| 1. |
- Ascencio, F, et al.
(författare)
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Production and secretion of collagen-binding proteins from Aeromonas veronii
- 2000
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 89:4, s. 607-616
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Tidskriftsartikel (refereegranskat)abstract
- Collagen-binding protein (CNBP) synthesized by Aeromonas veronii is located conserved within the subcellular fraction. The results of this study show that 98% of the total CNBP produced by Aer. veronii is present in the extracellular medium, and that the remaining CNBP is distributed either on the cell surface, within the periplasm or anchored on the outer membrane. CNBP is specifically secreted from Aer. veronii into the culture medium, because all the -lactamase activity was located in the cells and could be released by polymixin B extraction of periplasmic proteins. CNBP was produced at growth temperatures from 12 °C to 42 °C, but not at 4 °C. The findings indicate that the level of CNBP in the medium increases during the exponential growth phase and reaches a maximum during the early stationary phase. There was less CNBP production in poor nutrient MMB medium than in the rich LB nutrient medium. CNBP secretion, in contrast to aerolysin secretion, was unaffected by the exeA mutation of Aer. hydrophila. It is concluded that CNBP secretion from Aer. veronii must be achieved by a mechanism different from that reported for aerolysin secretion.
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| 2. |
- Bengtsson, Göran, et al.
(författare)
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Effects of carbon substrate enrichment and DOC concentration on biodegradation of PAHs in soil
- 2003
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 94:4, s. 608-617
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Two common reasons to explain slow environmental biodegradation of polycyclic aromatic hydrocarbons (PAHs), namely lack of appropriate carbon sources for microbial growth and limited bioavailability of PAHs, were tested in a laboratory bioassay using a creosote-contaminated soil. Methods and Results: The soil, containing a total of 8 mg g(-1) of 16 PAHs, was sieved and incubated in bottles for 45 days. The first explanation was tested by enrichment with the analogue anthracene and the non-analogue myristic acid, and both failed to stimulate degradation of all PAHs except anthracene. The second explanation was tested by addition of different concentrations of dissolved organic carbon (DOC), with effects depending on the DOC concentration and the molecular size of the PAH. The degradation was enhanced from 10 to 35% for 12 PAHs when the soil was saturated. The degraded amounts of individual PAHs were proportional to their concentration in the soil. Conclusions: The slow in situ degradation of PAHs was enhanced by more than three times by adding water as a solvent. Addition of DOC facilitated the degradation of four- to six-ring PAHs. Significance and Impact of Study: Bioremediation of PAH-contaminated sites may be facilitated by creating water-saturated conditions but retarded by addition of other carbon substrates, such as analogue compounds.
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| 3. |
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| 4. |
- D'Aimmo, Maria Rosaria, 1975, et al.
(författare)
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The potential of bifidobacteria as a source of natural folate
- 2012
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1365-2672 .- 1364-5072. ; 112:5, s. 975-984
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To screen 19 strains of bifidobacteria for main folate forms composition in synthetic folate-free and complex folate-containing media. Methods and Results: HPLC was used to analyse deconjugated folates extracted from bacterial biomass. Most strains had a total folate content above 4000 mu g per 100 g dry matter (DM). The highest value of 9295 mu g per 100 g DM was found in Bifidobacterium catenulatum ATCC 27539 and the lowest in Bifidobacterium animalis ssp. animalis ATCC 25527 containing 220 mu g per 100 g DM. Ten strains grew in a synthetic folate-free medium (FFM), showing folate autotrophy and suggesting folate auxotrophy of the remaining nine. In the autotrophic strains, a consistently higher folate level was found in FFM as compared to a more complex folate-containing medium, suggesting reduced requirements for folates in the presence of growth factors otherwise requiring folates for synthesis. The contents of total folate, 5-CH3-H(4)folate and H(4)folate were strain dependent. 5-CH3-H(4)folate dominated in most strains. Conclusions: Our results show that bifidobacteria folate content and composition is dynamic, is strain specific and depends on the medium. Suitable selection of the growth conditions can result in high levels of folate per cell unit biomass. Significance and Impact of the Study: This suggests that certain bifidobacteria may contribute to the folate intake, either directly in foods, such as fermented dairy products, or in the intestine as folate-trophic probiotics or part of the natural microbiota.
