| 1. |
- Ampomah, Osei Y., et al.
(författare)
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The trehalose utilization gene thuA ortholog in Mesorhizobium loti does not influence competitiveness for nodulation on Lotus spp
- 2014
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Ingår i: World Journal of Microbiology & Biotechnology. - : Springer Science and Business Media LLC. - 0959-3993 .- 1573-0972. ; 30:3, s. 1129-1134
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Tidskriftsartikel (refereegranskat)abstract
- Competitiveness for nodulation is a desirable trait in rhizobia strains used as inoculant. In Sinorhizobium meliloti 1021 mutation in either of the trehalose utilization genes thuA or thuB influences its competitiveness for root colonization and nodule occupancy depending on the interacting host. We have therefore investigated whether mutation in the thuA ortholog in Mesorhizobium loti MAFF303099 also leads to a similar competitive phenotype on its hosts. The results show that M. loti thuA mutant Ml7023 was symbiotically effective and was as competitive as the wild type in colonization and nodule occupancy on Lotus corniculatus and Lotus japonicus. The thuA gene in M. loti was not induced during root colonization or in the infection threads unlike in S. meliloti, despite its induction by trehalose and high osmolarity in in vitro assays.
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| 2. |
- Arthurson, Veronica
(författare)
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Storage conditions and animal source influence the dominant bacterial community composition in animal manure
- 2011
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Ingår i: World Journal of Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 0959-3993 .- 1573-0972. ; 27, s. 2013-2022
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to determine the impact of storage, animal diet, and animal source on the bacterial community composition of manure. The differences among bacterial community structures in fresh manure from cows on two different diets, cow manure stored in a deep pit for about one month, and fresh pig manure were compared. A molecular approach consisting of terminal restriction fragment length polymorphism (T-RFLP), in combination with sequence information from clone libraries, facilitated the identification of specific dominant bacterial populations that varied significantly among manures from different sources and treatments. One such population, represented by TRF 157, the most dominant peak of the bacterial community from stored manure, was identified as a Spirochaeta sp. Interestingly, this peak was absent in the fresh manure communities. The prevailing species in the fresh manure bacterial communities were distinct from those in manure from the storage pit, indicating a major shift in bacterial community composition induced by storage conditions. Moreover, distinct differences in bacterial communities were observed among animal source, but not animal feed. Manure storage is consequently an important parameter to consider when handling fertilizers, in order to obtain an optimal soil microbial ecosystem functioning.
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| 3. |
- Baebprasert, Wipawee, et al.
(författare)
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Na(+)-stimulated nitrate uptake with increased activity under osmotic upshift in Synechocystis sp strain PCC 6803
- 2011
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Ingår i: World Journal of Microbiology & Biotechnology. - : Springer Science and Business Media LLC. - 0959-3993 .- 1573-0972. ; 27:10, s. 2467-2473
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Tidskriftsartikel (refereegranskat)abstract
- In the non-diazotrophic cyanobacterium Synechocystis sp. strain PCC 6803, an osmolality of 30 and 40 mosmol/kg sorbitol and NaCl resulted in 3.5- and 4.5-fold increase of nitrate uptake, respectively. The NaCl-stimulated uptake was abolished by treatment with chloramphenicol. At 25 mosmol/kg or higher, NaCl induced higher nitrate uptake than sorbitol suggesting an ionic effect of Na(+). The nitrate uptake in Synechocystis showed K (s) and V (max) values of 46 mu M and 1.37 mu mol/min/mg Chl, respectively. Mutants disrupted in nitrate and nitrite reductase exhibited a decreased nitrate uptake. Ammonium, chlorate, and dl-glyceraldehyde caused a reduction of nitrate uptake. Dark treatment caused a drastic reduction of uptake by 70% suggesting an energy-dependent system. Nitrate transport was sensitive to various metabolic inhibitors including those dissipating proton gradients and membrane potential. The results suggest that nitrate uptake in Synechocystis is stimulated by Na(+) ions and requires energy provided by the functioning electron transport chain.
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| 4. |
- Bari, Ehsan, et al.
