Recent Advances in Applications of Acidophilic Fungal Microbes for Bio-Chemicals

Lignocellulosic feedstock (cellulose, hemicellulose and lignin) has been used for a variety of purposes. Among them, lignin can produce value-added chemicals having phenyl-propanoid subunits known as core lignin, possessing either C-C bonds or ether linkages. It can be depolymerized by microbial activity together with certain enzymes (laccases and peroxidases). Both acetic acid and formic acid production by certain fungi contribute significantly to lignin depolymerization. Natural organic acids production by fungi has many key roles in nature that are strictly dependent upon organic acid producing fungus type. Enzymatic conversion of lignocellulosic is beneficial over other physiochemical processes. Laccases, the copper containing proteins oxidize a broad spectrum of inorganic as well as organic compounds but most specifically phenolic compounds by radical catalyzed mechanism. Similarly, lignin peroxidases (LiP), the heme containing proteins perform a vital part in oxidizing a wide variety of aromatic compounds with H₂O_2. Lignin depolymerization yields polyaromatics, the important ones are BTX (Benzene, Xylene and Toluene), found in several different configurations. However, most modern aromatics complexes enhance the production of p-xylene, benzene and sometimes o-xylene respectively. Thus, this review will provide a concept that chemical and biological modifications of lignin yield certain value added and environment friendly chemicals.