-(Sugarcane bagasse as a source of carbon for enzyme production by fi lamentous fungi). The aim of the present work was to assess the enzymatic activity of six strains of fi lamentous fungi grown in liquid media containing 1% sugarcane bagasse as the sole carbon source. All fungal strains were able to use this agro-industrial residue, producing various types of enzymes, such as cellulases, xylanases, amylases, pectinases, and laccases. However, Aspergillus japonicus Saito was the most effi cient producer, showing the highest enzymatic activity for laccase (395.73 U L -1 ), endo-β-1,4-xylanase (3.55 U mL -1 ) and β-xylosidase (9.74 U mL -1 ) at seven, fourteen and twenty-one days in culture, respectively. Furthermore, the endo-β-1,4-xylanases and β-xylosidases of A. japonicus showed maximum activity at 50°C, and pH 5.5 and pH 3.5-4.5, respectively. Thus, these results indicate that A. japonicus has a great biotechnological potential for the production of these enzymes using sugarcane bagasse as the sole source of carbon.

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Stx1 toxin is one of the AB 5 toxins of Shiga toxin-producing Escherichia coli (STEC) responsible for foodborne intoxication during outbreaks. The single-chain variable fragment (scFv) is the most common recombinant antibody format; it consists of both variable chains connected by a peptide linker with conserved specificity and affinity for antigen. The drawbacks of scFv production in bacteria are the heterologous expression, conformation and stability of the molecule, which could change the affinity for the antigen. In this work, we obtained a stable and functional scFv-Stx1 in bacteria, starting from IgG produced by hybridoma cells. After structural modifications, i.e., change in protein orientation, vector and linker, its solubility for expression in bacteria was increased as well as the affinity for its antigen, demonstrated by a scFv dissociation constant (K D ) of 2.26 × 10 −7 M. Also, it was able to recognize purified Stx1 and cross-reacted with Stx2 toxin by ELISA (Enzyme-Linked Immunosorbent Assay), and detected 88% of Stx1-producing strains using a rapid latex agglutination test. Thus, the scFv fragment obtained in the present work is a bacteria-produced tool for use in a rapid diagnosis test, providing an alternative for STEC diagnosis.