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21.
Impact of heavy metals on the degradative capabilities of soil bacterial communities 总被引：6，自引：0，他引：6
C. Burkhardt H. Insam T. C. Hutchinson H. H. Reber 《Biology and Fertility of Soils》1993,16(2):154-156
The degradative capabilities of six heavy-metal-affected and six unaffected bacterial communities from Canadian and German soils were determined by enumerating colony-forming units on 20 specific media. Each of these contained an aromatic substrate as the sole source of C and energy. Comparisons of plate counts revealed that heavy metal stress caused a decrease in the eveness of the distribution of the 20 degradative capabilities This suggests that in heavy-metal-affected bacterial communities, relatively rare degradative capabilities, irrespective of their nature, are even rarer than in unaffected communities, while the reverse is true for more common capabilities. The results are discussed with respect to the ease with which aromatic substrates can serve as C and energy sources. 相似文献
22.
Höner OP Wachter B Speck S Wibbelt G Ludwig A Fyumagwa RD Wohlsein P Lieckfeldt D Hofer H East ML 《Veterinary microbiology》2006,115(1-3):223-228
In a population of spotted hyenas (Crocuta crocuta) monitored between 1996 and 2005 in the Ngorongoro Crater, Tanzania, 16 individuals from five of eight social groups displayed clinical signs of an infection, including severe unilateral swelling of the head followed by abscess formation at the mandibular angle, respiratory distress, mild ataxia, and lethargy. Two (12.5%) of these 16 individuals died within days of developing signs. Clinical signs in hyenas were first noted in 2001, and most cases occurred between September 2002 and February 2003, suggesting an outbreak of infection during this period. Histopathological examination of internal organs from one hyena that died with signs revealed morphological changes consistent with severe bacterial infection. Phenotypic examination and phylogenetic analysis of the 16S rRNA gene of the causative agent of infection revealed a Lancefield group C Streptococcus with a high level of homology to S. equi subsp. ruminatorum, a subspecies of S. equi recently described in domestic sheep (Ovis aries) and goats (Capra hircus) with mastitis in Spain. Strains similar to this bacterium were also isolated from two hyenas without obvious clinical signs, suggesting that hyenas may be 'carriers' of this bacterium, and from a sympatric Burchell's zebra (Equus burchelli), a herbivore species often consumed by hyenas. To our knowledge this is the first report of a Streptococcus infection in these two wildlife species. The high genetic similarity between the hyena and zebra isolates indicates that inter-specific transmission may occur, possibly when hyenas consume infected zebra carcasses. 相似文献
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24.
East ML Moestl K Benetka V Pitra C Höner OP Wachter B Hofer H 《Veterinary microbiology》2004,102(1-2):1-9
Sera from 38 free-ranging spotted hyenas (Crocuta crocuta) in the Serengeti ecosystem, Tanzania, were screened for exposure to coronavirus of antigenic group 1. An immunofluorescence assay indicated high levels of exposure to coronavirus among Serengeti hyenas: 95% when considering sera with titer levels of > or = 1:10 and 74% when considering sera with titer levels of > or = 1:40. Cubs had generally lower mean titer levels than adults. Exposure among Serengeti hyenas to coronavirus was also confirmed by a serum neutralisation assay and an ELISA. Application of RT-PCR to 27 fecal samples revealed viral RNA in three samples (11%). All three positive fecal samples were from the 15 juvenile animals (<24 months of age) sampled, and none from the 12 adults sampled. No viral RNA was detected in tissue samples (lymph node, intestine, lung) from 11 individuals. Sequencing of two amplified products from the S protein gene of a positive sample revealed the presence of coronavirus specific RNA with a sequence homology to canine coronavirus of 76 and 78% and to feline coronavirus type II of 80 and 84%, respectively. Estimation of the phylogenetic relationship among coronavirus isolates indicated considerable divergence of the hyena variant from those in European, American and Japanese domestic cats and dogs. From long-term observations of several hundred known individuals, the only clinical sign in hyenas consistent with those described for coronavirus infections in dogs and cats was diarrhea. There was no evidence that coronavirus infection in hyenas caused clinical signs similar to feline infectious peritonitis in domestic cats or was a direct cause of mortality in hyenas. To our knowledge, this is the first report of coronavirus infection in Hyaenidae. 相似文献
25.
Alessandra Lagomarsino Brigitte A. Knapp M. Cristina Moscatelli Paolo De Angelis Stefano Grego Heribert Insam 《Journal of Soils and Sediments》2007,7(6):399-405
Background, Aims, and Scope The genetic structure and the functionality of soil microbes are both important when studying the role of soil in the C cycle
in elevated CO2 scenarios. The aim of this work was to investigate the genetic composition of the fungal community by means of PCR-DGGE and
the functional diversity of soil micro-organisms in general with MicroResp-based community level physiological profiling (CLPP)
in a poplar plantation (POPFACE) grown under elevated [CO2] with and without nitrogen fertilization.
