Abstract

The additives (activators or inhibitors) influencing the Alcaligenes faecalis NYSO (ac: KP859538) laccase productivity were studied in submerged fermentation as well as the exploitation the ultimate benefit from lignocellulosic waste through response surface methodology (RSM) was investigated in this study. Among the various amino acids and vitamins used as a growth factor and or/ nitrogen source, L-glutamine, L-cysteine, L-arginine, and biotin were found to be the most suitable for laccase production. Ethanol addition caused about 40% increment followed by petroleum ether, then acetonitrile and methanol whilst, isopropanol caused a slight decrease in production. Promotion of laccase production was achieved in media supplemented with fast blue, ethidium bromide and azure B by 37-35%. The humic acid, 2,2-azino-di-[3-ethylbenzo-thiazolin-sulphonate] (ABTS) and alkali lignin proved to be the best synthetic inducers for laccase. Among the various wastes used, sugarcane bagasse followed by black liquor and prickly pears peel were found to be the best natural substrates could be used for laccase production with maximum activity (1408 and 1365 U ml^-1 min^-1), respectively. Considering this trend, pre-formulation media was designed using yeast extract, copper sulfate, and mixture of black liquor and sugarcane bagasse, thereafter, the RSM was adopted to acquire the best process conditions among the selected variables where a five-level Central Composite Design (CCD) was employed to create a polynomial quadratic model creating the relationship between these variables and laccase activity.

Keywords: Agro-industrial wastes; Laccase; Central composite design; Response surface methodology; Alcaligenes faecalis; Phenolic compounds; Submerged fermentation; Bacterial bioremediation