Showing papers in "Canadian Journal of Microbiology in 2009"
TL;DR: This review focuses on the recent literature dealing with the effects of plant growth-promoting bacteria and AM fungi on the response of plants to heavy metal stress and points the way to strategies that may facilitate the practical realization of this technology.
Abstract: Heavy metal pollution is a major worldwide environmental concern that has recently motivated researchers to develop a variety of novel approaches towards its cleanup. As an alternative to traditional physical and chemical methods of environmental cleanup, scientists have developed phytoremediation approaches that include the use of plants to remove or render harmless a range of compounds. Both plant growth promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF) can be used to facilitate the process of phytoremediation and the growth of plants in metal-contaminated soils. This review focuses on the recent literature dealing with the effects of plant growth-promoting bacteria and AM fungi on the response of plants to heavy metal stress and points the way to strategies that may facilitate the practical realization of this technology.
213 citations
TL;DR: The results imply that inoculation with plant growth promoting rhizobacteria containing ACC-deaminase could be a useful approach for improving growth and yield of maize under salt-stressed conditions.
Abstract: Salt stress is one of the major constraints hampering agricultural production owing to its impact on ethylene production and nutritional imbalance. A check on the accelerated ethylene production in...
170 citations
TL;DR: Strain 34H recovered best from deep-freezing to -80 degrees C if first supplemented with a preparation of its own EPS, rather than other cryoprotectants like glycerol, suggesting EPS production as both a survival strategy and source of compounds with potentially novel properties for biotechnological and other applications.
Abstract: Extracellular polysaccharide substances (EPS) play critical roles in microbial ecology, including the colonization of extreme environments in the ocean, from sea ice to the deep sea After first developing a sugar-free growth medium, we examined the relative effects of temperature, pressure, and salinity on EPS production (on a per cell basis) by the obligately marine and psychrophilic γ-proteobacterium, Colwellia psychrerythraea strain 34H Over growth-permissive temperatures of ~10 to –4 °C, EPS production did not change, but from –8 to –14 °C when samples froze, EPS production rose dramatically Similarly, at growth-permissive hydrostatic pressures of 1–200 atm (1 atm = 101325 kPa) (at –1 and 8 °C), EPS production was unchanged, but at higher pressures of 400 and 600 atm EPS production rose markedly In salinity tests at 10‰–100‰ (and –1 and 5 °C), EPS production increased at the freshest salinity tested Extreme environmental conditions thus appear to stimulate EPS production by this strain Furtherm
149 citations
TL;DR: It is shown that probiotic lactobacilli can provide benefits to women being treated with antibiotics for an infectious condition and had a significantly higher cure rate of BV than the placebo group.
Abstract: Bacterial vaginosis (BV) is the most prevalent vaginal infection worldwide and is characterized by depletion of the indigenous lactobacilli. Antimicrobial therapy is often ineffective. We hypothesi...
147 citations
TL;DR: This study revealed the equivalent capability of different Bacillus strains from various microhabitats to produce the above-mentioned antibiotics and highlights the possibility of using some strains as potential biocontrol agents under different microhabits distant from their original habitat.
Abstract: Sarangi N.P. Athukorala, W.G. Dilantha Fernando, and Khalid. Y. Rashid Abstract: Although many Bacillus species are known to be good antibiotic producers capable of acting as biocontrol agents, the underlying antimicrobial mechanisms are often poorly understood. In this study, 21 Bacillus strains, demon- strating over 50% mycelial inhibition against Sclerotinia sclerotiorum as well as significant control in plant assays, were examined for the presence of antibiotic biosynthetic genes. Primers specific for bacillomycin D, iturin A, surfactin, myco- subtilin, fengycin, and zwittermicin A were used to amplify biosynthetic genes from these bacteria using PCR. The major- ity of strains harbored surfactin (21/21) and iturin A (20/21) biosynthetic genes. Three strains (Bacillus subtilis 3057, Bacillus amyloliquefaciens BS6, and Bacillus mycoides 4079) were positive for bacillomycin D, whereas 4 strains (B. sub- tilis H-08-02, B. subtilis 3057, B. amyloliquefaciens BS6, and B. mycoides 4079) showed the presence of the fengycin bio- synthetic gene. The zwittermicin A gene was detected in B. mycoides S, Bacillus thuringiensis BS8, and B. amyloliquefaciens BS6. Sequence analysis of purified PCR products revealed homology with corresponding genes from other Bacillus sp. in the GenBank database. Production of particular antibiotics in strains BS6, H-08-02, 3057, and 4079 was confirmed through matrix-assisted laser desorption ionization - time of flight - mass spectroscopy (MALDI-TOF-MS). This study revealed the equivalent capability of different Bacillus strains from various microhabitats to produce the above- mentioned antibiotics and highlights the possibility of using some strains as potential biocontrol agents under different mi- crohabitats distant from their original habitat. Furthermore, it will enable researchers to develop rational strategies for the application of the antagonists and their metabolites within an agroecosystem. To the best of our knowledge, this is the first report of a B. mycoides strain that carries biosynthetic genes and produces fengycin and surfactin.
