Dual functions of nonionic surfactant Tween-20 in enhancing productivity and elution efficiency of alkylresorcinols from Azotobacter vinelandii.

Alkylresorcinols (AR) are a class of phenolic lipids widely distributed in plants, algae, fungi, and bacteria. AR are high-value bioproducts with applications in a broad range of industries, ranging from agriculture to healthcare. They are, however, hydrophobic and found in trace amounts, especially in hard grain bran, and thus require intensive mechanical crushing and harmful organic solvent-based processes for elution. The aim of this study is to demonstrate a proof-of-concept of an innovative AR production and extraction technology to ensure hygienic and safe working environments. In this study, we examined the competency of AR production by diazotrophic bacteria Azotobacter vinelandii using various surfactants. The effect of selected surfactant was tested not only at the stage of AR elution from cysts but also during the cell culture forming cysts. It revealed that nonionic surfactants, Tween-20 and Tween-80, were capable of not only solubilizing AR from the mature cysts of A. vinelandii but also increasing their production during cyst formation. The production yield of AR in soluble form maximally reached 5.5 mg/L in Burk's nitrogen-free liquid medium containing 0.2% n-butanol and 0.1% Tween-20. These findings contribute to the development of an efficient and solvent-free green production method for AR.