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| 5. |
- Jarvis, Åsa, et al.
(författare)
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Activity and composition of ammonia oxidizing bacterial communities and emission dynamics of NH3 and N2O in a compost reactor treating organic household waste
- 2009
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Ingår i: JOURNAL OF APPLIED MICROBIOLOGY. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 106:5, s. 1502-1511
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Tidskriftsartikel (refereegranskat)abstract
- To monitor emissions of NH3 and N2O during composting and link these to ammonia oxidation rates and the community structure of ammonia oxidizing bacteria (AOB). A laboratory-scale compost reactor treating organic household waste was run for 2 months. NH3 emissions peaked when pH started to increase. Small amounts of N2O and CH4 were also produced. In total, 16% and less than 1% of the initial N was lost as NH3-N and N2O-N respectively. The potential ammonia oxidation rate, determined by a chlorate inhibition assay, increased fourfold during the first 9 days and then remained high. Initially, both Nitrosospira and Nitrosomonas populations were detected using DGGE analysis of AOB specific 16S rRNA fragments. Only Nitrosomonas europaea was detected under thermophilic conditions, but Nitrosospira populations re-established during the cooling phase. Thermophilic conditions favoured high potential ammonia oxidation rates, suggesting that ammonia oxidation contributed to reduced NH3 emissions. Small but significant amounts of N2O were emitted during the thermophilic phase. The significance of different AOBs detected in the compost for ammonia oxidation is not clear. This study shows that ammonia oxidation occurs at high temperature composting and therefore most likely reduces NH3 emissions.
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| 6. |
- Li, Yujing, et al.
(författare)
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Impact of temperature on growth and metabolic efficiency of Penicillium roqueforti - Correlations between produced heat, ergosterol content and biomass
- 2009
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 106:Online 4 Feb 2009, s. 1494-1501
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Tidskriftsartikel (refereegranskat)abstract
- The influence of temperature on the growth of the mould Penicillium roqueforti growing on malt extract agar was studied by correlating the produced heat (measured by isothermal calorimetry), ergosterol content (quantified by GC-MS/MS) and biomass of the mould at 10, 15, 20, 25 and 30°C. The results were analysed with a simple metabolic model from which the metabolic efficiency was calculated. The results show that the impact of temperature on growth rate and metabolic efficiency are different: although the mould fungus had the highest growth rate (in terms of thermal power, which was continuously measured) at 25°C, the substrate carbon conversion efficiency (biomass production divided by substrate consumption, both counted as moles carbon) was highest at 20°C. The temperature of the most rapid growth did therefore not equal the temperature of the most efficient growth.
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| 7. |
- Liu, Zhidan, et al.
(författare)
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Effects of inoculation strategy and cultivation approach on the performance of microbial fuel cell using marine sediment as bio-matrix
- 2008
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 104:4, s. 1163-1170
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To investigate the effects of inoculation strategy and cultivation approach on the performance of microbial fuel cell (MFC). Methods and Results: A dual-chamber sediment fuel cell was set up fed with glucose under batch condition. At day 30, the supernatant consortium was partly transferred and used as inoculum for the evaluation of cultivation approach. Power output gradually increased to 9.9 mW m(-2) over 180 days, corresponding to coulombic efficiency (CE) of 29.6%. Separated biofilms attached anode enabled power output and CE dramatically up to 100.9 mW m(-2) and over 50%, respectively, whereas the residual sediment catalysed MFC gave a poor performance. MFC catalysed by in situ supernatant consortium demonstrated more than twice higher power than MFC catalysed by the supernatant consortium after Fe(OH)(3) cultivation. However, the re-generation of biofilms from the latter largely enhanced the cell performance. Conclusions: MFC exhibited a more efficient inducement of electroactive consortium than Fe(OH)(3) cultivation. MFC performance varied depending on different inoculation strategies. Significance and Impact of the Study: This is the first time to study cultivation approach affecting electricity generation. In addition, anodic limitations of mass and electron transfer were discussed through MFC catalysed by sediment-based bio-matrix.
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| 8. |
- Masurat, Peter, 1970, et al.
