Developing an in vitro quasi-symbiotic culture system of Aquilaria malaccensis with potentially beneficial microbes on agarwood resinous formation

Abstract

Agarwood is the most valuable resinous wood used in the production of products such as incenses, perfumes, and traditional medicines. However, such production has led to the destruction of wild Aquilaria forests. In the current study, an in vitro culture system was established by combining Aquilaria malaccensis with a quasi-symbiotic bacteria strain, A329, cultured on a medium designed for agarwood production. The quasi-symbiotic bacteria A329 derived from A. malaccensis agarwood has Bacillus-like characteristics, is low in phytopathogens, and can coculture with A. malaccensis with the current designed culture medium. The prolonged culture induced agarwood production at the base of A. malaccensis in vitro. Using high solid-phase microextraction gas chromatography-mass spectrometry, 23 compounds were tentatively identified, including several fingerprinting compounds, agarospirol, eudesmanes, guaianes, valencanes, selinenes, aristolone and 2-(2-phenylethyl) chromone. Using the in vitro system established in this study, the duration of agarwood resin formation can be shortened to 3 months in a well-controlled environment with 100% yield, constituting a promising platform with high commercial value for the selection of Aquilaria spp., the quasi-symbiotic microbes, and the combination of the two.