Browsing by Subject "Pseudomonas"

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  • Kaitala, Veijo; Hiltunen, Teppo; Becks, Lutz; Scheuerl, Thomas (2019)
    Predator-prey relationships belong to the most important and well-studied ecological interactions in nature. Understanding the underlying mechanisms is important to predict community dynamics and to estimate coexistence probability. Historically, evolution has been considered to be too slow to affect such ecological interactions. However, evolution can occur within ecological time scales, potentially affecting predator-prey communities. In an antagonistic pair-wise relationship the prey might evolve to minimize the effect caused by the predator (e.g. mortality), while the predator might evolve to maximize the effect (e.g. food intake). Evolution of one of the species or even co-evolution of both species in predator-prey relationships is often difficult to estimate from population dynamics without measuring of trait changes in predator and/or prey population. Particularly in microbial systems, where microorganisms evolve quickly, determining whether co-evolution occurs in predator-prey systems is challenging. We simulate observational data using quantitative trait evolution models and show that the interaction between bacteria and ciliates can be best explained as a co-evolutionary process, where both the prey and predator evolve. Evolution by prey alone explains the data less well, whereas the models with predator evolution alone or no evolution are both failing. We conclude that that ecology and evolution both interact in shaping community dynamics in microcosms. Ignoring the contribution of evolution might lead to incorrect conclusions.
  • Stefanowicz, Karolina; Lannoo, Nausicaä; Zhao, Yafei; Eggermont, Lore; Van Hove, Jonas; Al Atalah, Bassam; Van Damme, Els J M (BioMed Central, 2016)
    Abstract Background A small group of F-box proteins consisting of a conserved F-box domain linked to a domain homologous to the glycan-binding protein has been identified within the genome of Arabidopsis thaliana. Previously, the so-called F-box-Nictaba protein, encoded by the gene At2g02360, was shown to be a functional lectin which binds N-acetyllactosamine structures. Here, we present a detailed qRT-PCR expression analysis of F-box-Nictaba in Arabidopsis plants upon different stresses and hormone treatments. Results Expression of the F-box-Nictaba gene was enhanced after plant treatment with salicylic acid and after plant infection with the virulent Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000). β-glucuronidase histochemical staining of transgenic Arabidopsis plants displayed preferential activity of the At2g02360 promoter in trichomes present on young rosette leaves. qRT-PCR analyses confirmed high expression of F-box-Nictaba in leaf trichomes. A. thaliana plants overexpressing the gene showed less disease symptoms after Pst DC3000 infection with reduced bacterial colonization compared to infected wild type and F-box-Nictaba knock-out plants. Conclusions Our data show that the Arabidopsis F-box-Nictaba gene is a stress-inducible gene responsive to SA, bacterial infection and heat stress, and is involved in salicylic acid related plant defense responses. This knowledge enriched our understanding of the physiological importance of F-box-Nictaba, and can be used to create plants with better performance in changing environmental conditions.
  • Jääskeläinen, Elina; Jakobsen, Louise M.A.; Hultman, Jenni; Eggers, Nina; Bertram, Hanne C.; Björkroth, Johanna (2019)
    Microbial (colony counts, 16S rRNA gene amplification), chemical (pH, 1H NMR spectroscopy) and sensory changes in raw Atlantic Salmon (Salmo salar) and tuna (Thunnus albacares) fillets stored under vacuum at 3 °C were evaluated over a period of 12 days. Both species of fish are globally important and among the ten most consumed fishes in the world. Although the sensory analyses showed a decrease in the quality of both fish species, only the salmon fillets were considered spoiled at the end of the storage period. In salmon, trimethylamine was the main spoilage product and bacterial colony counts reached an average of 7.3 log10 cfu/g. The concentration of glucose decreased and the concentration of organic acids increased during storage revealing glucose fermentation. Photobacterium was the dominating genus in the salmon studied. In the tuna studied, the bacterial colony counts reached only an average of 4.6 log10 cfu/g. The dominating bacteria in tuna were Pseudomonas spp. Glucose levels did not decrease, suggesting that amino acids and lactate most likely acted as carbon sources for bacteria in tuna. In conclusion, the study revealed that salmon was clearly a more perishable fish than tuna.
  • Akinpelu, Atinuke Motunrayo (Helsingfors universitet, 2016)
    Raw milk storage continues to be a problem for both the developed and developing worlds until new technologies to properly store the milk are readily available to both economies during cold storage. Major causes of spoilage of raw milk are psychrotrophic bacteria belonging to the genus Pseudomonas. In order to extend the shelf life of raw milk, more knowledge of the nitrogen (N2) gas flushing and lactoperoxidase system (LP-s) along with refrigeration on microflora is required and for this reason, a study has been set up. Three experiments where raw milk was stored at 60C for 3 and 7 days under the LP-s and N2-flushing treatment with a control were considered. The milk samples at various conditions were analyzed for total bacterial counts (TBA), psychrotrophs, Gram-negative bacteria, lipase and protease producers; also, the pH was followed. 210 isolates were selected to represent the milk samples for the 3 experiments. All the isolates were characterized by the determination of their spoilage and phenotypic features: proteolytic, lipolytic, phospholipase activities, hemolytic factors and CLP production. In the end, N2-flushing showed a long term (7 days) inhibition of all bacteria types compared to LP-s (which better inhibited bacteria at 3 days) and compared to the control. 11 isolates were further subjected to 16S rRNA partial sequencing to adequately identify them and BLAST GenBank proposed the presence of representatives of the Pseudomonas genus for the 11 isolates. Continuous N2-flushing and activation of LP-s have demonstrated the ability to lower bacterial population in milk to varying degrees.
  • Hall, James P. J.; Harrison, Ellie; Parnanen, Katariina; Virta, Marko; Brockhurst, Michael A. (2020)
    Carriage of resistance genes can underpin bacterial survival, and by spreading these genes between species, mobile genetic elements (MGEs) can potentially protect diversity within microbial communities. The spread of MGEs could be affected by environmental factors such as selection for resistance, and biological factors such as plasmid host range, with consequences for individual species and for community structure. Here we cultured a focal bacterial strain,Pseudomonas fluorescensSBW25, embedded within a soil microbial community, with and without mercury selection, and with and without mercury resistance plasmids (pQBR57 or pQBR103), to investigate the effects of selection and resistance gene introduction on (1) the focal species; (2) the community as a whole; (3) the spread of the introducedmerresistance operon. We found thatP. fluorescensSBW25 only escaped competitive exclusion by other members of community under mercury selection, even when it did not begin with a mercury resistance plasmid, due to its propensity to acquire resistance from the community by horizontal gene transfer. Mercury pollution had a significant effect on community structure, decreasing alpha diversity within communities while increasing beta diversity between communities, a pattern that was not affected by the introduction of mercury resistance plasmids byP. fluorescensSBW25. Nevertheless, the introducedmerAgene spread to a phylogenetically diverse set of recipients over the 5 weeks of the experiment, as assessed by epicPCR. Our data demonstrates how the effects of MGEs can be experimentally assessed for individual lineages, the wider community, and for the spread of adaptive traits.
  • Lusa, Merja; Help-Rinta-Rahko, Hanna; Honkanen, Ari-Pekka; Knuutinen, Jenna; Parkkonen, Joni; Kalasová, Dominika; Bomberg, Malin (2019)