Materials and Methods The POPFACE experimental plantation and FACE facility are located in central Italy, Tuscania (VT). Clones of Populus alba, Populus nigra and Populus x euramericana were grown, from 1999 to 2004, in six 314 m2 plots treated either with atmospheric (control) or enriched (550 μmol mol−1) CO2 with FACE (Free Air CO2 Enrichment) technology in each growing season. Each plot is divided into six triangular sectors, with two sectors per poplar
genotype: three species × two nitrogen levels. After removal of the litter layer one soil core per genotype (10 cm wide, 20
cm depth) was taken inside each of the three sectors in each plot, for a total of 36 soil cores (3 replicates × 2 [CO2] × 2 fertilization × 3 species) in October 2004 and in July 2005. DNA was extracted with a bead beating procedure. 18S rDNA
gene fragments were amplified with PCR using fungal primers (FR1 GC and FF390). Analysis of CLPP was performed using the MicroResp
method. Carbon substrates were selected depending on their ecological relevance to soil and their solubility in water. In
particular rhizospheric C sources (carboxylic acids and carbohydrates) were chosen considering the importance of root inputs
for microbial metabolism.
Results The fertilization treatment differentiated the fungal community composition regardless of elevated [CO2] or the poplar species; moreover the number of fungal species was lower in fertilized soil. The effect of elevated [CO2] on the fungal community composition was evident only as interaction with the fertilization treatment as, in N-sufficient
soils, the elevated [CO2] selected a different microbial community. For CLPP, the differ ent poplar species were the main factors of variation. The
FACE treatment, on average, resulted in lower C utilization rates in un-fertilized soils and higher in fertilized soils.
Discussion Fungal biomass and fungal composition depend on different factors: from previous studies we know that the greater quantity
and the higher C/N ratio of organic inputs under elevated [CO2] influenced positively the fungal biomass both in fertilized and in un-fertilized soil, whereas nitrogen availability resulted
to be the main determinant of fungal community composition in this work. Whole active microbial community was directly influenced
by the soil nutrient availability and the poplar species. Under elevated CO2 the competition for N with plants strongly affected the microbial communities, which were not able to benefit from added
rhizospheric substrates. Under Nsufficient conditions, the increase of microbial activity due to [CO2] enrichment was related to a more active microbial community, favoured by the current availability of C and N.
Conclusions Different factors influenced the microbial community at different levels: poplar species and root exudates affected the functional
properties of the microbial community, while the fungal specific composition (as seen with DGGE) remained unaffected. On the
other hand, factors such as N and C availability had a strong impact on the community functionality and composition. Fungal
community structure reflected the availability of N in soils and the effect of elevated [CO2] on community structure and function was evident only in N-sufficient soils. The simultaneous availability of C and N was
therefore the main driving force for microbial structure and function in this plantation.
Recommendations and Perspectives Using the soil instead of soil extracts for CLPP determination provides a direct measurement of substrate catabolism by microbial
communities and reflects activity rather than growth because more immediate responses to substrates are measured. Further
applications of this approach could include selective inhibition of different microbial functional groups to investigate specific
CLPPs. To combine the structural analysis and the catabolic responses of specific microbial communities (i.e. fungi or bacteria)
could provide new outlooks on the role of microbes on SOM decomposition.
ESS-Submission Editor: Dr. Kirk Semple (k.semple@lancaster.ac.uk) 相似文献
26.
D'Hondt S Jørgensen BB Miller DJ Batzke A Blake R Cragg BA Cypionka H Dickens GR Ferdelman T Hinrichs KU Holm NG Mitterer R Spivack A Wang G Bekins B Engelen B Ford K Gettemy G Rutherford SD Sass H Skilbeck CG Aiello IW Guèrin G House CH Inagaki F Meister P Naehr T Niitsuma S Parkes RJ Schippers A Smith DC Teske A Wiegel J Padilla CN Acosta JL 《Science (New York, N.Y.)》2004,306(5705):2216-2221
Diverse microbial communities and numerous energy-yielding activities occur in deeply buried sediments of the eastern Pacific Ocean. Distributions of metabolic activities often deviate from the standard model. Rates of activities, cell concentrations, and populations of cultured bacteria vary consistently from one subseafloor environment to another. Net rates of major activities principally rely on electron acceptors and electron donors from the photosynthetic surface world. At open-ocean sites, nitrate and oxygen are supplied to the deepest sedimentary communities through the underlying basaltic aquifer. In turn, these sedimentary communities may supply dissolved electron donors and nutrients to the underlying crustal biosphere. 相似文献