115 citations
TL;DR: It appears that multidrug resistance is low among native Antarctic bacteria but is increased by human habitation, while antibiotic resistance in microorganisms isolated from the Antarctic marine waters and a penguin rookery is low.
Abstract: Antibiotic resistance in aquatic bacteria has increased steadily as a consequence of the widespread use of antibiotics, but practice and international treaty should have limited antibiotic contamin
93 citations
TL;DR: The adherence of Candida albicans cells to one another and to various host and biomaterial surfaces is an important prerequisite for the colonization and pathogenesis of this organism as mentioned in this paper.
Abstract: The adherence of Candida albicans to one another and to various host and biomaterial surfaces is an important prerequisite for the colonization and pathogenesis of this organism. Cells in establish...
92 citations
TL;DR: These results confirmed that the one-step inactivation technique can be used to generate large deletions in E. amylovora and demonstrated that these determinants are not involved in virulence in plants.
Abstract: An easy gene-knockout technique, PCR-based one-step inactivation of chromosomal genes, is widely used in Escherichia coli and related enterobacteria to construct mutants. In this study, we adapted this technique to construct genomic island and large operon deletion mutants of Erwinia amylovora, including the 33.4 kb hrp-type III secretion (T3SS) pathogenicity island (PAI1) and the 15.8 kb amylovoran biosynthesis (AMS) operon. Deletion of 2 novel T3SS pathogenicity islands (PAI2 and PAI3) and an operon encoding a type II secretion system (T2SS) demonstrated that these determinants are not involved in virulence in plants. Co-inoculation experiments demonstrated that the hrp-T3SS and AMS deletion mutants could complement each other. These results further confirmed that the one-step inactivation technique can be used to generate large deletions in E. amylovora.
88 citations
TL;DR: Results of this study indicate that despite relatively high nutrient levels and microbial biomass, bacterial communities of ornithogenic soils were not more diverse than those of mineral soils of the Ross Sea region of Antarctica.
Abstract: In the Ross Sea region of Antarctica, ornithogenic soils form on land under Adelie Penguin rookeries. Compared with mineral soils of the Ross Sea region, ornithogenic soils are generally high in mi...
83 citations
TL;DR: The multivariate statistical analyses conducted indicate that the extracts of endophytic fungi isolated from leaves of terrestrial orchids in semideciduous forest were more active against Escherichia coli, whereas extracts ofendophytic mushrooms from roots of rupicolous orchid collected in rock fields were moreactive against Candida krusei and Candida albicans.
Abstract: The purpose of this study was to examine antimicrobial activity of endophytic fungi isolated from the leaves, stems, and roots of 54 species of Orchidaceae collected in a Brazilian tropical ecosyst...
81 citations
TL;DR: The results presented here indicate that the improvements in root activity and the coarse root system of mycorrhizal maize may help in alleviating salt stress on the plant.
Abstract: Salt stress has become a severe global problem, and salinity is one of the most important abiotic factors limiting plant growth and yield. It is known that arbuscular mycorrhizal (AM) fungi decreas...
TL;DR: The microbial community isolated from the indoor artworks and air environment was examined by cultural and molecular methods, and a new PCR-based method, RAMP, was used for the first time to cluster the microfilamentous fungi and to characterize and select especially Penicillium and Aspergillus strains, which were isolated in a large number.
