and yeast extract sucrose agars after 2 d incubation at 25°C. Of the 120 strains ofA. flavus, A. parasiticus, and two related species inA. flavus group:A. oryzae andA. sojae tested in this study, only the AF-producing strains ofA. flavus andA. parasiticus showed the pink pigmentation. The color change occurred immediately after the colony was contacted with ammonia vapor. This method was useful for rapid screening the AF-producing strains ofA. flavus andA. parasiticus.     

Screening and identification of actinobacteria from marine sediments: Investigation of potential producers for antimicrobial agents and type I polyketides

Marine actinobacteria were isolated from the sediment samples collected in Xinghai Bay, Xiaoping Island and Changhai in Dalian, China. Fifteen selective media were employed, of which Humic acid-Vitamin medium recovered the highest number of isolates. Eleven of the 239 isolates obtained from the selective media were selected for further investigations based on colony morphology and pigment formation. Phylogenetic analysis of their 16S rRNA sequences showed that these strains belong to the genera of Streptomyces and Micromonospora. One of these strains identified is a new species of Streptomyces. Type I polyketide synthase (PKSI) gene fragments were amplified from three strains. The PKSI sequence of one of these strains (S187) showed high homology to the KS gene involved in meridamycin biosynthesis. Based on this result, the neurotrophic activity of S187 was further investigated. Culture broth of S187 was applied to rat pheochromocytoma (PC12) cells, and a 2.3-fold increase in growth over control cells was observed by the 3-(4,5-dimethylthiazolyl)-2,5-diphenyltetrazolium bromide assay. These results indicated the importance of further exploration of the marine actinobacteria in Dalian sea area for antimicrobial agents and type I polyketides.     

Phylogenetic Analysis of the Genus Bifidobacterium and Related Genera Based on 16S rDNA Sequences

The 16S rRNA gene sequences were determined for type strains of 21 Bifidobacterium species. A phylogenetic tree was constructed using the determined sequences and sequences from DNA databases, which contain the sequences of 11 type strains of Bifidobacterium species and 11 strains of related genera. All species of the genus Bifidobacterium and Gardnerella vaginalis ATCC 14018 belonged to a cluster phylogenetically distinct from the other genera. The cluster was divided into two subclusters: subcluster 1 composed of most species of Bifidobacterium and G. vaginalis, and subcluster 2 consisting of two species, B. denticolens and B. inopinatum; both of which were isolated from human dental caries. In the genus Bifidobacterium, four groups of species are known to be moderately to highly related by DNA-DNA hybridization. The four groups of species exhibited more than 99% similarity among their 16S rDNA sequences within each group. These results indicated that species with around 99% or more similarity in their 16S rDNA sequences should be confirmed for species identities.     

The structured diversity of specialized gut symbionts of the New World army ants

Symbiotic bacteria play important roles in the biology of their arthropod hosts. Yet the microbiota of many diverse and influential groups remain understudied, resulting in a paucity of information on the fidelities and histories of these associations. Motivated by prior findings from a smaller scale, 16S rRNA‐based study, we conducted a broad phylogenetic and geographic survey of microbial communities in the ecologically dominant New World army ants (Formicidae: Dorylinae). Amplicon sequencing of the 16S rRNA gene across 28 species spanning the five New World genera showed that the microbial communities of army ants consist of very few common and abundant bacterial species. The two most abundant microbes, referred to as Unclassified Firmicutes and Unclassified Entomoplasmatales, appear to be specialized army ant associates that dominate microbial communities in the gut lumen of three host genera, Eciton, Labidus and Nomamyrmex. Both are present in other army ant genera, including those from the Old World, suggesting that army ant symbioses date back to the Cretaceous. Extensive sequencing of bacterial protein‐coding genes revealed multiple strains of these symbionts coexisting within colonies, but seldom within the same individual ant. Bacterial strains formed multiple host species‐specific lineages on phylogenies, which often grouped strains from distant geographic locations. These patterns deviate from those seen in other social insects and raise intriguing questions about the influence of army ant colony swarm‐founding and within‐colony genetic diversity on strain coexistence, and the effects of hosting a diverse suite of symbiont strains on colony ecology.     