(författare)
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Fungal behavior and recent developments in biopulping technology
- 2024
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Ingår i: World Journal of Microbiology & Biotechnology. - : Springer Nature. - 0959-3993 .- 1573-0972. ; 40:7
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Tidskriftsartikel (refereegranskat)abstract
- Biological pretreatment of wood chips by fungi is a well-known approach prior to mechanical- or chemical pulp production. For this biological approach, a limited number of white-rot fungi with an ability to colonize and selectively degrade lignin are used to pretreat wood chips allowing the remaining cellulose to be processed for further applications. Biopulping is an environmentally friendly technology that can reduce the energy consumption of traditional pulping processes. Fungal pretreatment also reduces the pitch content in the wood chips and improves the pulp quality in terms of brightness, strength, and bleachability. The bleached biopulps are easier to refine compared to pulps produced by conventional methodology. In the last decades, biopulping has been scaled up with pilot trials towards industrial level, with optimization of several intermediate steps and improvement of economic feasibility. Nevertheless, fundamental knowledge on the biochemical mechanisms involved in biopulping is still lacking. Overall, biopulping technology has advanced rapidly during recent decades and pilot mill trials have been implemented. The use of fungi as pretreatment for pulp production is in line with modern circular economy strategies and can be implemented in existing production plants. In this review, we discuss some recent advances in biopulping technology, which can improve mechanical-, chemical-, and organosolv pulping processes along with their mechanisms.
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| 5. |
- Berg, Andreas, et al.
(författare)
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Cyanobacteria as a source of hydrogen for methane formation
- 2014
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Ingår i: World Journal of Microbiology & Biotechnology. - : Springer Verlag (Germany). - 0959-3993 .- 1573-0972. ; 30:2, s. 539-545
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Tidskriftsartikel (refereegranskat)abstract
- In a study during the 1970s co-variation of nitrogenase activity and methane formation associated with Sphagnum riparium was observed. This was suggested as evidence for a possible mechanism of hydrogen transfer from cyanobacteria to methanogens. We show experimentally that such a pathway is feasible. In a series of laboratory experiments, using a hydrogenase deficient strain of the heterocystous cyanobacterium Nostoc punctiforme and the hydrogenotrophic methanogen Methanospirillum hungateii in co-cultures, increasing light intensities resulted in elevated nitrogenase activity and methane production. The increase in methane production can be directly deduced from the nitrogenase activity of the N. punctiforme based on hydrogen balance calculations. These experimental results clearly suggest the possible existence of a novel photosynthetically regulated pathway for methane formation.
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| 6. |
- Cavero Olguin, Victor Hugo, et al.
(författare)
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Stress induced biofilm formation in Propionibacterium acidipropionici and use in propionic acid production.
- 2019
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Ingår i: World Journal of Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 0959-3993 .- 1573-0972. ; 35:101
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Tidskriftsartikel (refereegranskat)abstract
- Propionibacterium acidipropionici produces propionic acid from different sugars and glycerol; the production can be improved by high cell density fermentations using immobilized cells that help to overcome the limitations of the non-productive lag phase and product inhibition. In this study, the use of stress factors to induce P. acidipropionici to form biofilm and its use as an immobilization procedure in fermentations in bioreactors for producing propionic acid was investigated. Citric acid and sodium chloride increased exopolysaccharide production, biofilm capacity index and trehalose production. Analysis of the expression of trehalose synthesis-related genes otsA and treY by RT-qPCR showed significantly increased expression of only treY during log phase with citric acid, while FISH analysis showed expression of treY and luxS under the influence of both stress factors. The stress factors were then used for development of microbial biofilms as immobilization procedure on Poraver® and AnoxKaldnes® carriers in recycle batch reactors for propionic acid production from 20 g/L glycerol. Highest productivities of 0.7 and 0.78 g/L/h were obtained in Poraver® reactors, and 0.39 and 0.43 g/L/h in AnoxKaldnes® reactors with citric acid and NaCl, respectively.
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| 7. |
- Christakopoulos, Paul, et al.
(författare)
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Enhanced acetyl esterase production by Fusarium oxysporum
- 1999
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Ingår i: World Journal of Microbiology & Biotechnology. - 0959-3993 .- 1573-0972. ; 15:4, s. 443-446
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Tidskriftsartikel (refereegranskat)abstract
- Production of acetyl esterase (EC 3.1.1.6) by Fusarium oxysporum strain F3 was enhanced by optimization of growth conditions. Under optimal conditions, activities as high as 0.89 U/ml of culture medium were obtained. The culture filtrate was equally active on p-nitrophenyl acetate and acetylxylan. The enzyme produced 71% deacetylation of acetylxylan in 2 h at 40 ∘C. Activity was optimized at pH6.5 and at 55 ∘C. The respective Km values for p-nitrophenyl acetate and acetylxylan were 0.25 mM and 1.05% (w/v) and the Vm values were 0.65 and 0.43 μmol acetate/min/mg protein.