Abstract: This study deals with establishing the characteristics of a microbial community isolated from indoor artworks and the surrounding air environment. It is one of the few studies on microbial degradation of indoor artworks. It shows the potential biodegradative risk that can occur if artworks are not exhibited and conserved in an appropriate environment. The microbial community isolated from the indoor artworks and air environment was examined by cultural and molecular methods. Different plate assays were used to screen the biodegradative activity of the isolated microflora: Remazol Bril- liant Blue R, phenol red, and Azure B for the ligninolytic properties; Ostazin brilliant red H-3B for cellulose degradation; CaCO3 glucose agar for solubilization activity; and B4 agar for biomineralization. To type the bacterial and fungal isolates, 2 PCR methods, repetitive extragenic palindromes (REP) and random amplified microsatellite polymorphisms (RAMP) were used. The art objects were principally colonized by fungi. The most commonly isolated strains were represented by hyphomycetes of the genera Penicillium, Aspergillus, Cladosporium, and Chaetomium. Members of these genera showed intensive biodegradation activity, both on wood and on stone. Bacteria were predominant in the air, exhibiting complex communities, both in the air and on the artworks. The most frequently isolated genera were Bacillus and Staphylococcus with extensive biodegradation abilities. REP-PCR revealed high variability within strains belonging to the same genus. RAMP is a new PCR-based method, used in this research for the first time to cluster the microfilamentous fungi and to characterize and select especially Penicillium and Aspergillus strains, which were isolated in a large number.
TL;DR: This study is the first to identify biofilms in the chronic wounds of horses, and demonstrates the importance of combining DGGE-PCR with culture techniques to provide better microbiology analysis of chronic wounds.
Abstract: Evidence of biofilms in human chronic wounds are thought to be responsible for preventing healing in a timely manner. However, biofilm evidence in horse wounds has not yet been documented. Consequently, this study aimed to determine whether biofilms could be detected in wounds, and to investigate the microbiology of chronic wounds in horses. Prior to analysis, wound surfaces were irrigated with 5 mL of sterile saline to remove debris. All wounds were swabbed twice (1 cm2 area) using sterile cotton-tipped swabs. In addition to this, 2 tissue biopsies were taken to investigate evidence of biofilm and the microbiology richness of the wounds. All swabs and 1 biopsy sample were transported to the laboratory in Robertson's cooked meat broth. Traditional culturable techniques and denaturing gradient gel electrophoresis with PCR were utilized to identify common bacteria isolated in all wounds. Following analysis of a number of the biopsy samples, biofilms could be clearly seen. The most common bacteria isolated from each wound analysed included Pseudomonas aeruginosa, Staphylococcus epidermidis, Serratia marcescens, Enterococcus faecalis, and Providencia rettgeri. Sequencing of the 16S ribosmonal DNAs, selected on the basis of DGGE profiling, enabled identification of bacterial species not identified using culturable technology. This study is the first to identify biofilms in the chronic wounds of horses. In addition, this study also demonstrated the importance of combining DGGE-PCR with culture techniques to provide better microbiology analysis of chronic wounds.
TL;DR: Two types of known rhizobial conjugative plasmid are summarized, including quorum sensing regulated plasmids and RctA-repressedPlasmids, and a comparison of the different types of conjugation genes found in members of the rhizobia that have had their genomes sequenced so far is provided.
Abstract: Rhizobia are agriculturally important bacteria that can form nitrogen-fixing nodules on the roots of leguminous plants. Agricultural application of rhizobial inoculants can play an important role in increasing leguminous crop yields. In temperate rhizobia, genes involved in nodulation and nitrogen fixation are usually located on one or more large plasmids (pSyms) or on symbiotic islands. In addition, other large plasmids of rhizobia carry genes that are beneficial for survival and competition of rhizobia in the rhizosphere. Conjugative transfer of these large plasmids thus plays an important role in the evolution of rhizobia. Therefore, understanding the mechanism of conjugative transfer of large rhizobial plasmids provides foundations for maintaining, monitoring, and predicting the behaviour of these plasmids during field release events. In this minireview, we summarize two types of known rhizobial conjugative plasmids, including quorum sensing regulated plasmids and RctA-repressed plasmids. We provide e...