Importance of free living mustelid carnivores in circulation of adiaspiromycosis

The study of adiaspiromycosis in 8 species of free living mustelid carnivores (266 specimens) revealed the average intensity of infection to be 41.4%. The highest incidence rate was found in the exoanthropic species Putorius eversmanni (73.1 %) and Martes martes (72.2%) while the lowest was observed in the hemisynanthropic species Putorius putorius (30.6%). The stone marten (Martes foina) is a new, still unknown reservoir host of C. parvum var. crescens, C. parvum for which Putorius eversmanni and Mustela nivalis are new hosts, was also demonstrated in 3 cases. In the present paper, the role of mustelid carnivores in natural foci of adiaspiromycosis is discussed and evaluated. The importance of these predators in the circulation of C. parvum var. crescens is relatively wide. They make possible the liberation of adiaspores from the lungs of their prey — primarily small mammals — into the environment and participate in the spread of infection in both the horizontal and vertical directions. They play a part in the process of distributing of the organism to the vicinity of human dwellings, in the development of new elementary foci, and also act as important reservoir hosts of C. parvum var. crescens.     

Formation of biogenic amines as criteria for the selection of wine yeasts

This work deals with biogenic amine production by yeast strains isolated from grapes and wines. A total of 50 strains were tested for their capacity to produce biogenic amines in wine. In general, all the species produced very low or non-detectable amounts of histamine, whereas methylamine and agmatine were formed by all the species considered. The highest concentration of total biogenic amines was formed by Brettanomyces bruxellensis, with an average value of 15 mg/l, followed by Saccharomyces cerevisiae with an average of 12.14 mg/l. The other species formed less than 10 mg of total biogenic amines per litre. Wines fermented with the most fermentative strains of S. cerevisiae species had the highest contents of ethanolamine, from 2.3 to 16 mg/l, and of agmatine, from 3.1 to 7.5 mg/l. The strains of the other species, which exhibited a low fermentative ability, Kloeckera apiculata, B. bruxellensis and Metschnikowia pulcherrima, varied in the production of agmatine and phenylethylamine. A significant variability in the production of cadaverine was characteristic of Candida stellata strains, which varied also in ethanolamine production. Our results emphasize the importance of using selected strains of S. cerevisiae, not only for the expression of desirable technological traits, but also to avoid potentially negative effects on human health. Therefore, the characterization of strains of S. cerevisiae for the 'production of biogenic amines' becomes of applicative interest.     

INDUCIBLE COLONY FORMATION WITHIN THE SCENEDESMACEAE: ADAPTIVE RESPONSES TO INFOCHEMICALS FROM TWO DIFFERENT HERBIVORE TAXA1

We studied the occurrence of colony formation within 40 different strains of Scenedesmaceae (Chlorococcales, Chlorophyta) in response to grazing‐released infochemicals from the herbivorous zooplankters Brachionus calyciflorus Pallas (Rotifera) and Daphnia magna Strauss (Cladocera). With the exception of two strains, all strains showed similar responses to both B. calyciflorus and D. magna infochemicals, either no response or inducible colony formation. Colony size was found to increase with B. calyciflorus infochemical concentration and could be described by a sigmoid function. The increase in colony size was more pronounced in the Scenedesmus species tested than in Desmodesmus species, which was probably due to higher threshold infochemical concentrations for colony induction in Desmodesmus. Therefore, the adaptivity of colony formation to the herbivory threat only holds above the threshold concentration for colony induction and as long as maximum colony size has not been attained. Taking this into account, our results suggest that inducible colony formation is a common adaptive response of many Scenedesmaceae to the threat of herbivory.     

