Beauveria Bassiana Amylase-Polygalacturonase Production Using Lignocellulosic Biomass and Application in Juice Processing

Background: The search for sources of industrial biocatalysts, which are non-pathogenic and can utilise cheap nutrientsources, has been a continuous endeavour in the ~ 7 billion USD enzyme industry. Beauveria bassiana, an endophyticfungal entomopathogen, is non-pathogenic and possesses the potential to secrete various bioproducts while utilisingreadily available lignocellulosic biomass. Objective: This study investigated the optimised production of two glycosyl hydrolases, amylase and polygalacturonase,by B. bassiana while utilising readily available agricultural residues. Subsequently, the industrial potential of the enzymesin the clarification of fruit juice was evaluated. Materials and Methods: Initially, seven agro residues were screened for the concomitant production of amylase andpolygalacturonase by B. bassiana SAN01. Subsequently, statistical optimisation tools, Plackett Burman Design (PBD)and Central Composite Design (CCD), were employed for the optimisation of enzyme production. The enzyme mixturewas partially purified and applied in the clarification of pineapple juice. Result: The production of B. bassiana SAN01 amylase and polygalacturonase was found to be maximal while utilisingwheat bran. Subsequent to PBD and CCD optimisation, the optimal conditions for enzyme production were identified tobe at 30 °C, pH 6.0 and wheat bran concentration of ~40 g.L^-1. Under these optimised conditions, heightened productionlevels of 34.82 and 51.05 U.mL^-1 were recorded for amylase and polygalacturonase, respectively, which were 179% and187% of the initial unoptimised levels. In addition, the most effective clarification of the juice (~90%) was observed at 35°C after an incubation time of 120 min with no significant effect on the pH and total dissolved solids. Conclusion: B. bassiana, a well-known biocontrol agent, was shown to produce amylase and polygalacturonase usingreadily available agricultural residues for the first time. These enzyme production levels are the highest for these enzymesfrom any known endophytic fungal entomopathogen. This study further demonstrates the potential applicability of B.bassiana in other industrial processes besides its widespread use as a biopesticide.