| 1. |
- Bjerketorp, Joakim, et al.
(författare)
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Formulation and stabilization of an Arthrobacter strain with good storage stability and 4-chlorophenol-degradation activity for bioremediation
- 2018
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Ingår i: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 0175-7598 .- 1432-0614. ; 102:4, s. 2031-2040
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Tidskriftsartikel (refereegranskat)abstract
- Chlorophenols are widespread and of environmental concern due to their toxic and carcinogenic properties. Development of less costly and less technically challenging remediation methods are needed; therefore, we developed a formulation based on micronized vermiculite that, when air-dried, resulted in a granular product containing the 4-chlorophenol (4-CP)-degrading Gram-positive bacterium Arthrobacter chlorophenolicus A6. This formulation and stabilization method yielded survival rates of about 60% that remained stable in storage for at least 3 months at 4 °C. The 4-CP degradation by the formulated and desiccated A. chlorophenolicus A6 cells was compared to that of freshly grown cells in controlled-environment soil microcosms. The stabilized cells degraded 4-CP equally efficient as freshly grown cells in two different set-ups using both hygienized and non-treated soils. The desiccated microbial product was successfully employed in an outdoor pot trial showing its effectiveness under more realistic environmental conditions. No significant phytoremediation effects on 4-CP degradation were observed in the outdoor pot experiment. The 4-CP degradation kinetics from both the microcosms and the outdoor pot trial were used to generate a predictive model of 4-CP biodegradation potentially useful for larger-scale operations, enabling better bioremediation set-ups and saving of resources. This study also opens up the possibility of formulating and stabilizing also other Arthrobacter strains possessing different desirable pollutant-degrading capabilities.
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| 2. |
- Garcia, Armando Hernández, et al.
(författare)
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Isothermal microcalorimetry for rapid viability assessment of freeze-dried Lactobacillus reuteri
- 2017
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Ingår i: Process Biochemistry. - : Elsevier BV. - 1359-5113. ; 55, s. 49-54
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Tidskriftsartikel (refereegranskat)abstract
- The rapid assessment of viable cells in freeze-dried formulations of probiotic Lactobacilli is an important issue in the probiotic industry. The probiotic Lactobacillus reuteri DSM 17938 is the active ingredient of BioGaia Protectis whose viable cell concentrations are currently determined using the classical and time-consuming viable count technique. In this paper we present a rapid method based on Isothermal microcalorimetry (IMC) for viability assessment of freeze-dried DSM 17938. Fresh and rehydrated freeze-dried cells were incubated in MRS medium at different cell concentration and the thermal power (mu W) at 37 degrees C was measured over time. A linear dependence between the time to reach a certain thermal power value and the decimal logarithm of viable cells was found. This allowed rapid viability assessment of rehydrated cells, reducing the detection time from 48 h (viable count) to 10 h (microcalorimetry) in samples with 3 x 10(3) cfu/mL, and to 4 h in samples with 4 x 10(6) cfu/mL. No significant differences were found between the two methods when freeze-dried rehydrated cells were analysed (p > 0.05). Therefore, IMC is a promising tool to be used in the quality control of freeze-dried DSM 17938 as well as other bacteria-based products. (C) 2017 Elsevier Ltd. All rights reserved.
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| 3. |
- Hernández, Armando, et al.
(författare)
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Impact of the fermentation parameters pH and temperature on stress resilience of Lactobacillus reuteri DSM 17938
- 2019
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Ingår i: AMB Express. - : Springer Science and Business Media LLC. - 2191-0855. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- This study was undertaken to investigate the impact of culture pH (4.5–6.5) and temperature (32–37 °C) on the stress resilience of Lactobacillus reuteri DSM 17938 during freeze-drying and post freeze-drying exposure to low pH (pH 2)and bile salts. Response-surface methodology analysis revealed that freeze-drying survival rates Ncells after drying/Ncells before drying*100 were linearly related to pH with the highest survival rate of 80% when cells were cultured at pH 6.5 and the lowest was 40% when cells were cultured at pH 4.5. The analysis further revealed that within the chosen temperature range the culture temperature did not significantly affect the freeze-drying survival rate. However, fermentation at pH 4.5 led to better survival rates when rehydrated cells were exposed to low pH shock or bile salts. Thus, the effect of pH onfreeze-drying survival was in contrast to effects on low pH and bile salts stress tolerance. The rationale behind this irreconcilability is based on the responses being dissimilar and are not tuned to each other. Culturing strain DSM17938 at pH values higher than 5.5 could be a useful option to improve the survivability and increase viable cell numbers in the final freeze-dried product. However, the dissimilar responses for the process- and application parameterstested here suggest that an optimal compromise has to be found in order to obtain the most functional probiotic product possible.
