Production of β- N-acetylhexosaminidase of Verticillium lecanii by solid state and submerged fermentations utilizing shrimp waste silage as substrate and inducer

Abstract

The aim of this study was to utilise shrimp waste silage both as substrate and inducer of β- N-acetylhexosaminidase of Verticillium lecanii in submerged (SF) and solid state fermentations (SSF), taking advantage of the abundance and composition of crustacean wastes (main commercial source of chitin). β- N-Acetylhexosaminidase was produced in SF (initial pH 6) inoculated with spores or mycelia, 540 and 965.5 U/g of initial dry substrate (U/g IDS), respectively. SSF were carried out using a mixture of shrimp waste silage and sugar cane pith bagasse at initial pH of 6. The increment of moisture content and mycelia as inoculum in SSF improved the enzyme yield significantly and reduced the lag phase, i.e. 75% of moisture content inoculated with spores or mycelia produced 1016 and 1673 U/g IDS, respectively. SSF produced a higher β- N-acetylhexosaminidase yield than SF, but required a longer time (24 h). Specific activity in SSF was only 40% higher than SF, due to impurities from shrimp waste silage and sugar cane bagasse. Shrimp waste silage was an efficient inducer of the extracellular enzyme, compared with media supplemented with sucrose where enzymic activity was not detected.