Sixteen samples of two soil cores (about 550 and 180 cm in depth) were drilled at intervals in the lower reach of Heihe river basin (northwest of China) in order to illustrate soil microbial characteristics and diversity of culturable bacteria in an extreme by arid environment. Soil water content, organic matter, total nitrogen, pH, direct cell counts, and culturable microorganism counts were evaluated. The total cell concentration was 19-1120/microg (i.e. 0.19-11.2 x 10(8) per g) soil, the culturable bacteria count being 0.2-10.9 per microg (i.e. 2 x 10(5)-10.9 x 10(6) CFU/g) soil. The number of direct cell counts obtained by 4',6-diamidino-2-phenylindole-staining or the cound of culturable microbes after enrichment with different media were statistically significantly correlated with soil organic matters, total nitrogen content, soil water content and surface vegetation; this partly explained the larger number in the deeper first core than in the shallower one. As part of identification of 228 colonies isolated from the two cores, thirty-two were selected for 16S rDNA amplification, sequencing and molecular identification. These 32 isolates were affiliated to 5 major groups of bacteria: alpha-Proteobacteria, 5-Proteobacteria, gamma-Proteobacteria, the high-G+C G+-bacteria, the low-G+C G- -bacteria, and the Cytophaga-Flexibacter-Bacteroides group. Twenty-eight were rod- or short-rod shaped, which accounted for >87.5% of all species; only 4 of 32 species were cocci (<12.5%).

• MeSH
• Bacteria izolace a purifikace   MeSH
• biodiverzita MeSH
• počet mikrobiálních kolonií * MeSH
• půdní mikrobiologie * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The microbial community structure along an altitude gradient was investigated in different localities, in Kalasi lake, Urumqi river and Sangong river, Xingjiang (China). The mean numbers of DAPI (4',6-diamidino-2-phenylindole)-stained cells were lower in Kalasi lake than that in Urumqi river and Sangong river; these differences were attributed to increasing environmental harshness including lower soil organic carbon and nitrogen content, more acidic pH and lower annual temperature. In each locality, the numbers of bacteria and archaea measured with two fluorescence-labeled 16S rRNA oligonucleotide probes (EUB338 and ARCH915) were higher in a coniferous forest and lower in desert vegetation. A significant and positive relationship was found between microbial and soil organic carbon and total nitrogen along the altitudinal gradient, indicating that plant communities and soil nutrients influence the soil microbial structure. The results show that the microbial population in higher latitudinal site was fewer than lower latitudinal one, soil microorganisms were positively correlated to soil organic carbon and total nitrogen, and plant communities had an obviously impact on soil microbes.

• MeSH
• Archaea genetika   izolace a purifikace   MeSH
• archeální geny MeSH
• Bacteria genetika   izolace a purifikace   MeSH
• bakteriální geny MeSH
• barvení a značení MeSH
• dusík analýza   MeSH
• ekosystém MeSH
• geny rRNA MeSH
• geologické sedimenty chemie   mikrobiologie   MeSH
• indoly metabolismus   MeSH
• koncentrace vodíkových iontů MeSH
• nadmořská výška MeSH
• počet mikrobiálních kolonií MeSH
• půdní mikrobiologie * MeSH
• ribozomální DNA analýza   MeSH
• RNA ribozomální 16S genetika   MeSH
• teplota MeSH
• uhlík analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Čína MeSH
• Názvy látek
• DAPI MeSH Prohlížeč
• dusík MeSH
• indoly MeSH
• ribozomální DNA MeSH
• RNA ribozomální 16S MeSH
• uhlík MeSH

Three ice core samples were collected from the Malan ice core drilled from the Tibetan Plateau, and three 16S rDNA clone libraries by direct amplification from the ice-melted water were established. Ninety-four clones containing bacterial 16S rDNA inserts were selected. According to restriction fragment-length polymorphism analysis, 11 clones were unique in the library from which they were obtained and used for partial sequence and phylogenetic analysis, and compared with 8 reported sequences from the same ice core at depth 70 m. Differences among the samples were apparent in clone libraries. The phylotypes were dominated by the Proteobacteria group, Acinetobacter sp. and Cytophaga-Flavobacterium-Bacteroides (CFB) group. They accounted for 92.5% (Proteobacteria), 100% (Acinetobacter sp.), 34.4% (CFB) and 100% (beta-Proteobacteria) in the clone libraries from the samples at ice depths 35, 64, 70, and 82 m, respectively. The Acinetobacter sp. was only found in the deposition at ice depth 82 m and closely clustered with gamma-Proteobateria. Two members (Malan A-21 and 101) of alpha-Proteobacteria from the sample of 35 m and two (Malan B-26 and 48) of beta-Proteobacteria of 64 m were loosely clustered (< 95% similarity) with known bacteria, represented new genera in ice bacteria.

• MeSH
• Bacteria klasifikace   genetika   izolace a purifikace   MeSH
• geologické sedimenty mikrobiologie   MeSH
• led * MeSH
• mikrobiologie vody * MeSH
• ribozomální DNA analýza   MeSH
• RNA ribozomální 16S analýza   genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Tibet MeSH
• Názvy látek
• led * MeSH
• ribozomální DNA MeSH
• RNA ribozomální 16S MeSH

The relationship between the physiological group of gelatinolytic bacteria and the abundance of heterotrophic bacteria in freshwater ecosystems was described, based on analysis of 1082 different freshwater samples collected in Croatia. Percentages of gelatinolytic bacteria among the population of heterotrophic bacteria showed a significant negative correlation with the abundance of heterotrophic bacteria. The relation between the physiological group (gelatinolytic bacteria) and heterotrophic bacteria can be considered to be an indicator of the pollution degree of freshwaters. A high relative content of gelatinolytic bacteria (> 76%) always indicates the colony-forming units of heterotrophic bacteria < 1000/mL, which corresponds to the high water quality; gelatinolytic bacteria < 11% indicate polluted waters. Isolated strains of aerobically grown gelatinolytic bacteria were Gram-negative rod-shaped or Gram-positive endospore-forming rod-shaped cells.

• MeSH
• Bacteria izolace a purifikace   metabolismus   MeSH
• gramnegativní aerobní tyčinky a koky izolace a purifikace   metabolismus   MeSH
• grampozitivní sporulující tyčinky izolace a purifikace   metabolismus   MeSH
• mikrobiologie vody * MeSH
• počet mikrobiálních kolonií MeSH
• sladká voda mikrobiologie   MeSH
• želatina metabolismus   MeSH
• znečištění vody analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Chorvatsko MeSH
• Názvy látek
• želatina MeSH