TL;DR: It can be concluded that constantly negative redox potentials as characteristic for the near permafrost table horizons of the investigated soil did effectively shape the structure of the indigenous bacterial community limiting its phylum-level diversity and carbon turnover capacity.
Abstract: Arctic permafrost environments store large amounts of organic carbon. As a result of global warming, intensified permafrost degradation and release of significant quantities of the currently conserved organic matter is predicted for high latitudes. To improve our understanding of the present and future carbon dynamics in climate sensitive permafrost ecosys- tems, the present study investigates structure and carbon turnover of the bacterial community in a permafrost-affected soil of the Lena Delta (72822'N, 126828'E) in northeastern Siberia. 16S rRNA gene clone libraries revealed the presence of all major soil bacterial groups and of the canditate divisions OD1 and OP11. A shift within the bacterial community was observed along the soil profile indicated by the absence of Alphaproteobacteria and Betaproteobacteria and a simultaneous increase in abundance and diversity of fermenting bacteria like Firmicutes and Actinobacteria near the permafrost table. BIOLOG EcoPlates were used to describe the spectrum of utilized carbon sources of the bacterial community in different horizons under in situ temperature conditions in the presence and absence of oxygen. The results revealed distinct qualitative differen- ces in the substrates used and the turnover rates under oxic and anoxic conditions. It can be concluded that constantly nega- tive redox potentials as characteristic for the near permafrost table horizons of the investigated soil did effectively shape the structure of the indigenous bacterial community limiting its phylum-level diversity and carbon turnover capacity.
TL;DR: Results show that C. rosea produces beta-1,3-glucanase in situ, which can degrade hyphae of Fusarium and Pythium and contribute to biological control efficacy.
Abstract: Clonostachys rosea f. catenulata (syn. Gliocladium catenulatum) is an effective fungal biological agent against Fusarium root and stem rot and Pythium damping-off diseases on cucumber plants. Both chitinase and beta-1,3-glucanase enzymes were produced when C. rosea was grown on a synthetic medium containing chitin or laminarin as a sole carbon source, respectively. Chitinase production was also induced by Fusarium cell walls, while beta-1,3-glucanase activity was induced by both Fusarium and Pythium cell walls, as well as by growth on homogenized cucumber roots and on low-carbon media. Mycelial growth of Fusarium and Pythium, when exposed to C. rosea culture filtrates that contain glucanase activity, was significantly reduced compared with the controls, and cell walls of both pathogens were degraded. On excised cucumber roots, hyphae of C. rosea formed appressorium-like structures and coiled around hyphae of Pythium. In culture, C. rosea caused localized degradation of Fusarium hyphae. Cucumber root tissues colonized by C. rosea showed higher levels of beta-1,3-glucanase activity at 7 days post-application compared with untreated controls. To determine if this activity was derived from C. rosea, glucanase isoforms were separated on activity gels. Fungal culture filtrates and root extracts contained the same predominant 20 kDa isoform. Reverse-transcription polymerase chain reaction (RT-PCR) using primers designed to amplify a beta-1,3-glucanase gene in C. rosea confirmed glucanase expression on roots. These results show that C. rosea produces beta-1,3-glucanase in situ, which can degrade hyphae of Fusarium and Pythium and contribute to biological control efficacy.
TL;DR: Seed inoculations with PGPR resulted in a positive response only for 'Guelph Millennium', for which both single or multiple inoculations enhanced plant growth under drought stress, and single inoculations of seedlings enhanced growth of 'Jersey Giant" under optimum conditions.
Abstract: Plant growth-promoting rhizobacteria (PGPR) can have positive effects on vigour and productivity, especially under stress conditions. In asparagus (Asparagus officinalis L.) field culture, seeds are planted in high-density nurseries, and 1-year-old crowns are transplanted to production fields. Performance can be negatively affected by water stress, transplant shock, and disease pressure on wounded roots. PGPR inoculation has the potential to alleviate some of the stresses incurred in the production system. In this study, the effects of PGPR (Pseudomonas spp.) treatment were determined on 3-week-old greenhouse-grown seedlings and germinating seeds of 2 asparagus cultivars. The pots were irrigated to a predetermined level that resulted in optimum growth or the plants were subjected to drought or flooding stress for 8 weeks. The cultivars responded differently to PGPR: single inoculations of seedlings enhanced growth of ‘Guelph Millennium’ under optimum conditions and ‘Jersey Giant’ seedlings under drought s...
