Alisa Gricajeva is currently a PhD student at the Department of Microbiology and Biotechnology, Institute of Biosciences, Life Sciences Center, Vilnius University. Her final thesis work is associated with the study of microbial lipolytic enzymes: search of unstudied enzymes and their activity analysis. Alisa Gricajeva is an author of publications and conference theses dealing with characterization of lipolytic enzymes, improvement of their properties and assumption of their use in biotechnology. Alisa Gricajeva is also a junior researcher and lecturer of Food Microbiology and Biotechnologies and Enzymology lectures at Vilnius University.
Today microbial lipases find vast applications and have firmly established themselves in diverse areas of industrial microbiology and biotechnology. Among hydrolytic enzymes which are currently published to be the most widely used in industrial processes, lipases represent the third most commercialized group of enzymes and their production need is constantly increasing. For that reason, there is a perpetual interest in obtainment of low-cost, highly active and stable lipases which could be applied in different biotechnology branches. Furthermore, usually, immobilized enzymes are preferred over their free forms since immobilization not only improves enzyme features but also makes it possible to reuse the enzyme and increases its turnover. Whereas easily cultivable bacteria are one of the cheapest sources of lipases with different suitable features, in the present study, potential of Staphylococcus saprophyticus as a lipase producer was assayed. S. saprophyticus GTC1 isolate which was found and identified previously in our work showed remarkable lipolytic activity. As a species it is published to be a part of natural human flora sometimes causing uncomplicated urinary tract infections and is also found in soils. Secretion of the enzyme (LipGTC) was obtained in TSB liquid medium without addition of any inducers. After (NH4)2SO4 precipitation, using SDS-PAGE and tributyrin overlay zymography, LipGTC was determined to be ~50 kDa. LipGTC was eluted from the gel and was further analyzed. Enzyme had optimal activity at 35 – 50oC, pH 9 and hydrolyzed synthetic p-NP substrates and different natural lipids releasing highly valuable fatty acids. Some tested chemicals (detergents, different metal ions), as well as immobilization of the enzyme onto octyl-sepharose, hyperactivated LipGTC (relative activity in methanol and Ca2+ were 113% and 122%, respectively). LipGTC showed to be highly stable in the range of 30 – 50oC up to 6 h without remarkable loss of activity. To conclude, until now there were works published dealing with only one S. saprophyticus membrane associated Ssp lipase, therefore, present study widens knowledge about secreted S. saprophyticus lipolytic enzymes and emphasizes its potential to be applied industrially.
Gemma is currently a fourth year medical student of the international “Medicine and Surgery” English-taught program activated at Università Cattolica del Sacro Cuore, Rome, Italy. She is interested in child neuropsychiatric disorders. Gemma had the opportunity to join GNOSIS, a non profit research organiza-tion devoted to the study of movement disorders and behavioural child and is grateful for the privilege of being involved in a research project on the psychiatric aspects of infectious diseases.
A girl with Tourette syndrome (TS) and increased an-tibody levels against Streptococcus pyogenes was monitored longitudinally for the presence of nasopha-ryngeal bacteria, specific antibody titres, and autoim-munity directed against brain antigens (Fig.1). This case presented overlapping similarities with PAN-DAS patients (Paediatric Autoimmune Neuropsychi-atric Disorders Associated with Group A Streptococ-cal Infections) where tics and obsessive compulsive disorders follow acute Streptococcus pyogenes infec-tions. Microbiological monitoring indicated that the child was an intermittent Staphylococcus aureus naso-pharyngeal carrier. Clinical improvements in motor tic frequency and severity were observed during the S. aureus colonization phase and were temporally corre-lated with the downregulation of anti-streptococcal and anti-D1/D2 dopamine receptor antibody produc-tion. S. aureus is known to be very effective in the downregulation of the host immune response to pro-mote immune evasion. Dopamine is a crucial neuro-transmitter in motor control, and autoimmunity against its neuronal receptors may alter central dopa-mine pathways leading to movement and neuropsy-chiatric disorders, especially in childhood. After de-colonization, clinical conditions reverted to the poor scores previously observed, suggesting a possible role of the immune response in bacterial clearance as a trigger of symptom recrudescence. This hypothesis is consistent with the data from animal models showing that a pro-inflammatory, Th17 cell-associated immune response, is required for S. aureus nasal decoloniza-tion. These findings imply that a cause– effect rela-tionship exists between S. aureus colonization and tic improvement, as well as between bacterial decoloni-zation and tic exacerbation. Conclusion & Signifi-cance: This case is the first demonstration of the mod-ulation of tic manifestation in a S. aureus intermittent carrier with TS. A shift occurred from an anti-inflammatory modulatory response during the coloni-zation phase to a pro-inflammatory state during the clearing process. Thus, S. aureus nasal carriage possi-bly provides a new human model for the in vivo study of the interplay between infections, immunity, auto-immunity, and tic disorders.