(författare)
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Identification of Meiothermus as the dominant genus in a storage system for spent nuclear fuel
- 2005
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 98:3, s. 727-740
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To characterize the biofilms in an interim wet storage system (CLAB) for spent nuclear fuel. Methods and Results: Planktonic cells and biofilms were analysed with fluorescence microscopy, and scanning and transmission electron microscopy. The organisms in the biofilms were filamentous, consisting of sheaths with series of rod-shaped cells in them. Planktonic cell populations ranged between 1·4 × 103 and 5·2 × 103 ml-1, correlated with the system configuration, and was inversely correlated with total organic carbon (TOC) levels. Analysis of 16S rDNA indicated that a potentially novel Meiothermus sp. was dominant in the CLAB biofilms. A Meiothermus-specific probe was designed, and statistical analysis of fluorescence in situ hybridization results confirmed that Meiothermus sp. composed up to 98% of the biofilm. The low TOC levels (255 μg l-1) in the system combined with elevated water temperatures (ca 36°C) mimic the natural environments of Meiothermus sp. as well as the recommended conditions for isolating Meiothermus sp., thus supporting the results of the 16S rDNA analysis. Conclusions: A possibly novel Meiothermus sp. is the predominant genus found in the CLAB biofilms. Significance and Impact of the Study: TOC levels are often kept low to protect industrial systems from biofouling. However, the present study shows that, rather than protecting industrial systems against biofouling per se, maintaining low TOC levels might still result in biofilms, dominated by new, unknown bacterial species.
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| 9. |
- Pedersen, Karsten, 1952
(författare)
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Analysis of copper corrosion in compacted bentonite clay as a function of clay density and growth conditions for sulfate-reducing bacteria
- 2010
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 108:3, s. 1094-1104
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Tidskriftsartikel (refereegranskat)abstract
- Aims: This work investigated the relationships between sulfate-reducing bacteria (SRB), growth conditions, bentonite densities, and copper sulfide generation under circumstances relevant to underground, high-level radioactive waste repositories. Methods and Results: Experiments took place 450 m underground, connected under in situ pressure to groundwater containing SRB. The microbial reduction of sulfate to sulfide and subsequent corrosion of copper test plates buried in compacted bentonite were analysed using radioactive sulfur (35SO42−) as tracer. Mass distribution of copper sulfide on the plates indicated a diffusive process. The relationship between average diffusion coefficient (Ds) and tested density (ρ) was linear. Ds (m2 s−1) = −0.004 ×ρ (kg m−3) + 8.2, decreasing by 0.2 Ds units per 50 kg m−3 increase in density, from 1·2 × 10−11 m2 s−1 at 1750 kg m−3 to 0·2 × 10−11 m2 s−1 at 2000 kg m−3 Conclusions: Sulfide corrosion of waste canisters in future radioactive waste repositories likely depends mainly on sulfide concentration at the boundary between groundwater and the buffer, which in turn depends on SRB growth conditions (e.g., sulfate accessibility, carbon availability, and electron donors) and geochemical parameters (e.g., presence of ferrous iron, which immobilizes sulfide). Maintaining high bentonite density is also important in mitigating canister corrosion. Significance and impact of the study: The sulfide diffusion coefficients can be used in safety calculations regarding waste canister corrosion. The work supports findings that microbial activity in compacted bentonite will be restricted. The study emphasizes the importance of growth conditions for sulfate reduction at the groundwater boundary of the bentonite buffer and linked sulfide production.
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| 10. |
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| 11. |
- Quillaguaman, Jorge, et al.
