LAUSR

Dear Readers, It is our pleasure to present the third Special Issue on “Plant cells and algae in bioreactors”. This Special Issue has been compiled based of the success of the previous two, published in 2009 and 2014, and presents recent achievements and the state of-the-art in this emerging area of bioprocess engineering. Over the years after the first Special Issue, the interest in microalgae and plant cells as sources of ingredients for the food, pharmaceutical and cosmetic industries, biofuels and many other domains has been increasing continuously. While, the application of microalgae in various areas like environmental clean-up and improvement of bioreactor technologies for micropropagation of economically valuable plant species are also currently receiving considerable attention. Thus, the aim of this Special Issue is to present the most recent achievements and research focused on the current status, advancement, and the prospects for further developments in that field. The advantages of plant in vitro technology for production of bioactive substances are widely discussed. However, the problems with low and unstable yields of target metabolites remain unsolved, despite researchers’ efforts for more than 60 years. This area is addressed in the review presented by Sanchez-Muñoz et al., who have summarized accumulated knowledge about the relationship between in vitro maintenance and epigenetic changes in plant in vitro systems and the prospects of avoiding decline in metabolite production. When optimization of the production processes based on plant in vitro systems is discussed, the elicitation approach cannot be omitted. Halder et al. have contributed with an interesting review presenting their point of view about elicitation as a main tool in enhancing the production of secondary metabolites by hairy roots. The authors have paid special attention to the simultaneous application of more than one elicitor as part of the integrated approach for optimization of secondary metabolites production. Despite the significant progress, bioreactor cultivation and the complex scale-up remain major limitations for the industrial implementation of plant in vitro systems, as far as the choice of bioreactor type largely depends on the type of the