Inducción de la degradación de lignina de paja de trigo en aromáticos por Aspergillus spp. y Penicillium chrysogenum

Abstract

Wheat straw is a recalcitrant agricultural waste; incineration of this material represents an important environmen- tal impact. Different reports have been made regarding the use of the structural components of wheat straw, i.e. cellulose, hemicellulose and lignin; however, lignin has been less exploited because it is largely considered the recalcitrant part. Residual wheat straw lignin (REWSLI) has a potential biotechnological value if depolymeriza- tion is attained to produce aromatics. Ligninolytic mitosporic fungus represent an alternative where very little research has been done, even though they are capable of depolymerize REWSLI in simple nutritional conditions in relatively short periods, when compared to basidiomycetes. The aim of this research was to study the depolymeri- zation activity of Aspergillus spp and Penicillium spp on semipurified REWSLI as the sole carbon source to produce aromatics. The depolymerization capacity was determined by the activity of the laccase, lignin peroxidase and manganese peroxidase enzymes. The generated aromatics derived from the REWSLI depolymerization were identified by gas chromatography. Obtained results revealed that Penicillium chrysogenum depolymerized the lignin material by 34.8% during the 28-day experimentation period. Laccase activity showed the largest activity with 111 U L-1 in a seven-day period, this enzyme induction was detected in a smaller period than that required by basidiomycetes to induce it. Moreover, the enzymatic activity was produced without the addition of an extra carbon source as metabolic inductor. Aspergillus spp and Penicillium spp generated guaiacol, vanillin, and hydroxybenzoic, vanillinic, syringic and ferulic acid with a maximum weekly production of 3.5, 3.3, 3.2, 3.3, 10.1 and 21.9 mg mL-1, respectively.