(författare)
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Poly(beta-hydroxybutyrate) production by a moderate halophile, Halomonas boliviensis LC1 using starch hydrolysate as substrate
- 2005
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 99:1, s. 151-157
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The objective of the present work was to enable the use of starch hydrolysate, generated by the action of a recombinant maltooligosaccharide forming amylase from Bacillus halodurans LBK 34, as the carbon source for the production of poly-beta- hydroxybutyrate ( PHB) by Halomonas boliviensis LC1. Methods and Results: In this work, different amounts of the alpha- amylase ( Amy 34) were utilized for starch hydrolysis, resulting in the production of mixtures of maltooligosaccharides ( G1 - G6) at varying ratios. The highest PHB accumulation ( 56 wt%) by H. boliviensis cultivated in shake flasks ( with agitation at 160 rev min(-1)) was obtained when 6.4 U ml(-1) of the amylase was used for starch hydrolysis. When H. boliviensis cells were grown in a fermentor with no oxygen limitation the accumulation of PHB was decreased to 35 wt%. Although some improvements in PHB accumulation and cell mass concentration were reached by the addition of peptone and phosphate, respectively, major enhancements were attained when oxygen limitation was induced in the fermentor. Conclusions: Halomonas boliviensis uses preferentially maltose for PHB formation from starch hydrolysate. It is also able to hydrolyse higher sugars if no other simpler carbon source is available but with a significantly lower polymer yield. Furthermore, H. boliviensis is able to adjust its metabolism to oxygen limitation, most probably by directing the excess NAD( P) H to PHB accumulation. Significance and Impact of the Study: There have been no reports related to PHB production amongst the members of the genus Halomonas. The use of a maltooligosaccharide forming alpha- amylase, which is active at a temperature and pH close to that required for growth of H. boliviensis, and the versatility of this bacterium in the selection of the carbon source may provide an attractive alternative for the utilization of starch- derived raw materials.
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| 12. |
- Waldenström, Jonas, et al.
(författare)
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Species diversity of campylobacteria in a wild bird community in Sweden
- 2007
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 102:2, s. 424-432
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Tidskriftsartikel (refereegranskat)abstract
- To analyse the occurrence and host species distribution of campylobacteria species in shorebirds, geese and cattle on grazed coastal meadows in Sweden. Species identification was performed through a polyphasic approach, incorporating Amplified Fragment Length Polymorphism (AFLP) profiling, 16S RNA gene sequence analysis together with extensive phenotypic characterization. From 247 sampled birds and 71 cattle, we retrieved 113 urease positive thermophilic Campylobacter (UPTC) and 16 Campylobacter jejuni ssp. jejuni isolates. Furthermore, 18 isolates of Helicobacter canadensis, and five isolates that potentially represent a new genus of micro-aerophilic, spiral and Gram-negative bacteria were isolated. The distribution of bacterial species on hosts was uneven: all H. canadensis isolates were retrieved from geese, while all but one of the Campylobacter lari UPTC isolates were found in shorebirds. AFLP type distribution of Camp. lari UPTC isolates among individual, resampled and breeding-paired Redshank birds generally indicated a constant shift in strain populations over time and absence of geographical clustering. The large number of isolated campylobacteria, including species that are zoonotic enteropathogens, indicates that these wild birds potentially may serve as reservoirs of human infections. However, despite a common environment, the different host species largely carried their own campylobacteria populations, indicating that cross-species transmission is rare. Our study is one of few that provide data on the occurrence of campylobacteria in wild animals, adding information on the ecology and epidemiology of micro-organisms that are of public health concern.
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| 13. |
- Löfblom, John, et al.
(författare)
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Optimization of electroporation-mediated transformation : Staphylococcus carnosus as model organism
- 2007
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 102:3, s. 736-747
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Tidskriftsartikel (refereegranskat)abstract
- The study was conducted with an aim to optimize the transformation efficiency of the Gram-positive bacterium Staphylococcus carnosus to a level that would enable the creation of cell surface displayed combinatorial protein libraries. Methods and Results: We have thoroughly investigated a number of different parameters for: (i) the preparation of electrocompetent cells; (ii) the treatment of cells before electroporation; (iii) the electroporation step itself; and (iv) improved recovery of transformed cells. Furthermore, a method for heat-induced inactivation of the host cell restriction system was devised to allow efficient transformation of the staphylococci with DNA prepared from other species, such as Escherichia coli. Previously described protocols for S. carnosus, giving transformation frequencies of approximately 10(2) transformants per transformation could be improved to reproducible procedures giving around 10(6) transformants for a single electroporation event, using plasmid DNA prepared from either S. carnosus or E. coli. The transformed staphylococcal cells were analysed using flow cytometry to verify that the entire cell population retained the introduced plasmid DNA and expressed the recombinant protein in a functional form on the cell surface at the same level as the positive control population. Conclusions: The results demonstrate that the transformation frequency for S. carnosus could be dramatically increased through optimization of the entire electroporation process, and that the restriction barrier for interspecies DNA transfer, could be inactivated by heat treatment of the cells prior to electroporation. Significance and Impact of the Study: The generation of large combinatorial protein libraries, displayed on the surface of S. carnosus can be envisioned in the near future, thus dramatically improving the selection compared with the traditional biopanning procedure used in phage display.
