BackgroundFor a commercially feasible microalgal triglyceride (TAG) production, high TAG productivities are required. The operational strategy affects TAG productivity but a systematic comparison between different strategies is lacking. For this, physiological responses of Nannochloropsis sp. to nitrogen (N) starvation and N-rich medium replenishment were studied in lab-scale batch and repeated-batch (part of the culture is periodically harvested and N-rich medium is re-supplied) cultivations under continuous light, and condensed into a mechanistic model.ResultsThe model, which successfully described both strategies, was used to identify potential improvements for both batch and repeated-batch and compare the two strategies on optimized TAG yields on light (amount of TAGs produced per mol of supplied PAR photons). TAG yields on light, for batch, from 0.12 (base case at high light) to 0.49 g molph−1 (at low light and with improved strain) and, for repeated-batch, from 0.07 (base case at high light) to 0.39 g molph−1 (at low light with improved strain and optimized repeated-batch settings). The base case yields are in line with the yields observed in current state-of-the-art outdoor TAG production.ConclusionsFor continuous light, an optimized batch process will always result in higher TAG yield on light compared to an optimized repeated-batch process. This is mainly because repeated-batch cycles start with N-starved cells. Their reduced photosynthetic capacity leads to inefficient light use during the regrowth phase which results in lower overall TAG yields compared to a batch process.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0475-4) contains supplementary material, which is available to authorized users.

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Lactic acid fermentation (LAF) is known to improve nutritional properties and functionality and to extend the shelf life of foods. We studied the LAF of Arthrospira platensis as the sole substrate using Lactobacillus plantarum as the starter culture. Fermented (FB) and non-fermented broth (NFB) were analysed by means of pH, lactic acid bacteria (LAB) count, lactic acid concentration, microbiological safety, and nutritional composition. Additionally, water and ethanol extracts were prepared on which total phenolic content, DPPH radical scavenging activity, and cellular antioxidant activity were determined. The maximum increase in LAB count and lactic acid concentration and drop in pH was observed in the first 24 h of fermentation. Total phenolic content and DPPH radical scavinging activity of ethanol extracts increased after fermentation compared with NFB. Ethanol extracts of FB have been shown as a potential source of antioxidants, which efficiently lowered oxidation level in the cells of yeast Saccharomyces cerevisiae, as well as the oxidative damage of lipids. Additionally, the level of non-protein nitrogen increased, indicating higher protein bioavailability, and fat content decreased in comparison with NFB. No presence of pathogenic bacteria and low pH indicate enhancement of FB microbiological stability. Therefore, inclusion of fermented A. platensis into food products could lead to added-value foods based on microalgae.

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Mobing v ožjem pomenu pomeni šikaniranje na delovnem mestu, ki ga običajno izvaja nadrejena oseba nad žrtvijo, ki je nad početjem, ki ga doživlja, nemočna. V širšem pomenu pa govori o poniževanju, zaničevanju, zatiranju in izločevanju iz delovne organizacije. Je vrsta psihičnega nasilja nad osebo. Ustrahovanje in nasilje pa se opredeljuje kot psihično nasilje, ki lahko v vsakem času preide tudi v fizično nasilje nad osebo. Velikokrat govorimo o ustrahovanju kot o le psihičnem nadlegovanju, ki je izvedeno v stanju afekta osebe, pa vendar ne nosi hujših posledic in je večkrat sestavljeno le iz praznih besed, žaljivk, ki izzvenijo. Načeloma se osebe, ki so ustrahovane, ne bojijo napadalcev kot v primeru mobinga ali nasilja. Nasilje pa je v večini primerov fizične narave. Velikokrat ga zdravstveni delavci doživljajo s strani pacientov, s tem da tudi sodelavcev in nadrejenih ne smemo izpustiti. Namen raziskave je ugotoviti, v kolikšni meri so zaposleni v zdravstvu na svojih delovnih mestih izpostavljeni mobingu, ustrahovanju in nasilju.