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| 4. |
- Håkansson, Sebastian
(författare)
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Survival and phosphate solubilisation activity of desiccated formulations of Penicillium bilaiae and Aspergillus niger influenced by water activity
- 2018
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Ingår i: Journal of Microbiological Methods. - : Elsevier BV. - 0167-7012 .- 1872-8359. ; 150, s. 39-46
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Tidskriftsartikel (refereegranskat)abstract
- The impact of formulation and desiccation on the shelf life of phosphate (P)-solubilising microorganisms is often under-studied, particularly relating to their ability to recover P-solubilisation activity. Here, Penicilllium bilaiae and Aspergillus niger were formulated on vermiculite (V) alone, or with the addition of protectants (skimmed milk (V + SM) and trehalose (V + T)), and on sewage sludge ash with (A + N) and without nutrients (A), and dried in a convective air dryer. After drying, the spore viability of P. bilaiae was greater than that of A. niger. V formulations achieved the highest survival rates without being improved by the addition of protectants. P. bilaiae formulated on V was selected for desiccation in a fluidised bed dryer, in which several temperatures and final water activities (aw) were tested. The highest spore viability was achieved when the formulation was dried at 25 degrees C to a final aw > 0.3. During three months' storage, convective air dried formulations were stable for both strains, except in the presence of skimmed milk for P. bilaiae which saw a decrease in spore viability. In the fluidised bed-dried formulations, when aw > 0.3, the loss in viability was higher, especially when stored at 20 degrees C, than at aw < 0.1. P-solubilisation activity performed on ash was preserved in most of the formulations after desiccation and storage. Overall, a low drying temperature and high final aw positively affected P. bilaiae viability, however a trade-off between higher viability after desiccation and shelf life should be considered. Further research is needed to optimise viability over time and on more sustainable carriers.
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| 5. |
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| 6. |
- Kämpfer, Peter, et al.
(författare)
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Proposal of Coetzeea brasiliensis gen. nov. sp. nov. isolated from larvae of Anopheles darlingi
- 2016
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Ingår i: International Journal of Systematic and Evolutionary Microbiology. - : Microbiology Society. - 1466-5026 .- 1466-5034. ; 66, s. 5211-5217
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Tidskriftsartikel (refereegranskat)abstract
- A Gram-stain-negative, rod-shaped strain, Braz8T, isolated from larvae ofAnopheles darlingiwas investigatedusing a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences showed that strainBraz8Twas related most closely to species of the genusThorsellia, with 95.6, 96.5 and 96.6% similarity to thetype strains ofThorsellia anophelis,Thorsellia kandunguensisandThorsellia kenyensis, respectively, andformed a separate branch in the phylogenetic tree next to the monophyletic cluster of the genusThorsellia.Chemotaxonomic data supported the allocation of the strain to the familyThorselliaceae. The major fatty acidswere C18:1!7c, C16:0and C14:0. The quinone system was composed of ubiquinones Q-8 and Q-7 (1:0.3),the predominant polar lipids were diphosphatidylglycerol and phosphatidylglycerol, and the polyamine patternshowed the major compound putrescine. However, qualitative and quantitative differences in the majorpolyamine, polar lipid profile and fatty acid patterns distinguished strain Braz8Tfrom species of the genusThorsellia. Phylogenetic analysis based on 16S rRNA gene sequences, average nucleotide identity, DNA–DNAhybridization, multilocus sequence analysis as well as physiological and biochemical tests distinguished strainBraz8Tboth genotypically and phenotypically from the threeThorselliaspecies but also showed its placementin the familyThorselliaceae. Thus, strain Braz8Tis considered to represent a novel species of a new genus mostclosely related to the genusThorsellia, for which the nameCoetzeea brasiliensisgen. nov., sp. nov. is proposed.The type strain ofCoetzeea brasiliensisis Braz8T(=LMG 29552T=CIP 111088T)
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| 7. |
- Kämpfer, Peter, et al.
