Enzymatic Treatment of Lignin in Alkaline Homogeneous Systems: A Review on Alkaliphilic Laccases

Abstract This short review explores the enzymatic treatment of lignin in alkaline homogeneous systems, focusing on alkaliphilic laccases. In acidic conditions, native laccases are known to promote lignin polymerization, while the addition of mediators enables depolymerization into valuable small molecules. Alkaliphilic laccases, which remain active in basic pH where the vast majority of industrial lignins are soluble, present an interesting alternative. However, the literature shows varied outcomes – polymerization, depolymerization, or both processes – making it difficult to draw clear trends. This review aims to summarize the current state of the art of the enzymatic treatment of lignin in alkaline conditions.