Carlos Regalado*¹ · Immer Vázquez-Obregón¹ · Blanca Estela García-Almendárez¹ · Jorge Domínguez-Domínguez² · Araceli Aguilera-Barreyro³ · Aldo Amaro-Reyes¹

¹DIPA, PROPAC, Facultad de Química, Universidad Autónoma de Querétaro, México
²Centro de Investigación en Matemáticas, A.C., Guanajuato, México
³Laboratorio de Nutrición Animal, Facultad de Ciencias Naturales, Universidad Autónoma de Querétaro, México

*Corresponding author: carlosr@uaq.mx

Financial Support: Consejo Nacional de Ciencia y Tecnología (México) for MS fellowship to I.V.O. and Ph D fellowship to A.A.R.

Keywords: Aspergillus niger GS1, corn stover, digestibility, solid-state fermentation, xylanolytic activity.

Hemicellulosic agricultural by-products such as corn stover (CS) are highly available materials which represent an opportunity to develop value added products. Native Aspergillus niger GS1 was used for solid-state fermentation (SSF) on alkali pre-treated CS (ACS) aimed to optimize xylanolytic enzymes production, and their effect on in vitro ruminal and true digestibility of ACS. Enzyme production was empirically modelled using a fractional factorial design 2^9-5, and the resulting significant factors were glucose, yeast extract and two mineral salts, which were arranged in a Draper-Lin optimization design at two levels. Predicted optimum xylanolytic activity of 33.6 U (mg protein)^-1 was achieved at 48 hrs of SSF, and was validated by confirmatory experiments. ACS was incubated with a semipurified enzymatic extract (EE) showing a xylanolytic activity of 1600 U kg^-1 dry ACS for 12 hrs before exposure to cow’s ruminal liquid for 72 hrs, which led to 5% and 10% increase of in vitro ruminal and true digestibility, respectively. CS is a readily available by-product in different regions which after alkaline treatment and partial hydrolysis with the EE, may be advantageously used as supplement for ruminant feed.