Table 1.

List of studies cited in the text and their major findings on laccase‐catalyzed lignin polymerization arranged according to publication date.

Substrates	Laccase origin	Highlighted findings	Ref.
lignosulfonates	Trametes hirsuta	low‐molecular‐weight lignin fraction favored polymerization	[63]
flax soda, mild acidolysis spruce, eucalyptus organosolv lignins	Trametes hirsuta	lowest degree of polymerization in spruce mild acidolysis lignin attributed to low solubility in the reaction mixture	[59]
spruce alkali, steam‐exploded wheat straw alkali lignins	Mycelia Sterillia YY‐5 (MS‐Lac) from Rhus chinensis	molecular weight increased for both lignins; MS‐Lac more effective in wheat straw alkali lignin than in spruce alkali lignin	[62a]
various types of lignosulfonates	Trametes villosa, Myceliophthora thermophila	high redox TviL gave higher increase in molecular weight than the low redox MtL; polymerization improved at higher initial lignin concentration and at higher enzyme activity for MtL; degree of sulfonation influenced the extent of polymerization	[65]
lignosulfonates	Trametes villosa, Trametes hirsuta	Tvil more effective than ThL in increasing the molecular weight; use of mediator improved polymerization	[66]
birch organosolv, mixed hardwood organosolv, steam‐exploded softwood and hardwood lignins	Trametes hirsuta, Melanocarpus albomyces, Thielavia arenaria TaLcc and TaLcc2	highest polymerization observed at pH 6 where the lignins are better dissolved; higher polymerization in hardwood than in SW lignin; TaLcc1 and 2 were less effective than MaL and ThL	[60]
birch organosolv, spruce organosolv, hardwood and softwood kraft lignins	Melanocarpus albomyces, Streptomyces ipomoea	low initial molecular weight of lignin and high phenolic hydroxy groups favored polymerization; efficiency of SiL improved and made similar to MaL with the use of mediator	[62b]
eucalyptus kraft lignin	Myceliophthora thermophila	organic solvent‐based fractionation yielded fractions with varying reactivity towards laccases; decrease in syringyl/guiacyl ratio seemed to favor polymerization; low‐molecular‐weight mediators had no effect on polymerization	[61a]
mixed hardwood organosolv, wheat straw soda, mixed sarkanda grass/wheat straw soda, Indulin AT softwood kraft, alkali‐ pretreated wheat straw lignins	Trametes versicolor	fractionation enabled the isolation of low‐molecular‐weight lignin fractions favorable for polymerization; highest increase in molecular in alkali wheat straw lignin	[61b]
enzyme saccharified, lignosulfonate, steam‐exploded pine, stea‐exploded eucalyptus, karft lignins	Trametes hirsuta	polymerization correlated well with low molecular weight and high amount of monomeric phenolics in the starting lignin	[64]
hardwood organosolv, softwood Indulin AT kraft lignins and softwood lignosulfonates	Trametes villosa, Myceliophthora thermophila	highest increase in molecular weight observed in lignosulfonates for both laccases; oxygen supply had no clear correlation with increase in molecular weight but reduced the reaction time	[67]
lignosulfonates	Trametes villosa, Aspergillus oryzea	polymerization improved with the use of mediators	[68]
lignosulfonates	Myceliophthora thermophila	polymerization was favored with continuous oxygen supply over use of mediators	[69]
lignosulfonates and kraft lignin	Myceliophthora thermophila	lignosulfonates polymerized more than kraft lignin using immobilized MtL; increasing MtL dosage improved polymerization only for lignosulfonates	[70]
hardwood organosolv lignin and softwood lignosulfonates	Trametes versicolor	lignosulfonates with higher number of phenolic hydroxy groups per molecule had higher degree of polymerization than the organosolv lignin	[71]
lignosulfonates	Trametes hirsuta	low degree of polymerization at pH 3, 4, and 8; extensive polymerization at pH 6 and 7; increase in temperature increased the rate of oxidation	[72]
hardwood lignosulfonates	Myceliophthora thermophila	increasing enzyme dosage increased the extent of polymerization	[73]