TL;DR: A novel feather-degrading bacterium was isolated from a polluted river and identified as Bacillus licheniformis RPk, which exhibited high proteinase production when grown in chicken-feather media and its DNA sequence was determined.
Abstract: A novel feather-degrading bacterium was isolated from a polluted river and identified as Bacillus licheniformis RPk The isolate exhibited high proteinase production when grown in chicken-feather m
TL;DR: Along a 570 km north-south transect from the Yukon River to the North Slope of Alaska, the 15N content was strongly reduced in ectomycorrhizal and ericoid mycorrhIZal plants including Betula, Salix, Picea mariana (P.S. Mill.) B.P., Pice a glauca Moench (Voss), and eriaceous plants.
Abstract: Symbiotic fungi's role in providing nitrogen to host plants is well-studied in tundra at Toolik Lake, Alaska, but little-studied in the adjoining boreal forest ecosystem. Along a 570 km north-south transect from the Yukon River to the North Slope of Alaska, the . N content was strongly reduced in ectomycorrhizal and ericoid mycorrhizal plants including Betula, Salix, Picea mariana (P. Mill.) B.S.P., Picea glauca Moench (Voss), and ericaceous plants. Compared with the . 15 N content of soil, the foliage of nonmycorrhizal plants (Carex and Eriophorum) was unchanged, whereas content of the ecto- mycorrhizal fungi was very much higher (e.g., Boletaceae, Leccinum and Cortinarius). It is hypothesized that similar proc- esses operate in tundra and boreal forest, both nitrogen-limited ecosystems: (i) mycorrhizal fungi break down soil polymers and take up amino acids or other nitrogen compounds; (ii) mycorrhizal fungi fractionate against . 15 N during production of transfer compounds; (iii) host plants are accordingly depleted in . N; and (iv) mycorrhizal fungi are enriched in . 15 N. In- creased N availability for plant roots or decreased light availability to understory plants may have decreased N allocation to mycorrhizal partners and increased d. Nb y 3%-4% for southern populations of Vaccinium vitis-idaea L. and Salix. Fungal
TL;DR: The bacterial diversity exhibited an altitude gradient with a gradual decline in the number of genera with increase in altitude, and the isolates exhibited close phylogenetic affinities to bacteria from other cold habitats.
Abstract: High-altitude cold habitats of the Himalayas are little explored with respect to bacterial diversity. Diverse bacterial species and phylotypes obtained by culture-dependent and culture-independent ...
TL;DR: A successful and significant improvement in the production of protease by the A26 strain was accomplished using inexpensive carbon substrate (hulled grain of wheat), allowing a significant reduction in the cost of medium constituents.
Abstract: A fibrinolytic enzyme producing bacterium was isolated and identified as Bacillus subtilis A26 on the basis of the 16S rRNA gene sequence. The fibrin zymography analysis reveals the presence of at least three fibrinolytic enzymes. The crude enzyme exhibited maximal activity at 60 °C and pH 8.0. Medium composition and culture conditions for the enzyme production by B. subtilis A26 were optimized using two statistical methods. The Plackett–Burman statistical design was applied to find the key ingredients and conditions for the best yield of enzyme production. Five significant variables (hulled grain of wheat, casein peptone, NaCl, CaCl2, and initial pH) were selected for the optimization studies. The response surface methodological approach was used to determine the optimal concentrations and conditions. The optimized medium contained 40.0 g·L–1 hulled grain of wheat, 3.53 g·L–1 casein peptone, 4.0 g·L–1 CaCl2, 3.99 g·L–1 NaCl, 0.01 g·L–1 MgSO4, and 0.01 g·L–1 KH2PO4, pH 7.78. The medium optimization result...
TL;DR: For the first time, a Gram-negative bacterium, Fusobacterium nucleatum, is shown to produce and secrete poly-gamma-glutamate, suggesting that it has a role in virulence for pathogens and one in survival for other Gram- negative bacteria.