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| 14. |
- Cirne, Dores, et al.
(författare)
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Hydrolysis and microbial community analyses in two-stage anaerobic digestion of energy crops
- 2007
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 103:3, s. 516-527
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Tidskriftsartikel (refereegranskat)abstract
- Aims: The roles of the diverse populations of micro-organisms responsible for biodegradation of organic matter to form methane and carbon dioxide are rudimentarily understood. To expand the knowledge on links between microbial communities and the rate limiting, hydrolytic stage of two-stage biogas production from energy crops, this study was performed. Methods and Results: The process performance. and microbial communities (as determined by fluorescence in situ hybridization) in two separate two-stage batch digestions of sugar beets and grass/clover were studied. The microbial populations developed in the hydrolytic stage of anaerobic digestion of beets and grass/clover showed very few similarities, despite that the hydrolysis dynamics were similar. In both substrates, the solubilization of organic material was rapid for the first 10 days and accompanied by a build-up of volatile fatty acids (VFAs) and lactate. Between days 10 and 15, VFA and lactate concentrations decreased, as did the solubilization rates. For both substrates, Archaea started to appear in the hydrolytic stage between days 10 and 15, and the fraction of Bacteria decreased. The major bacterial group detected in the leachate fraction for beets was Alphaproteobacteria, whereas for grass/clover it was Firmicutes. The number of cells that bound to probes specifically targeting bacteria with cellulolytic activity was higher in the digestion of grass than in the digestion of beet. Conclusions: This study allowed the identification of the general bacterial groups involved, and the identification of a clear shift in the microbial population when hydrolysis rate became limiting for each of the substrates investigated. Significance and Impact of the Study: The findings from this study could be considered as a first step towards the development of strategies to stimulate hydrolysis further and ultimately increasing the methane production rates and yields from reactor-based digestion of these substrates.
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| 15. |
- Doan Van, Thuoc, et al.
(författare)
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Utilization of agricultural residues for poly(3-hydroxybutyrate) production by Halomonas boliviensis LC1
- 2008
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 104:2, s. 420-428
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Utilization of cheap and readily available agricultural residues as cheap carbon sources for poly(3-hydroxybutyrate) (PHB) production by Halomonas boliviensis. Methods and results: Wheat bran was hydrolysed by a crude enzyme preparation from Aspergillus oryzae NM1 to provide a mixture of reducing sugars composed mainly of glucose, mannose, xylose and arabinose. Growth of H. boliviensis using a mixture of glucose (0.75% w/v) and xylose (0.25% w/v) in the medium led to a PHB content and concentration of 45 wt% and 1 g l(-1), respectively, after 30 h. A similar PHB concentration was attained when H. boliviensis was grown on wheat bran hydrolysate but with a lower PHB content, 34 wt%. In a batch cultivation mode in a fermentor, using 1.8% (w/v) reducing sugars, the maximum PHB accumulation by H. boliviensis was attained in 20 h, but was reduced to about 30 wt%. By adding butyric acid (0.8% v/v), sodium acetate (0.8% w/v) and decreasing the reducing sugars concentration to 1.0% w/v in the medium, PHB accumulation and concentration were increased to 50 wt% and 4 g l(-1), respectively, after 20 h. Butyric acid and sodium acetate for PHB production could also be provided by anaerobic digestion of solid potato waste. Conclusions: Cheap and readily available agricultural residues can be used as substrates to produce PHB. The production of PHB by H. boliviensis using wheat bran hydrolysate as source of carbon is expected to reduce the production cost and motivates further studies. Significance and Impact of the Study: Large-scale commercial utilization of PHB is mainly hampered by its high production cost. Carbon source for PHB production accounts up to 50% of the total production costs. Thus, the use of waste agricultural residues can substantially reduce the substrate cost (and in turn even provide value to the waste), and can downsize the production costs. This improves the market competitiveness. Studies on PHB production by moderate halophiles were recently initiated with H. boliviensis and findings show that it has potential for commercial exploitation. PHB production by H. boliviensis using wheat bran and potato waste is hence interesting.