(författare)
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Proposal of Thorsellia kenyensis sp. nov. and Thorsellia kandunguensis sp. nov., isolated from the larvae of Anopheles arabiensis as members of the family Thorselliaceae fam. nov.
- 2015
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Ingår i: International Journal of Systematic and Evolutionary Microbiology. - : Microbiology Society. - 1466-5026 .- 1466-5034. ; 65, s. 444-451
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Tidskriftsartikel (refereegranskat)abstract
- Two Gram-negative, rod-shaped strains, T2.1T and W5.1.1T, isolated from larvae of the mosquito Anopheles arabiensis, were investigated using a polyphasic approach. On the basis of 16S rRNA gene sequence similarity studies, strains T2.1T and W5.1.1T were shown to belong to the genus Thorsellia, both showing 97.8 % similarity to the type strain of Thorsellia anophelis, with 98.1 % similarity to each other. Chemotaxonomic data supported the allocation of the strains to the genus Thorsellia: their major fatty acids were C18 : 1ω7c, C16 : 0 and C14 : 0 and they harboured a ubiquinone Q-8 quinone system and a polyamine pattern with the major compound 1,3-diaminopropane. Qualitative and quantitative differences in their polar lipid profiles distinguished strains T2.1T and W5.1.1T from each other and from T. anophelis. Average nucleotide identity (ANI), DNA–DNA hybridization, multilocus sequence analysis (MLSA) as well as physiological and biochemical tests allowed T2.1T and W5.1.1T to be distinguished both genotypically and phenotypically from each other and from the type strain of T. anophelis. Thus, we propose that these isolates represent two novel species of the genus Thorsellia, named Thorsellia kenyensis sp. nov. (type strain T2.1T = CCM 8545T = LMG 28483T = CIP 110829T) and Thorsellia kandunguensis sp. nov. (type strain W5.1.1T = LMG 28213T = CIP 110794T). Furthermore, phylogenetic analysis based on nearly full-length 16S rRNA gene sequences showed that the genus Thorsellia forms a separate branch, distinct from the families Enterobacteriaceae, Pasteurellaceae and Orbaceae. As a consequence, a new family Thorselliaceae fam. nov. is proposed. An emended description of Thorsellia anophelis is also provided.
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| 8. |
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| 9. |
- Nilsson, Louise K. J., et al.
(författare)
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Characterization of Bacterial Communities in Breeding Waters of Anopheles darlingi in Manaus in the Amazon Basin Malaria-Endemic Area
- 2019
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Ingår i: Microbial Ecology. - : Springer Science and Business Media LLC. - 0095-3628 .- 1432-184X. ; 78:4, s. 781-791
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Tidskriftsartikel (refereegranskat)abstract
- The microbiota in mosquito breeding waters can affect ovipositing mosquitoes, have effects on larval development, and can modify adult mosquito-gut bacterial composition. This, in turn, can affect transmission of human pathogens such as malaria parasites. Here, we explore the microbiota of four breeding sites for Anopheles darlingi, the most important malaria vector in Latin America. The sites are located in Manaus in the Amazon basin in Brazil, an area of active malaria transmission. Using 16S rRNA gene sequencing by MiSeq, we found that all sites were dominated by Proteobacteria and Firmicutes and that 94% of the total number of reads belonged to 36 operational taxonomic units (OTUs) identified in all sites. Of these, the most common OTUs belonged to Escherichia/Shigella, Staphylococcus, and Pseudomonas. Of the remaining 6% of the reads, the OTUs found to differentiate between the four sites belonged to the orders Burkholderiales, Actinomycetales, and Clostridiales. We conclude that An. darlingi can develop in breeding waters with different surface-water bacteria, but that the common microbiota found in all breeding sites might indicate or contribute to a suitable habitat for this important malaria vector.
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| 10. |
- Nilsson, Louise K. J.
