Tween 80-induced esterase production by Trichoderma harzianum in submerged fermentation: An esterase activity assay using α-naphthyl acetate as substrate

Tween 80 is a surfactant that has been used for several purposes in microbial cultures. In bioremediation studies, the addition of surfactants in the medium is a common practice, since it makes hydrophobic substrates available to the microorganism. In this work, the influence of Tween 80 (100 or 400 μL/L) on the biomass production, protein content, esterase activities and, growth and enzymatic yield parameters of Trichoderma harzianum grown in submerged fermentation was evaluated. Assessments of esterase activities through biochemical tests and zymographic assays were carried out using α-naphthyl acetate as substrate. A single band with esterase activity was observed in the different concentrations of Tween 80 tested. However, 400 μL of Tween 80 induced higher esterase production (148.2 U/L) in T. harzianum as compared to that esterase activity (79.5 U/L) shown in the medium added with 100 μL of Tween 80 per liter. These results showed that high concentrations (e.g. 400 μL/L) of Tween 80 enhanced the esterase activity in T. harzianum. The single band with esterase activity revealed on zymograms suggests that this enzyme (of 38 kDa approx.) may be present in both forms as a constitutive as well as an inducible esterase, since it was observed in both glucose- and Tween 80-supplemented media.