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| 8. |
- Deraz, Sahar, et al.
(författare)
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Production and physicochemical characterization of acidocin D20079, a bacteriocin produced by Lactobacillus acidophilus DSM 20079
- 2007
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Ingår i: World Journal of Microbiology & Biotechnology. - : Springer Science and Business Media LLC. - 0959-3993 .- 1573-0972. ; 23:7, s. 911-921
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Tidskriftsartikel (refereegranskat)abstract
- Lactobacillus acidophilus DSM 20079 is the producer of a novel bacteriocin termed acidocin D20079. In this paper, a partial sequence of this peptide is determined, together with data on its secondary structure. A modification of the MRS-growth medium (replacing the detergent Tween 80 with oleic acid), was shown to improve the production level of the peptide by one order of magnitude, as well as to stabilize the activity level. Addition of a detergent (Tween 20, less interfering in mass spectrometric analysis), was however necessary for solubilization of the purified acidocin D20079. Digestion of the peptide followed by de-novo sequencing of generated fragments, allowed determination of a partial sequence consisting of 39 of the totally estimated 65 residues. Acidocin D20079 has a high content of glycine residues, hydrophobic residues, and acidic residues. No modified amino acids were found. Edman degradation, and C-terminal sequencing failed, suggesting that the peptide may be cyclic, and a novel member of class IIc bacteriocins. Circular dichroism spectroscopy and secondary structure prediction showed random coil conformation in aqueous solution, but secondary structure was induced in the presence of sodium-dodecyl sulfate. The data could be fitted assuming 2-13% of the residues to be in alpha-helix and 23-27% of the residues to be in beta-strand conformation. This indicates that a membrane/membrane-mimicking hydrocarbon-water interface induces an active conformation.
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| 9. |
- Dogaris, Ioannis, Ph.D., et al.
(författare)
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Prospects of integrating algae technologies into landfill leachate treatment
- 2020
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Ingår i: World Journal of Microbiology & Biotechnology. - : SPRINGER. - 0959-3993 .- 1573-0972. ; 36:3
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Forskningsöversikt (refereegranskat)abstract
- Landfilling of municipal waste, an environmental challenge worldwide, results in the continuous formation of significant amounts of leachate, which poses a severe contamination threat to ground and surface water resources. Landfill leachate (LL) is generated by rainwater percolating through disposed waste materials and must be treated effectively before safe discharge into the environment. LL contains numerous pollutants and toxic substances, such as dissolved organic matter, inorganic chemicals, heavy metals, and anthropogenic organic compounds. Currently, LL treatment is carried out by a combination of physical, chemical, and microbial technologies. Microalgae are now viewed as a promising sustainable addition to the repertoire of technologies for treating LL. Photosynthetic algae have been shown to grow in LL under laboratory conditions, while some species have also been employed in larger-scale LL treatments. Treating leachate with algae can contribute to sustainable waste management at existing landfills by remediating low-quality water for recycling and reuse and generating large amounts of algal biomass for cost-effective manufacturing of biofuels and bioproducts. In this review, we will examine LL composition, traditional leachate treatment technologies, LL toxicity to algae, and the potential of employing algae at LL treatment facilities. Emphasis is placed on how algae can be integrated with existing technologies for biological treatment of LL, turning leachate from an environmental liability to an asset that can produce value-added biofuels and bioproducts for the bioeconomy.
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| 10. |
- Hatzinikolaou, D.G, et al.
(författare)
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Comparative growth studies of the extreme thermophile Sulfolobus acidocaldarius in submerged and solidified substrate cultures
- 2001
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Ingår i: World Journal of Microbiology & Biotechnology. - 0959-3993 .- 1573-0972. ; 17:3, s. 229-234
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Tidskriftsartikel (refereegranskat)abstract
- An attempt was made, for the first time, to exploit cultures on solidified substrates (SSC) as an alternative to submerged cultures (SmC) for growing extremophilic micro-organisms. The extreme thermophilic archaebacterium Sulfolobus acidocaldarius was grown on a number of carbon sources and, in all experiments, biomass yields and growth rates were always higher in SSC than in the corresponding SmC. Inoculum age significantly affected growth characteristics on both types of fermentation. Heavy growth of the micro-organism in SSC was observed on low-cost carbon sources such as starch. Wheat bran significantly enhanced growth characteristics when used to supplement starch media. The results of this work show that cultures on solid surfaces could be a promising alternative method for growing extreme thermophiles.
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