Abstract: Poly-gamma-glutamate has been described in many Gram-positive organisms. When anchored to the surface, it is a capsule and as such a virulence factor. Based on sequence similarities, few Gram-negative organisms have been suggested to synthesize poly-gamma-glutamate. For the first time, a Gram-negative bacterium, Fusobacterium nucleatum, is shown to produce and secrete poly-gamma-glutamate. Putative poly-gamma-glutamate-synthesizing genes from Gram-negative organisms have been compared with their Gram-positive homologs by in silico analysis, i.e., gene sequence and phylogenetic analysis. Clusters of three instead of four genes were highlighted by our screen. The products of the first two genes display similarity with their Gram-positive equivalents, yet the sequences from the Gram-negative organisms can be distinguished from those of the Gram-positives. Interestingly, the sequence of the predicted product of the third gene is conserved among Gram-negative bacteria but displays no similarity to that of either the third or fourth gene of the Gram-positive operons. It is suggested that, like for Gram-positive bacteria, poly-gamma-glutamate has a role in virulence for pathogens and one in survival for other Gram-negative bacteria.
TL;DR: Observations point to the importance of changes in the quantity and chemistry of the exopolymeric matrix in the response to antimicrobial agents and suggest their importance as targets for control.
Abstract: Confocal laser scanning microscopy (CLSM) and scanning transmission X-ray microscopy (STXM) were used to examine the morphological and biochemical changes in Pseudomonas fluorescens biofilms grown ...
TL;DR: The principle component analysis and regression analyses revealed that the gene expression and the biomolecular responses are not well correlated in stressed populations of E. coli, underlining the importance of multiple strategies to begin to understand the effect on the whole cell.
Abstract: The global gene expression and biomolecular composition in an Escherichia coli model strain exposed to 10 adverse conditions (sodium chloride, ethanol, glycerol, hydrochloric and acetic acid, sodiu...
TL;DR: The results strongly suggest that the SR-rich motif is critical for effective virus replication in SARS-CoV.
Abstract: The multimerization/self-interaction of viral proteins is an important step in the process of viral assembly and maturation. Our previous study indicated that the severe acute respiratory syndrome-...
TL;DR: The characterization of surfactin-producing Bacillus subtilis isolates collected from different ecological zones of Iran is presented, and bioassay results indicated that isolate BS119m showed high inhibitory effects against A. flavus and C. gloeosporioides.
Abstract: The characterization of surfactin-producing Bacillus subtilis isolates collected from different ecological zones of Iran is presented. Characterization was performed using blood agar, PCR, drop-collapse, and reverse-phase high-performance liquid chromatography (HPLC) analyses, and the isolates' biocontrol effects against the aflatoxin-producing agent Aspergillus flavus and the citrus antracnosis agent Colletotrichum gloeosporioides were studied. In total, 290 B. subtilis isolates were isolated from phylosphere and rhizosphere samples collected from fields and gardens of 5 provinces of Iran. Blood agar assays showed that 185 isolates produced different biosurfactants. Isolates containing the sfp gene, coding for surfactin, were detected using the PCR method. It was found that 14 different isolates contained the sfp gene. Drop-collapse assays, which detect isolates with high production of surfactin, showed that 7 isolates produced high levels of surfactin. It was found from HPLC analysis that the isolates containin the sfp gene produced between 55 and 1610 mg of surfactin per litre of broth medium. Four isolates, named BS119m, BS116l, N3dn, and BS113c, produced more than 1000 mg of surfactin per litre of broth. The highest surfactin production level was observed for isolate BS119m (1610 mg/L). The antagonistic potential of the sfp gene-containing isolates was determined using dual culture and chloroform vapour methods. Our bioassay results indicated that isolate BS119m showed high inhibitory effects against A. flavus (100%) and C. gloeosporioides (88%). Furthermore, the effect of purified surfactin on the growth of A. flavus was evaluated. Mycelia growth was considerably reduced with increasing concentration of surfactin, and 36%, 54%, 84%, and 100% inhibitions of mycelia growth were, respectively, observed at 20, 40, 80, and 160 mg/L after 7 days of incubation.