高望界土壤放线菌抗菌活性筛选及生物学特征

为了从土壤环境中筛选产生抗菌活性物质的放线菌,采用琼脂扩散法对分离自湖南省高望界自然保护区森林土壤的169株放线菌进行抗菌活性检测,采用16S RNA基因序列分析法进行系统发育分析,采用常规方法进行生物学特性研究。结果表明,有47株受试菌株的发酵产物显示抗菌活性阳性(27.8%),其中6株具有较强抗菌活性。形态观察结果表明,这6株菌株均为典型的产丝产孢放线菌,在多数培养基上生长良好,气生菌丝和孢子丝丰富。系统发育分析表明,6株菌株均属于链霉菌属(Streptomyces),归为5个物种。菌株JSM 147612、JSM 147786、JSM 147831和JSM 147846分别与链霉菌属的已知物种S.violascens(序列相似性为99.93%)、S.malachitospinus(99.65%)、S.anulatus(99.72%)和S.aureus(99.38%)系统发育关系最为密切;菌株JSM 147823和JSM 147842之间的序列相似性为99.86%,应该属于同一物种,与它们系统发育关系最为密切的是S.albidoflavus(相似性分别为99.72%和99.58%)。     

广东中山地区气单胞菌环境株的分离、鉴定及系统发生关系

从广东省中山市的池塘水样、底泥、健康鱼、肠道及稻田土样中用Aeromonas的选择培养基分离到10株气单胞菌。通过生理生化测试、16S rDNA序列测定、与气单胞菌典型菌株的16S rDNA序列进行比对和聚类分析,对它们进行了鉴定,并研究了它们之间的系统发生关系。结果显示该地区环境中气单胞菌的优势种除A. hydrophila（HG1组）外, 还有A. caviae（HG4组）、A. jandaei(HG9组)和A. veronii(HG10组),其中后两种是国内新记录。这是国内首次对环境中气单胞菌多样性进行研究。     

Efficient production of aculeacin A acylase in recombinant Streptomyces strains

The productivities of aculeacin A acylase in various recombinant Streptomyces strains were examined. When the acylase gene was introduced into six species (S. lividans, S. albus, S. ambofaciens, S. parvulus, S. griseus and S. avermitilis) using Streptomyces multi-copy vector pIJ702, all strains produced the acylase extracellularly. The recombinant S. Griseus was the most efficient producer of the enzyme, producing 25-fold more than the original producer, Actinoplanes utahensis. On the other hand, the recombinant strains of S. lividans and S. avermitilis showed almost the same productivity as A. utahensis. The purified recombinant acylases from four strains, S. albus, S. ambofaciens, S. parvulus and S. griseus, were composed of two subunits; however, the molecular mass values of their small subunits were higher than that of the original acylase. Further, immunoblot analysis showed that the presumed precursor peptide and its degradation products were also detected in the low-producing strains, A. utahensis and S. avermitilis. These findings indicate that the productivity of the acylase was affected by proteolytic activity in the host strains. Correspondence to: S. mura     

Comparative Genomics of Cultured and Uncultured Strains Suggests Genes Essential for Free-Living Growth of Liberibacter

The full genomes of two uncultured plant pathogenic Liberibacter, Ca. Liberibacter asiaticus and Ca. Liberibacter solanacearum, are publicly available. Recently, the larger genome of a closely related cultured strain, Liberibacter crescens BT-1, was described. To gain insights into our current inability to culture most Liberibacter, a comparative genomics analysis was done based on the RAST, KEGG, and manual annotations of these three organisms. In addition, pathogenicity genes were examined in all three bacteria. Key deficiencies were identified in Ca. L. asiaticus and Ca. L. solanacearum that might suggest why these organisms have not yet been cultured. Over 100 genes involved in amino acid and vitamin synthesis were annotated exclusively in L. crescens BT-1. However, none of these deficiencies are limiting in the rich media used to date. Other genes exclusive to L. crescens BT-1 include those involved in cell division, the stringent response regulatory pathway, and multiple two component regulatory systems. These results indicate that L. crescens is capable of growth under a much wider range of conditions than the uncultured Liberibacter strains. No outstanding differences were noted in pathogenicity-associated systems, suggesting that L. crescens BT-1 may be a plant pathogen on an as yet unidentified host.     

