ABSTRACT
Aims: Temporary Immersion Bioreactor (TIB) system is an advanced technology for commercial mass production of potato microtubers. Despite of several advantages, this system possess a great risk of culture loss at any stage of micropropagation due to microbial contamination. The aims of this study were to identify microbial contaminants isolated during potato shoot growth in the TIB system, evaluate the efficacy of antimicrobial agents to prevent them, to investigate the effect of those agents in vitro on growth and morphology of potato plantlets. Methodology and results: Six bacteria namely Pseudomonas, Staphylococcus, Klebsiella, Corynebacterium, Proteus, Bacillus and five fungi Aspergillus, Penicillium, Mucor, Fusarium and Rhizopus were isolated from the TIB system. We examined the effect of three antibacterial (Gentamycin, Vancomycin and Tetracycline) and four antifungal agents (Mencozeb, Propiconazole, Bavistin and Copper oxychloride) on the contaminants and on potato shoot growth. Results show that Gentamycin (50 mg/L) and Propiconazole (0.15%) were most effective against the isolated bacteria (35 mm inhibition zone) and fungi (100%) respectively, whereas Gentamycin in combination with Bavistin showed better performance on potato shoot and root development. Conclusion, significance and impact of study: Present study will provide useful guidelines to reduce or eliminate the risk of contamination during micropropagation.
ABSTRACT
Deschampsia antarctica (DA), the only species in the Gramineae family endemic to the Antarctic territory, is characterized by a combination of high levels of free endogenous phenylpropanoid compounds under normal in situ and in vitro growth conditions. In this article, we describe the design and use of a specific temporary immersion photobioreactor to produce both increased DA biomass and secondary metabolite accumulation by UV-B elicitation during cultivation. Three min-long immersions in an induction medium applied every 4 hrs at 14ºC +/- 1 and 20/4 hrs light/darkness photoperiod increased DA biomass production over previous in vitro reports. Biomass duplication was obtained at day 10.7 of culturing, and maximum total phenolics and antioxidant activity were observed after 14 day of culturing. The addition of UV-B radiation pulses for 0.5 hrs at 6 hrs intervals increased total phenolics and antioxidant activity more than 3- and 1.5- fold, respectively, compared to controls with no UV-B. Significant accumulation of scopoletin, chlorogenic acid, gallic acid and rutin was found in these plantlets. This is the first bioreactor designed to optimize biomass and phenylpropanoid production in DA.