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| 16. |
- Antal, Taras, et al.
(författare)
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Production of H2 by sulphur-deprived cells of the unicellular cyanobacteria Gloeocapsa alpicola and Synechocystis sp. PCC 6803 during dark incubation with methane or a various extracellular pH
- 2005
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 98, s. 114-120
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To examine sulphur (S) deprivation in combination with the presence of methane (CH4) and changes in extracellular pH as a method to enhance in situ hydrogen (H2) generation during fermentation in the unicellular non-diazotrophic cyanobacteria Gloeocapsa alpicola and Synechocystis PCC 6803.Methods and Results: The level of H2 production, measured using a gas chromatography, was determined in S-deprived cells of G. alpicola and Synechocystis PCC 6803 during fermentation. Starvation on S enhanced the rate of H2 production by more than fourfold in both strains. S-deprived cyanobacteria were able to maintain maximum rate of H2 production during at least 8 h of fermentaion representing the entire dark period of a day. Increased H2 production was observed during dark anoxic incubation with a gas phase of 100% CH4 (up to four times) at lower pH of the medium (5.0-5.5)Conclusions: S-deprivation in combination with CH4, added or maybe produced by another micro-organisms, and the changes in the pH of the media can be used to further increase the specific capacity of unicellular non-N2-fixing cyanobacteria to produce H2 during fermentaion with the overall aim of applying it for outdoor photobiological H2 production.Significance and Impact of the Studies: S-deprivation with respect to H2 production is well studied in the green algae Chlamydomonas reinhardtii while its application for H2 production of cyanobacteria is novel. Similarly, the stimulation of H2 generation in the presence of CH4 opens up new possibilities to increase the H2 production. Natural gas enriched with H2 seems to be a perspective fuel and may be an intermediate step on the pathway to the exploitation of pure biohydrogen.
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| 17. |
- Bagge, Elisabeth, et al.
(författare)
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Diversity of spore-forming bacteria in cattle manure, slaughterhouse waste and samples from biogas plants
- 2010
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 109, s. 1549-1565
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Tidskriftsartikel (refereegranskat)abstract
- Aims:As biowaste intended for biogas production can contain pathogenic micro-organisms, the recommended treatment is pasteurization at 70 degrees C for 60 min. This reduces pathogens such as Salmonella spp., whereas spore-forming bacteria (Bacillus spp. and Clostridium spp.) survive. Most spore-forming bacteria are harmless, but some can cause diseases such as blackleg, botulism and anthrax. In this study, the effect of the biogas process on Bacillus spp. and Clostridium spp. was investigated.Methods and Results:We analysed 97 faecal samples, 20 slaughterhouse waste samples and 60 samples collected at different stages in the biogas process. Bacillus spp. and Clostridium spp. were quantified and subcultured. The isolates were identified by biochemical methods and by 16S rRNA gene sequencing. Phylogenetic trees were constructed from the sequences obtained from isolates from the samples. Clostridium botulinum/Clostridium spp. and Clostridium sordellii were found both before and after pasteurization, but not after digestion (AD). Some of the isolated strains probably represented new members of the genera Clostridium and Bacillus.Conclusion:After digestion, the numbers of clostridia decreased, but none of the pathogenic bacteria did, whereas Bacillus spp. remained constant during the process.Significance and Impact of the Study:Biogas is gaining in importance as an energy source and because the residues are used as fertilizers, we needed to study the prevalence of pathogenic bacteria in such material.
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| 18. |
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| 19. |
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| 20. |
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| 21. |
- Borjesson, Stefan, et al.
(författare)
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Methicillin-resistant Staphylococcus aureus (MRSA) in municipal wastewater: an uncharted threat?
