Essential oils from condiment and medicinal plants in the control of contaminants from the micropropagation of Myrciaria dubia

The main limitation of the micropropagation of camu-camu (Myrciaria dubia) is related to in vitro contamination. In order to overcome contamination, the effect of essential oils was studied as an alternative to conventional chemi-cal treatments. This study aimed to analyze the action of essential oils from four condiment and medicinal plants (Oregano, Origanum vulgare L.; Garlic, Allium sa-tivum L.; Citronella, Cymbopogon nardus L.; and Ginger, Zingiber officinale Rosc.) in reducing microbial contamination growth and on the survival rate of explants in the micropropagation of camu-camu. The antimicrobial activity of essential oils was analyzed on the in vitro contamination of tissue culture from camu-camu at concentrations of 0.5, 1, 2, 3 and 4 & mu;L mL-1 in woody plant medium (WPM), emul-sified with 1% Polysorbate 80 (Tween 80). The antibacterial activity of essential oils on strains isolated from camu-camu tissue culture was also analyzed using agar diffusion and broth microdilution methods. The use of essential oils allowed a reduction in the rate of in vitro contamination in tissue culture, it being ob-served that, from the concentration of 2 & mu;L mL-1, there was no manifestation of fungal contaminants, with a significant reduction in the rate of bacterial contami-nation, with the exception of ginger essential oil that showed significant contam-ination in all analyzed concentrations. Inversely in relation to the reduction in mi-crobial growth in vitro, there is an increase in explant oxidation as concentrations increase, with citronella and oregano oils showing phytotoxic potential from the lowest concentrations. Garlic essential oil showed better balance, with lower ox-idation rates and greater control of microorganisms in tissue culture at concen-trations of 0.5 and 1 & mu;L mL-1. Oregano and citronella essential oils showed better antibacterial activity in the agar diffusion test.