TL;DR: The protocol included use of a quenching agent to rapidly reduce ozone concentrations to safe levels allowing treatment times of less than 1 h for the majority of organisms tested and reductions in bacterial load of greater than 3 log values were recorded for a number of organisms.
Abstract: Environmental disinfection in a health care setting is an important aspect of infection control. Recently, there has been interest in the use of vapor- and gas-based treatments for decontamination of surfaces and rooms. We describe preliminary results for an ozone-based decontamination of surfaces seeded with a range of vegetative cells and spores of bacteria of clinical relevance. The efficacy of the approach for room sanitization was also assessed. The protocol included use of a quenching agent to rapidly reduce ozone concentrations to safe levels allowing treatment times of less than 1 h for the majority of organisms tested. Using bacteria seeded onto agar plates and solid surfaces, reductions in bacterial load of greater than 3 log values were recorded for a number of organisms including Escherichia coli and methicillin-resistant Staphylococcus aureus. Application of the process in a 30 m3 room showed similar reductions in viable counts for these organisms and for Clostridium difficile spores. We suggest that the potential of this ozone-quench approach should be further evaluated for disinfection or decontamination of healthcare environments.
TL;DR: Inoculation with the Microbacterium sp.
Abstract: A polycyclic aromatic hydrocarbon degrading bacterium isolated from oil-polluted soil was identified as Microbacterium sp. F10a based on 16S rDNA gene sequence analysis. Plant growth promoting characteristics of the strain, degradation rate of phenanthrene and pyrene, and cell surface hydrophobicity characteristics of the strain were further characterized. The strain was also evaluated for promoting the growth of wheat and phenanthrene and pyrene removal from soil artificially contaminated with a mixture of phenanthrene (200 mg.kg-1) and pyrene (150 mg.kg-1) in pot experiments. The strain had the plant growth promoting characteristics of producing indole acetic acid, siderophore, and 1-aminocyclopropane-1-carboxylate deaminase activity and solubilizing inorganic phosphate. The strain also has a cell surface hydrophobicity that could increase the aqueous polycyclic aromatic hydrocarbon solubility. High-performance liquid chromatographic analysis showed that the degradation rates of phenanthrene (50 mg.L-1) and pyrene (20 mg.L-1) were 98% and 65%, respectively, under 28 degrees C after 7 days. Inoculation with the strain was found to significantly increase (p < 0.05) the growth of wheat and phenanthrene and pyrene removal in the unplanted or planted soils in a low-temperature environment. There were no significant differences in culturable bacterial numbers between live bacterial inoculation and dead bacterial inoculation controls in the unplanted and planted soils. However, the numbers of polycyclic aromatic hydrocarbon degrading bacteria were significantly greater in the inoculated planted or unplanted soils compared with the dead bacterial inoculation controls.
TL;DR: The DNA concentrations and soil microbial C and N correlated positively and significantly, suggesting that these are decisive nutrients for microbial growth and time required for microbial biomass renewal.
Abstract: Microbial populations are primarily responsible for the decomposition of organic residues, the nutrients cycle, and the flow of energy inside of soil. The present study was undertaken to link soil ...
TL;DR: This paper found Cadophora species previously found to attack historic wooden structures on Ross Island, Antarctica, were found at all but 1 location sampled in the Peninsula region, and they were cultured on several different media and pure cultures obtained and identified by DNA sequencing of the internal transcribed spacer region.
Abstract: Investigations of microbial diversity in Antarctic are important to begin to understand ecosystem functioning and decomposition processes. This study documents fungi at 9 historic sites on the Antarctic Peninsula collected from wooden structures, other organic materials, and soils during a joint National Science Foundation and British Antarctic Survey expedition in 2007. Many of these sites had wooden structures built by the British during the World War II Operation Tabarin, but others visited included the American “East Base” on Stonington Island and the Swedish hut on Snow Hill Island. Fungi were cultured on several different media and pure cultures were obtained and identified by DNA sequencing of the internal transcribed spacer region. Cadophora species previously found to attack historic wooden structures on Ross Island, Antarctica, were found at all but 1 location sampled in the Peninsula region. Fungi causing decay in the historic wooden structures and artifacts and those causing mold problems insi...