The effect of lignin-related compounds on the growth and production of laccases by the ascomycete, Botryosphaeria sp.

The concentration at which 50% inhibition (I50) of fungal growth occurred for various lignin-related compounds was evaluated on Botryosphaeria sp. MAMB-5 cultivated on agar medium. A trend for inhibition of growth on lignin-related aromatic acids and phenolic compounds was observed and was based upon chemical structural features: benzoic acids containing di-methoxyl substituents on the aromatic ring were less inhibitory than the parent unsubstituted compound; p-phenolic benzoates containing a single methoxyl group were less inhibitory than those containing a di-methoxyl group; methoxylated derivatives of p-phenolic cinnamic acids were less inhibitory than the unsubstituted parent compound; but un-methylated hydroxyls on di-phenols allowed growth compared to the mono- and di-O-methylated derivatives, which were inhibitory. Botryosphaeria sp. grew on basal media containing up to 10% (w/v) lignosulfonate and kraft lignin in stationary liquid culture. In submerged liquid cultivation, Botryosphaeria sp. grew on basal medium containing abietic acid, catechol, 4-chlorophenol, guaiacol, vanillyl alcohol, veratraldehyde and lignosulfonate, and in each case produced laccases. The production of laccases implicated a possible role for their involvement in the biodegradation of aromatic compounds by Botryosphaeria sp. 4-Chlorophenol was the most toxic of the compounds examined.