In the last years, tannase has been the subject of a lot of studies due to its commercial importance and complexity as catalytic molecule. Tannases are capable of hydrolyzing complex tannins, which represent the main chemical group of natural anti-microbials occurring in the plants. The general outline of this work includes information of the substrates, the enzyme, and the applications. This review considers in its introduction the concepts and history of tannase and explores scientific and technological aspects. The "advances" trace the route from the general, molecular, catalytic, and functional information obtained under close to optimal conditions for microbial production through purification, description of the enzyme properties, and the commercial applications to the "perspectives" including expression studies, regulation, and potential uses; aspects related to the progress in our understanding of tannin biodegradation are also included.

Two Aspergillus niger strains (GH1 and PSH) previously isolated from a semiarid region of Mexico were characterized for their effectiveness in converting pomegranate ellagitannins (ET) into ellagic acid (EA) in a solid state fermentation (SSF). Pomegranate seeds and husk were used as support for the SSF. Released EA was evaluated by liquid chromatography. Yields of 6.3 and 4.6 mg of EA per gram of dried pomegranate husk were obtained with A. niger GH1 and PSH, respectively. Total hydrolyzable polyphenols of pomegranate husk were degraded during the first 72 h of culture (71 and 61%, by GH1 and PSH strains, respectively). Tannin acyl hydrolase activity was not clearly associated with EA production. EA that accumulated in cultures of A. niger GH1 was remarkably pure after a simple extraction process. Pomegranate husk is a good support, and at the same time an excellent substrate in the production of high commercial interest metabolites like EA due the degradation of its ET content.

Tannase is one of the most versatile biocatalysts and plays an important role in a wide range of bioconversion reactions under protein-precipitating conditions. A comprehensive and illustrative review on the applied aspects of microbial tannases in modern biotechnological practices is presented. After a brief description of different substrates of tannases, fundamental biotechnological and catalytic aspects are reviewed and discussed to illustrate the pivotal role of tannases in the food and bioprocess industry. An emphasis on the biotechnological advances and challenges of tannase study is made.

Ten agro industrial wastes were assessed for their suitability as fungus immobilization carrier for solid-state fermentation (SSF). The wastes included creosote bush leaves (Larrea tridentata), variegated Caribbean agave (Agave lechuguilla), lemon peel (Citrus aurantifolia), orange peel (Citrus sinensis), apple pomace (Malus domestica), pistachio shell (Pistacia vera), wheat bran (Triticum spp.), coconut husk (Cocos nucífera), pecan nutshell (Carya illinoinensis), and bean residues (Phaseolus vulgaris). All of them were physical-chemically and microbiologically characterized. Physical-chemical tests consisted in the determination of the critical humidity point and the water absorption index; while the microbiological tests were based on the evaluation of Aspergillus niger Aa-20 growth rate in such materials. The study pointed out that coconut husk, apple pomace, lemon and orange peels were the materials of greater potential for use as immobilization carrier in SSF, since they have high water absorption capacity, and allowed good microorganism growth rate. This result is of significant interest due to the low cost and abundant availability of such wastes.

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