Tallinn University of Technology

About: Tallinn University of Technology is a education organization based out in Tallinn, Estonia. It is known for research contribution in the topics: European union & Computer science. The organization has 3688 authors who have published 10313 publications receiving 145058 citations. The organization is also known as: Tallinn Technical University & Tallinna Tehnikaülikool.

Understanding How Microorganisms Respond to Acid pH Is Central to Their Control and Successful Exploitation

Abstract: Microbes from the three domains of life, Bacteria, Archaea, and Eukarya, share the need to sense and respond to changes in the external and internal concentrations of protons. When the proton concentration is high, acidic conditions prevail and cells must respond appropriately to ensure that macromolecules and metabolic processes are sufficiently protected to sustain life. While, we have learned much in recent decades about the mechanisms that microbes use to cope with acid, including the unique challenges presented by organic acids, there is still much to be gained from developing a deeper understanding of the effects and responses to acid in microbes. In this perspective article, we survey the key molecular mechanisms known to be important for microbial survival during acid stress and discuss how this knowledge might be relevant to microbe-based applications and processes that are consequential for humans. We discuss the research approaches that have been taken to investigate the problem and highlight promising new avenues. We discuss the influence of acid on pathogens during the course of infections and highlight the potential of using organic acids in treatments for some types of infection. We explore the influence of acid stress on photosynthetic microbes, and on biotechnological and industrial processes, including those needed to produce organic acids. We highlight the importance of understanding acid stress in controlling spoilage and pathogenic microbes in the food chain. Finally, we invite colleagues with an interest in microbial responses to low pH to participate in the EU-funded COST Action network called EuroMicropH and contribute to a comprehensive database of literature on this topic that we are making publicly available.

Enhancement of anoxic phosphorus uptake of denitrifying phosphorus removal process by biomass adaption

Abstract: Economical and efficient phosphorus (PO4-P) removal technologies with low oxygen and organic carbon demand are needed to avoid eutrophication and reduce wastewater treatment costs. A sequencing batch reactor (SBR) treating synthetic wastewater with similar characteristics to real domestic wastewater using peptone and meat extract as carbon sources and nitrate as terminal electron acceptor was set up to enhance anoxic PO4-P uptake of denitrifying phosphorus removal process. In the anaerobic/anoxic/oxic SBR, activated sludge inoculum was gradually adapted to prolonged anoxic and shortened aerobic phase durations of 3.5 h and 1 h, respectively. During biomass adaption, anoxic PO4-P uptake fraction from total PO4-P (anoxic + aerobic) uptake was enhanced from 70.5 to 90.4%. SBR long-term operation results showed that dosed nitrate loading and aeration phase duration affected PO4-P and total nitrogen (TN) removal. The highest PO4-P removal of 22.4 mg PO4-P g−1 mixed liquor suspended solids (MLSS) and average TN removal efficiency of 74.2% were achieved with 1-h aeration duration. The best dosed nitrate loading ranges for effective PO4-P and TN removal were 11.3–13.7 and 11.1–19.4 mg N g−1 MLSS d−1, respectively. Chemical oxygen demand and dissolved organic carbon removal efficiencies remained unaffected by changes in operating conditions with average values up to 96.3% and 98.0%, respectively. Pyrosequencing results demonstrated that during biomass adaption microbial community changed and adapted sludge probably contained some novel denitrifying phosphorus accumulating organisms. Therefore, this research shows that biomass adaption enabled to achieve efficient denitrifying phosphorus removal without acetate/propionate addition in the conditions similar to real domestic wastewater.

Stochastic multiresonance and correlation-time-controlled stability for a harmonic oscillator with fluctuating frequency.

Abstract: The long-time behavior of the first two moments and the correlation function for the output signal of a harmonic oscillator with fluctuating frequency subjected to an external periodic force and an additive thermal noise is considered analytically. The colored fluctuations of the oscillator frequency are modeled as a three-level Markovian noise. Using the Shapiro-Loginov formula, the exact expressions of several stochastic resonance (SR) characteristics such as the spectral amplification, the variance of the output signal, the signal-to-noise ratio, and the SR gain have been calculated. The nonmonotonic dependence of the SR characteristics versus the noise parameters as well as versus the input signal frequency and also the conditions for the appearance of energetic instability are analyzed. In particular, the multiresonancelike behavior of the variance and the signal-to-noise ratio as functions of the noise correlation time are observed and the connection between the occurrence of energetic instability and the phenomenon of stochastic multiresonance is established. Some unexpected effects such as the hypersensitive response of the spectral amplification to small variations of the noise amplitude encountered in the case of a large flatness of the colored noise are also discussed.

Myosins XI-K, XI-1, and XI-2 are required for development of pavement cells, trichomes, and stigmatic papillae in Arabidopsis

Abstract: The positioning and dynamics of vesicles and organelles, and thus the growth of plant cells, is mediated by the acto-myosin system. In Arabidopsis there are 13 class XI myosins which mediate vesicle and organelle transport in different cell types. So far the involvement of five class XI myosins in cell expansion during the shoot and root development has been shown, three of which, XI-1, XI-2, and XI-K, are essential for organelle transport. Simultaneous depletion of Arabidopsis class XI myosins XI-K, XI-1, and XI-2 in double and triple mutant plants affected the growth of several types of epidermal cells. The size and shape of trichomes, leaf pavement cells and the elongation of the stigmatic papillae of double and triple mutant plants were affected to different extent. Reduced cell size led to significant size reduction of shoot organs in the case of triple mutant, affecting bolt formation, flowering time and fertility. Phenotype analysis revealed that the reduced fertility of triple mutant plants was caused by delayed or insufficient development of pistils. We conclude that the class XI myosins XI-K, XI-1 and XI-2 have partially redundant roles in the growth of shoot epidermis. Myosin XI-K plays more important role whereas myosins XI-1 and XI-2 have minor roles in the determination of size and shape of epidermal cells, because the absence of these two myosins is compensated by XI-K. Co-operation between myosins XI-K and XI-2 appears to play an important role in these processes.