- 2010
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Ingår i: JOURNAL OF APPLIED MICROBIOLOGY. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 108:4, s. 1244-1251
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Tidskriftsartikel (refereegranskat)abstract
- Aims: (i) To cultivate methicillin-resistant Staphylococcus aureus (MRSA) from a full-scale wastewater treatment plant (WWTP), (ii) To characterize the indigenous MRSA-flora, (iii) To investigate how the treatment process affects clonal distribution and (iv) To examine the genetic relation between MRSA from wastewater and clinical MRSA. Methods: Wastewater samples were collected during 2 months at four key sites in the WWTP. MRSA isolates were characterized using spa typing, antibiograms, SSCmec typing and detection of Panton-Valentine leukocidin (PVL). Conclusions: MRSA could be isolated on all sampling occasions, but only from inlet and activated sludge. The number of isolates and diversity of MRSA were reduced by the treatment process, but there are indications that the process was selected for strains with more extensive antibiotic resistance and PVL+ strains. The wastewater MRSA-flora had a close genetic relationship to clinical isolates, most likely reflecting carriage in the community. Significance and Impact of the Study: This study shows that MRSA survives in wastewater and that the WWTP may be a potential reservoir for MRSA.
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| 22. |
- Egervärn, Maria, et al.
(författare)
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Identification and characterization of antibiotic resistance genes in Lactobacillus reuteri and Lactobacillus plantarum
- 2009
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 107, s. 1658-1668
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Tidskriftsartikel (refereegranskat)abstract
- Aims:The study aimed to identify the resistance genes mediating atypical minimum inhibitory concentrations (MICs) for tetracycline, erythromycin, clindamycin and chloramphenicol within two sets of representative strains of the species Lactobacillus reuteri and Lactobacillus plantarum and to characterize identified genes by means of gene location and sequencing of flanking regions.Methods and Results:A tet(W) gene was found in 24 of the 28 Lact. reuteri strains with atypical MIC for tetracycline, whereas four of the six strains with atypical MIC for erythromycin were positive for erm(B) and one strain each was positive for erm(C) and erm(T). The two Lact. plantarum strains with atypical MIC for tetracycline harboured a plasmid-encoded tet(M) gene. The majority of the tet(W)-positive Lact. reuteri strains and all erm-positive Lact. reuteri strains carried the genes on plasmids, as determined by Southern blot and a real-time PCR method developed in this study.Conclusions:Most of the antibiotic-resistant strains of Lact. reuteri and Lact. plantarum harboured known plasmid-encoded resistance genes. Examples of putative transfer machineries adjacent to both plasmid- and chromosome-located resistance genes were also demonstrated.Significance and Impact of the Study:These data provide some of the knowledge required for assessing the possible risk of using Lact. reuteri and Lact. plantarum strains carrying antibiotic resistance genes as starter cultures and probiotics.
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| 23. |
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| 24. |
- Feng, X. M., et al.
(författare)
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Image analysis for monitoring the barley tempeh fermentation process
- 2007
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Ingår i: Journal of Applied Microbiology. - Oxon, United Kingdom : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 103:4, s. 1113-1121
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To develop a fast, accurate, objective and nondestructive method for monitoring barley tempeh fermentation. Methods and Results: Barley tempeh is a food made from pearled barley grains fermented with Rhizopus oligosporus. Rhizopus oligosporus growth is important for tempeh quality, but quantifying its growth is difficult and laborious. A system was developed for analysing digital images of fermentation stages using two image processing methods. The first employed statistical measures sensitive to image colour and surface structure, and these statistical measures were highly correlated (r = 0.92, n = 75, P < 0.001) with ergosterol content of tempeh fermented with R. oligosporus and lactic acid bacteria (LAB). In the second method, an image-processing algorithm optimized to changes in images of final tempeh products was developed to measure number of visible barley grains. A threshold of 5 visible grains per Petri dish indicated complete tempeh fermentation. When images of tempeh cakes fermented with different inoculation levels of R. oligosporus were analysed the results from the two image processing methods were in good agreement. Conclusion: Image processing proved suitable for monitoring barley tempeh fermentation. The method avoids sampling, is nonintrusive, and only requires a digital camera with good resolution and image analysis software. Significance and Impact of the Study: The system provides a rapid visualization of tempeh product maturation and qualities during fermentation. Automated online monitoring of tempeh fermentation by coupling automated image acquisition with image processing software could be further developed for process control.
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