The scaling of colony size with nest volume in termites: a role in population dynamics?

相似文献   

Influence of <Emphasis Type="Italic">Daphnia</Emphasis> infochemicals on functional traits of <Emphasis Type="Italic">Microcystis</Emphasis> strains (Cyanobacteria)

We conducted a laboratory experiment to investigate the influence of Daphnia infochemicals on growth rate, microcystin production, colony formation and cell size of eight Microcystis strains isolated from two lakes. The strains were characterized genetically by their 16S-23S rDNA ITS sequence. The experiment was composed of four treatments: (1) a control using filtered WC medium, (2) addition of Scenedesmus obliquus culture medium filtrate, (3) addition of Daphnia magna culture medium filtrate and (4) addition of sodium octyl sulphate, a commercially available Daphnia infochemical. Our results showed that sympatric strains differed strongly for the measured functional traits, while no correlations between traits were found. Between-strain differences in growth rate, microcystin production, colony formation and cell size were generally larger than the differences in phenotypes observed between treatments. Despite this, several strains reacted to the infochemicals by changing functional trait values. Daphnia culture medium filtrate and, to a lesser extent, sodium octyl sulphate had a negative influence on the growth rate of half of the strains and stimulated microcystin production in one strain, but the latter effect was not Daphnia-specific as Scenedesmus culture medium filtrate had the same effect. Daphnia culture medium filtrate also induced colony formation in one strain. Our data suggest that Daphnia infochemicals generally have a weak influence on growth rate, microcystin production and colony formation of Microcystis strains as compared to the inter-strain variability, while existing inducible effects are highly strain-specific.     

CONTROL OF COLONY AND UNICELL FORMATION IN A SYNCHRONIZED SCENEDESMUS12

Colony formation in a synchronized Scenedesmus could be controlled by the addition of 0.05% Na₃ citrate or 85 μM EDTA to modified Bristol's medium. No unicells were formed; only S. quadricauda-like or S. longispina-type colonies were observed in young cultures grown in that medium. A colony population could be made completely unicellular in 2 days if grown in soil-Bristol's medium and transferred daily. The pleomorphic Scenedesmus was examined in synchronized culture. When the organism was grown in a defined medium in a 15-hr light /9-hr dark cycle on a roller tube rotator at 2-6 rpm and transferred daily, synchrony of cell division and release of the products were achieved. In a synchronized culture 2 doublings/day were recorded, with most cytoplasmic cleavages and all releasing of daughter cells taking place in the dark period. In many observations with several synchronized strains of Scenedesmus, no fixed pattern of release of daughter products from mother cells or colonies was detected. Colonies or unicells had their full spine complement at the time of release. As a cell or colony aged the spines sometimes increased in thickness. Other Scenedesmus strains were examined to provide supporting data.     

Tracing Streptococcus thermophilus strains in three-component yogurt starters

Three-component starters for yogurt were obtained on the base of starter LBB.BY 5-12 for traditional Bulgarian yogurt, containing strains Lactobacillus delbrueckii ssp. bulgaricus B5 and Streptococcus thermophilus A with the addition of either an exopolysaccharide-producing S. thermophilus strain 6V or the fast acidifying S. thermophilus strain N1. To differentiate between the three strains in the starter cultures, randomly amplified polymorphic DNA (RAPD) technique was applied to develop strain-specific probes. Southern hybridization against dot-blots of chromosomal DNA from the three S. thermophilus strains confirmed that two probes, derived from a 770 bp RAPD product obtained with primer RAPD-4 and a 290 bp sequence obtained with primer OPP-7 were specific for S. thermophilus 6V and S. thermophilus A, respectively, while no hybridization to S. thermophilus N1 DNA was observed. The selected probes were used to differentiate between S. thermophilus colonies on a solid agar medium by colony hybridization. The evaluation of the viable cell counts revealed that the populations of S. thermophilus A and the added S. thermophilus strains 6V or N1 in the three-component starters and in yogurt had nearly equal proportion allowing each strain to contribute to the enriched properties of starter and product.