(författare)
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Exploration of bacteria associated with Anopheles mosquitoes around the world : For the prevention of transmission of malaria
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Every year, hundreds of thousands of people die from malaria. Malaria is a disease caused by parasites, which are spread by female vector mosquitoes of the genus Anopheles. Current control measures against malaria are based on drugs against the parasites and vector control using insecticides. A problem with these measures is the development of resistance, both in the parasites against the drugs and the mosquitoes against the insecticides. Therefore, additional areas of malaria control must be explored. One such area involves the bacteria associated with the vector mosquitoes. Bacteria have been shown to affect mosquitoes at all life stages, e.g. by affecting choice of oviposition site by female mosquitoes, development of larvae and susceptibility to parasite infection in adults. Furthermore, genetic modification of symbiotic bacteria has been suggested as a mean of killing the parasites in the mosquitoes. This thesis is based on four field studies and one laboratory study and aims to investigate the naturally occurring bacteria associated with different life stages of malaria mosquitoes and how they are acquired. All studies are based on amplicon sequencing of the 16S rRNA gene. We found that overall mosquitoes contain different bacterial communities. However, bacteria associated with adults reflect their life history and can predict the origin of mosquitoes. Bacteria in larvae are similar during the developmental stages but vary with breeding site. Also in larvae, the bacteria could be used to predict the origin of breeding site. Some bacteria could be related to the presence or absence of Anopheles around human habitations and the diversity of aquatic bacteria in breeding sites is large, though some taxa are common. Overall, both environmental and host-genetic factors affect the gut bacterial composition in adult females. In conclusion, this thesis contributes to increasing the knowledge of bacterial diversity associated with Anopheles mosquitoes and to provide insight into how the bacteria are acquired, which can be useful in malaria control.
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| 11. |
- Nykyri, Johanna, et al.
(författare)
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Isothermal microcalorimetry for thermal viable count of microorganisms in pure cultures and stabilized formulations
- 2019
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Ingår i: Journal of Applied Toxicology. - : Springer Science and Business Media LLC. - 0260-437X .- 1099-1263. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundQuantification of viable microorganisms is an important step in microbiological research as well as in microbial product formulation to develop biological control products or probiotics. Often, the efficiency of the resulting product is dependent on the microbial cell density and their viability, which may decrease over time. Commonly, the number of viable cells is determined by serial dilution and plating techniques or flow cytometry. In 2017, we developed a mathematical model for isothermal microcalorimetry (IMC) data analysis and showed that the new method allows for a more rapid quantification of viable fresh and freeze-dried anaerobic Lactobacillus reuteri cells than traditional viable count methods.ResultsThis study developed the new method further by applying it to well-known aerophilic plant-beneficial microbial species (Pseudomonas brassicacearum, Bacillus amyloliquefaciens subsp. plantarum and Clonostachys rosea) used in biological control products. We utilized IMC to quantify viable cells in microbial pure cultures as well as when coated onto wheat seeds. The results from this study confirmed that thermal viable count methods are more rapid and sensitive than traditional viable count techniques. Most interestingly, a thermal viable count method was able to quantify microbes coated on seeds despite the presence of the natural microbiota of the seeds. Our results also showed that, in contrast to plating techniques for which clustered cells skew the results, IMC does not require single cells for accurate viable counts.ConclusionsThermal viable count methods are novel methods for the rapid quantification of divergent bacterial and fungal species and enhance the speed, sensitivity, and accuracy of routine viable counts of pure cultures and controlled microbiomes such as plant seed coatings.
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| 12. |
- Svensson, Fredric, et al.
(författare)
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Hybrid Drug Delivery Patches Based on Spherical Cellulose Nanocrystals and Colloid Titania-Synthesis and Antibacterial Properties
- 2018
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Spherical cellulose nanocrystal-based hybrids grafted with titania nanoparticles were successfully produced for topical drug delivery. The conventional analytical filter paper was used as a precursor material for cellulose nanocrystals (CNC) production. Cellulose nanocrystals were extracted via a simple and quick two-step process based on first the complexation with Cu(II) solution in aqueous ammonia followed by acid hydrolysis with diluted H2SO4. Triclosan was selected as a model drug for complexation with titania and further introduction into the nanocellulose based composite. Obtained materials were characterized by a broad variety of microscopic, spectroscopic, and thermal analysis methods. The drug release studies showed long-term release profiles of triclosan from the titania based nanocomposite that agreed with Higuchi model. The bacterial susceptibility tests demonstrated that released triclosan retained its antibacterial activity against Escherichia coli and Staphylococcus aureus. It was found that a small amount of titania significantly improved the antibacterial activity of obtained nanocomposites, even without immobilization of model drug. Thus, the developed hybrid patches are highly promising candidates for potential application as antibacterial agents.
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